Edaphic arthropods as indicators of the ecological condition of temperate grassland ecosystems: A systematic review

Abstract

Temperate grasslands are part of one of the biggest biomes on earth, sustaining high levels of biodiversity and providing multiple ecosystem services. However, the area covered by this open ecosystem is decreasing worldwide, due to several threats like land use change or climate change. Ground-dwelling arthropods are an important group of the community of grassland soil invertebrates, and they play a key role within this ecosystem, while at the same time being sensitive to the changes caused by management practices like grazing, mowing, prescribed fire, etc. Using the Web of Science database, we conducted a systematic review to identify which groups of arthropods are being used as indicators to evaluate the ecological condition of grasslands in temperate regions, and which indices are being measured. As grasslands have been traditionally managed by humans for centuries, their ecological condition is intrinsically linked to the development of different management practices like grazing, mowing or restoration strategies, which usually affect soil and vegetation structure. We found that macro-arthropods were used in a greater number of studies than micro-arthropods (91% vs 15%), and within that size group, beetles were the preferred indicator in most of the temperate grassland types (49% of the studies), followed by spiders and ants. Few studies used grasshoppers to monitor grasslands changes. The indices more frequently assessed were species richness and abundance, and we identified that the response to the different management practices was quite heterogeneous. Restoration and grazing effects were the two factors more frequently evaluated for macro-arthropods, while micro-arthropods (Acari and Collembola) were dominant to assess land use type. Overall, our findings highlight the need to increase the number of studies in some temperate regions, to explore the potential of overlooked groups of arthropods, and to include indices that measure functional diversity or community composition