Stockholms universitet

Rozália KapásDoktorand

Publikationer

I urval från Stockholms universitets publikationsdatabas

  • Grazing livestock increases both vegetation and seed bank diversity in remnant and restored grasslands

    2020. Rozália E. Kapás (et al.). Journal of Vegetation Science 31 (6), 1053-1065

    Artikel

    Questions: Restoring grasslands is of great importance to biodiversity conservation to counteract widespread, ongoing losses of plant species diversity. Using source populations in remnant habitats and increasing functional connectivity mediated by grazing animals within and between habitats can benefit grassland restoration efforts. Here we investigate how grazing contributes to vegetation and seed bank diversity and composition in remnant and restored grassland communities in fragmented landscapes.

    Location: Stockholm archipelago, Sweden.

    Methods: We investigated the effects of the presence or absence of grazing animals as potential elements of functional connectivity on grassland species composition in both the vegetation layer and in the seed bank. Species inventory and seed bank sampling were carried out in 2 m × 2 m plots in remnant grassland habitats and adjacent restored grasslands on former arable fields.

    Results: Species composition varied between remnant and restored grasslands, with management-dependent species more common in remnant grasslands. Remnant habitats with active grazing management contained a higher number of species in both the vegetation and seed bank compared to restored grasslands, but grazing reduced dispersal limitation from higher distance to source populations for specialist species. Where grazing was absent fewer plant species occurred in both the vegetation and in the seed bank.

    Conclusion: Our results show that grazing livestock play a key role in facilitating both spatial and temporal dispersal in fragmented grasslands. This results in increased species diversity in the vegetation and the seed bank of grazed grasslands compared to those maintained by mowing only. Functional connectivity provided by grazing management increases the possibility for species establishment from both the below-ground seed bank and the surrounding landscape, thus increasing the resilience of plant communities against disturbances or climatic changes.

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  • Grassland restoration: Connectivity, plant community change and cows

    2023. Rozália E. Kapás.

    Avhandling (Dok)

    The ecological significance of semi-natural grasslands is high because these habitats provide a home for a diverse flora and fauna and support a range of associated ecosystem services. Due to large-scale land-use changes the extent of grassland habitat has declined. Hence, restoration efforts to mitigate grassland losses are now being prioritized across the globe and there is an increasing need to understand the drivers behind the recovery of degraded habitats. Since many restoration initiatives rely on spontaneous dispersal of plant species from sources at both local- and landscape-scales, community assembly is influenced by a range of factors which interact both over time and across spatial scales. Given this complexity over the scales, gaps remain in our understanding of how post-restoration management can be designed to facilitate the effective dispersal and establishment of target species in restored grasslands.

    In this thesis, I examined colonization patterns in Swedish grasslands by comparing plant communities in both ancient and restored grasslands and under contrasting management regimes. At small spatial scales and over the short-term following restoration, I investigated species recruitment sources and their relative contribution to colonization and regeneration. At larger temporal and spatial scales, I examined how the composition of vegetation and seed bank communities is determined by local environmental factors together with distance to species pool and presence of grazing livestock.

    I found that species mostly colonized spatially from local species sources through seed rain. The seed bank contributed to species colonization to a greater extent in ancient grasslands than in restored grasslands. Management through livestock grazing and shorter distance to species pool were positively associated with the number of species found in grasslands. Grazing livestock facilitated target species establishment into restored sites and the differences between ancient and restored grassland communities were smaller when grazing was active, highlighting that ancient sites can provide a source of colonizing species for restored sites. I found that plant species associated with former land-use declined immediately following restoration, while the occurrence of target species generally increased. However, there was a high initial stochasticity in the establishment of the target species and communities in restored grasslands were still distinct from continuously managed sites even after several decades.

    These results demonstrate that species presence in nearby ancient grasslands and potential dispersal from the local seed sources drives species colonization in restored and ancient grasslands. Livestock grazing was shown to be an important driver of grassland recovery, either by mediating spatial dispersal of seeds or improving site conditions for establishment. Target species are able to accumulate in the vegetation and seed bank over the long-term, as restored grasslands age. This accumulation will ensure an increasing resilience of grassland communities against future disturbances or changes in the climate. However this depends upon active management, for example by implementing management plans which include continued livestock grazing, and upon conserving remaining ancient grasslands as hotspots for biodiversity within the wider landscape.

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  • Grassland species colonization of a restored grassland on a former forest varies in short-term success but is facilitated by greater functional connectivity

    2023. Rozália E. Kapás, Adam Kimberley, Sara A. O. Cousins. Nordic Journal of Botany

    Artikel

    In recent years, restoration on former grassland sites has been widely encouraged globally, aiming to address the historical loss of 90% of ancient species-rich grasslands, and to mitigate the associated threat to grassland biodiversity. The objective of our study was to investigate on a small-scale how plant species spontaneously colonize restored grasslands. We inventoried 275 permanent plots twice (in 2019 and 2021) in a restored grassland, following the removal of a conifer plantation. Species richness and vegetation cover in surveyed plots were dependent on grazing activity and distance to adjacent grassland. Plant species associated with forest habitats declined, while the occurrence of generalist species together with a few grassland specialists generally increased. However, not all grassland specialists gained occurrence and the colonization pattern was not consistent over time, possibly due to the lack of continuous seed arrival and low livestock activity and hence lack of disturbance. These results suggest that successful colonization of plant species benefits from links to species-rich sites adjacent to the restoration target, with spatial dispersal and improved conditions for species establishment being key to species occurrence. Both dispersal and establishment potential are likely facilitated through the presence of grazing livestock with access to both species-rich grasslands and restoration targets. However, the shift towards a more typical grassland community takes place gradually, with vulnerable populations of early colonizing grassland species prone to local extinction in short-term. As a result, continued functional connectivity provided by grazing animals is necessary to improve the diversity of the restored site and ensure the establishment of grassland specialists and to maintain the plant community composition. 

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