@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{DeFrenneKolbGraaeetal.2011, author = {De Frenne, P. and Kolb, Annette and Graae, Benete Jessen and Decocq, Guillaume and Baltora, S. and De Schrijver, A. and Brunet, J. and Chabrerie, Olivier and Cousins, Sara A. O. and Dhondt, Rob and Diekmann, Martin and Gruwez, R. and Heinken, Thilo and Hermy, Martin and Liira, J. and Saguez, R. and Shevtsova, Anna and Baskin, Carol C. and Verheyen, Kris}, title = {A latitudinal gradient in seed nutrients of the forest herb Anemone nemorosa}, series = {Plant biology}, volume = {13}, journal = {Plant biology}, number = {3}, publisher = {Wiley-Blackwell}, address = {Malden}, issn = {1435-8603}, doi = {10.1111/j.1438-8677.2010.00404.x}, pages = {493 -- 501}, year = {2011}, abstract = {The nutrient concentration in seeds determines many aspects of potential success of the sexual reproductive phase of plants, including the seed predation probability, efficiency of seed dispersal and seedling performance. Despite considerable research interest in latitudinal gradients of foliar nutrients, a similar gradient for seeds remains unexplored. We investigated a potential latitudinal gradient in seed nutrient concentrations within the widespread European understorey forest herb Anemone nemorosa L. We sampled seeds of A. nemorosa in 15 populations along a 1900-km long latitudinal gradient at three to seven seed collection dates post-anthesis and investigated the relative effects of growing degree-hours > 5 degrees C, soil characteristics and latitude on seed nutrient concentrations. Seed nitrogen, nitrogen:phosphorus ratio and calcium concentration decreased towards northern latitudes, while carbon:nitrogen ratios increased. When taking differences in growing degree-hours and measured soil characteristics into account and only considering the most mature seeds, the latitudinal decline remained particularly significant for seed nitrogen concentration. We argue that the decline in seed nitrogen concentration can be attributed to northward decreasing seed provisioning due to lower soil nitrogen availability or greater investment in clonal reproduction. This pattern may have large implications for the reproductive performance of this forest herb as the degree of seed provisioning ultimately co-determines seedling survival and reproductive success.}, language = {en} } @article{DeFrenneBrunetShevtsovaetal.2011, author = {De Frenne, Pieter and Brunet, Jorg and Shevtsova, Anna and Kolb, Annette and Graae, Bente J. and Chabrerie, Olivier and Cousins, Sara Ao and Decocq, Guillaume and De Schrijver, An and Diekmann, Martin and Gruwez, Robert and Heinken, Thilo and Hermy, Martin and Nilsson, Christer and Stanton, Sharon and Tack, Wesley and Willaert, Justin and Verheyen, Kris}, title = {Temperature effects on forest herbs assessed by warming and transplant experiments along a latitudinal gradient}, series = {Global change biology}, volume = {17}, journal = {Global change biology}, number = {10}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {1354-1013}, doi = {10.1111/j.1365-2486.2011.02449.x}, pages = {3240 -- 3253}, year = {2011}, abstract = {Slow-colonizing forest understorey plants are probably not able to rapidly adjust their distribution range following large-scale climate change. Therefore, the acclimation potential to climate change within their actual occupied habitats will likely be key for their short-and long-term persistence. We combined transplant experiments along a latitudinal gradient with open-top chambers to assess the effects of temperature on phenology, growth and reproductive performance of multiple populations of slow-colonizing understorey plants, using the spring flowering geophytic forb Anemone nemorosa and the early summer flowering grass Milium effusum as study species. In both species, emergence time and start of flowering clearly advanced with increasing temperatures. Vegetative growth (plant height, aboveground biomass) and reproductive success (seed mass, seed germination and germinable seed output) of A. nemorosa benefited from higher temperatures. Climate warming may thus increase future competitive ability and colonization rates of this species. Apart from the effects on phenology, growth and reproductive performance of M. effusum generally decreased when transplanted southwards (e. g., plant size and number of individuals decreased towards the south) and was probably more limited by light availability in the south. Specific leaf area of both species increased when transplanted southwards, but decreased with open-top chamber installation in A. nemorosa. In general, individuals of both species transplanted at the home site performed best, suggesting local adaptation. We conclude that contrasting understorey plants may display divergent plasticity in response to changing temperatures which may alter future understorey community dynamics.}, language = {en} }