Nematodes as an indicator of plant–soil interactions associated with desertification

TitleNematodes as an indicator of plant–soil interactions associated with desertification
Publication TypeJournal Article
Year of Publication2012
AuthorsKlass JR, Peters DC, Trojan JM, Thomas SH
JournalApplied Soil Ecology
Start Page66
Date Published04/2012
Accession NumberJRN49888
ARIS Log Number279754
KeywordsBouteloua eriopoda, connectivity, Nematode communities, Nematode diversity, prosopis glandulosa, semi-arid grasslands

Conversion of perennial grasslands to shrublands is a desertification process that is important globally.
Changes in aboveground ecosystem properties with this conversion have been well-documented, but
little is known about how belowground communities are affected, yet these communities may be important
drivers of desertification as well as constraints on the reversal of this state change. We examined
nematode community structure and feeding as a proxy for soil biotic change across a desertification
gradient in southern NM, USA. We had two objectives: (1) to compare nematode trophic structure and
species diversity within vegetation states representing different stages of desertification, and (2) to compare
nematode community structure between bare and vegetated patches that may be connected via a
matrix of endophytic fungi and soil biotic crusts. The gradient included a perennial grassland dominated
by Bouteloua eriopoda, the historic dominant in the Chihuahuan Desert, a duneland dominated by the
shrub, Prosopis glandulosa, and the ecotone between them. We also sampled a relatively undisturbed,
ungrazed B. eriopoda grassland at a nearby site to serve as an end member of our gradient. Nematode
communities were sampled using soil cores to depth of 50 cm at each location in 2009 and 2010. Results
showed that grasslands and mesquite dunelands had different trophic groupings and herbivorous nematode
communities with lower species diversity and evenness compared with the ecotone. Nematode
trophic structure and herbivore communities were significantly different in all vegetation states with
the highest observed diversity in the undisturbed, ungrazed B. eriopoda grassland in 2010. Vegetated and
bare ground patches within the two grassland sites had similar herbivore communities, especially species
from the family Tylenchinae. However, the mesquite duneland showed the lowest sampled diversity of
all sites, but had significantly larger nematode abundances in vegetated dunes than interdune areas that
are void of vegetation and soil biotic crusts where bacteriovores dominated. Decreased nematode trophic
structure and species diversity in the Jornada black grama grassland samples compared with the undisturbed
grassland illustrate the effect of desertification on the soil biotic community. Our results show
that nematodes can be used to identify changes in belowground community structure based on trophic
interactions. Large-scale disturbances like desertification can have consequences on the diversity and
soil biotic functioning at finer spatial scales.