@article{WieczorekKruseEppetal.2017, author = {Wieczorek, Mareike and Kruse, Stefan and Epp, Laura Saskia and Kolmogorov, Alexei and Nikolaev, Anatoly N. and Heinrich, Ingo and Jeltsch, Florian and Pestryakova, Luidmila Agafyevna and Zibulski, Romy and Herzschuh, Ulrike}, title = {Dissimilar responses of larch stands in northern Siberia to increasing temperatures-a field and simulation based study}, series = {Ecology : a publication of the Ecological Society of America}, volume = {98}, journal = {Ecology : a publication of the Ecological Society of America}, publisher = {Wiley}, address = {Hoboken}, issn = {0012-9658}, doi = {10.1002/ecy.1887}, pages = {2343 -- 2355}, year = {2017}, abstract = {Arctic and alpine treelines worldwide differ in their reactions to climate change. A northward advance of or densification within the treeline ecotone will likely influence climate-vegetation feedback mechanisms. In our study, which was conducted in the Taimyr Depression in the North Siberian Lowlands, w present a combined field-and model-based approach helping us to better understand the population processes involved in the responses of the whole treeline ecotone, spanning from closed forest to single-tree tundra, to climate warming. Using information on stand structure, tree age, and seed quality and quantity from seven sites, we investigate effects of intra-specific competition and seed availability on the specific impact of recent climate warming on larch stands. Field data show that tree density is highest in the forest-tundra, and average tree size decreases from closed forest to single-tree tundra. Age-structure analyses indicate that the trees in the closed forest and forest-tundra have been present for at least similar to 240 yr. At all sites except the most southerly ones, past establishment is positively correlated with regional temperature increase. In the single-tree tundra, however, a change in growth form from krummholz to erect trees, beginning similar to 130 yr ago, rather than establishment date has been recorded. Seed mass decreases from south to north, while seed quantity increases. Simulations with LAVESI (Larix Vegetation Simulator) further suggest that relative density changes strongly in response to a warming signal in the forest-tundra while intra-specific competition limits densification in the closed forest and seed limitation hinders densification in the single-tree tundra. We find striking differences in strength and timing of responses to recent climate warming. While forest-tundra stands recently densified, recruitment is almost non-existent at the southern and northern end of the ecotone due to autecological processes. Palaeo-treelines may therefore be inappropriate to infer past temperature changes at a fine scale. Moreover, a lagged treeline response to past warming will, via feedback mechanisms, influence climate change in the future.}, language = {en} } @article{LiangHeinrichSimardetal.2013, author = {Liang, Wei and Heinrich, Ingo and Simard, Sonia and Helle, Gerhard and Linan, Isabel Dorado and Heinken, Thilo}, title = {Climate signals derived from cell anatomy of Scots pine in NE Germany}, series = {Tree physiology}, volume = {33}, journal = {Tree physiology}, number = {8}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0829-318X}, doi = {10.1093/treephys/tpt059}, pages = {833 -- 844}, year = {2013}, abstract = {Tree-ring chronologies of Pinus sylvestris L. from latitudinal and altitudinal limits of the species distribution have been widely used for climate reconstructions, but there are many sites within the temperate climate zone, as is the case in northeastern Germany, at which there is little evidence of a clear climate signal in the chronologies. In this study, we developed long chronologies of several cell structure variables (e. g., average lumen area and cell wall thickness) from P. sylvestris growing in northeastern Germany and investigated the influence of climate on ring widths and cell structure variables. We found significant correlations between cell structure variables and temperature, and between tree-ring width and relative humidity and vapor pressure, respectively, enabling the development of robust reconstructions from temperate sites that have not yet been realized. Moreover, it has been shown that it may not be necessary to detrend chronologies of cell structure variables and thus low-frequency climate signals may be retrieved from longer cell structure chronologies. The relatively extensive resource of archaeological material of P. sylvestris covering approximately the last millennium may now be useful for climate reconstructions in northeastern Germany and other sites in the temperate climate zone.}, language = {en} } @article{LiangHeinrichHelleetal.2013, author = {Liang, Wei and Heinrich, Ingo and Helle, Gerhard and Linan, Isabel Dorado and Heinken, Thilo}, title = {Applying CLSM to increment core surfaces for histometric analyses a novel advance in quantitative wood anatomy}, series = {Dendrochronologia : an interdisciplinary journal of tree-ring science}, volume = {31}, journal = {Dendrochronologia : an interdisciplinary journal of tree-ring science}, number = {2}, publisher = {Elsevier}, address = {Jena}, issn = {1125-7865}, doi = {10.1016/j.dendro.2012.09.002}, pages = {140 -- 145}, year = {2013}, abstract = {A novel procedure has been developed to conduct cell structure measurements on increment core samples of conifers. The procedure combines readily available hardware and software equipment. The essential part of the procedure is the application of a confocal laser scanning microscope (CLSM) which captures images directly from increment cores surfaced with the advanced WSL core-microtome. Cell wall and lumen are displayed with a strong contrast due to the monochrome black and green nature of the images. Consecutive images are merged into long images representing entire increment cores which are then analysed for cell structures in suitable software.}, language = {en} }