Giesecke, Thomas

[["dc.bibliographiccitation.firstpage","209"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","The Holocene"],["dc.bibliographiccitation.lastpage","220"],["dc.bibliographiccitation.volume","19"],["dc.contributor.author","Seppa, Heikki"],["dc.contributor.author","Alenius, Teija"],["dc.contributor.author","Muukkonen, Petteri"],["dc.contributor.author","Giesecke, Thomas"],["dc.contributor.author","Miller, Paul A."],["dc.contributor.author","Ojala, Antti E. K."],["dc.date.accessioned","2018-11-07T08:32:08Z"],["dc.date.available","2018-11-07T08:32:08Z"],["dc.date.issued","2009"],["dc.description.abstract","Recent investigations show that the pollen accumulation rate (PAR) of the common tree taxa is directly related to the biomass and, by inference, to the population size of the taxa around the study site. Fossil PAR records preserved in lakes provide therefore a potential proxy for quantitative biomass and population reconstructions. We use the high-resolution PAR records obtained from two accurately dated lake sediment cores in Finland to generate quantitative Holocene biomass records for Pinus, Picea and Betula, the most common tree taxa of the European Boreal forest. PAR values were calibrated to biomass values by comparing the modern PAR values with the modern biomass values and assuming a linear relationship between the past PAR and biomass values. The obtained PAR and biomass values and trends are remarkably coherent between the two records. Pinus has a stable Holocene biomass size and its modern biomass, about 20 t/ha corresponds with the natural Pinus biomass in the study regions. In contrast, Picea immigrated from the East during the mid Holocene, had a maximum biomass, 50-60 t/ha, at 3500-1000 cal. yr BP, and declined strongly during the last 1500-1000 years as a result of increased human activity and related rise of fire frequency. Thus, the modern Picea biomass in the study regions, about 22 t/ha, is only 35-40% of the natural Picea biomass. The results of this pilot study demonstrate the potential of the calibrated PAR data in quantitative biomass and population reconstructions. Such reconstructions can provide fresh insights into the structure of past plant communities and, when combined with records reflecting palaeoclimates, natural disturbances, and human activity, can help to disentangle the long-term importance of different enviromental drivers to changes in plants populations and ecosystems."],["dc.description.sponsorship","Academy of Finland; European Science Foundation [2003-980409]"],["dc.identifier.doi","10.1177/0959683608100565"],["dc.identifier.isi","000264239900004"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/13075"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/17274"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Sage Publications Ltd"],["dc.relation.issn","0959-6836"],["dc.rights","Goescholar"],["dc.rights.uri","https://goescholar.uni-goettingen.de/licenses"],["dc.title","Calibrated pollen accumulation rates as a basis for quantitative tree biomass reconstructions"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","661"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","CLIMATE OF THE PAST"],["dc.bibliographiccitation.lastpage","680"],["dc.bibliographiccitation.volume","10"],["dc.contributor.author","Strandberg, G."],["dc.contributor.author","Kjellstrom, E."],["dc.contributor.author","Poska, Anneli"],["dc.contributor.author","Wagner, S."],["dc.contributor.author","Gaillard, M.-J."],["dc.contributor.author","Trondman, A.-K."],["dc.contributor.author","Mauri, A."],["dc.contributor.author","Davis, B. A. S."],["dc.contributor.author","Kaplan, Jed O."],["dc.contributor.author","Birks, H. John B."],["dc.contributor.author","Bjune, Anne E."],["dc.contributor.author","Fyfe, Ralph M."],["dc.contributor.author","Giesecke, Thomas"],["dc.contributor.author","Kalnina, Laimdota"],["dc.contributor.author","Kangur, Mikhel"],["dc.contributor.author","van der Knaap, Willem O."],["dc.contributor.author","Kokfelt, U."],["dc.contributor.author","Kunes, Petr"],["dc.contributor.author","Latalowa, Malgorzata"],["dc.contributor.author","Marquer, Laurent"],["dc.contributor.author","Mazier, Florence"],["dc.contributor.author","Nielsen, A. B."],["dc.contributor.author","Smith, B."],["dc.contributor.author","Seppa, Heikki"],["dc.contributor.author","Sugita, Shinya"],["dc.date.accessioned","2018-11-07T09:46:16Z"],["dc.date.available","2018-11-07T09:46:16Z"],["dc.date.issued","2014"],["dc.description.abstract","This study aims to evaluate the direct effects of anthropogenic deforestation on simulated climate at two contrasting periods in the Holocene, similar to 6 and similar to 0.2 k BP in Europe. We apply We apply the Rossby Centre regional climate model RCA3, a regional climate model with 50 km spatial resolution, for both time periods, considering three alternative descriptions of the past vegetation: (i) potential natural vegetation (V) simulated by the dynamic vegetation model LPJ-GUESS, (ii) potential vegetation with anthropogenic land use (deforestation) from the HYDE3.1 (History Database of the Global Environment) scenario (V + H3.1), and (iii) potential vegetation with anthropogenic land use from the KK10 scenario (V + KK10). The climate model results show that the simulated effects of deforestation depend on both local/regional climate and vegetation characteristics. At similar to 6 k BP the extent of simulated deforestation in Europe is generally small, but there are areas where deforestation is large enough to produce significant differences in summer temperatures of 0.5-1 degrees C. At similar to 0.2 k BP, extensive deforestation, particularly according to the KK10 model, leads to significant temperature differences in large parts of Europe in both winter and summer. In winter, deforestation leads to lower temperatures because of the differences in albedo between forested and unforested areas, particularly in the snow-covered regions. In summer, deforestation leads to higher temperatures in central and eastern Europe because evapotranspiration from unforested areas is lower than from forests. Summer evaporation is already limited in the southernmost parts of Europe under potential vegetation conditions and, therefore, cannot become much lower. Accordingly, the albedo effect dominates in southern Europe also in summer, which implies that deforestation causes a decrease in temperatures. Differences in summer temperature due to deforestation range from -1 degrees C in south-western Europe to +1 degrees C in eastern Europe. The choice of anthropogenic land-cover scenario has a significant influence on the simulated climate, but uncertainties in palaeoclimate proxy data for the two time periods do not allow for a definitive discrimination among climate model results."],["dc.identifier.doi","10.5194/cp-10-661-2014"],["dc.identifier.isi","000335374600016"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/11681"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/34832"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Copernicus Gesellschaft Mbh"],["dc.relation.issn","1814-9332"],["dc.relation.issn","1814-9324"],["dc.rights","CC BY 3.0"],["dc.rights.uri","https://creativecommons.org/licenses/by/3.0"],["dc.title","Regional climate model simulations for Europe at 6 and 0.2 k BP: sensitivity to changes in anthropogenic deforestation"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]