Ecohydrological implications of aeolian sediment trapping by sparse vegetation in drylands

TitleEcohydrological implications of aeolian sediment trapping by sparse vegetation in drylands
Publication TypeJournal Article
Year of Publication2018
AuthorsGonzales HB, Ravi S, Li J, Sankey JB
Accession NumberSEV.795

Aeolian processes are important drivers of ecosystem dynamics in drylands, and
important feedbacks exist among aeolian—hydrological processes and vegetation.
The trapping of wind‐borne sediments by vegetation canopies may result in changes
in soil properties beneath the vegetation, which, in turn, can alter hydrological and
biogeochemical processes. Despite the relevance of aeolian transport to ecosystem
dynamics, the interactions between aeolian transport and vegetation in shaping dryland
landscapes where sediment distribution is altered by relatively rapid changes in
vegetation composition such as shrub encroachment, are not well understood. Here,
we used a computational fluid dynamics modelling framework to investigate the sediment
trapping efficiencies of vegetation canopies commonly found in a shrub‐grass
ecotone in the Chihuahuan Desert (New Mexico, USA) and related the results to spatial
heterogeneity in soil texture and infiltration measured in the field. The vegetation
structures were created using a computer‐aided design software, with inherent canopy
porosities, which were derived using Light Detection and Ranging (LiDAR) measurements
of plant canopies. Results show that considerable heterogeneity in
infiltration and soil grain size distribution exist between the microsites, with higher
infiltration and coarser soil texture under shrubs. Numerical simulations further indicate
that the differential trapping of canopies might contribute to the observed heterogeneity
in soil texture. In the early stages of encroachment, the shrub canopies,
by trapping coarser particles more efficiently, might maintain higher infiltration rates
leading to faster development of the microsites with enhanced ecological productivity,
which might provide positive feedbacks to shrub encroachment.