TY - JOUR A1 - Düvel, Martina A1 - Ristow, Michael A1 - Scholz, Hildemar T1 - Scolochloa marchica sp. nova : ein neues Röhrichtgras aus Mitteleuropa Y1 - 2001 SN - 0014-8962 ER - TY - JOUR A1 - Fischer, Wolfgang A1 - Ristow, Michael T1 - Bericht über die 31. Brandenburgische Botanikertagung vom 23. bis 26. Juni 2000 in Linowsee bei Rheinsberg Y1 - 2002 ER - TY - JOUR A1 - Gemeinholzer, B. A1 - May, F. A1 - Ristow, Michael A1 - Batsch, C. A1 - Lauterbach, D. T1 - Strong genetic differentiation on a fragmentation gradient among populations of the heterocarpic annual Catananche lutea L. (Asteraceae) JF - Plant systematics and evolution N2 - In landscapes which are predominately characterised by agriculture, natural ecosystems are often reduced to a mosaic of scattered patches of natural vegetation. Species with formerly connected distribution ranges now have restricted gene flow among populations. This has isolating effects upon population structure, because species are often confined by their limited dispersal capabilities. In this study, we test the effects of habitat fragmentation, precipitation, and isolation of populations on the genetic structure (AFLP) and fitness of the Asteraceae Catananche lutea. Our study area is an agro-dominated ecosystem in the desert-Mediterranean transition zone of the Southern Judea Lowlands in Israel. Our analysis revealed an intermediate level of intra-population genetic diversity across the study site with reduced genetic diversity on smaller scale. Although the size of the whole study area was relatively small (20 x 45 km), we found isolation by distance to be effective. We detected a high level of genetic differentiation among populations but genetic structure did not reflect spatial patterns. Population genetic diversity was correlated neither with position along the precipitation gradient nor with different seed types or other plant fitness variables in C. lutea. KW - AFLP KW - Heterocarpy KW - Population structure KW - Precipitation gradient KW - Asteraceae Y1 - 2012 U6 - https://doi.org/10.1007/s00606-012-0661-1 SN - 0378-2697 VL - 298 IS - 8 SP - 1585 EP - 1596 PB - Springer CY - Wien ER - TY - JOUR A1 - Giladi, Itamar A1 - May, Felix A1 - Ristow, Michael A1 - Jeltsch, Florian A1 - Ziv, Yaron T1 - Scale-dependent species-area and species-isolation relationships: a review and a test study from a fragmented semi-arid agro-ecosystem JF - Journal of biogeography N2 - Aim Patterns that relate species richness with fragment area (the species-area relationship, SAR) and with isolation (the species-isolation relationship, SIR) are well documented. However, those that relate species density - the number of species within a standardized area - with fragment area (D-SAR) or isolation (D-SIR) have not been sufficiently explored, despite the potential for such an analysis to disentangle the underlying mechanisms of SARs and SIRs. Previous spatial theory predicts that a significant D-SAR or D-SIR is unlikely to emerge in taxa with high dispersal limitation, such as plants. Furthermore, a recent model predicts that the detection and the significance of D-SARs or D-SIRs may decrease with grain size. We combined a literature review with grain size-dependent sampling in a fragmented landscape to evaluate the prevalence and grain size-dependent nature of D-SARs and D-SIRs in plants. Location Worldwide (review) and a semi-arid agro-ecosystem in Israel (case study). Methods We combined an extensive literature review of 31 D-SAR studies of plants in fragmented landscapes with an empirical study in which we analysed grain size-dependent D-SARs and D-SIRs using a grain size-dependent hierarchical sampling of species density and species richness in a fragmented, semi-arid agro-ecosystem. Results We found that significantly increasing D-SARs are rare in plant studies. Furthermore, we found that the detection of a significant D-SAR is often possible only after the data have been stratified by species, habitat or landscape characteristics. The results from our case study indicated that the significance and the slopes of both D-SARs and D-SIRs increase as grain size decreases. Main conclusions These results call for a careful consideration of scale while analysing and interpreting the responses of species richness and species density to fragmentation. Our results suggest that grain size-dependent analyses of D-SARs and D-SIRs may help to disentangle the mechanisms that generate SARs and SIRs and may enable early detection of the effects of fragmentation on plant biodiversity. KW - species density KW - isolation KW - scale-dependence KW - habitat fragmentation KW - extinction debt KW - Conservation biogeography KW - species-area relationship KW - island ecology KW - habitat islands KW - island biogeography theory Y1 - 2014 U6 - https://doi.org/10.1111/jbi.12299 SN - 0305-0270 SN - 1365-2699 VL - 41 IS - 6 SP - 1055 EP - 1069 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Groth, Birgit A1 - Seitz, Birgit A1 - Ristow, Michael T1 - Naturschutzfachlich geeignete Baum- und Straucharten für die Verwendung bei Kompensationsmaßnahmen in der freien Landschaft in Brandenburg Y1 - 2003 ER - TY - JOUR A1 - Hanspach, Dietrich A1 - Ristow, Michael T1 - Bericht über die 34. Brandenburgische Botanikertagung vom 20. bis 23. Juni 2003 in Ortrand Y1 - 2005 ER - TY - JOUR A1 - Horn, Sebastian A1 - Hempel, Stefan A1 - Ristow, Michael A1 - Rillig, Matthias C. A1 - Kowarik, Ingo A1 - Caruso, Tancredi T1 - Plant community assembly at small scales: Spatial vs. environmental factors in a European grassland JF - Acta oecologica : international journal of ecology N2 - Dispersal limitation and environmental conditions are crucial drivers of plant species distribution and establishment. As these factors operate at different spatial scales, we asked: Do the environmental factors known to determine community assembly at broad scales operate at fine scales (few meters)? How much do these factors account for community variation at fine scales? In which way do biotic and abiotic interactions drive changes in species composition? We surveyed the plant community within a dry grassland along a very steep gradient of soil characteristics like pH and nutrients. We used a spatially explicit sampling design, based on three replicated macroplots of 15 x 15, 12 x 12 and 12 x 12 m in extent. Soil samples were taken to quantify several soil properties (carbon, nitrogen, plant available phosphorus, pH, water content and dehydrogenase activity as a proxy for overall microbial activity). We performed variance partitioning to assess the effect of these variables on plant composition and statistically controlled for spatial autocorrelation via eigenvector mapping. We also applied null model analysis to test for non-random patterns in species co-occurrence using randomization schemes that account for patterns expected under species interactions. At a fine spatial scale, environmental factors explained 18% of variation when controlling for spatial autocorrelation in the distribution of plant species, whereas purely spatial processes accounted for 14% variation. Null model analysis showed that species spatially segregated in a non-random way and these spatial patterns could be due to a combination of environmental filtering and biotic interactions. Our grassland study suggests that environmental factors found to be directly relevant in broad scale studies are present also at small scales, but are supplemented by spatial processes and more direct interactions like competition. (C) 2015 Elsevier Masson SAS. All rights reserved. KW - Assembly pattern KW - Dispersal limitation KW - Festuca brevipila KW - Niche partitioning KW - Null model KW - Plant community ecology KW - Variance partitioning Y1 - 2015 U6 - https://doi.org/10.1016/j.actao.2015.01.004 SN - 1146-609X SN - 1873-6238 VL - 63 SP - 56 EP - 62 PB - Elsevier CY - Paris ER - TY - JOUR A1 - Lauterbach, D. A1 - Roemermann, C. A1 - Jeltsch, Florian A1 - Ristow, Michael T1 - Factors driving plant rarity in dry grasslands on different spatial scales: a functional trait approach JF - BIODIVERSITY AND CONSERVATION N2 - 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. KW - Species frequency KW - Species endangerment KW - Fragmentation KW - Eutrophication KW - SLA Y1 - 2013 U6 - https://doi.org/10.1007/s10531-013-0455-y SN - 0960-3115 VL - 22 IS - 10 SP - 2337 EP - 2352 PB - SPRINGER CY - DORDRECHT ER - TY - JOUR A1 - Lauterbach, Daniel A1 - Ristow, Michael A1 - Gemeinholzer, Birgit T1 - Population genetics and fitness in fragmented populations of the dioecious and endangered Silene otites (Caryophyllaceae) JF - Plant systematics and evolution N2 - Population fragmentation is often correlated with loss of genetic diversity and reduced fitness. Obligate out-crossing (dioecy) is expected to enhance genetic diversity, reduce genetic differentiation, and avoid inbreeding depression through frequent gene flow. However, in highly fragmented populations dioecy has only diminishing effects upon genetic structure as pollination limitations (e.g. flight distance of pollinators) most often restrict inter-population gene flow in insect pollinated species. In fragmented dry grasslands in northeastern Germany, we analysed genetic structure, fitness, and habitat quality of the endangered dioecious Silene otites (Caryophyllaceae). Using AFLP markers, a high level of differentiation among ten populations was found (F (st) = 0.36), while the intra-population genetic diversities (H (E) = 0.165-0.240) were similar as compared to hermaphroditic species. There was neither a correlation between geographic and genetic distance nor between genetic diversity and population size, which indicates reduced gene flow among populations and random genetic drift. Plant size was positively correlated with genetic diversity. Seed set and number of juveniles were positively related to population size. Higher total coverage resulted in reduced plant fitness, and the number of juveniles was negatively correlated to cryptogam cover. Additionally, we found a sex ratio bias towards more male plants in larger populations. Overall, our results indicate that on a regional geographic scale dioecy does not necessarily prevent genetic erosion in the case of habitat fragmentation, especially in the absence of long distance seed and pollen dispersal capacity. KW - AFLP KW - Population size KW - Mating system KW - Isolation by distance KW - Sex ratio Y1 - 2012 U6 - https://doi.org/10.1007/s00606-011-0533-0 SN - 0378-2697 VL - 298 IS - 1 SP - 155 EP - 164 PB - Springer CY - Wien ER - TY - JOUR A1 - Lauterbach, Dirk A1 - Ristow, Michael A1 - Gemeinholzer, B. T1 - Genetic population structure, fitness variation and the importance of population history in remnant populations of the endangered plant Silene chlorantha (Willd.) Ehrh. (Caryophyllaceae) JF - Plant biology N2 - Habitat fragmentation can lead to a decline of genetic diversity, a potential risk for the survival of natural populations. Fragmented populations can become highly differentiated due to reduced gene flow and genetic drift. A decline in number of individuals can result in lower reproductive fitness due to inbreeding effects. We investigated genetic variation within and between 11 populations of the rare and endangered plant Silene chlorantha in northeastern Germany to support conservation strategies. Genetic diversity was evaluated using AFLP techniques and the results were correlated to fitness traits. Fitness evaluation in nature and in a common garden approach was conducted. Our analysis revealed population differentiation was high and within population genetic diversity was intermediate. A clear population structure was supported by a Bayesian approach, AMOVA and neighbour-joining analysis. No correlation between genetic and geographic distance was found. Our results indicate that patterns of population differentiation were mainly caused by temporal and/or spatial isolation and genetic drift. The fitness evaluation revealed that pollinator limitation and habitat quality seem, at present, to be more important to reproductive fitness than genetic diversity by itself. Populations of S. chlorantha with low genetic diversity have the potential to increase in individual number if habitat conditions improve. This was detected in a single large population in the investigation area, which was formerly affected by bottleneck effects. KW - AFLP KW - fitness KW - population genetic structure KW - population history Y1 - 2011 U6 - https://doi.org/10.1111/j.1438-8677.2010.00418.x SN - 1435-8603 VL - 13 IS - 4 SP - 667 EP - 677 PB - Wiley-Blackwell CY - Hoboken ER -