Comparison of Nematode Communities in Agricultural Soils of North Carolina and Nebraska

Abstract

Samples of agricultural soils were collected across North Carolina in 1992 and Nebraska in 1993 to determine which indices of nematode communities could be applied to distinguish ecological pattern at regional geographic scales. Sampling density was proportional to the area of agriculture in each region of each state. Maturity indices (based on life-history characteristics) were calculated to determine the successional status of nematode communities, and diversity indices were calculated to estimate relative abundance of nematode trophic groups. Population densities of nematode families were also compared between states and among regions within states. The range of maturity-index values for free-living and plant-parasitic nematodes was greater for soils in North Carolina than in Nebraska. The relative distribution of nematode trophic groups (bacterial feeders, fungal feeders, plant parasites, omnivores, and predators) was similar in the two states. Significant differences in maturity-index values for free-living and plant-parasitic nematodes were found between but not within states. We conclude that regional or national assessments of soil ecological condition based on measures of nematode community structure can be made at a geographic resolution of 125 000-200 000 km 2 of land area.

Distinguishing Sensitivity of Free-Living Soil Nematode Genera to Physical and Chemical Disturbances

“…Our results could be made more robust by testing the following conditions. First, differences in nematode community composition, abundances, and successional maturities between states of North Carolina and Nebraska (Neher et al 1998) could be considered in developing TS and CS ratings. We also did not attempt to correct nematode abundances for regional variation.…”

“…Community successional status is known to proceed rapidly within the initial weeks following severe disturbance (Yeates et al 1991, Ettema and Bongers 1993, Wardle et al 1995b and to move downward in the soil profile (Brussaard 1998). Third, successful methodologies of sampling, feeding type classification, analysis, and interpretation are better known for nematodes than other soil microfauna (Yeates et al 1993a, Elliott 1994, Neher et al 1998.…”

Soil nematode communities are ecologically more mature beneath late- than early-successional stage biological soil crusts

“…Nematoda are a phylum of soil fauna that play a key role in mediating soil nutrients by feeding on fungi, bacteria, cyanobacteria, green algae, plant roots, and other soil fauna (Bardgett et al, 1999;Whitford, 1996). Nematodes are employed as indicators of the structure and function of the soil community (Neher and Campbell, 1996;Neher et al, 1998) because they represent multiple trophic groups and are ubiquitous, intimately linked to the soil environment, and sensitive to environmental changes (Neher, 2001). One pertinent tool for analysis is the maturity index (MI) to indicate the successional maturity of nematode communities and, thus, the biological condition of the soil habitat (Bongers, 1990).…”

Spatial pattern analysis of entomopathogenic and other free‐living nematodes at landscape scales

“…Filling various ecological roles, different species feed on detritus, bacteria, algae, fungi, higher plants, other soil invertebrates or have some combination of roles (Yeates et al 1993;Traunspurger 1997;Beier & Traunspurger 2003). Nematodes possess characteristics which make them useful as ecological indicators (Freckman 1988;Neher & Campbell 1994) and, because of their ability to reflect change in soil structure, show promise for monitoring soil ecological conditions (Neher et al 1998). Entomopathogenic nematodes (EPN) have received considerable attention because they can serve as environmentally safe biological control agents for soil insect pests (Gaugler & Kaya 1990;Kaya & Gaugler 1993).…”

“…1993; Traunspurger 1997; Beier & Traunspurger 2003). Nematodes possess characteristics which make them useful as ecological indicators (Freckman 1988; Neher & Campbell 1994) and, because of their ability to reflect change in soil structure, show promise for monitoring soil ecological conditions (Neher et al . 1998).…”