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Plant-soil feedbacks (PSFs) underlying grassland plant richness and productivity are typically coupled with nutrient availability; however, we lack understanding of how restoration measures to increase plant diversity might affect PSFs. We examined the roles of sward disturbance, seed addition and land-use intensity (LUI) on PSFs.We conducted a disturbance and seed addition experiment in ten grasslands along a LUI gradient and characterized plant biomass and richness, soil microbial biomass, community composition and enzyme activities.Greater plant biomass at high LUI was related to a decrease in the fungal to bacterial ratios, indicating highly productive grasslands to be dominated by bacteria. Lower enzyme activity per microbial biomass at high plant species richness indicated a slower C cycling. The relative abundance of fungal saprotrophs decreased, while pathogens increased with LUI and disturbance. Both fungal guilds were negatively associated with plant richness, indicating the mechanisms underlying PSFs depended on LUI.We show that LUI and disturbance affect fungal functional composition, which may feedback on plant species richness by impeding the establishment of pathogen-sensitive species. Therefore, we highlight the need to integrate LUI including its effects on PSFs when planning for practices that aim to optimize plant diversity and productivity.

Aim Large and ecologically functioning steppe complexes have been lost historically across the globe, but recent land‐use changes may allow the reversal of this trend in some regions. We aimed to develop and map indicators of changing human influence using satellite imagery and historical maps, and to use these indicators to identify areas for broad‐scale steppe rewilding. Location Eurasian steppes of Kazakhstan. Methods We mapped decreasing human influence indicated by cropland abandonment, declining grazing pressure and rural outmigration in the steppes of northern Kazakhstan. We did this by processing ~5,500 Landsat scenes to map changes in cropland between 1990 and 2015, and by digitizing Soviet topographic maps and examining recent high‐resolution satellite imagery to assess the degree of abandonment of >2,000 settlements and >1,300 livestock stations. We combined this information into a human influence index (HI), mapped changes in HI to highlight where rewilding might take place and assessed how this affected the connectivity of steppe habitat. Results Across our study area, about 6.2 million ha of cropland were abandoned (30.5%), 14% of all settlements were fully and 81% partly abandoned, and 76% of livestock stations were completely dismantled between 1990 and 2015, suggesting substantially decreasing human pressure across vast areas. This resulted in increased connectivity of steppe habitat. Main conclusions The steppes of Eurasia are experiencing massively declining human influence, suggesting large‐scale passive rewilding is taking place. Many of these areas are now important for the connectivity of the wider steppe landscape and can provide habitat for endangered megafauna such as the critically endangered saiga antelope. Yet, this window of opportunity may soon close, as recultivation of abandoned cropland is gaining momentum. Our aggregate human influence index captures key components of rewilding and can help to devise strategies for fo

QUESTION: How do contrasting influences of inundation and historical land uses affect restoration of soil propagule bank composition in floodplain wetlands? LOCATION: Northern Nature Reserve (large ephemeral floodplain), Macquarie Marshes, New South Wales, Australia. METHODS: We conducted germination assays on soil samples collected from fields with different land‐use histories, stratified along an inundation gradient. We used GLM to determine whether native and exotic species richness and abundance varied along gradients of inundation and land use. RESULTS: Species richness and plant abundance in soil propagule banks were positively related to inundation and negatively related to intense historic land use. The abundance of native species was significantly higher in more frequently inundated areas. Abundances of exotic and ruderal species were higher in areas of intense prior land use. Overall species richness was generally similar across land‐use histories. CONCLUSIONS: Land‐use legacies compromised the ability of propagule banks to rejuvenate native vegetation in this floodplain wetland, especially in less frequently flooded parts of the floodplain, which harboured more ruderal and exotic species. Negative effects of prior land use may be alleviated by increased inundation. Native soil propagule banks were remarkably intact, providing a reservoir for restoration of wetland vegetation, even in soils highly disturbed by up to 20 yr of agricultural cropping. With appropriate inundation, soil propagule banks in less degraded areas of the Macquarie Marshes can provide diverse mixtures of desired species in high abundance but, in highly degraded areas, full restoration may be delayed.

One of the key questions in ecosystem restoration is the choice of seed material for restoring plant communities. More and more scientists and practitioners are currently advocating the use of regional seed sources, based on the argument that plants are often adapted to local or regional environmental conditions, and thus, regional seed sources should provide the best restoration success. However, there is still substantial debate about this approach, partly because of a lack of solid empirical data.We conducted a multispecies transplant experiment in which we compared the performance of eight seed origins of seven plant species frequently used in grassland restoration in four common gardens across Germany.We found that, on average, plants of regional origins produced 10% more inflorescences and 7% more biomass than those of foreign origins. There were substantial differences among species in the strength of these effects, but in the majority of the study species fitness decreased with increasing geographical distance of seed origins or with increasing climatic differences between plant origins and experimental sites.In addition to these effects on plant fitness, increasing geographical or climatic distances of origin were often also correlated with increasing differences in plant phenology. Since phenology is important for biotic interactions, especially with pollinators and seed predators, using foreign seed sources may have cascading effects on local ecosystems.Synthesis and applications. Genetic differentiation is widespread in grassland species and often shows the patterns of regional adaptation. Our study thus supports the use of regional seed sources in restoration. Moreover, using non-regional seed sources in grassland restoration may not only decrease the performance of plants, but it will likely also affect their biotic interactions.

Ecological restoration of grasslands is increasingly based on regional seeds derived from predefined seed transfer zones. However, the degree and spatial pattern of genetic differentiation among provenances of different seed transfer zones is largely unknown.We assessed the genetic differentiation among eight out of 22 German seed transfer zones for seven common grassland species (Arrhenatherum elatius, Centaurea jacea, Daucus carota, Galium album, Hypochaeris radicata, Knautia arvensis and Lychnis flos-cuculi) using AFLP markers. We analysed genetic population structure with AMOVA and Bayesian cluster analysis and tested for isolation by distance and isolation by environment.In all of the investigated species, almost all pairs of provenances were genetically differentiated. Bayesian cluster analysis revealed species-specific numbers and spatial patterns of gene pools, with between two (Arrhenatherum) and eight clusters (Lychnis). Most investigated seed transfer zones represented a unique gene pool in the majority of the species.We found isolation by distance in four species, isolation by environment, driven by climatic seasonality, in three species, and a lack of both in three species. Thus, the observed genetic differentiation appears to be caused by both neutral and adaptive processes.Synthesis and applications. Our study shows that grassland plants are indeed strongly genetically differentiated across Germany supporting the strategy of seed transfer zones for ecological restoration. Although the predefined seed transfer zones are unlikely to match the exact genetic structure of many species, they serve their purpose by capturing a substantial amount of intraspecific genetic variation across species.