@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{DeFrenneGraaeKolbetal.2011, author = {De Frenne, Pieter and Graae, Bente J. and Kolb, Annette and Shevtsova, Anna and Baeten, Lander and Brunet, J{\"o}rg and Chabrerie, Olivier and Cousins, Sara A. O. and Decocq, Guillaume and Dhondt, Rob and Diekmann, Martin and Gruwez, Robert and Heinken, Thilo and Hermy, Martin and Oster, Mathias and Saguez, Robert and Stanton, Sharon and Tack, Wesley and Vanhellemont, Margot and Verheyen, Kris}, title = {An intraspecific application of the leaf-height-seed ecology strategy scheme to forest herbs along a latitudinal gradient}, series = {Ecography : pattern and diversity in ecology ; research papers forum}, volume = {34}, journal = {Ecography : pattern and diversity in ecology ; research papers forum}, number = {1}, publisher = {Wiley-Blackwell}, address = {Malden}, issn = {0906-7590}, doi = {10.1111/j.1600-0587.2010.06399.x}, pages = {132 -- 140}, year = {2011}, abstract = {We measured LHS traits in 41 Anemone nemorosa and 44 Milium effusum populations along a 1900-2300 km latitudinal gradient from N France to N Sweden. We then applied multilevel models to identify the effects of regional (temperature, latitude) and local (soil fertility and acidity, overstorey canopy cover) environmental factors on LHS traits. Both species displayed a significant 4\% increase in plant height with every degree northward shift (almost a two-fold plant height difference between the southernmost and northernmost populations). Neither seed mass nor SLA showed a significant latitudinal cline. Temperature had a large effect on the three LHS traits of Anemone. Latitude, canopy cover and soil nutrients were related to the SLA and plant height of Milium. None of the investigated variables appeared to be related to the seed mass of Milium. The variation in LHS traits indicates that the ecological strategy determined by the position of each population in this three-factor triangle is not constant along the latitudinal gradient. The significant increase in plant height suggests greater competitive abilities for both species in the northernmost populations. We also found that the studied environmental factors affected the LHS traits of the two species on various scales: spring-flowering Anemone was affected more by temperature, whereas early-summer flowering Milium was affected more by local and other latitude-related factors. Finally, previously reported cross-species correlations between LHS traits and latitude were generally unsupported by our within-species approach.}, language = {en} } @article{PlueDeFrenneAcharyaetal.2013, author = {Plue, Jan and De Frenne, Pieter and Acharya, Kamal P. and Brunet, Jorg and Chabrerie, Olivier and Decocq, Guillaume and Diekmann, Martin and Graae, Bente J. and Heinken, Thilo and Hermy, Martin and Kolb, Annette and Lemke, Isgard and Liira, Jaan and Naaf, Tobias and Shevtsova, Anna and Verheyen, Kris and Wulf, Monika and Cousins, Sara A. O.}, title = {Climatic control of forest herb seed banks along a latitudinal gradient}, series = {Global ecology and biogeography : a journal of macroecology}, volume = {22}, journal = {Global ecology and biogeography : a journal of macroecology}, number = {10}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {1466-822X}, doi = {10.1111/geb.12068}, pages = {1106 -- 1117}, year = {2013}, abstract = {Aim Seed banks are central to the regeneration strategy of many plant species. Any factor altering seed bank density thus affects plant regeneration and population dynamics. Although seed banks are dynamic entities controlled by multiple environmental drivers, climatic factors are the most comprehensive, but still poorly understood. This study investigates how climatic variation structures seed production and resulting seed bank patterns. Location Temperate forests along a 1900km latitudinal gradient in north-western (NW) Europe. Methods Seed production and seed bank density were quantified in 153 plots along the gradient for four forest herbs with different seed longevity: Geum urbanum, Milium effusum, Poa nemoralis and Stachys sylvatica. We tested the importance of climatic and local environmental factors in shaping seed production and seed bank density. Results Seed production was determined by population size, and not by climatic factors. G.urbanum and M.effusum seed bank density declined with decreasing temperature (growing degree days) and/or increasing temperature range (maximum-minimum temperature). P.nemoralis and S.sylvatica seed bank density were limited by population size and not by climatic variables. Seed bank density was also influenced by other, local environmental factors such as soil pH or light availability. Different seed bank patterns emerged due to differential seed longevities. Species with long-lived seeds maintained constant seed bank densities by counteracting the reduced chance of regular years with high seed production at colder northern latitudes. Main conclusions Seed bank patterns show clear interspecific variation in response to climate across the distribution range. Not all seed banking species may be as well equipped to buffer climate change via their seed bank, notably in short-term persistent species. Since the buffering capacity of seed banks is key to species persistence, these results provide crucial information to advance climatic change predictions on range shifts, community and biodiversity responses.}, language = {en} } @article{CaronDeFrenneBrunetetal.2015, author = {Caron, Maria Mercedes and De Frenne, Pieter and Brunet, J{\"o}rg and Chabrerie, Olivier and Cousins, Sara A. O. and Decocq, Guillaume and Diekmann, Martin and Graae, Bente Jessen and Heinken, Thilo and Kolb, Annette and Lenoir, Jonathan and Naaf, Tobias and Plue, Jan and Selvi, Federico and Wulf, Monika and Verheyen, Kris}, title = {Divergent regeneration responses of two closely related tree species to direct abiotic and indirect biotic effects of climate change}, series = {Forest ecology and management}, volume = {342}, journal = {Forest ecology and management}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0378-1127}, doi = {10.1016/j.foreco.2015.01.003}, pages = {21 -- 29}, year = {2015}, abstract = {Changing temperature and precipitation can strongly influence plant reproduction. However, also biotic interactions might indirectly affect the reproduction and recruitment success of plants in the context of climate change. Information about the interactive effects of changes in abiotic and biotic factors is essential, but still largely lacking, to better understand the potential effects of a changing climate on plant populations. Here we analyze the regeneration from seeds of Acer platanoides and Acer pseudoplatanus, two currently secondary forest tree species from seven regions along a 2200 km-wide latitudinal gradient in Europe. We assessed the germination, seedling survival and growth during two years in a common garden experiment where temperature, precipitation and competition with the understory vegetation were manipulated. A. platanoides was more sensitive to changes in biotic conditions while A. pseudoplatanus was affected by both abiotic and biotic changes. In general, competition reduced (in A. platanoides) and warming enhanced (in A. pseudoplatanus) germination and survival, respectively. Reduced competition strongly increased the growth of A. platanoides seedlings. Seedling responses were independent of the conditions experienced by the mother tree during seed production and maturation. Our results indicate that, due to the negative effects of competition on the regeneration of A. platanoides, it is likely that under stronger competition (projected under future climatic conditions) this species will be negatively affected in terms of germination, survival and seedling biomass. Climate-change experiments including both abiotic and biotic factors constitute a key step forward to better understand the response of tree species' regeneration to climate change. (C) 2015 Elsevier B.V. All rights reserved.}, language = {en} } @article{GraaeVerheyenKolbetal.2009, author = {Graae, Bente Jessen and Verheyen, Kris and Kolb, Annette and van der Veken, Sebastian and Heinken, Thilo and Chabrerie, Olivier and Diekmann, Martin and Valtinat, Karin and Zindel, Renate and Karlsson, Elisabeth and Str{\"o}m, Lotta and Decocq, Guillaume and Hermy, Martin and Baskin, Carol C.}, title = {Germination requirements and seed mass of slow- and fast-colonizing temperate forest herbs along a latitudinal gradient}, issn = {1195-6860}, doi = {10.2980/16-2-3234}, year = {2009}, abstract = {Predictions on displacement of suitable habitats due to climate change suggest that plant species with poor colonization ability may be unable to move fast enough to match forecasted climate-induced changes in habitat distribution. However, studies on early Holocene plant migration show fast migration of many plant species that are poor colonizers today. We hypothesize that warmer temperatures during the early Holocene yielded higher seed quality, contributing to explaining the fast migration. We studied how the 3 seed quality variables, seed mass, germinability, and requirements for break of seed dormancy, vary for seeds of 11 forest herb species with varying colonization capacity collected along a 1400-km latitudinal gradient. Within species, seed mass showed a positive correlation with latitude, whereas germinability was more positively correlated with temperature (growing degree hours obtained at time of seed collection). Only slow-colonizing species increased germinability with temperature, whereas only fast-colonizing species increased germinability with latitude. These interactions were only detectable when analyzing germinability of the seeds, even though this trait and seed mass were correlated. The requirement for dormancy break did not correlate with latitude or temperature. The results indicate that seed development of slow colonizers may be favoured by a warmer climate, which in turn may be important for their migration capacity.}, language = {en} } @article{CaronDeFrenneChabrerieetal.2015, author = {Caron, Maria Mercedes and De Frenne, P. and Chabrerie, Olivier and Cousins, S. A. O. and De Backer, L. and Decocq, G. and Diekmann, M. and Heinken, Thilo and Kolb, A. and Naaf, T. and Plue, J. and Selvi, F. and Strimbeck, G. R. and Wulf, M. and Verheyen, Kris}, title = {Impacts of warming and changes in precipitation frequency on the regeneration of two Acer species}, series = {Flora : morphology, distribution, functional ecology of plants}, volume = {214}, journal = {Flora : morphology, distribution, functional ecology of plants}, publisher = {Elsevier}, address = {Jena}, issn = {0367-2530}, doi = {10.1016/j.flora.2015.05.005}, pages = {24 -- 33}, year = {2015}, language = {en} } @article{CaronDeFrenneBrunetetal.2015, author = {Caron, Maria Mercedes and De Frenne, Pieter and Brunet, J. and Chabrerie, Olivier and Cousins, S. A. O. and De Backer, L. and Decocq, G. and Diekmann, M. and Heinken, Thilo and Kolb, A. and Naaf, T. and Plue, J. and Selvi, Federico and Strimbeck, G. R. and Wulf, Monika and Verheyen, Kris}, title = {Interacting effects of warming and drought on regeneration and early growth of Acer pseudoplatanus and A. platanoides}, series = {Plant biology}, volume = {17}, journal = {Plant biology}, number = {1}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {1435-8603}, doi = {10.1111/plb.12177}, pages = {52 -- 62}, year = {2015}, abstract = {Climate change is acting on several aspects of plant life cycles, including the sexual reproductive stage, which is considered amongst the most sensitive life-cycle phases. In temperate forests, it is expected that climate change will lead to a compositional change in community structure due to changes in the dominance of currently more abundant forest tree species. Increasing our understanding of the effects of climate change on currently secondary tree species recruitment is therefore important to better understand and forecast population and community dynamics in forests. Here, we analyse the interactive effects of rising temperatures and soil moisture reduction on germination, seedling survival and early growth of two important secondary European tree species, Acer pseudoplatanus and A.platanoides. Additionally, we analyse the effect of the temperature experienced by the mother tree during seed production by collecting seeds of both species along a 2200-km long latitudinal gradient. For most of the responses, A.platanoides showed higher sensitivity to the treatments applied, and especially to its joint manipulation, which for some variables resulted in additive effects while for others only partial compensation. In both species, germination and survival decreased with rising temperatures and/or soil moisture reduction while early growth decreased with declining soil moisture content. We conclude that although A.platanoides germination and survival were more affected after the applied treatments, its initial higher germination and larger seedlings might allow this species to be relatively more successful than A.pseudoplatanus in the face of climate change.}, language = {en} } @article{CaronDeFrenneBrunetetal.2014, author = {Caron, Maria Mercedes and De Frenne, P. and Brunet, J. and Chabrerie, Olivier and Cousins, S. A. O. and De Backer, L. and Diekmann, M. and Graae, B. J. and Heinken, Thilo and Kolb, A. and Naaf, T. and Plue, J. and Selvi, F. and Strimbeck, G. R. and Wulf, Monika and Verheyen, Kris}, title = {Latitudinal variation in seeds characteristics of Acer platanoides and A. pseudoplatanus}, series = {Plant ecology : an international journal}, volume = {215}, journal = {Plant ecology : an international journal}, number = {8}, publisher = {Springer}, address = {Dordrecht}, issn = {1385-0237}, doi = {10.1007/s11258-014-0343-x}, pages = {911 -- 925}, year = {2014}, abstract = {Climate change will likely affect population dynamics of numerous plant species by modifying several aspects of the life cycle. Because plant regeneration from seeds may be particularly vulnerable, here we assess the possible effects of climate change on seed characteristics and present an integrated analysis of seven seed traits (nutrient concentrations, samara mass, seed mass, wing length, seed viability, germination percentage, and seedling biomass) of Acer platanoides and A. pseudoplatanus seeds collected along a wide latitudinal gradient from Italy to Norway. Seed traits were analyzed in relation to the environmental conditions experienced by the mother trees along the latitudinal gradient. We found that seed traits of A. platanoides were more influenced by the climatic conditions than those of A. pseudoplatanus. Additionally, seed viability, germination percentage, and seedling biomass of A. platanoides were strongly related to the seed mass and nutrient concentration. While A. platanoides seeds were more influenced by the environmental conditions (generally negatively affected by rising temperatures), compared to A. pseudoplatanus, A. platanoides still showed higher germination percentage and seedling biomass than A. pseudoplatanus. Thus, further research on subsequent life-history stages of both species is needed. The variation in seed quality observed along the climatic gradient highlights the importance of studying the possible impact of climate change on seed production and species demography.}, language = {en} } @article{LemkeKolbGraaeetal.2015, author = {Lemke, Isgard H. and Kolb, Annette and Graae, Bente J. and De Frenne, Pieter and Acharya, Kamal P. and Blandino, Cristina and Brunet, Jorg and Chabrerie, Olivier and Cousins, Sara A. O. and Decocq, Guillaume and Heinken, Thilo and Hermy, Martin and Liira, Jaan and Schmucki, Reto and Shevtsova, Anna and Verheyen, Kris and Diekmann, Martin}, title = {Patterns of phenotypic trait variation in two temperate forest herbs along a broad climatic gradient}, series = {Plant ecology : an international journal}, volume = {216}, journal = {Plant ecology : an international journal}, number = {11}, publisher = {Springer}, address = {Dordrecht}, issn = {1385-0237}, doi = {10.1007/s11258-015-0534-0}, pages = {1523 -- 1536}, year = {2015}, abstract = {Phenotypic trait variation plays a major role in the response of plants to global environmental change, particularly in species with low migration capabilities and recruitment success. However, little is known about the variation of functional traits within populations and about differences in this variation on larger spatial scales. In a first approach, we therefore related trait expression to climate and local environmental conditions, studying two temperate forest herbs, Milium effusum and Stachys sylvatica, along a similar to 1800-2500 km latitudinal gradient. Within each of 9-10 regions in six European countries, we collected data from six populations of each species and recorded several variables in each region (temperature, precipitation) and population (light availability, soil parameters). For each plant, we measured height, leaf area, specific leaf area, seed mass and the number of seeds and examined environmental effects on within-population trait variation as well as on trait means. Most importantly, trait variation differed both between and within populations. Species, however, differed in their response. Intrapopulation variation in Milium was consistently positively affected by higher mean temperatures and precipitation as well as by more fertile local soil conditions, suggesting that more productive conditions may select for larger phenotypic variation. In Stachys, particularly light availability positively influenced trait variation, whereas local soil conditions had no consistent effects. Generally, our study emphasises that intra-population variation may differ considerably across larger scales-due to phenotypic plasticity and/or underlying genetic diversity-possibly affecting species response to global environmental change.}, language = {en} } @article{deFrenneGraaeKolbetal.2010, author = {de Frenne, Pieter and Graae, Bente Jessen and Kolb, Annette and Brunet, J{\"o}rg and Chabrerie, Olivier and Cousins, Sara A. O. and Decocq, Guillaume and Dhondt, Rob and Diekmann, Martin and Eriksson, Olof and Heinken, Thilo and Hermy, Martin and J{\"o}gar, uelle and Saguez, Robert and Shevtsova, Anna and Stanton, Sharon and Zindel, Renate and Zobel, Martin and Verheyen, Kris}, title = {Significant effects of temperature on the reproductive output of the forest herb Anemone nemorosa L.}, issn = {0378-1127}, doi = {10.1016/j.foreco.2009.04.038}, year = {2010}, abstract = {Climate warming is already influencing plant migration in different parts of the world. Numerous models have been developed to forecast future plant distributions. Few studies, however, have investigated the potential effect of warming on the reproductive output of plants. Understorey forest herbs in particular, have received little attention in the debate on climate change impacts. This study focuses on the effect of temperature on sexual reproductive output (number of seeds, seed mass, germination percentage and seedling mass) of Anemone nemorosa L., a model species for slow colonizing herbaceous forest plants. We sampled seeds of A. nemorosa in populations along a 2400 km latitudinal gradient from northern France to northern Sweden during three growing seasons (2005,2006 and 2008). This study design allowed us to isolate the effects of accumulated temperature (Growing Degree Hours; GDH) from latitude and the local abiotic and biotic environment. Germination and seed sowing trials were performed in incubators, a greenhouse and under field conditions in a forest. Finally, we disentangled correlations between the different reproductive traits of A. nemorosa along the latitudinal gradient. We found a clear positive relationship between accumulated temperature and seed and seedling traits: reproductive output of A. nemorosa improved with increasing GDH along the latitudinal gradient. Seed mass and seedling mass, for instance, increased by 9.7\% and 10.4\%, respectively, for every 1000 degrees C h increase in GDH. We also derived strong correlations between several seed and seedling traits both under field conditions and in incubators. Our results indicate that seed mass, incubator-based germination percentage (Germ\%(Inc)) and the output of germinable seeds (product of number of seeds and Germ\%(Inc) divided by 100) from plants grown along a latitudinal gradient (i.e. at different temperature regimes) provide valuable proxies to parameterize key population processes in models. We conclude that (1) climate warming may have a pronounced positive impact on sexual reproduction of A. nemorosa and (2) climate models forecasting plant distributions would benefit from including the temperature sensitivity of key seed traits and population processes.}, language = {en} }