Soil Nematodes and Their Prokaryotic Prey Along an Elevation Gradient in The Mojave Desert (Death Valley National Park, California, USA)

Amy Treonis,Kelsey Sutton,Archana Narla,Jasmine Felder,Sarah Thomas,Cecilia O’Leary,Alyxandra Pikus,Timothy Mcllarky,Brendan Kavanaugh,Megan Riley

doi:10.3390/d4040363

Abstract

We characterized soil communities in the Mojave Desert across an elevation gradient. Our goal was to test the hypothesis that as soil quality improved with increasing elevation (due to increased productivity), the diversity of soil prokaryotes and nematodes would also increase. Soil organic matter and soil moisture content increased with elevation as predicted. Soil salinity did not correlate to elevation, but was highest at a mid-gradient, alluvial site. Soil nematode density, community trophic structure, and diversity did not show patterns related to elevation. Similar results were obtained for diversity of bacteria and archaea. Relationships between soil properties, nematode communities, and prokaryotic diversity were site-specific. For example, at the lowest elevation site, nematode communities contained a high proportion of fungal-feeding species and diversity of bacteria was lowest. At a high-salinity site, nematode density was highest, and overall, nematode density showed an unexpected, positive correlation to salinity. At the highest elevation site, nematode density and species richness were attenuated, despite relatively high moisture and organic matter content for the soils. Our results support emerging evidence for the lack of a relationship between productivity and the diversity of soil nematodes and prokaryotes.

Highlights

The diversity of soil organisms is both massive and relatively poorly understood [1,2].Conventionally, species diversity is thought to be related to the productivity of a habitat [3], which is determined primarily by abiotic factors such as rainfall and temperature [4]
The six sites sampled in Death Valley National Park represented an elevation gradient
We found that bacteria-feeding nematode species generally were the most abundant across the sites, ranging from 36–98% of the nematodes found in each sample

Summary

Introduction

The diversity of soil organisms is both massive and relatively poorly understood [1,2].Conventionally, species diversity is thought to be related to the productivity of a habitat [3], which is determined primarily by abiotic factors such as rainfall and temperature [4]. The diversity of soil organisms is both massive and relatively poorly understood [1,2]. Recent studies of soil communities suggest that soil biota and microorganisms may not share diversity patterns often exhibited by plants and animals [5,6,7]. We characterized the relationship between soil prokaryotic and nematode diversity at six sites in. Death Valley National Park (Mojave Desert, California, USA). The Park includes the largest elevation gradient in the contiguous United States, ranging from the Badwater Basin at 86 m below sea level to Telescope Peak at 3,368 m above sea level (m.a.s.l.). The North American temperature record was measured in Death Valley in 1913 (56.7 °C), and daytime temperatures at the lower elevations exceed

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