Aim: Land use and climate change interact to impact functional and phylogenetic diversity globally, but this pattern is largely unknown in the eastern Himalayas. We aim to discern the response of community diversity and structure of terrestrial mammals and birds to anthropogenic land use and climate change in this hitherto understudied landscape. Location: Himalayan biodiversity hotspot, Bhutan

Methods: We used camera trap and point-count transect data to estimate taxonomic, functional, and phylogenetic diversity while accounting for detectability. We calculated the abundance-weighted standardised effect sizes (ses) of mean pairwise distance and mean nearest taxon distance. The ses metrics were regressed against land use (agriculture and forest) and climate (temperature and precipitation) variables using linear mixed effect models.

Results: Community diversity declined with agriculture in both groups. Mammal diversity was higher farther from the settlement but birds remained indifferent. Temperature and precipitation were positively associated with mammal diversity, but birds displayed a mixed response: negative with temperature and positive with precipitation. Agriculture had a strong negative effect on the functional structure of birds but not mammals. The functional and phylogenetic structure declined farther from the settlement for mammals but increased for birds. Except for the functional structure, all other metrics increased with temperature and precipitation for mammals. Except for the positive relationship between functional structure and temperature, other metrics showed a mixed response to climate in birds. 

Main conclusions: Our findings provide evidence that land use rather than climate has an imminent effect in shaping local and regional patterns of terrestrial vertebrate diversity in a Himalayan biodiversity hotspot. Climate effects, although weak, may reduce functional traits and consequently diminish functional roles. Species that can persist in human-modified environments are clustered within a phylogeny, suggesting possible loss of phylogenetic diversity.

Mammal: camera trap survey (refer to Penjor et al., 2018 (EcoEvol), 2019 (BioCon), 2020 (EcolInd) for details.

Bird: transect, point count survey, repeated observation (Penjor et al., 2021, J Applied Ecology).

Detection, non-detection data (binary), occupancy models (MacKenzie et al., 2002 Ecol)

Follow the script to run MSOM, obtain detection-corrected site x species matrix (z-matrix) and use this matrix to calculate FD and PD (eg., Chapman et al., 2018, J Applied Ecol).