@unpublished{CierjacksKowarikJoshietal.2013, author = {Cierjacks, Arne and Kowarik, Ingo and Joshi, Jasmin Radha and Hempel, Stefan and Ristow, Michael and von der Lippe, Moritz and Weber, Ewald}, title = {Biological flora of the british isles: robinia pseudoacacia}, series = {The journal of ecology}, volume = {101}, journal = {The journal of ecology}, number = {6}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0022-0477}, doi = {10.1111/1365-2745.12162}, pages = {1623 -- 1640}, year = {2013}, abstract = {This account presents information on all aspects of the biology of Robinia pseudoacacia L. that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, and history and conservation.Robinia pseudoacacia, false acacia or black locust, is a deciduous, broad-leaved tree native to North America. The medium-sized, fast-growing tree is armed with spines, and extensively suckering. It has become naturalized in grassland, semi-natural woodlands and urban habitats. The tree is common in the south of the British Isles and in many other regions of Europe.Robinia pseudoacacia is a light-demanding pioneer species, which occurs primarily in disturbed sites on fertile to poor soils. The tree does not tolerate wet or compacted soils. In contrast to its native range, where it rapidly colonizes forest gaps and is replaced after 15-30years by more competitive tree species, populations in the secondary range can persist for a longer time, probably due to release from natural enemies.Robinia pseudoacacia reproduces sexually, and asexually by underground runners. Disturbance favours clonal growth and leads to an increase in the number of ramets. Mechanical stem damage and fires also lead to increased clonal recruitment. The tree benefits from di-nitrogen fixation associated with symbiotic rhizobia in root nodules. Estimated symbiotic nitrogen fixation rates range widely from 23 to 300kgha(-1)year(-1). The nitrogen becomes available to other plants mainly by the rapid decay of nitrogen-rich leaves.Robinia pseudoacacia is host to a wide range of fungi both in the native and introduced ranges. Megaherbivores are of minor significance in Europe but browsing by ungulates occurs in the native range. Among insects, the North American black locust gall midge (Obolodiplosis robiniae) is specific to Robinia and is spreading rapidly throughout Europe. In parts of Europe, Robinia pseudoacacia is considered an invasive non-indigenous plant and the tree is controlled. Negative impacts include shading and changes of soil conditions as a result of nitrogen fixation.}, language = {en} } @article{LauterbachRoemermannJeltschetal.2013, author = {Lauterbach, D. and Roemermann, C. and Jeltsch, Florian and Ristow, Michael}, title = {Factors driving plant rarity in dry grasslands on different spatial scales: a functional trait approach}, series = {BIODIVERSITY AND CONSERVATION}, volume = {22}, journal = {BIODIVERSITY AND CONSERVATION}, number = {10}, publisher = {SPRINGER}, address = {DORDRECHT}, issn = {0960-3115}, doi = {10.1007/s10531-013-0455-y}, pages = {2337 -- 2352}, year = {2013}, abstract = {In European dry grasslands land-use changes affect plant species performance and frequency. Potential driving forces are eutrophication and habitat fragmentation. The importance of these factors is presumably scale dependent. We used a functional trait approach to detect processes that influence species frequency and endangerment on different spatial scales. We tested for associations between functional traits and (1) frequency and (2) degree of endangerment on local, regional and national scales. We focussed on five selected traits that describe the life-history of plant species and that are related to competition, dispersal ability and habitat specificity. Trait data on plant height, SLA, plant coverage, peak of flowering and diaspore mass were measured for 28 perennials from common to rare and endangered to non-endangered on 59 dry grassland sites in north-eastern Germany. Multiple regression models revealed that species frequency is positively and species endangerment negatively related to plant height, plant coverage and SLA on more than one spatial scale. On the local scale, diaspore mass has a negative effect on species frequency. More frequent and less endangered species show a later peak of flowering on nationwide and regional scales. We concluded that competition traits are more important on larger scales, whereas dispersal traits are more important for species frequency on the smaller scale. On national and regional scales, eutrophication and habitat loss may be the main drivers of species threat, whereas on the local scale fragmentation plays a crucial role for the performance of dry grassland species.}, language = {en} } @article{MayGiladiRistowetal.2013, author = {May, Felix and Giladi, Itamar and Ristow, Michael and Ziv, Yaron and Jeltsch, Florian}, title = {Metacommunity, mainland-island system or island communities? : assessing the regional dynamics of plant communities in a fragmented landscape}, series = {Ecography : pattern and diversity in ecology ; research papers forum}, volume = {36}, journal = {Ecography : pattern and diversity in ecology ; research papers forum}, number = {7}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0906-7590}, doi = {10.1111/j.1600-0587.2012.07793.x}, pages = {842 -- 853}, year = {2013}, abstract = {Understanding the regional dynamics of plant communities is crucial for predicting the response of plant diversity to habitat fragmentation. However, for fragmented landscapes the importance of regional processes, such as seed dispersal among isolated habitat patches, has been controversially debated. Due to the stochasticity and rarity of among-patch dispersal and colonization events, we still lack a quantitative understanding of the consequences of these processes at the landscape-scale. In this study, we used extensive field data from a fragmented, semi-arid landscape in Israel to parameterize a multi-species incidence-function model. This model simulates species occupancy pattern based on patch areas and habitat configuration and explicitly considers the locations and the shapes of habitat patches for the derivation of patch connectivity. We implemented an approximate Bayesian computation approach for parameter inference and uncertainty assessment. We tested which of the three types of regional dynamics - the metacommunity, the mainland-island, or the island communities type - best represents the community dynamics in the study area and applied the simulation model to estimate the extinction debt in the investigated landscape. We found that the regional dynamics in the patch-matrix study landscape is best represented as a system of highly isolated island' communities with low rates of propagule exchange among habitat patches and consequently low colonization rates in local communities. Accordingly, the extinction rates in the local communities are the main drivers of community dynamics. Our findings indicate that the landscape carries a significant extinction debt and in model projections 33-60\% of all species went extinct within 1000 yr. Our study demonstrates that the combination of dynamic simulation models with field data provides a promising approach for understanding regional community dynamics and for projecting community responses to habitat fragmentation. The approach bears the potential for efficient tests of conservation activities aimed at mitigating future losses of biodiversity.}, language = {en} } @article{MayGiladiRistowetal.2013, author = {May, Felix and Giladi, Itamar and Ristow, Michael and Ziv, Yaron and Jeltsch, Florian}, title = {Plant functional traits and community assembly along interacting gradients of productivity and fragmentation}, series = {Perspectives in plant ecology, evolution and systematics}, volume = {15}, journal = {Perspectives in plant ecology, evolution and systematics}, number = {6}, publisher = {Elsevier}, address = {Jena}, issn = {1433-8319}, doi = {10.1016/j.ppees.2013.08.002}, pages = {304 -- 318}, year = {2013}, abstract = {Quantifying the association of plant functional traits to environmental gradients is a promising approach for understanding and projecting community responses to land use and climatic changes. Although habitat fragmentation and climate are expected to affect plant communities interactively, there is a lack of empirical studies addressing trait associations to fragmentation in different climatic regimes. In this study, we analyse data on the key functional traits: specific leaf area (SLA), plant height, seed mass and seed number. First, we assess the evidence for the community assembly mechanisms habitat filtering and competition at different spatial scales, using several null-models and a comprehensive set of community-level trait convergence and divergence indices. Second, we analyse the association of community-mean traits with patch area and connectivity along a south-north productivity gradient. We found clear evidence for trait convergence due to habitat filtering. In contrast, the evidence for trait divergence due to competition fundamentally depended on the null-model used. When the null-model controlled for habitat filtering, there was only evidence for trait divergence at the smallest sampling scale (0.25 m x 0.25 m). All traits varied significantly along the S-N productivity gradient. While plant height and SLA were consistently associated with fragmentation, the association of seed mass and seed number with fragmentation changed along the S-N gradient. Our findings indicate trait convergence due to drought stress in the arid sites and due to higher productivity in the mesic sites. The association of plant traits to fragmentation is likely driven by increased colonization ability in small and/or isolated patches (plant height, seed number) or increased persistence ability in isolated patches (seed mass). Our study provides the first empirical test of trait associations with fragmentation along a productivity gradient. We conclude that it is crucial to study the interactive effects of different ecological drivers on plant functional traits.}, language = {en} }