|
fil. dr., docent, - Ph. D., Associate Professor |
| Startsida/ Home page |
| Min
avhandling/ My doctoral dissertation |
| Mina
publikationer/ My publications |
| - 1990 |
| - 1991 |
| - 1992 |
| - 1993 |
| - 1994 |
| - 1995 |
| - 1996 |
| - 1997 |
| - 1998 |
| - 1999 |
| - 2000 |
| - 2001 |
| - 2002 |
| - 2003 |
| - 2004 |
| - 2005 |
| Kvartärgeologiska
avdelningen (Quaternary Gelogy) |
Geologiska
institutionen (Dept. of Geology) |
Lunds
universitet (Lund University) |
||
Mina publikationerMy publicationsNedan finner du min publikationslista. Den omfattar alla mina artiklar och konferensabstracts publicerade på svenska eller engelska och har länkar till abstracts och sammanfattningar där sådana finns. Artiklar markerade med * är publicerade i internationella fackgranskade tidskrifter. Below you find a list of
my publications
(also including publications in Swedish with/or without abstracts, or
summaries). * Denotes articles published in internationally
peer-reviewed journals. Björkman, L. 1990: Mistel Viscum album, och idegran Taxus baccata, i Sverige under postglacial tid [Mistletoe, Viscum album, and yew, Taxus baccata, in Sweden during the Holocene]. Fauna och Flora 85, 32–39. [In Swedish, no English abstract] Björkman, L. 1991: Vegetationshistorisk undersökning av en förhistorisk jordmånsprofil begravd under en stensträng i Rösered, Västergötland [A pollen analytical investigation of a soil profile buried below a stone wall in Rösered, Västergötland, southern Sweden]. Examensarbete i geologi vid Lunds universitet nr 35, 1–28. [Undergraduate thesis in Quaternary Geology at the Dept. of Geology, Lund University; In Swedish with an English summary] Björkman, L. 1991: Barklevande gelélavar i Nässjö kommun [Corticolous Collema species of Nässjö municipality, south central Sweden.]. Institutionen för Systematisk botanik, Lund. 26p. [Undergraduate thesis in Systematic Botany at the Department of Systematic Botany, Lund University; In Swedish with an English summary] Björkman, L. 1992: Vad kan en jordmånsprofil säga om vegetation och markutnyttjande? Exemplet Rösered i Västergötland [What can a soil profile tell us about vegetation and land-use? The Rösered example in the province of Västergötland]. Bebyggelsehistorisk Tidskrift 23, 27–38. [In Swedish with an English summary] Björkman, L. 1992: Vegetationen i Almesåkra socken år 1865 [The vegetation in Almesåkra parish, central northern Småland, Sweden, in the year 1865]. Parnassia 1992:1, 22–27. [In Swedish, no English abstract]Till sidans topp/Up 1993 Björkman, L. 1993: Barklevande
gelélavar i Småland [Corticolous species of Collema in
Småland, Sweden]. Svensk Botanisk Tidskrift 87, 113–132.
[In Swedish with an English abstract] Björkman, L. & Bradshaw, R. 1994: The dynamics of tree invasion: high resolution pollen analysis of recent tree immigration in S. Sweden. AMQUA Abstracts. American Quaternary Association, Program and Abstracts of the 13th biennial meeting June 19-22, 1994. University of Minnesota. p. 63. [Conference abstract] *Bradshaw, R., Gemmel, P. & Björkman,
L.
1994: Development of nature-based silvicultural models in southern
Sweden: The scientific background. Forestry and Landscape Research
1, 95–110. [Abstract] Björkman, L. 1995: The
history of
Fagus
sylvatica and Picea abies in southern Sweden: high resolution pollen
analysis of recent tree immigration at two sites in the boreo-nemoral
vegetational zone. The ecological setting of Europe: from the past
to the future. The establishment of plant and animal communities in
Europe since the last glaciation. La Londe les Maures, France, 7-12
October 1995. p. 46. [Conference abstract] *Björkman, L. 1996: Long-term population dynamics of Fagus sylvatica at the northern limits of its distribution in southern Sweden: a palaeoecological study. The Holocene 6, 225–234. [Abstract] *Björkman, L. & Bradshaw, R. 1996: The immigration of Fagus sylvatica L. and Picea abies (L.) Karst. into a natural forest stand in southern Sweden during the last 2000 years. Journal of Biogeography 23, 235–244. [Abstract] Björkman, L. 1996: Is Fagus sylvatica still migrating northwards in Europe? Implications of a palaeoecological study of an outlying Fagus stand in southern Sweden. Second international workshop on disturbance dynamics in boreal forest. Rouyn-Noranda, Québec, Canada, August 1996. pp. 19-22. [Extended conference abstract] Björkman, L. 1996: The Late Holocene history of beech Fagus sylvatica and Norway spruce Picea abies at stand-scale in southern Sweden. LUNDQUA Thesis 39, 1–44. [Doctoral dissertation in Quaternary Geology at the Department of Quaternary Geology, Lund University; Abstract] [Svensk sammanfattning] [Till avhandlingen/to the thesis] Lagerås, P. & Björkman, L. 1996:
From nemoral to boreal forest: mid- and late-Holocene forest dynamics
in
the Småland Uplands, southern Sweden. The Geological Society of
Sweden, Jubilee Meeting, Stockholm, Oct. 16-18 1996. GFF 118,
A66–A67.
[Conference abstract] Björkman, L. 1997: Bokens och granens historia i sydligaste Sverige [The history of beech, Fagus sylvatica,and Norway spruce, Picea abies,in southernmost Sweden]. Parnassia 1997:1, 17–24. [In Swedish, no English abstract] *Björkman, L. 1997: The role of human disturbance in the local Late Holocene establishment of Fagus andPiceaforests at Flahult, western Småland, southern Sweden. Vegetation History and Archaeobotany 6, 79–90. [Abstract] *Björkman, L. 1997: The history of Fagus
forest
in southwestern Sweden during the last 1500 years. The Holocene 7,
419–432.
[Abstract] Björkman, L. 1998: Bokens historia i södra Sverige - en litteraturöversikt [The history of beech, Fagus sylvatica,in southern Sweden - a review]. Svensk Botanisk Tidskrift 91, 573–583. [In Swedish with an English abstract] Björkman, L. 1998: Bokens historia på en nordlig utpostlokal - Mattarps bokdunge på det Småländska höglandet [The history of beech, Fagus sylvatica,at an outlying stand in the Småland Uplands, Sweden]. Svensk Botanisk Tidskrift 92, 11–21. [In Swedish with an English abstract] Björkman, L. 1998: Bokens och granens
historia i Siggaboda naturreservat i sydligaste Småland [The
history of beech, Fagus sylvatica,and Norway spruce, Picea
abies,at Siggaboda nature reserve in southernmost Småland,
Sweden]. Svensk Botanisk Tidskrift 92, 83–93. [In Swedish with
an English abstract] *Björkman, L. 1999: The establishment of Fagus sylvatica at the stand-scale in southern Sweden. The Holocene 9, 237–245. [Abstract] Berglund, B. E. & Björkman, L. 1999: Utmarksskogens historia i nordvästra Blekinge. Exempel från Ire och Siggaboda [The history of outland forests in northwestern Blekinge. Examples from Ire and Siggaboda]. Blekinges Natur Årsbok 1999, 13–29. [In Swedish, no English abstract] Björkman, L. & Karlsson, M. 1999:
Bokskogens historia i sydvästra Sverige - exempel från
paleoekologiska undersökningar av bokskogslokaler i Halland. [The
history of beech, Fagus sylvatica, forests in southwestern Sweden -
examples from palaeoecological studies of beech forest sites in
Halland] Svensk Botanisk Tidskrift 93, 107–122. [In Swedish
with
an English abstract] [Med tillstånd
från Svensk Botanisk Tidskrift/With permisson from Svensk
Botanisk
Tidskrift (published by the Swedish Botanical Society): Hela texten som pdf-fil/article as PDF (292
Kb)] Regnell, M., Björkman, L. , Olsson, S., Regnéll, J., Risberg, J. & Sandgren, P. 2000: The palaeoenvironment around a Mesolithic central place in southern Sweden - reconstruction of sea level changes, water conditions and vegetation during Littorina time. Environmental changes in Fennoscandia during the Late Quaternary. Lund, May 28-30. LUNDQUA Report 37, p. 136. [Conference abstract] Sjögren, P. & Björkman, L. 2000: Ires utmark genom tiderna. Nya rön om äldre markanvändning i NV Blekinge. Blekinges Natur Årsbok 2000, 62–84. [In Swedish, no English abstract] Björkman, L. 2000: Pollenanalytisk undersökning av en torvmarkslagerföljd från Trälhultet i Biskopstorps naturreservat, Halmstads kommun. LUNDQUA Uppdrag 29, 1–9. [In Swedish, no English abstract] Björkman, L. 2000: Pollenanalys av en
lagerföljd från Uddared, Laholms kommun. LUNDQUA Uppdrag
31,
1–8. [In Swedish, no English abstract] Björkman, L. & Regnéll, J. 2001: Paleoekologiska undersökningar av jordprover från röjningsrösen och gravar inom fastigheten Värmunderyd 1:1, Vetlanda socken, Vetlanda kommun. LUNDQUA Uppdrag 32, 1–22. [In Swedish, no English abstract] Björkman, L. 2001: Pollenanalys av jordprover från ett röjningsröse vid Vetlandabäcken inom fastigheten Upplanda 10:1, Vetlanda socken, Vetlanda kommun. LUNDQUA Uppdrag 33, 1–3. [In Swedish, no English abstract] Regnell, M., Björkman, L., Olsson, S., Regnéll, J., Risberg, J. & Sandgren, P. 2001: Hav och land. Sedimentanalyser av en transgressionslagerföljd [Summary: Sea and land. Sediment analyses of a sequence of transgression layers]. In: Karsten, P. & Knarrström, B. (eds.): Tågerup specialstudier. Riksantikvarieämbetet, Lund. 238–259. [In Swedish with an English summary] *Onac, B.P., Björkman, L., Björck, S., Clichici, O., Tamas, T., Peate, D. & Wohlfarth, B. 2001: The first dated Eemian lacustrine deposit in Romania. Quaternary Research 56, 62–65. [Abstract] Björkman, L. & Regnéll, J. 2001: Markanvändning och vegetationshistoria i Hestraområdet, Borås kommun. LUNDQUA Uppdrag 34, 1–8. [In Swedish, no English abstract] Björkman, L. 2001: Pollenanalytisk undersökning av en mosselagerföljd från Alseda, Vetlanda kommun. LUNDQUA Uppdrag 35, 1–10. [In Swedish, no English abstract] Björkman, L. 2001: Paleoekologisk rekognosering av torvmarker vid Skogshyddan, Markaryds kommun. LUNDQUA Uppdrag 36, 1–4. [In Swedish, no English abstract] *Björkman, L. 2001: The role of human disturbance in Late Holocene vegetation changes on Kullaberg, southern Sweden. Vegetation History and Archaeobotany 10, 201–210. [Abstract] Feurdean, A., Björkman,
L. & Wohlfarth, B. 2001:
A paleoecological reconstruction of the Late Glacial and Holocene based
on multidisciplinary studies at Steregoiu site (Gutai Mts., NW
Romania). Studia Universitatis
Babes-Bolyai, Geologica, XLVI, 2, 125–140. Björkman, L. 2002: Paleoekologiska förundersökningar av torvmarker inför ombyggnaden av Riksväg 31, delen Öggestorp-Rogberga, Jönköpings kommun. LUNDQUA Uppdrag 37, 1–25. [In Swedish, no English abstract] Björkman, L. 2002: Paleoekologisk
undersökning av torvmarker i Dömestorps naturreservat
på Hallandsås nordsluttning, Hasslövs socken, Laholms
kommun. LUNDQUA Uppdrag 38, 1–13. [In Swedish,
no English abstract] Ekström, J. & Björkman, L. 2002: Paleoekologisk förundersökning av torvmarker inför ombyggnaden av E4:an vid och förbi Markaryd, Markaryds kommun. LUNDQUA Uppdrag 41, 1–14. [In Swedish, no English abstract] *Subetto, D. A., Wohlfarth, B., Davydova, N. N., Sapelko, T. V., Björkman, L., Solovieva, N., Wastegård, S., Possnert, G. & Khomutov, V. I. 2002: Climate and environment on the Karelian Isthmus, northwestern Russia, 13000–9000 cal. yrs BP. Boreas 31, 1–19. [Abstract] *Björkman, L., Feurdean, A., Cinthio, K., Wohlfarth, B. & Possnert, G. 2002: Lateglacial and early Holocene vegetation development in the Gutaiului Mountains, NW Romania. Quaternary Science Reviews 21, 1039–1059. [Abstract] *Wohlfarth,
B.,
Filimonova, L., Bennike, O., Björkman,
L., Brunnberg, L., Lavrova, N., Demidov, I. & Possnert, G. 2002:
Late Glacial and earlier Holocene environmental and climatic change in
south-eastern Russian Karelia: The sediment record from Lake
Tambichozero. Quaternary Research 58,
261–272. [Abstract] *Niklasson,
M.,
Lindbladh, M. & Björkman, L. 2002:
A long-term record of Quercus decline, logging and fires in a southern
Swedish Fagus-Picea forest. Journal
of Vegetation Science 13, 765–774. [Abstract] Björkman,
L. &
Ekström, J. 2002:
Bedömning av förutsättningarna för pollenanalytiska
studier i Särö Västerskogs naturreservat och
Särö Nordanskog i norra Halland. LUNDQUA Uppdrag 42, 1–5. [In
Swedish,
no English abstract] Björkman,
L. 2003:
Pollenanalytisk undersökning av jordprover från gravar,
röjningsrösen och markprofiler vid trafikplatsen
Öggestorp i Öggestorps socken inför ombyggnaden av
Riksväg 31, delen Öggestorp–Åkarp, Jönköpings
kommun. LUNDQUA Uppdrag 44,
1–25. [In Swedish,
no English abstract] Björkman, L. 2003: Pollenanalytisk slutundersökning av tre torvmarkslokaler från Öggestorps och Rogberga socknar inför ombyggnaden av Riksväg 31, delen Öggestorp–Åkarp, Jönköpings kommun. LUNDQUA Uppdrag 45, 1–22. [In Swedish, no English abstract] Björkman, L. & Ekström, J. 2003: Pollenanalytisk undersökning av en torvmarkslagerföljd från den arkeologiska undersökningslokalen ”Område 12/13” nordväst om Exhult inför ombyggnaden av E4:an, delen länsgränsen till Strömsnäsbruk, Markaryds kommun. LUNDQUA Uppdrag 47, 1–9. [In Swedish, no English abstract] *Björkman,
L.,
Feurdean, A. & Wohlfarth, B. 2003:
Lateglacial and Holocene forest dynamics at Steregoiu in the Gutaiului
Mountains, NW Romania. Review of
Palaeobotany and Palynology 124, 79–111. [Abstract] *Björkman,
L.
& Sjögren, P. 2003:
Long-term history of land-use and vegetation at Ire, an agriculturally
marginal area in Blekinge, south Sweden. Vegetation History and Archaeobotany 12,
61–74. [Abstract] Björkman,
L. 2003:
Pollenanalytisk undersökning av en torvmarkslagerföljd
från den arkeologiska undersökningslokalen ”Område 2”
nordost om Köphult inför ombyggnaden av E4:an, delen
länsgränsen till Strömsnäsbruk, Markaryds kommun. LUNDQUA Uppdrag 48, 1–10. [In
Swedish,
no English abstract] Liljegren, R. & Björkman,
L. 2003: Vegetationshistoria i östra Skåne. En
jämförelse med Ystadområdet [Summary: Vegetation
history in south-east Skåne. A comparison with the Ystad area].
I: Söderberg, B. (red): Järrestad. Huvudgård i
centralbygd. Riksantikvarieämbetet
Arkeologiska Undersökningar Skrifter 51, 83–108. [Summary] Björkman, L. 2004: Pollenanalytisk undersökning av råhumusprofiler från Särö Västerskogs naturreservat och Särö Nordanskog i norra Halland. LUNDQUA Uppdrag 50, 1–12. [In Swedish, no English abstract] Björkman,
L. & Sköld, P. 2004:
Pollenanalytisk undersökning av jordprover från brunnar
på den arkeologiska undersökningsplatsen MK 15, Västra
Klagstorp, Malmö. LUNDQUA
Uppdrag 51, 1–5. [In Swedish,
no English abstract] Björkman, L. 2004: Vegetation och markanvändning i Öggestorpsområdet under de senaste 5000 åren. Tidskrift – arkeologi i sydöstra Sverige 4, 7–21. [In Swedish with an English abstract] Björkman,
L. 2004: Detaljerad pollenanalytisk undersökning av tre
lagerföljder (Flinkasjön, E4:13, E4:16) från
Örkelljungatrakten i nordvästra Skåne. LUNDQUA Uppdrag 54, 1–20. [In
Swedish,
no English abstract] 2005 Björkman, L. 2005: Pollenanalytisk undersökning av en torvmarkslagerföljd från Baggabygget i Rönnö naturreservat, Laholms kommun. LUNDQUA Uppdrag 55, 1–9. [In Swedish, no English abstract] Björkman, L. & Persson, T. 2005: Pollenanalytisk undersökning av en torvmarkslagerföljd från Käringsjön i Övraby socken, Halmstads kommun. LUNDQUA Uppdrag 56, 1–20. [In Swedish, no English abstract] Till sidans topp/Up Abstracts/Summaries of articlesBjörkman, L. 1991: Vegetationshistorisk undersökning av en förhistorisk jordmånsprofil begravd under en stensträng i Rösered, Västergötland [A pollen analytical investigation of a soil profile buried below a stone wall in Rösered, Västergötland, southern Sweden]. Examensarbete i geologi vid Lunds universitet nr 35, 1–28. Summary This study deals with local vegetation and land use history contemporary with prehistoric clearance cairns and stone walls in the area of Rösered, province of Västergötland, south-western Sweden. Pollen analysis of a humusrich layer buried below a stone wall was carried out. It revealed that: - the layer developed as mull, first in open woodland dominated by birch, later in grassland with some scrubs of birch. - the pollen stratigraphy was dominated by Betula, but that Poaceae, Calluna, Polypodiaceae and Tubuliflorae also made up a large part of the pollen content. - there was some arable land in the vicinity, but the pollen frequencies of Cerealia and weeds were low, so the soil profile was probably never tilled or cultivated. - the area with clearance cairns probably
consisted of a
mosaic of
pastures, fallow and small tilled fields. Björkman, L. 1991: Barklevande gelélavar i Nässjö kommun [Corticolous Collema species of Nässjö municipality, south central Sweden.]. Institutionen för Systematisk botanik, Lund. 26p. Summary All localities in Nässjö municipality
of
corticolous Collema species, i.e. C. subnigrescens Degel.,
C.
nigrescens (Huds.) DC and C. occultatum Bagl., known from
herbaria and literature were revisited during the spring 1991. C.
subnigrescens were known from all the 15 localities revisited, C.
nigrescens from two localities and C. occultatum from one
locality. C. subnigrescens were only found again on three
localities. C. nigrescens and C. occultatum could not
be found on their old localities. C. subnigrescens were also
found on four new localities and C. occultatum on one new
locality. Today C. subnigrescens is only known from seven
localities. This means a total decrease in the abundance of the
species. C. nigrescens has probably disappeared from the area.
C.
occultatum is probably still as abundant as before. In seven cases
C.
subnigrescens has disappeared from its old localities because of
forestry activities. In three cases (all near the town
Nässjö) the species has disappeared because of building
activities or building activities in combination with forestry
activities. In two cases no certain causes could be found, but could
perhaps be changes in the land-use. All localities with C.
subnigrescens are suggested to be protected from forestry
activities, which are the main reason for the decrease of the species
in the investigated area. Björkman, L. 1992: Vad kan en jordmånsprofil säga om vegetation och markutnyttjande? Exemplet Rösered i Västergötland [What can a soil profile tell us about vegetation and land-use? The Rösered example in the province of Västergötland]. Bebyggelsehistorisk Tidskrift 23, 27–38. Summary This study deals with local vegetation and land-use history contemporary with prehistoric clearance cairns and stone walls in the Rösered area in the province of Västergötland in south-west Sweden. Pollen analysis of a humus-rich layer buried below a stone wall was carried out. The analysis revealed that: - the layer developed as mull, first in open woodland dominated by birch-trees, later in grassland with some scrubs of birch. - the pollen stratigraphy was dominated by Betula,but
that
Poaceae, Calluna, Polypodiaceae and Tubuliflorae also made up
a
large part of the pollen content. - the area with clearance cairns probably consisted of a mosaic of pastures and small tilled fields. The pollen diagram from Rösered only
represents
rather local
changes in the vegetation and for this reason it was not possible to
achive any certain correlation with regional pollen diagrams. The
pollen content implies that the soil profile definitely developed after
the pollen zone AT 2, but before the regional rise of Picea, c.
400–500 A.D. It is likely that the soil profile developed during early
Iron Age, c. 300–100 B.C., since its pollen content has many
similarities with the pollen content found in Lake Tranemosjön
from this time. It was possible to confirm the archeological hypothesis
regarding extensive land-use. It is likely that the fields with
clearance cairns in the Rösered area were dominated by grassland.
The arable fields were small and were only tilled for a few years in
succession each time. Björkman, L. 1993: Barklevande gelélavar i Småland [Corticolous species of Collema in Småland, Sweden]. Svensk Botanisk Tidskrift 87, 113–132. Abstract In Småland, S. Sweden, five strictly
corticolous
species of the lichen genus Collema occur. All known and
identifiable localities were revisited in 1990-92, except some which
were detected during the 1980s. C. subnigrescens is known from
c. 60 localities mainly in the west and in the uplands. Thirty were
visited; the species was still present on six of them. Ten new finds
were made in a limited part of the uplands. The species usually grows
in humid mixed woods rich in Populus tremula,a rare habitat in
areas where modern forestry is practiced. C. nigrescens is
known from 15 localities. It is still present on five of these, and
four
new ones were found. Its distribution has become reduced to a small
area
in westernmost Småland. Nowadays it only grows on Acer
platanoides. C. fasciculare was looked for in vain on seven
localities. The last find is from 1894. C. occultatum was not
found on its six known localities, but three new finds were made. It
sometimes occurs together with C. subnigrescens; probably the
threats are the same. C. furfuraceum is known from two
localities and was searched for without success in one of these. Björkman, L. & Bradshaw, R. 1994: The dynamics of tree invasion: high resolution pollen analysis of recent tree immigration in S. Sweden. AMQUA Abstracts. American Quaternary Association, Program and Abstracts of the 13th biennial meeting June 19-22, 1994. University of Minnesota. p. 63. Conference abstract The continental scale migrations of Fagus
sylvatica andPicea
abies are under a broad climatic control, but disturbance and
local factors influence the immigration of these species into
individual forest stands. Palaeoecological analysis of small forest
hollows in the boreo-nemoral zone of southern Sweden has shown that a
forest stand with largely unbroken forest continuity resisted
immigration of Fagus for almost 1000 years. Two fires about
950 and 330 years ago were the disturbing factors that facilitated
eventual Fagus immigration. Picea immigrated and
acheived co-dominance in a single generation, without resistance from
the existing forest. Thus migrational lag is demonstrable for Fagus
but
not Picea.Fagus and Tilia cordata were co-dominant
for several centuries at a second site, but human intervention
disadvantaged competitiors to Fagus,which now dominates the
present forest stand. The immigration of Fagus and Picea,coupled
with a severe reduction in tree species diversity, has resulted in a
total change in forest composition during the last few centuries
despite the maintenance of a structural forest continuity. Some of
these changes in forest composition are attributable to changes in the
grazing regime. *Bradshaw, R., Gemmel, P. & Björkman, L. 1994: Development of nature-based silvicultural models in southern Sweden: The scientific background. Forestry and Landscape Research 1, 95–110. Abstract Biological archives of forest history provide
rich
material to guide the development of nature-based silvicultural models.
The historical approch is particularly valuable in southern Sweden
where few natural reference forest stands remain. Study of the archives
suggests that species-rich, mixed deciduous forest is the natural
condition for southern Sweden, but former and current management
practices have frequently created monotonous, species-poor forest
types. New management initiatives could reverse this trend, but not
under the present regime of intensive browsing by elk and deer which is
very disadvantageous for deciduous species. Forest structure and
composition has been highly variable through time, and simulation of
processes such as disturbance and succession are of greater long-term
ecological value than static protection of threatened species. We
identify goals shared by both production and environmental
considerations such as altered grazing regime, diversity of forest
types, mixed forest stands, and disturbance measures that stimulate
regeneration, and practical silvicultural methods that will achieve
these goals are outlined. Björkman, L. 1995: The history of Fagus sylvatica and Picea abies in southern Sweden: high resolution pollen analysis of recent tree immigration at two sites in the boreo-nemoral vegetational zone. The ecological setting of Europe: from the past to the future. The establishment of plant and animal communities in Europe since the last glaciation. La Londe les Maures, France, 7-12 October 1995. p. 46. Conference abstract The continental scale migrations of Fagus
sylvatica
and Picea abies are under a broad climatic control, but
disturbance and local factors influence the immigration of these
species into individual forest stands. Palaeoecological analysis of
small forest hollows in the boreo-nemoral zone of southern Sweden has
shown that a forest stand with largely unbroken forest continuity
resisted immigration of Fagus for almost 1000 years. Two fires
about 950 and 350 years ago were the disturbing factors that
facilitated eventual Fagus immigration. Picea
immigrated
and achieved co-dominance in a single generation, without resistance
from the existing forest. Thus migrational lag is demonstrable for Fagus
but not for Picea. Fagus and Tilia cordata were
co-dominant for several centuries at a second site, but human
intervention disadvantaged competitiors to Fagus, which now
dominates the present forest stand. The immigration of Fagus
and Picea,
coupled with a severe reduction in tree species diversity, has resulted
in a total change in forest composition during the last few centuries
despite the maintenance of a structural forest continuity. Some of
these changes in forest composition are probably attributable to
changes in the grazing regime. *Björkman, L. 1996: Long-term population dynamics of Fagus sylvatica at the northern limits of its distribution in southern Sweden: a palaeoecological study. The Holocene 6, 225–234. Abstract Regional pollen diagrams indicate that Fagus may
have been present close to its northern distributional limits in
southern Sweden for as long as 1000 years. Fagus has probably
always been rare in this region, except for some small and scattered
stands. Many of these outlying Fagus stands have been regarded
as planted but no previous studies have investigated this in detail. At
Mattarp, a small outpost Fagus stand in northern
Småland, the pollen record of the deposit of a small hollow
indicates that Fagus became established c. 400 BP.
The
local establishment was associated with an earlier phase of woodland
clearance and the former system of land-use. Local factors seem to have
controlled the immigration and establishment at the stand-scale at this
site. Regional climate had probably been favourable for Fagus for
almost 2000 years and cannot be regarded as the direct cause for
establishment at this site. The complex south Swedish cultural
landscape may have favoured Fagus establishment in many areas,
particularly when there has been a temporary reduction in human
influence. Picea became regionally established around 800 BP,
but a local expansion did not occur until c. 400 BP, coinciding
with the establishment of Fagus. Picea expansion also seems to
have been favoured by a moderate human influence at this site. Fagus
pollen
influx values have steadily increased since the time of establishment.
It seems likely that the Fagus stand has continually increased
in size, and probably would continue to do so if this were not
prevented by human activities. *Björkman, L. & Bradshaw, R. 1996:
The
immigration of Fagus sylvatica L. and Picea abies (L.)
Karst. into a natural forest stand in southern Sweden during the last
2000 years. Journal of Biogeography 23, 235–244. Abstract The continental scale migrations of Fagus
sylvatica L.
and Picea abies (L.) Karst. are under a broad climatic
control, but disturbance and local factors influence the immigration of
these species into individual forest stands. Palaeoecological analysis
of a small forest hollow in the boreo-nemoral zone of southern Sweden
has shown that a forest stand with largely unbroken forest continuity
resisted immigration of Fagus for almost 1000 years. Two fires
about 950 and 330 years ago were the disturbing factors that
facilitated eventual Fagus immigration. Picea immigrated
and achieved co-dominance in a single generation, without resistance
from the existing forest. Thus migrational lag is demonstrable for Fagus
but
not for Picea. The immigration of these two dominating species
coupled with a severe reduction in tree species diversity has resulted
in a total change in forest competition during the last few centuries
despite the maintenance of a structural forest continuity. Some of
these changes are attributable to changes in the grazing regime, but
the forest stand is as close to "natural" conditions as can be found in
S. Sweden. Björkman, L. 1996: Is Fagus sylvatica still migrating northwards in Europe? Implications of a palaeoecological study of an outlying Fagus stand in southern Sweden. Second international workshop on disturbance dynamics in boreal forest. Rouyn-Noranda, Québec, Canada, August 1996. pp. 19–22. Extended conference abstract The boreo-nemoral vegetation belt in southern Sweden (sensu Sjörs 1965) is highly dynamic. It can be regarded as a transition zone between the nemoral belt in the south, and the boreal belt in the north (Figure 1). Today this zone has a "boreal" character owing to changes in land-use and forestry practices during the last 150 years (Nilsson 1992). These changes and practices have favoured Picea abies at the expense of deciduous trees. Deciduous trees such as Quercus robur and Tilia cordata,and shrubs as Corylus avellana, have today only a restricted presence throughout the boreo-nemoral zone, but they were certainly more important in the past (Bradshaw et. al. 1994). Fagus sylvatica is a late immigrant into Sweden from the south (Huntley & Birks 1983, Huntley 1988). It has been present in Sweden for probably more than 3000 years, but significant populations have only built up during the last 1500 years. Fagus is an abundant tree in the nemoral belt, but significant populations also occur in the southernmost part of the boreo-nemoral zone. Picea is also a late immigrant into southern Sweden, but in contrast to Fagus it has immigrated from the north. Picea reached its southern distribution limits during the last 300 years (Hesselman & Schotte 1906). Picea is probably still migrating southwards, but its natural limits has been obscured by planting. Picea and Fagus are both potential forest dominants, i.e. they easily out-compete other species in forest stands. These trees have met each other relatively recently, and their distributional limits overlap in the southernmost part of the boreo-nemoral zone (Figure 1). The competitive interactions between these potential forest dominants makes this area one of the most dynamic in Europe. Only small and scattered Fagus stands occur north of the limit where the abundance of Fagus rapidly declines in the forests (Lindquist 1931, 1959). These outlying stands may suggest a migrating front where small Fagus populations in front of the main distribution act as "infection centres." However, the history of Fagus in these outlying stands is not well known. Regional pollen data indicate a presence of Fagus in the area for at least 1000 years. These regional pollen diagrams often also show decreasing Fagus pollen percentages during the last centuries, but generally the percentages are low even when peak values are reached (1-1.5% as most). This may indicate that regional pollen data are not sensitive enough to detect whether Fagus or not has an active migrating front. One way to answer the question whether or not Fagus is migrating is to study outlying stands. One small outlying Fagus stand (Mattarps bokdunge) was selected for a palynological study (Figure 1). The aim of this study was to date the establishment of Fagus at this site, and to deduce if the local stand was expanding or not. The studied site lies within a climatically less favourable area called the Småland uplands, an elevated area in southern Sweden where climatic conditions resemble those in south middle Sweden (Sveriges Nationalatlas 1995). If Fagus grows well in this area, climate is certainly not a limiting factor for growth even some distance to the north, where it does not grow naturally today. The studied site and the results of the palaeoecological investigation have been thoroughly described by Björkman (1996). Only a brief summary of the main results are given here. The pollen record from a small peatland close to the present day Fagus stand indicate that Fagus became established c. 400 BP (Figure 2). The local establishment was associated with an earlier phase of woodland clearance and the former system of land-use. Local factors seem to have controlled the immigration and establishment at stand-scale at this site. Regional climate had probably been favourable for Fagus for almost 2000 years and cannot be regarded as the direct cause for establishment at this site. The complex south Swedish cultural landscape may have favoured Fagus establishment in many areas, particularly when there has been a temporary reduction in human influence. Picea became regionally established around 800 BP, but a local expansion did not occur until c. 400 BP, coinciding with the establishment of Fagus. Picea expansion also seems to have been favoured by a moderate human influence at this site. Fagus pollen influx values have steadily increased since the time of establishment (Figure 2). It seems likely that the Fagus stand has continually increased in size, and probably would continue to do so if this were not prevented by human activities. This study indicates a healthy Fagus population at an outlying stand. Climate does not hinder Fagus regeneration at this site. It is tempting to postulate that the northern distribution limits of Fagus represent an active front, and that outlying stands are acting as "infection centres." It seems that present day land-use is the limiting factor for Fagus expansion in its outpost area in Europe. If Fagus grows well in this climatically less favourable area it probably also could grow well some distance further to the north, where Fagus is not yet established. References Björkman, L. 1996: The Late Holocene history of beech Fagus sylvatica and Norway spruce Picea abies at stand-scale in southern Sweden. LUNDQUA Thesis 39, 1–44. [Till avhandlingen/to the thesis] Abstract High resolution pollen analysis was carried out on five peat profiles from small forest hollows at four sites in southern Sweden. The general aim was to investigate the establishment of Fagus sylvatica and Picea abies at stand-scale. Additionally, the aim was also to reveal the composition of the forests before these species immigrated. The sites used for this study (Bocksten in Halland; Flahult, Mattarp, and Siggaboda in Småland) were all located within the area where the present distribution limits of Fagus and Picea overlap each other. All forest hollows used to reconstruct the past vegetation have relatively small pollen source areas. The results from the different sites are presented in separate papers (Appendices I–IV). These results are compared and discussed in more detail in this synthesis. Viewed on a continental scale the migration pattern of Fagus can be correlated with climate and its change over the millennia, but at finer scales such a correlation is weaker. At stand-scale there are factors other than climate that are crucial for the establishment of Fagus (e.g., disturbance, seed dispersal, human activities). The establishment of Fagus does not show a regional coherence in southern Sweden, and this may imply that climate was not the limiting factor for its establishment. The present day distribution of Fagus in southern Sweden suggests a migration with a discontinuous front with outlying populations, and this model probably applies to its past distribution. This type of migration means that the landscape becomes infilled by dispersal from outpost stands. The timing of stand-scale establishment is then largely influenced by site-specific factors and chance. Fagus may still be migrating northwards in Sweden. It grows well in its outpost area, and it seems that present day land-use, not climate, is the limiting factor for local Fagus expansion. The northern distribution limits of Fagus probably still represents an active front, and outlying stands acts as "infection centres." Fagus seeds are highly dependent on ground disturbance for successful establishment, and an undisturbed forest then consequently would be able to resist Fagus invasion for some time. A semi-open cultural landscape may be optimal for Fagus establishment, as cultural activities may create conditions particularly suitable for its regeneration. At two of the studied sites cultural activities seems to have created conditions that favoured establishment of Fagus (Mattarp at 400 BP, Flahult at 900 BP). At the other studied sites the local forest stands seem to have been relatively unaffected by cultural activities prior to the establishment of Fagus (Siggaboda at 950 BP, Bocksten at 1450 BP), at least no semi-open vegetation was present locally. At Siggaboda the pre-Fagus vegetation was dominated by Quercus, but Corylus and Tilia were also present. At this site fires (human-induced?) probably facilitated establishment and expansion of Fagus. At Bocksten the pre-Fagus vegetation was dominated by Quercus, Tilia, Alnus, and Corylus. Picea invaded southern Sweden from the north during a period when the cultural landscape had already been evolving for some time. Picea is a dominant tree with an effective seed dispersal, and the relatively open and probably grazed forests in the area were not particular resistant to Picea invasion. An intensive grazing regime may not affect Picea, as grazing animals normally avoid Picea. The timing of local Picea establishment
seems
to be mostly controlled by its migration, i.e., it became established
when its front reached the studied sites. Picea invaded
Mattarp c. 800 BP, but did not expand much locally until 400 BP, in
connection with the establishment of Fagus. Picea invaded
Siggaboda at about 200 BP. The population increase for Picea was
very rapid and within c. 50 years it co-dominated the local forest
stand together with Fagus. The establishment of Picea at
the other studied sites was late. At Flahult Picea became
established in the local forest stand at c. 100 BP, but it has not yet
come to dominate the vegetation. At Bocksten Picea was
probably planted, or self-sown from nearby plantations. Björkman, L. 1996: The Late Holocene history of beech Fagus sylvatica and Norway spruce Picea abies at stand-scale in southern Sweden. LUNDQUA Thesis 39, 1–44. [Till avhandlingen/to the thesis] Svensk sammanfattning (Swedish summary) Denna avhandling är resultatet av min doktorandutbildning vid Kvartärgeologiska avdelningen, Geologiska institutionen, Lunds universitet. Avhandlingen baseras på pollenanlytiska undersökningar av ett antal lokaler i södra Sverige. I denna syntes sammanfattas resultaten av undersökningarna. Introduktion och bakgrund Avsikten med avhandlingen har varit att studera etableringen av bok (Fagus sylvatica) och gran (Picea abies) på beståndsnivå i södra Sverige. Dessa träd har invandrat i relativt sen tid. Boken har invandrat från söder, och de första bokarna nådde troligen Skåne för lite mer än 3500 år sedan. Det var dock först långt senare, för omkring 1500 år sedan, som boken blev ett vanligt träd i sydligaste Sverige. Granen har däremot invandrat från norr. De första granarna vandrade in i norra Sverige för 4000–5000 år sedan. Granen har därefter vandrat söderut, och först ganska nyligen nått ned till sydligaste Sverige. Utifrån historiskt källmaterial, t ex kartor och ägobeskrivningar, har man lyckats belägga när de första granarna började att uppträda i norra Skåne. Man har visat att detta skedde under slutet av 1500-talet och början av 1600-talet. Som källmaterial för min undersökning har jag använt fossila pollen som bevarats i små torvmarker (dvs i små mossar och kärr). Att jag har använt mig av små torvmarker medför att den lokala skogsutvecklingen kan rekonstrueras. De pollenkorn som deponeras på en liten torvmark har i allmänhet inte transporteras så långt från källan. Större lokaler har tyvärr den nackdelen att de pollen som deponeras har transporterats från större avstånd, och dessutom deponeras pollen från många olika vegetationstyper samtidigt. Därför visar ett pollendiagram från en större lokal i allmänhet vegetationsutvecklingen för ett större område. Om man vill beskriva den lokala vegetationsutvecklingen inom ett speciellt skogsbestånd måste små lokaler användas. Mitt huvudsakliga undersökningsområde
har
varit den region i södra Sverige där bokens och granens
nutida utbredningsområden överlappar varandra. Inom detta
område har fyra lokaler utvalts. Lokalerna är Siggaboda,
Flahult och Mattarp i Småland, och Bocksten i Halland (se fig.
1). På dessa lokaler har pollendiagram upprättats
för
att man skall kunna beskriva och diskutera den lokala
vegetationsutvecklingen. Kritiska nivåer i pollendiagrammen har
daterats med hjälp av 14C-metoden.
Resultaten av dessa undersökningar finns redovisade i de bifogade
artiklarna (Appendix I–IV). Fullständiga pollendiagram finns
också redovisade (Plate 1–5). I de ursprungliga artiklarna har
endast förenklade pollendiagram presenterats.  Figur 1. Undersökta lokaler i södra Sverige. Resultat I Appendix I redovisas resultatet av en undersökning av Siggaboda naturreservat (tidigare Stensjönäs domänreservat) i sydligaste Småland (fig. 1, se också fig. 4–8). Reservatet domineras i dag av bok och gran, antingen växande i blandbestånd, eller i mer eller mindre rena grupper. Reservatet har tidigare uppmärksammats för sin rika lavflora och insektsfauna, där flera sällsynta och hotade arter indikerar lång skoglig kontinuitet. I reservatets centrala delar finns knappast några tecken på att mänskliga ingrepp gjorts under de senaste århundradena. I reservatets kantzon finns en del stubbar som visar att det förekommit en begränsad trädfällning under detta århundrade. Förekomsten av sällsynta och hotade skogsarter i reservatet står i stark kontrast till avsaknaden av sådana i det omgivande landskapet, som till största delen utgörs att rationellt skötta gran- och tallbestånd. Målsättningen med studien var dels att försöka datera den lokala etableringen av bok och gran, dels att försöka utröna om den nuvarande skogstypen har lång kontinuitet. En pollenanalys utfördes på en lagerföljd från en liten torvmark som ligger centralt i reservatet (Plate 1). Resultatet av analysen visar att boken etablerades på lokalen för ungefär 950 år sedan i samband med en brand. För ungefär 350 år sedan inträffade ytterligare en brand som i sin tur ledde till att skogsbeståndet kom att domineras av bok och ek under en period av ungefär 150 år. För ungefär 200 år sedan började det lokala ekbeståndet att minska, och kort tid därefter försvann eken helt från området. Inga gamla ekar finns kvar i det nuvarande beståndet vilket gör det troligt att den försvann som en effekt av selektiv huggning. Vid ungefär samma tidpunkt som eken började att minska etablerades granen på lokalen. De äldsta granarna i reservatet är ca 200 år gamla, och dessa etablerades troligen när den framryckande granfronten nådde fram till området. Den nuvarande skogstypen med en blandning av bok och gran utvecklades först under de senaste 200 åren. Pollendiagrammet från den analyserade delen av lagerföljden täcker ungefär 2800 år. Under hela denna period domineras pollenspektrumen av trädpollen, vilket indikerar att reservatet haft lång skoglig kontinuitet. Denna kontinuitet är sannolikt en av förklaringarna till den nutida förekomsten av sällsynta och hotade arter. Den långa skogliga kontinuiteten innebär dock inte att det rådit stabila förhållanden i skogen. Reservatet har utsatts för åtminstone två bränder och genomgått kraftiga förändringar av trädartssammansättningen under de senaste 1000 åren. I Appendix II redovisas resultatet av en undersökning av ett litet utpostbestånd av bok vid Mattarp (Mattarps bokdunge) i norra Småland (fig. 1, se också fig. 9–10). Målsättningen med denna studie var att datera bokens och granens lokala etablering, och att avgöra om boken fortfarande håller på att expandera. Om boken fortfarande befinner sig under spridning på det Småländska höglandet utgör knappast klimatet en begränsande faktor för dess vidare expansion norrut. I direkt anslutning till den studerade bokdungen finns en mindre torvmark, vars lagerföljd har använts till en pollenanalys (Plate 2). Resultatet av analysen visade att boken etablerades på lokalen för ungefär 400 år sedan. Bokens etablering skedde i samband med en lokal röjning av skog. Det verkar varit lokala faktorer som kontrollerade etableringen av bok på denna lokal. Klimatet kan knappast ha varit en bakomliggande faktor för bokens etablering, eftersom det troligen varit gynnsamt för boken i detta område under lång tid. Det är fullt möjligt att enstaka bokar fanns spridda i skogarna på det Småländska höglandet redan för 1000 år sedan, men boken lyckades inte sprida sig till den studerade lokalen förrän för 400 år sedan. Granen etablerades på lokalen för ungefär 800 år sedan, men en expansion ägde inte rum förrän för 400 år sedan i samband med bokens etablering. Det är fullt möjligt att den lokala markanvändningen gynnade både boken och granen vid denna tidpunkt. Antalet bokpollen som deponerats i den studerade lagerföljden har ökat kraftigt under hela den period som boken varit etablerad på lokalen. Detta förhållande pekar på att bokbeståndet hela tiden har ökat i omfattning, och troligen skulle det fortsätta att öka om detta inte förhindrades av den nuvarande markanvändningen. I Appendix III redovisas resultatet av en undersökning av ett skogsområde nära Bocksten i centrala Halland (fig. 1, se också fig. 11–14). I detta område, som tillhör det sk Centralhalländska bokskogsområdet, finns stora sammanhängande bokskogar. Skogarna vid Bocksten domineras i dag till stor del av rationellt skötta bok- och granskogar. Granskogarna är i de flesta fallen mycket unga. Området låg under början av detta sekel strax utanför granskogens naturliga västgräns. Målsättningen med denna studie har varit att undersöka när boken etablerades, samt att studera hur områdets skogar såg ut innan boken invandrade. I det studerade området finns många torvmarker som är lämpliga för paleoekologiska studier. På grund av detta förhållande kom två närbelägna torvmarker att undersökas för om möjligt påvisa beståndsmässiga skillnader i skogens struktur och sammansättning. De två pollendiagrammen (Plate 3 och 4) visade att området dominerades av en rik nemoral skogstyp innan boken etablerades för ungefär 1500 år sedan. Ek, lind, al och hassel var viktiga arter i denna skogstyp. Bokens expansion var snabb och inom loppet av 100–200 år dominerade den det lokala beståndet. Det är fullt möjligt att den snabba expansionen på något sätt gynnades av mänskliga aktiviteter. Granen etablerades mycket sent på lokalen, troligen skedde detta under slutet av 1800-talet eller början av detta århundrade. Granens etablering skedde troligen i samband med att ett närbeläget torp övergavs. Det är högst troligt att huvuddelen av granbestånden i området är planterade. Dagens homogena bokbestånd (och granbestånd) i området är troligen en produkt av skogsskötsel under detta århundrade. Det ena av de upprättade pollendiagrammen (lokal A, Plate 3) visar att det fläckvis funnits kvarvarande nemorala skogsbestånd så sent som för 200 år sedan. De två pollendiagrammen påvisade också att det förekommit skillnader i sammansättning mellan näraliggande bestånd, och att människans påverkan på vegetationen skiftat från bestånd till bestånd. Vid lokal A (som låg längre ifrån en torpbebyggelse än lokal B) växte boken i ett blandbestånd tillsammans med lind, ek och hassel under nästan 1200 år, fram tills beståndet röjdes för ungefär 200 år sedan. Vid lokal B (Plate 4) blev boken nästan helt dominerande redan snabbt efter att den etablerats. Lind och hassel försvann också i och med boketableringen. I Appendix IV redovisas resultatet av en undersökning av ett bokbestånd vid Flahult, strax öster om sjön Bolmen i västra Småland (fig. 1, se också fig. 15–16). I dag är bokbestånd relativt vanliga i detta område, dessutom visar historiska dokument att boken var vanlig i området under sen medeltid. Målsättningen med denna studie var att datera den lokala etableringen av bok och gran, samt att studera hur det nuvarande bokbeståndets struktur uppkommit. Centralt i det undersökta bokbeståndet finns ett litet alkärr vars lagerföljd har använts för en pollenanalys (Plate 5). Resultatet av analysen visade att boken etablerades i ett halvöppet kulturlandskap för ungefär 900 år sedan. Expansionen av kulturmarker inleddes ungefär samtidigt som bokens lokala etablering. Det var troligen den intensifierade markanvändningen som skapade förutsättningar för boken att etableras på denna lokal. Boken fanns möjligen i regionen redan tidigare, men den lyckades inte etableras sig i det studerade beståndet förrän lämpliga förutsättningar skapades för ungefär 900 år sedan. Boken dominerar helt det nutida beståndet, men denna dominans verkar ha ett sentida ursprung. Bokpollenfrekvensen stiger kraftigt först under de senaste 50-100 åren. Det nutida beståndets sammansättning och struktur är troligen en effekt av markanvändningsförändringar under de senaste 100 åren. Granen etablerades i det lokala beståndet för ungefär 100 år sedan, men den har ännu inte fått någon större betydelse. I dag finns endast ett fåtal granar spridda i bokbeståndet. Granen har däremot fått större betydelse i områdets skogar under senare tid, troligen som en effekt av skogsbruk under de senaste 50 åren. Diskussion De storskaliga holocena migrationsmönstren för träd i Europa verkar vara styrda av klimatet och dess förändringar över tiden. Detta gäller troligen också för bokens och granens storskaliga migrationsmönster. När man däremot betraktar bokens etablering och expansion på beståndsnivå verkar helt andra faktorer, t ex störningar, vara betydelsefulla. Redan innan boken expanderade i södra Sverige var det regionala klimatet gynnsamt. Därför kan klimatet knappast anses vara den enda faktor som fick boken att etableras i södra Sverige. Bokens etablering påverkas av en rad faktorer där t ex den vegetationstyp som invaderas, störningsregimen (bränder, stormar, betestryck mm) och mänsklig påverkan, är betydelsefulla. Tidpunkten för etableringen av bok i ett bestånd påverkas av lokala faktorer, där mänskliga aktiviteter kan ha stor betydelse. Slumpfaktorer kan även spela in, t ex när bokollon råkar spridas till ett bestånd där det råder goda förutsättningar för etablering. Perioder med snabb bokexpansion sammanfaller ofta med perioder då intensiteten i markanvändningen avtar, eller då den förändras efter en mera intensiv period. Vid tidpunkten för bokens invandring till södra Sverige var skogarna redan till stor del påverkade av människan. I en del områden (t ex Mattarp, Flahult) invandrade boken i ett halvöppet kulturlandskap, där vegetations sammansättning till stor del kontrollerades av mänskliga aktiviteter. Bokens etablering underlättades sannolikt där av den rika tillgången på störda marktyper. I det halvöppna kulturlandskapet fanns givetvis också skogsbestånd (som dominerades av björk, ek och hassel), men deras sammansättning styrdes till stor del av mänskliga aktiviteter (t ex genom betestrycket). I en del områden (t ex Bocksten, Siggaboda) verkar skogsvegetationen varit relativt opåverkad av mänskliga aktiviteter innan bokan invandrade, men lokala störningar (naturliga, eller inducerade av människan) underlättade troligen etableringen. Innan boken etablerades dominerades de relativt opåverkade skogstyperna i Småland och Halland av ek, lind och hassel. Den exakta sammansättningen och strukturen varierade dock en del mellan bestånden på grund av lokala faktorer. Det är fullt möjligt att boken fortfarande befinner sig på vandring norrut i Sverige. Det verkar som om bokpopulationerna på nordliga utpostlokaler är mycket livskraftiga och kan expandera lokalt om de tillåts till detta. Det verkar snarare som att det är den nuvarande markanvändningen, och inte klimatet, som sätter stopp för en vidare expansion. De nordliga utpostlokalerna kan sägas utgöra spridningskällor varifrån boken kan spridas till det omgivande landskapet. Granens expansion påverkas också av lokala faktorer, men den regionala spridningen i södra Sverige verkar mera styrd av dess spridningshastighet än av förändringar i t ex markanvändningen. Den lokala expansionen av gran sker vid den tidpunkt då dess front når fram till området. När granen nådde sydligaste Sverige mötte den ett halvöppet kulturlandskap som sedan lång tid tillbaka var påverkat av människan. Den ursprungliga skogstypen var då till stor del redan ersatt med betesmarker och relativt glesa och betade skogar. Denna vegetation var inte speciellt motståndskraftig mot granen, varför den snabbt kunde expandera när den väl nådde fram till ett nytt område. Boken och granen är båda dominanta
trädarter och konkurrensen dem emellan blir därför
mycket intensiv när de möts i samma bestånd.
Tyvärr har de ännu inte vuxit tillsammans under någon
längre tid på de studerade lokalerna, varför det
är svårt att säga något om utgången av
konkurrensen på längre sikt. På den sydligaste av de
studerade lokalerna (Siggaboda) har de vuxit tillsammans under ca 200
år. Det är också på denna lokal som de i nutid
konkurrerar intensivt med varandra. Åtminstone i beståndet
allra närmast provpunkten (fig. 8)
kan man notera att granen
konkurrerat ut boken, men detta gäller troligen inte generellt
för hela lokalen. Lagerås, P. & Björkman, L. 1996: From nemoral to boreal forest: mid- and late-Holocene forest dynamics in the Småland Uplands, southern Sweden. The Geological Society of Sweden, Jubilee Meeting, Stockholm, Oct. 16-18 1996. GFF 118, A66–A67. Conference abstract A recently finished pollen analytical study in the higher parts of the Smålands Uplands, southern Sweden (Lake Avegöl, 300 m a.s.l., and the bog Bråtamossen, 280 m a.s.l.; both sites at c. 57°41'N, 14°30'E), has provided new information on Holocene forest development (Lagerås et al. 1995; Lagerås 1996a,1996b). Compared to other parts of southern Sweden this region has low temperatures, short period between last frost in spring and first frost in autumn, short vegetation period, etc., and, today, it is agriculturally a marginal region that is covered to a large degree by coniferous forest. The general aim of the study was to shed light on the vegetation and land-use history of this area, but only results concerning the forest composition will be considered here. The present forest of the higher parts of the Småland Uplands has been characterised as the southern boreal vegetation zone (Ahti et al. 1968). The forest is dominated by spruce (Picea abies) and pine (Pinus sylvestris). Birch (Betula verrucosa and B. pubescens) is the most common deciduous tree. However, according to pollen analysis the forest composition has been very different in the past. Spruce, or at least spruce forest, has only been present in the area for about one thousand years. In Lake Avegöl and the nearby bog Bråtamossen, the first local establishment of a spruce forest is dated at cal. AD 900-1200. Because it is a dominant and shade-tolerant tree, the spruce expansion caused a rapid and major change of the forest composition. Light and grazed birch-oak woodlands of the Late Iron Age were transformed to darker spruce forest. Most trees except pine decreased, and this change is best characterised as a shift from a deciduous to a coniferous forest. The establishment of spruce forests in the investigation area was not synchronous with changes in the local land-use. More likely the timing of it was controlled by its migratory speed on a larger scale (e.g. Moe 1970). Recent pollen analytical studies of some small peat hollow in Småland provide valuable additional information (Björkman 1996; Björkman & Bradshaw 1996). They clearly show that spruce was able to establish without any major change in disturbance frequency or magnitude, which is in accordance with the results from Lake Avegöl and the bog Bråtamossen. These new results from southern Sweden stand in contrast to results from middle Sweden (Bradshaw & Hannon 1992; Almquist-Jacobson 1994), where local changes in land-use determined the timing of the spruce expansion (see also discussion in Huntley 1988). It should be noted, however, that spruce invaded a light and grazed forest at Lake Avegöl and the bog Bråtamossen (and probably in most other parts of Småland). Most forests of southern Sweden were used for wood pasturage during the Late Holocene. In undisturbed natural forests the expansion of spruce would probably have occurred later and the timing may have been more dependant on local land-use changes. In addition to the rapid change connected to the spruce immigration, the pollen diagrams from the Småland Uplands show that there has also been a slow and gradual change of the forest composition during the last cal. 5000 years. Trees typical of the boreal zone (pine and birch) have gradually become more common in comparison to trees more typical of the nemoral zone (oak, elm, lime, ash). When comparing the relationship between the early-successional trees/shrubs birch and hazel, it is evident that birch has increased in relation to hazel during the last cal. 5000 years. The boreal character of the higher parts of the Småland Uplands at present is thus not only due to the spruce immigration one thousand years ago, but also to the slow decline of many hardwood species typical for the nemoral zone. It seems reasonable to interpret this slow long-term development as an effect of natural processes like climate deterioration and soil leaching. However, it may also have been enhanced by land-use. The first wood pasturage in the Småland Uplands began already cal. 3900 BC (Early Neolithic), i.e., approximately at the same time as in, for example, southern Skåne (Berglund 1991), and continued until the last century. It is important to note that even in a marginal agricultural area like this, wood pasturage has been practised continuously for many thousands of years. It has certainly affected the forest composition, but the effect of it is probably difficult to separate and quantify. References *Björkman, L. 1997: The role of human disturbance in the local Late Holocene establishment of Fagus andPicea forests at Flahult, western Småland, southern Sweden. Vegetation History and Archaeobotany 6, 79–90. Abstract A pollen record from a small alder carr located
in the
centre of a Fagus stand near the hamlet of Flahult in southern
Småland has shown that Fagus became established in a
semi-open cultural landscape about 900 B.P. Human disturbance seems to
have controlled the local establishment of Fagus at this site
through an expansion of pastoral farming. The Fagus dominance
in the present stand seems to be of recent origin, as Fagus pollen
percentages and influx values have increased considerably during the
last 50 years. The modern composition and structure of the Fagus stand
are probably an effect of changes in land-use and decreased human
activity at the end of the last century. Today, only occasional Piceaindividuals
occur in the studied stand, and Picea does not appear to have
been more abundant in the recent past. The regional expansion of Piceahas
probably occurred during this century and has been favoured by modern
forestry during the last 50 years. *Björkman, L. 1997: The history of Fagus forest in southwestern Sweden during the last 1500 years. The Holocene 7, 419–432. Abstract In the recent past, Fagus forests in
southwestern Sweden were more common and widespread than today. The Fagus
forest
area has decreased considerably due to cultural activities, mainly
during the eighteenth and nineteenth centuries. The pollen records of
two small adjacent forest hollows (lying c. 50 m apart) in the
Bocksten area in central Halland indicate that the pre-Fagus forest
was of a rich nemoral type with many woody taxa present. Quercus,
Tilia, Alnus, andCorylus were
important components of this forest type. Fagus became
established in the area around 1450 14C
years BP, and rapidly became dominant in the forest. The expansion of Fagus
was
remarkably rapid, and probably facilitated by a slight human
disturbance. The rather pure Fagus stands found today in the
area are a product of recent human activities. The high pollen
percentages of Tilia at one of the sites (site A) until 200 BP
is remarkable, and stands in contrast to the picture seen in
regional-scale pollen diagrams from Sweden. At this site, Tilia grew
in a mixture with Fagus, Quercus and Corylus for
almost 1200 years until the stand was suddenly cleared c. 200
BP.
At the other site (B) Tilia shows a gradual decrease beginning
before the establishment of Fagus, which is in agreement with
the regional picture. It is evident that stand-level differences in
vegetation is not possible to detect with conventional pollen diagrams
based on regional-scale sites. Different grazing regimes, or human
influence, may have caused these stand-scale differences in vegetation.
The boreo-nemoral forest type found today in the studied area is
dominated by intensively managed Picea plantations and Fagus
stands.
This forest type has little resemblance to the vegetation that existed
during earlier periods. Björkman, L. 1998: Bokens historia i södra Sverige - en litteraturöversikt [The history of beech, Fagus sylvatica, in southern Sweden - a review]. Svensk Botanisk Tidskrift 91, 573–583. Abstract Forests dominated by beech Fagus sylvatica have
a pronounced southerly distribution in Sweden, mainly in the nemoral
zone. In the southernmost part of the boreo-nemoral zone, beech is
generally a minor component of the vegetation. Beech immigrated into
Sweden from the south. From the pollen-stratigraphical evidence it is
difficult to determine when it first became established. About 3500 BP (14C years before present) pollen
percentage
values indicate that it was established as small stands in Skåne.
Scattered individuals may have occurred earlier, but such occurrences
are difficult to prove. About 2200-1500 BP beech showed a substantial
expansion in S Skåne. The expansion in N Skåne, Halland and
Blekinge occurred around 1500-1200 BP. It probably reached its outlying
localities during the last 1500 years. Many outpost stands were
probably
established late, and some may even have been planted. Beech probably
achieved its greatest abundance during the early medieval period, but
human exploitation severely reduced its abundance during the late
medieval and early historic periods. Studies of historical documents
have shown a particularly marked reduction in beech forests in SW
Sweden during the 18th and 19th centuries. Viewed on a continental
scale, the migration pattern of beech can be correlated with climatic
changes. At stand-scale, factors other than climate are crucial for
establishment (e.g. disturbance, seed dispersal and human activities).
Beech seeds are highly dependent on ground disturbance for successful
establishment. Many palaeoecological studies indicate a strong
relationship between cultural activities and the expansion of beech.
Beech may still be migrating northwards, it grows well in its outpost
area, and it seems that present day land-use, not climate, is the
limiting factor for local expansion. Björkman, L. 1998: Bokens historia på en nordlig utpostlokal - Mattarps bokdunge på det Småländska höglandet [The history of beech, Fagus sylvatica, at an outlying stand in the Småland Uplands, Sweden]. Svensk Botanisk Tidskrift 92, 11–21. Abstract An outlying stand of beech Fagus sylvatica at
Mattarp in northern Småland, S. Sweden, became established at
about 400 14C years
before present,
as indicated by pollen records. The core taken for pollen analysis
originated from a small peatland deposit adjacent to the beech stand.
The local establishment coincides with a phase of woodland clearance.
Local factors such as disturbance seem to have controlled the
establishment at stand-scale at this site. Presumably dispersal factors
(and chance) also influenced the exact timing of beech establishment.
Regional climate had probably been favourable for beech for a
considerable period and cannot be regarded as a direct cause for
establishment at this site. Fagus pollen influx values have
increased more or less steadily since the time of establishment. It
seems likely that the beech stand has continually increased in size,
and probably would continue to do so if this was not prevented by human
activities. Beech may still be migrating northwards in Sweden. It grows
well in its outlying localities, and it seems that present day
land-use,
not climate, is the limiting factor for further expansion. Björkman, L. 1998: Bokens och granens historia i Siggaboda naturreservat i sydligaste Småland [The history of beech, Fagus sylvatica, and Norway spruce, Picea abies, at Siggaboda nature reserve in southernmost Småland, Sweden]. Svensk Botanisk Tidskrift 92, 83–93. Abstract The forest at Siggaboda nature reserve in
southern
Småland, S. Sweden, is dominated by mixed or more or less pure
stands of beech Fagus sylvatica and Norway spruce Picea
abies. The reserve is known for its high biodiversity,
particularly
among lichens and beetles typical for long forest continuity. Pollen
records, covering ca. 2800 years, from a core taken in a small peatland
deposit within the reserve, indicate that beech became established
after a fire ca. 950 years BP (before present). Previously, the forest
had been dominated by oak Quercus, lime Tilia cordata and
hazel Corylus avellana. Ca. 350 BP, another fire triggered a
succession towards a co-dominance of beech and oak. This stage lasted
until ca. 200 BP, when oak suddenly declined and disappeared, probably
due to selective cutting. Norway spruce became established at ca. 200
BP, after which the current forest composition developed. The oldest
spruces in the reserve are now ca. 200 years old and are probably
representatives of the first generation. Throughout the covered period
the tree pollen percentage have been high - an evidence of long forest
continuity. This may explain the present high biodiversity, but does
not imply stability, since the site has experienced at least two fires
and undergone a revolution in forest composition. The present forest
type, in spite of looking virtually undisturbed and showing old-growth
characteristics, apparently has a recent origin. *Björkman, L. 1999: The establishment of Fagus sylvatica at the stand-scale in southern Sweden. The Holocene 9, 237–245. Abstract Pollen analysis was carried out on peat profiles
from
small forest hollows at four sites in southern Sweden in order to
investigate the establishment of Fagus sylvatica at the
stand-scale. Viewed on a continental scale the migration pattern of Fagus
can
be correlated with climatic change, but at finer scales such a
correlation is weaker. At the stand-scale there are factors other than
climate that are crucial for the establishment of Fagus (e.g.,
disturbance, seed dispersal, human activities). The establishment of Fagus
does
not show any regional coherence in southern Sweden, and this may imply
that climate was not the limiting factor for its establishment. Fagus
seeds
are dependent on ground disturbance for successful establishment. A
semi-open cultural landscape may be optimal for Fagus establishment,
as cultural activities may create conditions particularly suitable for
its regeneration. At two of the studied sites cultural activities
probably created conditions that favoured the estblishment of Fagus
at
400 and 900 BP respectively. At the other sites the local forest stands
were relatively unaffected by cultural activities prior to the
establishment of Fagus at 950 BP and 1450 BP respectively,
where, fires (natural?) or slight human influence were effective. The
present-day distribution of Fagus in southern Sweden suggests
migration with a discontinuous front and outlying populations, and this
model probably applies to its past distribution. This type of migration
means that the landscape becomes filled in by dispersal from outlying
stands. The timing of stand-scale establishment is then largely
influenced by site-specific factors and chance. Fagus may
still
be migrationg northwards in Sweden. It grows well in its outlying area,
and it seems that present-day land use, not climate, is the limiting
factor for the local expansion of Fagus. The northern
distribution limits of Fagus probably still represent an
active front, and outlying stands act as 'infection centres'. Björkman, L. & Karlsson, M. 1999: Bokskogens historia i sydvästra Sverige - exempel från paleoekologiska undersökningar av bokskogslokaler i Halland. [The history of beech, Fagus sylvatica, forests in southwestern Sweden - examples from palaeoecological studies of beech forest sites in Halland] Svensk Botanisk Tidskrift 93, 107–122. Abstract Results from stand-scale palaeoecological studies
of two
beech, Fagus sylvatica,
forest sites in Halland, SW Sweden, are
presented (Bocksten, 20 km E of Varberg; Holkåsen, 10 km N of
Halmstad). Pollen analysis of small forest hollows in close connection
to these sites, revealed that both sites have had a long continuity
with beech trees and beech forest (at Bocksten for nearly 1500 years,
at Holkåsen for about 1200 years). The pre-Fagus vegetation
at Bocksten was of a rich nemoral type dominated by Quercus, Tilia
cordata, Alnus and Corylus avellana. The expansion of Faguswas
remarkably rapid, and probably facilitated by a slight human
disturbance. Fagus grew in a mixed stand together with Quercus,
Tilia andCorylus, for
nearly 1200 years, until the stand was suddenly cleared about 200 years
ago, probably in connection to an establishment of a nearby settlement.
Picea
abies became established late at this site, probably during the
latter part of the 19th or during the beginning of this century, most
likely when the nearby settlement was abandoned. A marked human
influence on the vegetation during the 18th and 19th centuries, and
forestry management during this century, have contributed to the shift
of forest type, from a nemoral type (climatically, a nemoral type could
easily still grow there) to a boreo-nemoral type. At Holkåsen the
pre-Fagus vegetation also was of a rich nemoral type. At this
site there is a close connection between a local fire and the
establishment of Fagus. Fagus grew in a mixed stand together
with Quercus and some Corylus, for nearly 800 years,
until Fagus became nearly dominant in the local stand (around
400 years ago), probably as an effect of human exploitation (the
studied site was probably used for grazing and pig breeding). Later on
the stand became more open, probably as an effect of continuing
grazing. The expansion of Picea also occurred late at this
site, probably mainly during this century. Regnell, M., Björkman, L., Olsson, S., Regnéll, J., Risberg, J. & Sandgren, P. 2000: The palaeoenvironment around a Mesolithic central place in southern Sweden - reconstruction of sea level changes, water conditions and vegetation during Littorina time. Environmental changes in Fennoscandia during the Late Quaternary. Lund, May 28-30. LUNDQUA Report 37, p. 136. Conference abstract During the construction of a railroad, in the valley of river Saxån in south-western Skåne, extensive archaeological remains were discovered at Tågerup. Excavations were focused towards Mesolithic settlements situated close to the former coastline. The conspicuous remains included large house constructions, a partly well preserved cemetery and refuse layers with an immense amount of artefacts in organic material. The archaeology of the site brings forward a hitherto unique opportunity to study and explain the social organisation of a Mesolithic society as well as different foraging strategies. Large quantities of plant remains and preserved animal bones give a thorough insight to the use of different resources. Palaeoecological investigations have been conducted in order to reconstruct the environment around the site with the aim to provide the excavations with a "colouring" of the image given by archaeology alone. Adjacent to the excavated areas a former basin with transgressive sediment sequence with a thickness up to 11 meters was cored. Sedimentation started during the initial transgression (c. 7800 BP) and continued until the final regression phase (c. 4500 BP). This rapid sedimentation admits a high time-resolution. Sediment accumulation in the basin was influenced by the proximity to the sea and by freshwater inflow from two streams. The presentation shows the preliminary results of the various palaeoecological analyses. The sediment chemistry (analyses of S, N organic and carbonate Carbon) and mineral magnetic analyses (seven different parameters) display a pattern of fluctuations which can be related to variations in freshwater influx, fluctuations in water depth and aerobic/anaerobic conditions. The analyses of siliceous microfossil (of which diatoms are the most important) reveal changes in water depth and salinity. Periods of increasing influx from the freshwater streams can be identified. The pollen analysis provides important information of the regional woodland vegetation as well as the more local vegetation of the coastland area. Since the analysed sequence covers the - from an archaeological point of view - important period of the introduction of agriculture, the development of the vegetation close to the Stone Age settlements is of crucial significance. The archaeological excavations reveals a
settlement with
a duration over several centuries, i.e. over a time where the close
relation to the sea seems to have been of vital importance for the
inhabitants. Any visualisation of this society and its relation to the
surroundings is totally dependent on the reconstruction of the
environmental changes. Regnell, M., Björkman, L., Olsson, S., Regnéll, J., Risberg, J. & Sandgren, P. 2001: Hav och land. Sedimentanalyser av en transgressionslagerföljd [Summary: Sea and land. Sediment analyses of a sequence of transgression layers]. In: Karsten, P. & Knarrström, B. (eds.): Tågerup specialstudier. Riksantikvarieämbetet, Lund. 236–259. Summary Sea and Land. Sediment Analyses of a Sequence of Transgression Layers. The article presents the results of various palaeoecological analyses of a 10.5-metre-long stratigraphy composed of marine-brackish sediments deposited during Middle Holocene Littorina transgressions. The methods applied are analyses of sediment chemistry, mineral magnetism, silica microfossils and pollen. The combined results reveal several phases of transgressions and regressions after the initial ingression at about 7800 BP (uncal.). Pollen analysis gives the opportunity to reconstruct the terrestrial environment and to define periods of human impact on the vegetation. Within the framework of the West Coast Line Project, a sub-project was defined, with the overall goal of carrying out local and regional environmental reconstructions of the Mesolithic site of Tågerup in order to support the archaeological investigations and the syntheses generated by them. The analyses seek to reconstruct the environment and activities in the immediate vicinity of the settlement site, as well as to elucidate the location of the site in the landscape with the vegetational environment as an important component (Regnell 1996, 1998). A number of different methods have been used: analyses of macrofossils, pollen, silica microfossils, sediment chemistry, wood types, and mineral magnetism. This article gives only a brief account of the stratigraphy, the results of the analyses, the interpretations, etc. More detailed descriptions of the results and interpretations of various palaeoecological analyses will be published later in the sub-project's own volume in the series. Studies of transgression processes occupy a large
space
in the investigations. The analyses involve a combination of
biological, physical, and chemical parameters together with carefully
compiled chronologies obtained from 14C
analyses. Tågerup, with its long and unbroken sequence of
transgression sediments, is a key site in this connection. *Onac, B.P., Björkman, L., Björck, S., Clichici, O., Tamas, T., Peate, D. & Wohlfarth, B. 2001: The first dated Eemian lacustrine deposit in Romania. Quaternary Research 56, 62–65. Abstract A complex interglacial sequence of lacustrine
sediments
has been found near the village of Turbuta in NW Romania. Mollusk,
plant macrofossil, and pollen analyses reftect climatic and
environmental changes around the last interglacial climatic optimum.
U-Th TIMS dating of snails strongly indicates an Eemian age of the
organic sediments. *Björkman, L. 2001: The role of human disturbance in Late Holocene vegetation changes on Kullaberg, southern Sweden. Vegetation History and Archaeobotany 10, 201–210. AbstractA pollen record from a small peatland located on Kullaberg in northwestern Skåne, southern Sweden, revealed that grazing pressure might have been the major disturbance agent controlling the vegetation, at least from ca. 1500 B.C. until the latter part of the 19th century. The pollen data also indicate a step-by-step increase in grazing pressure, expressed as a marked increase in pollen percentages for herbs and grasses, at ca. 1500 B.C., A.D. 650 and A.D. 1650. The increase at A.D. 650 probably indicates a more regular and pronounced use of the area, resulting in a forest structure that was much more open than earlier, and the expansion of Fagus, which rapidly replaced Quercus as the local forest dominant. At about this time the first patches with heath vegetation originated, but they probably only covered a small part of Kullaberg. Larger areas with an intensively grazed Calluna heath, as shown by 18th century maps, probably evolved around ca. A.D. 1650, when much of Kullaberg seems to have been deliberately deforested. Till sidans topp/Up *Subetto, D. A., Wohlfarth, B., Davydova, N. N., Sapelko, T. V., Björkman, L., Solovieva, N., Wastegård, S., Possnert, G. & Khomutov, V. I. 2002: Climate and environment on the Karelian Isthmus, northwestern Russia, 13000–9000 cal. yrs BP. Boreas 31, 1–19. Abstract Sediment sequences retrieved from Lake Medvedevskoye (60°13'N; 29°54'E) and Lake Pastorskoye (60°13'N; 30°02'E), Karelian Isthmus, northwestern Russia, were analysed for lithology, pollen and diatom stratigraphy, total organic carbon content and mineral magnetic parameters. Age control for both sequences was provided by AMS 14C measurements and the Vedde Ash tephra. The reconstructed climatic and environmental development shows the deglaciation of the sites and the establishment of sparse shrub and herb/grass vegetation before 12650 cal. yrs BP ('Allerød'; GI-1a). Steppe tundra and cold, dry conditions prevailed until about 11000 cal. yrs BP, i.e. throughout the 'Younger Dryas' (GS-1) and the earliest Holocene. The establishment of open Picea-Pinus-Betula forest around the lakes at about 11000 cal. yrs BP coincides with the first distinct change towards gradually warmer and more humid climatic conditions. Boreal forest with Picea, Pinus, Betula, Alnus incana and Corylus was present at the lower altitude site between c. 10700 and 10200 cal. yrs BP, while open Betula-Pinus forest continued to dominate the vegetation around the higher altitude site. After a short, possibly colder, phase around 10200-10000 cal. yrs BP, which is expressed by a marked reduction in vegetation cover and decreased lake productivity, climatic conditions became significantly warmer and possibly more humid. Boreal forest with Pinus, Betula, Picea, Alnus incana, Corylus and Ulmus became widespread in the region after 10000 cal. yrs BP. The delayed environmental response of the lakes and their catchment to hemispheric warming at the Pleistocene/Holocene boundary may be explained by a sustained blocking of westerly air masses due to the presence of the Scandinavian ice sheet and associated strengthened easterlies and anticyclonic circulation and/or extensive permafrost.Till sidans topp/Up
*Björkman, L., Feurdean, A., Cinthio, K., Wohlfarth, B. & Possnert, G. 2002: Lateglacial and early Holocene vegetation development in the Gutaiului Mountains, NW Romania. Quaternary Science Reviews 21, 1039–1059. Abstract Pollen analyses and AMS 14C
measurements were performed on lacustrine sediments and peat sequences
from two former crater lakes (Preluca Tiganului, Steregoiu) situated in
the Gutaiului Mountains in northwestern Romania, in order to
reconstruct the vegetation development during the Lateglacial and Early
Holocene. Before c. 14,700 cal. years BP (GS-2) open vegetation with
shrubs (Salix, Juniperus), grasses and herbs (e.g. Artemisia
and Chenopodiaceae) prevailed in the area. Around c.
14,700 cal. years
BP and coinciding with the beginning of GI-1e, Pinus expanded,
and patchy vegetation with scattered Pinus stands developed.
The
last 100 years of GI-1e (14,150-14,050 cal. years BP) were
characterised by an increase in Pinus and Betula and an
expansion of open forest communities. This development
was
shortly
interrupted between 14,050 and 13,800 cal. years BP (likely
corresponding to the cold phase GI-1d), when the tree cover became
reduced and open vegetation with scattered Pinus individuals
became frequent. The period with a significant
expansion of Betula
and Picea and the formation of an open forest (including Pinus
and Ulmus), which took place between 13,800 and c. 12,950 cal.
years BP, is tentatively correlated with GI-1c-a. A
renewed reduction
in tree cover (decrease of Picea and Betula,
disappearance of Ulmus) started at 12,950 cal. years BP and at
12,600 cal. years BP forest stands were rapidly replaced by open
vegetation communities with low shrubs (Salix, Juniperus),
grasses and herbs (e.g. Artemisia and Chenopodiaceae). The
period between 12,900 and 11,500 is correlated with the cold phase
GS-1. At 11,500 cal. years BP, most likely as a response to the warmer
climatic conditions at the beginning of the Holocene, an expansion of Betula
and Alnus and, slightly later, also of Ulmus can be
observed. Between 11,500 and 11,250 cal. years BP, open
forests with Betula,
Pinus
and Ulmus were widespread in the area. At
11,250 cal. years BP
dense forests dominated by Ulmus replaced the open forest type.
Around 10,700 cal. years BP Quercus, Tilia and Fraxinus
expanded strongly, and Acer and Corylus became
established. Mixed deciduous forest with Picea dominated the
upland vegetation between 10,700 and 10,150 cal. years BP. At 10,150
cal. years BP Corylus increased significantly and between
10,150
and 8500 cal. years BP, dense mixed deciduous forests with Picea
and Corylus were abundant in the area. Climatic fluctuations
seem
to have been the driving force behind vegetation changes during the
Lateglacial period, while the forest development during the Early
Holocene was mainly driven by migrational and successional processes.
*Wohlfarth, B., Filimonova, L., Bennike, O., Björkman, L., Brunnberg, L., Lavrova, N., Demidov, I. & Possnert, G. 2002: Late Glacial and earlier Holocene environmental and climatic change in south-eastern Russian Karelia: The sediment record from Lake Tambichozero. Quaternary Research 58, 261–272. Abstract High-resolution lithostratigraphy,
mineral magnetic,
carbon, pollen, and macrofossil analyses, and accelerator mass
spectrometry 14C measurements were performed
in the study of a sediment sequence from Lake Tambichozero,
southeastern Russian Karelia, to reconstruct late-glacial and early
Holocene aquatic and terrestrial environmental changes. The lake formed
ca. 14,000 cal yr B.P. and the area around the lake was subsequently
colonized by arctic plants, forming patches of pioneer communities
surrounded by areas of exposed soil. A minor rise in lake productivity
and the immigration of Betula pubescens occurred ca. 11,500 cal yr B.P.
The rise in summer temperatures probably led to increased melting of
remnant ice and enhanced erosion. The distinct increase in lake
productivity and the development of open Betula-Populus forests, which are
reconstructed based on plant macrofossil remains, indicate stable soils
from 10,600 cal yr B.P. onward. Pinus
and Picea probably became
established ca. 9900 cal yr B.P.
*Niklasson, M., Lindbladh, M. & Björkman, L. 2002: A long-term record of Quercus decline, logging and fires in a southern Swedish Fagus-Picea forest. Journal of Vegetation Science 13, 765–774. Abstract We reconstructed forest development and
disturbance
events (fire and logging) during the last 1000 yr with tree-ring data,
pollen and charcoal analysis from a seminatural Fagus sylvatica-Picea abies forest (ca. 1 km2)
in the hemiboreal zone. According to pollen analysis, Quercus robur together with Pinus sylvestris was abundant in
the forest until the turn of the 18th/19th centuries when these species
disappeared completely (Quercus)
or nearly
completely (Pinus) and were
replaced by Fagus and Picea. The disappearance of Quercus was corroborated by the
remarkable discovery of a single Quercus
stump that had been cut in the 18th century and had become overgrown
and preserved by a very old Picea.
In total 11 fires were dated from 1555 to 1748 from fire scars in
several Pinus stumps cut 100–200 yr ago. Since the last fire in 1748,
no Quercus or Pinus have regenerated in the core
of the reserve apart from single pines in neighbouring managed forest
(80 yr ago). During the period of documented fires Fagus was protected from fires in
a refuge made up of large boulders. Picea
colonized the region at the time when the fires ceased 250 yr ago. We
hypothesize that most of the fires were probably of human origin
because of their patchiness and high frequency compared to the natural
background levels of lightning ignitions in the region. On a 300-yr
time scale, logging and fire
suppression seem to strongly overshadow the effect of climate change on
forest composition and dynamics.
*Björkman, L., Feurdean, A. & Wohlfarth, B. 2003: Lateglacial and Holocene forest dynamics at Steregoiu in the Gutaiului Mountains, NW Romania. Review of Palaeobotany and Palynology 124, 79–111. Abstract Pollen analyses and AMS 14C
measurements were performed on lacustrine sediments and peat deposits
from the former crater lake Steregoiu in a mid-altitude area in the
Gutaiului Mountains in NW Romania in order to provide a detailed
reconstruction of the vegetational development of the area during the
Late-Glacial and Holocene. The bottom sediments are
siliciclastic and
were deposited probably during the Full Glacial, which is characterised
by open patchy vegetation consisting of a mosaic of shrubs, herbs, and
ungrown grounds. Around 14 700 cal yr BP an open Pinus-Betula forest expanded, at the same
time as organic-rich lake sediments started to be deposited. This
change was likely a response to the first deglacial warming phase at
the beginning of the Bølling period, or GI-1e, in the GRIP event
stratigraphy. Between 13 750 and 12 950 cal yr BP an open forest
dominated by Betula, Picea, Pinus, and Ulmus developed in the area. The
forest composition implies rather warm climatic conditions, which may
correspond to the Allerød, or GI-1c-GI-1a. Around 12 950 cal yr
BP the forest retracted, and at 12 600 cal yr BP open patchy vegetation
became re-established. These changes imply a return to significantly
colder conditions, which may correspond to the Younger Dryas, or GS-1.
At 11 500 cal yr BP Betula, Pinus, and Alnus quickly responded to the
temperature rise, characterising the beginning of the Holocene. Within
a few hundred years, around 11 300 cal yr BP, Ulmus and Picea became re-established and a
mixed forest type expanded. Quercus,
Tilia, and Fraxinus likely arrived at around
10 750 cal yr BP, and from about this time Betula, and Pinus started to diminish. Around
10 500 cal yr BP a dense mixed forest dominated by Ulmus, Picea, Quercus, Tilia, and Fraxinus had developed in the area.
Corylus probably
became locally established around 10 500 cal yr BP, but it did not
expand until 10 200 cal yr BP. Tilia
and Fraxinus were locally
important until 8600 cal yr BP, when Picea
gained renewed importance and the lake became completely overgrown. Picea was
probably an important
constituent in the carr forest at the site as well as in the upland
forest. Around 4800 cal yr BP Fagus
and Carpinus became important
in the local stand, apparently without any major disturbance of the
forest. Until around 3400 cal yr BP the forest was highly diverse, but
when Fagus eventually
expanded, Ulmus, Tilia, Picea, and Corylus diminished. From
about 2200
cal yr BP onwards Fagus has
been the local forest dominant, but some Quercus and Carpinus individuals have been
present as well. Pollen evidence for human influence on the local
vegetation is comparatively scant. The area may have been used for
forest grazing from about 1050 cal yr BP, but the grazing pressure was
probably low until ca. 300 cal yr BP.
*Björkman, L. & Sjögren, P. 2003: Long-term history of land-use and vegetation at Ire, an agriculturally marginal area in Blekinge, south Sweden. Vegetation History and Archaeobotany 12, 61–74. Abstract Pollen records from a small lake and a small
peatland at
Ire in northern Blekinge, Sweden, reveal that until A.D. 300 there was
a mixed deciduous type of woodland dominated by Quercus, Tilia and Corylus, with Betula, Pinus, Populus, Fraxinus, Ulmus and Acer as important constituents. The
first, but weak, signs of human influence on the vegetation are
detected around 2300 B.C. At this time, the area was probably used for
woodland grazing. The regional expansion of Fagus occurred around 100 B.C.-A.D.
200, and later, at about A.D. 500, woods
dominated by Fagus were
common in the area. Around A.D. 600-700 an isolated farmstead may have
been established in the area, as single pollen grains of Secale (rye) were found. This
farmstead may represent the first permanent settlement in the area. A
more widespread opening of the vegetation occurred around A.D. 1000,
probably as an effect of a more pronounced use of the area, and an
expansion of settlements in the region. The openness of the area seems
to have peaked around A.D. 1400-1800, and during this period the
vegetation was highly fragmented with small stands of woodland,
intensively grazed pastures, and arable fields where Secale and Triticum were mainly cultivated.
Around A.D. 1600 Fagus pollen
percentages sharply decrease, most probably caused by a deliberate and
selective felling of beech trees for the production of potash, which
consumed enormous amounts of wood. Picea
seems to have been established around A.D. 1600, but it did not become
a regional dominant until the first part of the 20th century, when land
use decreased and it became favoured by forestry.
Liljegren, R. & Björkman, L. 2003: Vegetationshistoria i östra Skåne. En jämförelse med Ystadområdet [Summary: Vegetation history in south-east Skåne. A comparison with the Ystad area]. I: Söderberg, B. (red): Järrestad. Huvudgård i centralbygd. Riksantikvarieämbetet Arkeologiska Undersökningar Skrifter 51, 83–108. Summary Vegetation
history in
south-east Skåne. A comparison with the Ystad area. This article deals with vegetation development in
south-eastern Scania mainly from the Neolithic to the early Middle
Ages. Our investigation area is the sandy plateau around the village of
Järrestad and the nearest clayey till surroundings. We also try to
see differences in the development between the Ystad area in southern
Scania, investigated during the 1980s in the Ystad project (Berglund
ed. 1991), and our investigation area. Since there are no useful profiles for regional
pollen
analyses in the Järrestad area we have to rely on a few
investigated profiles with local pollen representation (fig. 1). It is
therefore difficult to compare with the Ystad area, which was
investigated with a much broader perspective. The area within the Ystad
project that we think resembles the Järrestad area most is the
Köpinge plateau, and therefore we mainly try to compare with that. Our main results are: • Despite the fact that there are differences in
the
source material, we suggest that it is possible to see important
differences in the vegetation development and the use of the landscape
in southern and south-eastern Scania. • The Mesolithic landscape was about the same in
south-eastern and southern Scania, but due to differences in geology,
the south-eastern landscape was more diverse. Some landscape elements,
present in southeast, i.e. the sandstone plateaus, does not exist in
the Ystad area. This means that the woodland was often more open and
affected by dry ground in the Järrestad area. • The elm decline is reflected in the same way in
both
areas. However, directly after the elm decline, some differences are
seen. The vegetation in the Järrestad area becomes more affected
by grazing than it was in the Ystad area. The influence of farming,
seen for example in the abundance of pollen grains from weeds and
cerealia, is not so obvious in the Järrestad area. We suggest that
this shows that the keeping of livestock was of significant importance
in the Järrestad area. • Within our area, the Järrestad plateau
forms a
central area for grazing at an early stage. It is rather unaffected by,
for instance, regression periods after that. The plateau seems to have
an unbroken history as a grazing area during the remaining prehistoric
period. This fact could be given different archaeological
interpretations. • Farming in the Järrestad area came late
and was
weak at the start. On the other hand, the clayey till plains,
surrounding the Järrestad plateau was transformed early on into
grazing fields. This expansion comes much earlier than in the Ystad
area. • The central Järrestad plateau was not
affected by
farming until the end of Iron Age or the beginning of the Middle Ages.
Farming did not start on the top of the plateau but on the slopes. At
the same time the top of the plateau become overexploited by grazing. • There could be several reasons for the
differences
between our area and the Ystad area. Besides archaeological reasons,
the differences in geology are probably important too. The
Järrestad plateau landscape was dryer, which favoured grazing. On
the other hand, the till plains were probably wetter due to higher clay
content, which gave possibilities for grazing but not for tillage. In
an area dominated by animal husbandry, this expansion into the till
areas also seems to be a natural step. • The differences are obvious already close to
the elm
decline and they persist into the Middle Ages. The divergent
development therefore has a long tradition.
Björkman,
L. 2004: Vegetation och markanvändning i
Öggestorpsområdet under de senaste 5000 åren. Tidskrift – arkeologi i sydöstra
Sverige 4, 7–21. Abstract: Palaeoecological investigations have been carried
out in connection to the archaeological excavations brought about by
the planning of a new road between Öggestorp and Rogberga in
northern Småland. The article summarizes the vegetation
development and land-use history in the Öggestorp area during the
last 5000 years. The description is based on a detailed pollen diagram
from the site Öggestorpsdalen and on an existing diagram from the
small lake Femtingagölen. Mixed deciduous woodlands with oak, lime
and hazel dominated the area until about 1500 BC, when forest grazing
was introduced. Grazing pressure was low until 500–100 BC, when
grasslands expanded and extensive cultivation began. Land-use practices
increased substantially around the birth of Christ, and a mosaic-like
vegetation with pastures, cultivated fields and small forest stands
developed. Cultivation was intense from about AD 500 until AD 800 when
land-use suddenly decreased and woodlands dominated by birch expanded.
For about 300 years, until AD 1100, only grazing may have been
practised in the area. Around AD 1000 spruce expanded and within a few
hundred years spruce-dominated stands were common. About AD 1250
grazing and cultivation increased strongly, and again a patchy
vegetation were created. Land-use has been intense in the area during
Middle Ages, but also later during the last 300 years. Additionally,
the article also present results from pollen analyses of soil samples
taken in graves and cairns at the main archaeological excavation site
at Öggestorp.
*Wohlfarth,
B., Schwark, L., Bennike, O.,
Filimonova, L., Tarasov, P., Björkman,
L., Brunnberg, L., Demidov, I. & Possnert, G. 2004: Unstable early-Holocene
climatic and environmental conditions in northwestern Russia derived
from a multidisciplinary study of a lake-sediment sequence from
Pichozero, southeastern Russian Karelia. The Holocene 14, 732–746. A sediment core from Lake Pichozero (61°46' ; N, 37°25'; E 118 m a.s.l.) provides information on the environmental and climatic conditions in southeastern Russian Karelia during the Lateglacial and early Holocene (12 800 9300 cal. BP). The chronology of the sequence is constrained by varve counting and AMS 14C measurement of terrestrial plant macrofossils. Multiproxy analyses (magnetic susceptibility, grain size, TOC, TN, TS, Rock Eval, pollen and macrofossils) imply that cold and dry regional climatic conditions with sparse Arctic vegetation prevailed prior to 11500 cal. BP. Coincident with the transition to the Holocene at 11 500 cal. BP, air temperatures and lake productivity increased and Betula pubescens and Populus tremula started to migrate into the area, followed by Picea abies at 10 750 cal. BP. Although lake productivity decreased at around 11 000 cal. BP and remained low until 9600 cal. BP, pollen-based climate reconstructions imply variable climatic conditions in the region over time. Drier and colder summers prevailed from ~11 200 to 10 900 cal. BP, followed by an interval of higher annual temperatures and precipitation from 10 900 to 10 750 cal. BP. Lower annual temperatures and drier conditions existed from 10 750 to 10 200 cal. BP, and higher temperatures and precipitation are inferred between 10 200 and 10 000 cal. BP. Finally, declining temperatures and precipitation occurred from 10 000 cal. BP onwards, with a minimum at around 9600 cal. BP. These climatic shifts are temporally coincident with those recorded in North Atlantic terrestrial, marine and ice-core archives and indicate that relatively minor climate signals were transmitted further to the east. Till sidans topp/Up
|
||||