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 S.
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 below ground 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.