Strong homogenization effects of shrubs on nematode communities across
large spatial scales on the Qinghai-Tibet Plateau
Abstract
Climate change and shrub encroachment affect nematode biodiversity,
although shrub species had different effects on below-ground community.
Yet, the consequences of shrub species on the nematode beta diversity
under future climate change scenarios remain insufficiently explored.
Here, we studied the dominant shrub effects on the beta diversity of
soil nematode communities along climate gradients on the Qinghai-Tibet
Plateau. We investigated soil nematode communities in 31 sites of alpine
meadow ecosystems across a 1200 km × 1200 km area with widespread shrub
on the Qinghai-Tibet Plateau. We found that shrubs decreased the
nematode beta diversity through decreasing the nestedness component at
local and landscape scales. Leguminous shrubs had stronger effects on
the nematode beta diversity than non-leguminous shrub types at landscape
scale. MAP and MAT both significantly increased the negative shrub
effects on the nematode beta diversity, but they remained constant for
leguminous shrub. The pSEM analysis showed that shrubs had direct and
indirect effects on nematode beta diversity via plant species turnover.
Our results showed that shrub encroachment, particularly leguminous
shrubs, leads to the homogenization of nematode communities. The
“warming-wetting” trend will exacerbate shrub effects on the
homogenization of nematode communities on the Qinghai-Tibet Plateau. Our
study provides insight into the ecological processes that maintain soil
biodiversity and biogeographic patterns of soil communities on the
Qinghai-Tibet Plateau.