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The continuous decline in biodiversity in some European landscapes has led recently to the (re-) implementation of low-intensity grazing systems as an alternative to more cost-intensive conservation practices. This approach aims at developing habitat complexes comprising various successional stages and increasing plant species diversity on local (a-diversity) and landscape scales (b-, y-diversity). The primary objectives of this review were to uncover ecological processes in which large domestic herbivores (cattle, equids, sheep, goats, pigs) have a key function in affecting plant diversity and to provide a framework for future research and conservation practices. The reviewed literature covers a wide range of ecosystem types in various temperate regions of Europe with a main focus on recent results from Central Europe. Low-intensity grazing enhances existing environmental gradients and generates manifold disturbance patterns on various spatial scales resulting in high habitat diversity. Livestock trampling has a so far underestimated impact on plant species composition and richness. Additionally, selective herbivore behavior facilitates the coexistence of plant species representing different functional types including a considerable number of threatened and grazing-sensitive species. Co-occurrence of progressive and regressive successional processes on low-intensive pastures results in a high b- and y-diversity, an effect that has been observed soon after the (re-)implementation of grazing. Persistence of speciespoor successional stages of dominant competitive graminoid and herb species can in many cases be inhibited by grazing. Large domestic herbivores serve as effective vectors for the dispersal of diaspores, thus improving the connectivity of isolated plant populations. There is a combined effect of diaspore dispersal and microsite creation which can increase the probability of diaspores to successfully germinate and establish. Overall, low-intensity grazing represents a highly flexible concept to maintain and restore plant diversity in cultivated landscapes; general management implications are given.
Cryptogams form a large part of dry grassland plant species richness. As a frequently used tool in grassland restoration, hay transfer is known to transfer cryptogam species. This might result in cryptogam stands differing from those achieved by natural succession. To assess hay transfer as a medium for cryptogam restoration, I analysed species composition of cryptogams in the hay of dry grasslands in Southern Germany, how fast they establish, and how fast they colonize adjacent plots. Cryptogam samples from hay showed species combinations similar to those of the mown sites and large shoot numbers to be present in the hay. Even low-growing and rare species were found in the hay. Hay receptor sites showed larger pleurocarpous moss and fruticose lichen patches than comparable sites without hay transfer, indicating earlier arrival of viable diaspores at the receptor sites. For acrocarpous mosses that colonize new sites by spores, no differences in turf size between succession and restoration plots were found. This shows that species transferred by hay have a distinct advantage over species that have to arrive at newly opened sites by natural means, i.e. many years later. The colonization from small restoration sites into adjacent areas without hay transfer proceeds with moderate speeds of about 1 to 2 m per year, probably with wind drift as the most important dispersal agent. Abundant cryptogam species including most pleurocarpous mosses and some Cladonia species rarely producing spores will be greatly enhanced by hay transfer. Nevertheless, the facilitation of pleurocarpous mosses may be detrimental to acrocarpous moss and epigaeic and saxicolous lichen species diversity, which should be considered in dry grassland restoration. I suggest a combination of different restoration measures in a mosaic pattern to create suitable conditions for a maximum of cryptogam species.