Tue, Aug 03, 2021:On Demand
Background/Question/Methods
Land-use and climate change are known to be the greatest threat to biodiversity. The effects of both are even more pronounced in the fragile high-elevation trans-Himalayas and there is an urgent need to understand how biodiversity is being affected in this ecosystem as a consequence of human induced land-use and climate change. To study this, we use beta-diversity, a widely used concept to understand patterns of biodiversity distribution. The metrics of beta-diversity has the ability to be more interpretive than alpha-diversity and is better suited to test general ecological models, providing significant insights for conservation and management practices.
In this study, we ask how species and functional guilds contribute to beta-diversity, and partitions of beta-diversity across land-uses and seasons. We answer these questions using arthropods in the Trans-Himalayan region of India, (where agriculture and livestock rearing areas are the major land-uses and experiences a shot growth season) since they are one of the most diverse, abundant and ecologically significant phylums on earth, and contribute significantly to various ecological functions. Non-metric multidimensional scaling was performed using the metaMDS function in “vegan” R package. Species and local contribution to beta diversity were calculated using the beta.div function while temporal beta indices were calculate using TBI function within the “adespatial” R package and beta-diversity was partitioned into replacement and nestedness using beta.div.comp function.
Results/Conclusions We recorded 88 recognisable taxonomic units (RTU’s) of arthropods, classified into two classes and six orders. Arthropod community in agriculture land-use were very distinct from those in livestock grazing and wildlife areas. Overall, a species of Chrysomelidae beetle and the ant (Hymenoptera: Formicidae) Formica candida contributed the most to beta-diversity across all land-uses, whereas ticks (order Ixodida) contributed most in livestock grazing sites. At RTU levels, beta diversity of arthropod communities were explained more by turnover, however when grouped into functional guilds arthropod communities were highly nested in agriculture sites. We also observed a collapse in seasonal variation of beta diversity which suggests that treating dynamic communities as static assemblages may cause in failure to detect the full impact of anthropogenic stressors. Our results show that there is a systematic turnover of arthropod communities with seasons while land-use intensification leads to more nested communities at functional levels. Further change in climate or human intensification of land-use in this ecosystem will cause a disruption in arthropod communities and will degrade a fundamental facet of biodiversity affecting several important ecosystem functions.
Results/Conclusions We recorded 88 recognisable taxonomic units (RTU’s) of arthropods, classified into two classes and six orders. Arthropod community in agriculture land-use were very distinct from those in livestock grazing and wildlife areas. Overall, a species of Chrysomelidae beetle and the ant (Hymenoptera: Formicidae) Formica candida contributed the most to beta-diversity across all land-uses, whereas ticks (order Ixodida) contributed most in livestock grazing sites. At RTU levels, beta diversity of arthropod communities were explained more by turnover, however when grouped into functional guilds arthropod communities were highly nested in agriculture sites. We also observed a collapse in seasonal variation of beta diversity which suggests that treating dynamic communities as static assemblages may cause in failure to detect the full impact of anthropogenic stressors. Our results show that there is a systematic turnover of arthropod communities with seasons while land-use intensification leads to more nested communities at functional levels. Further change in climate or human intensification of land-use in this ecosystem will cause a disruption in arthropod communities and will degrade a fundamental facet of biodiversity affecting several important ecosystem functions.