Effects of plant species richness and evenness on soil microbial community diversity and function

Abstract

Understanding the links between plant diversity and soil communities is critical to disentangling the mechanisms by which plant communities modulate ecosystem function. Experimental plant communities varying in species richness, evenness, and density were established using a response surface design and soil community properties including bacterial and archaeal abundance, richness, and evenness were measured. The potential to perform a representative soil ecosystem function, oxidation of ammonium to nitrite, was measured via archaeal and bacterial amoA genes. Structural equation modeling was used to explore the direct and indirect effects of the plant community on soil diversity and potential function. Plant communities influenced archaea and bacteria via different pathways. Species richness and evenness had significant direct effects on soil microbial community structure, but the mechanisms driving these effects did not include either root biomass or the pools of carbon and nitrogen available to the soil microbial community. Species richness had direct positive effects on archaeal amoA prevalence, but only indirect impacts on bacterial communities through modulation of plant evenness. Increased plant evenness increased bacterial abundance which in turn increased bacterial amoA abundance. These results suggest that plant community evenness may have a strong impact on some aspects of soil ecosystem function. We show that a more even plant community increased bacterial abundance, which then increased the potential for bacterial nitrification. A more even plant community also increased total dissolved nitrogen in the soil, which decreased the potential for archaeal nitrification. The role of plant evenness in structuring the soil community suggests mechanisms including complementarity in root exudate profiles or root foraging patterns.

Soil Microbial Biomass Across a Gradient of Preserved Native Cerrado

“…Therefore, these differences in the litter contribution influenced the soil microbial biomass across the gradient. Additionally, some studies have reported that more diverse plant communities positively affect soil microorganisms (Berg & Smalla, 2009;Wallenstein et al, 2007;Malchair et al, 2010;Lamb et al, 2011). Wallenstein et al (2007) evaluated the bacterial community between Alaskan tussock and shrub tundra vegetation and found that plant communities regulate bacterial communities through the quantity and chemical quality of plant litter in the soil.…”

Factors Driving Potential Ammonia Oxidation in Canadian Arctic Ecosystems: Does Spatial Scale Matter?

“…1). The Truelove Lowland site (75°40=N, 84°35=W) has already been extensively described (6,37,64). The average July soil temperature in the upper 5 cm in 2008 was 13°C, with a maximum value of 24°C and a minimum of 6°C (17).…”

“…The topography of Truelove Lowland is distinguished by a series of raised beach crest ridge, lower foresope, and wet sedge meadow with regosolic static cryosols, brunisolic eutric turbic cryosols, and gleysolic turbic cryosols, respectively (64). The mean annual air temperature is approximately Ϫ16°C, with the highest recorded daily temperature of 21°C in July and Ϫ45°C as the lowest monthly temperatures (6,37). The total annual precipitation is about 185 mm, with 36 mm as rain.…”

Patterns of Soil Bacterial Richness and Composition Tied to Plant Richness, Soil Nitrogen, and Soil Acidity in Alpine Tundra

“…Many researchers have concentrated on the influences of plant community species richness and composition on belowground bacterial communities (Zak et al, 2003;Lamb et al, 2011), yet the relationships between plant and soil bacteria in richness are often inconsistent with distinct study methods or space and time lags. In general, positive effects of plant species richness on bacterial community richness could be attributed to the increasing soil nutrient pools and root exudate chemistry (Zak et al, 2003;Loranger-Merciris et al, 2006).…”