Land use change has been a major problem since the 20th century due to its contributions to biodiversity loss, as well as landscape fragmentation and degradation. These land use changes are often through agricultural intensification or abandonment, especially in calcareous grasslands (those on thin basic soil, such as chalk or limestone, with short and hardy vegetation – see image below). Due to calcareous grasslands having a high biodiversity and species richness, but also facing a severe decline due to fragmentation and land use change, conservation here is desperately needed. Therefore Loos et al. (2021) explored the local and landscape effects of calcareous grassland fragmentation on different taxonomic groups, and especially their diversity patterns, in order to understand the effects on different scales and identify future conservation options.
The authors surveyed 31 grassland fragments near Göttingen, Germany for vascular plants, butterflies and birds, using regression modelling to visualise the relationships between different environmental and ecological variables such as species richness, fragment size and percentage cover of arable land in the landscape.
Loos et al. (2021) observed 283 plant species, 53 butterfly species and 70 bird species, of which 59 plants, 19 butterfly, and 9 bird species were grassland specialists (specialised to grassland ecosystems). The authors also found that larger grassland fragments could support more species richness of both specialist and non-specialist plants, but not butterflies or birds, therefore both small and large fragments were important for biodiversity maintenance. Increasing the percentage cover of arable land within the grassland landscape could cause the loss of up to a third of plant species, along with some butterfly species, while birds were unaffected. Birds in particular were less affected by fragmentation, land use change, and connectivity of grasslands due to their high mobility.
The authors found that some results did not match their expectations, such as the often confirmed assumption that large habitats increased species richness, which was not the case in this research. They highlighted that considering both habitat area and connectivity could be important in explaining patterns in species diversity, as these were largely interlinked and had domino effects on taxonomic groups. Loos et al. (2021) emphasised that biodiversity management, especially in the long-term, should target local and landscape scales, and include both small and large grassland fragment conservation in order to reduce the amount of biodiversity lost to agricultural expansion or land abandonment. Consulting and including local peoples in conservation efforts and increasing stewardship were suggested by the authors as potentially fruitful alternatives to official management.
Loos et al. (2021) concluded that calcareous grasslands face a number of conservation threats, and their status as high-biodiversity landscapes is largely dependent on the maintenance of their connectivity and quality through small-scale management. Small grassland fragments are especially threatened by abandonment and shrub encroachment, therefore attention should be paid to both small and large grassland fragments in conservation efforts. To tackle this issue, the authors argued that new and less formal maintenance approaches are needed to conserve these grasslands and maintain biodiversity.
Check out this full paper by Loos et al. (2021) here.
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