Does seed dispersal by sheep affect the population genetic structure of the calcareous grassland species Bromus erectus?     

Christian Willerding  Peter Poschlod 《Biological conservation》2002,104(3):329-337

This study investigates the contribution of the traditional land-use system “sheep herding” (transhumance) to the gene flow among populations. Three sheep trails with altogether 12 calcareous grassland sites were chosen for the analysis of the tussock grass Bromus erectus, which is known to be the species with the highest rate of dispersal via sheep fleece. Each trail links two to four isolated populations. Allozymes were chosen as genetic markers. Six loci were used, five of which were polymorphic. While genetic variability within populations was found to be quite high (averaged h=0.352), only little between-population differentiation was measured (G_ST=5.5%). Despite this, the UPGMA-dendrogram of Nei's genetic distance shows genetic similarity relations largely congruent with the sheep herding trails. However, a (more) detailed comparison reveals several differences between genetic patterns and trail system. Hence, additional factors other than dispersal by sheep are regarded as being responsible for exchange of genes, and sheep herding is considered to have only minor importance for the genetic patterns of the investigated species. The comparison of Bromus erectus to species with the same life history traits (i.e. pollination by wind, a perennial life cycle, and autopolyploid constitution) shows similar values, thus providing further evidence for the relatively small contribution of dispersal via sheep fleece.  相似文献   

Plant species extinction debt in a temperate biodiversity hotspot: Community, species and functional traits approaches   总被引：1，自引：0，他引：1  

Julien Piqueray  Emmanuelle Bisteau  Sara Cristofoli  Rodolphe Palm  Peter Poschlod  Grégory Mahy 《Biological conservation》2011,(5):1619-1629

Destruction and fragmentation of (semi-) natural habitats are considered the main causes of biodiversity loss worldwide. Plant species may exhibit a slow response to fragmentation, resulting in the development of an extinction debt in fragmented plant communities. The detection of extinction debt is of primary importance in habitat conservation strategies. We applied two different approaches proposed in the literature to identify extinction debt in South-East Belgium calcareous grasslands. The first method compared species richness between stable and fragmented habitat patches. The second explored correlations between current species richness and current and past landscape configurations using multiple regression analyses. We subsequently examined results generated by both methods. In addition, we proposed techniques to identify species that are more likely to support extinction debt and associated functional traits. We estimated a respective extinction debt of approximately 28% and 35% of the total and specialist species richness. Similar results were obtained from both methods. We identified 15 threatened specialist species under the current landscape configuration. It is likely the landscape configuration no longer supports the species habitat requirements. We demonstrated that non-clonal species are most threatened, as well as taxa that cannot persist in degraded habitats and form only sparsely distributed populations. We discussed our results in light of other studies in similar habitats, and the overall implications for habitat conservation.  相似文献   

Functional rather than structural connectivity explains grassland plant diversity patterns following landscape scale habitat loss     

Kimberley  Adam  Hooftman  Danny  Bullock  James M.  Honnay  Olivier  Krickl  Patricia  Lindgren  Jessica  Plue  Jan  Poschlod  Peter  Traveset  Anna  Cousins  Sara A. O. 《Landscape Ecology》2021,36(1):265-280

Context

Functional connectivity is vital for plant species dispersal, but little is known about how habitat loss and the presence of green infrastructure interact to affect both functional and structural connectivity, and the impacts of each on species groups.

Objectives

We investigate how changes in the spatial configuration of species-rich grasslands and related green infrastructure such as road verges, hedgerows and forest borders in three European countries have influenced landscape connectivity, and the effects on grassland plant biodiversity.

Methods

We mapped past and present land use for 36 landscapes in Belgium, Germany and Sweden, to estimate connectivity based on simple habitat spatial configuration (structural connectivity) and accounting for effective dispersal and establishment (functional connectivity) around focal grasslands. We used the resulting measures of landscape change to interpret patterns in plant communities.

Results

Increased presence of landscape connecting elements could not compensate for large scale losses of grassland area resulting in substantial declines in structural and functional connectivity. Generalist species were negatively affected by connectivity, and responded most strongly to structural connectivity, while functional connectivity determined the occurrence of grassland specialists in focal grasslands. Restored patches had more generalist species, and a lower density of grassland specialist species than ancient patches.

Conclusions

Protecting both species rich grasslands and dispersal pathways within landscapes is essential for maintaining grassland biodiversity. Our results show that increases in green infrastructure have not been sufficient to offset loss of semi-natural habitat, and that landscape links must be functionally effective in order to contribute to grassland diversity.

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Surrounding landscape structures,rather than habitat age,drive genetic variation of typical calcareous grassland plant species     

Lehmair  Theresa Anna  Pagel  Ellen  Poschlod  Peter  Reisch  Christoph 《Landscape Ecology》2020,35(12):2881-2893

Landscape Ecology - Land use change reduced calcareous grasslands throughout Europe during the last decades. Subsequent fragmentation and habitat deterioration led, moreover, to a massive...  相似文献   

The historical and socioeconomic perspective of calcareous grasslands—lessons from the distant and recent past     

Peter Poschlod  Michiel F WallisDeVries 《Biological conservation》2002,104(3):361-376

Calcareous grasslands are one of the most species-rich habitats and a central issue in nature conservation management in Europe. Comparative vegetation ecological studies let us suppose that calcareous grasslands did not exist before the neolithic age except on small and isolated areas such as hilly domes or outcrops in the Jurassic mountains and, therefore, they are man-made. Species number increased from the neolithic age whereas calcareous grasslands only spread since the Roman Empire which is evident from palynological and macrofossil findings. A historical analysis of the more recent times showed that the maximum of spread was only between the fifteenth and twentieth century, the period of large sheep flock migrations and transhumance. However, there were many different types of land use beside grazing from which calcareous grasslands developed such as alternate husbandry and three field rotation system. Practices to establish calcareous grasslands included also the sowing of hayseed. During the twentieth century, the number and area of calcareous grasslands decreased tremendously due to abandonment and afforestation since hay making and especially traditional shepherding became more and more uneconomical. Today, calcareous grasslands are threatened. Conservation management such as mowing was not able to maintain species richness and characteristic species, especially indicators of land use history. An integrative approach combining historical and socio-economic issues is proposed to maintain and to redevelop calcareous grasslands in Europe.  相似文献