The functional role and diversity of soil nematodes are stronger at high elevation in the lesser Himalayan mountain ranges

Soil nematodes are a foremost component of terrestrial biodiversity, they
display the whole gamut of trophic guilds and life strategies, and by
their activity, affect major ecosystem process, such as organic matter
degradation and carbon cycling. Based on nematodes’ functional types,
nematode community indices have been developed, and can be used to link
variation in nematodes community composition and ecosystem processes. Yet,
the use of these indices has been mainly restricted to anthropogenic
stresses. In this study, we propose to expand the use of nematodes'
derived ecological indices in order to link soil and climate properties
with soil food webs, and ecosystem processes that all vary along steep
elevation gradients. For this purpose, we explored how elevation affects
the trophic and functional diversity of nematode communities sampled every
300 m, from about 1000 m to 3700 m above sea level, across four transects
in the lesser Himalayan range of Jammu and Kashmir. We found that (1) the
trophic and functional diversity of nematodes increases with elevation;
(2) differences in nematodes communities generate habitat-specific
functional diversity; (3) the maturity index (MI), increases with
elevation, while the enrichment index decreases, indicating less mature
and less productive ecosystems, enhanced fungal-based energy flow, and a
predominant role of nematodes in generating carbon influxes at high
elevation sites. We thus confirm that the functional contribution of soil
nematodes to belowground ecosystem processes, including carbon and energy
flow, is stronger at high elevation. Overall, this study highlights the
central importance of nematodes in sustaining soil ecosystems and brings
insights into their functional role, particularly in alpine and arctic
soils.