Ecosystem response of pasture soil communities to fumigation‐induced microbial diversity reductions: an examination of the biodiversity–ecosystem function relationship

Abstract

2000. Ecosystem response of pasture soil communities to fumigation-induced microbial diversity reductions: an examination of the biodiversity -ecosystem function relationship. -Oikos 90: 279 -294.A technique based on progressive fumigation was used to reduce soil microbial biodiversity, and the effects of such reductions upon the stability of key soil processes were measured. Mineral soil samples from a grassland were fumigated with chloroform for up to 24 h and then incubated for 5 months to allow recolonisation by surviving organisms. The diversity of cultivable and non-cultivable bacteria, protozoa and nematodes was progressively reduced by increasing fumigation times, as was the number of trophic groups, phyla within trophic groups, and taxa within phyla. Total microbial biomass was similar within fumigated soils, but lower than for unfumigated soil. There was no direct relationship between biodiversity and function. Some broad-scale functional parameters increased as biodiversity decreased, e.g. thymidine incorporation, growth on added nutrients, and the decomposition rate of plant residues. Other more specific parameters decreased as biodiversity decreased, e.g. nitrification, denitrification and methane oxidation. Thus specific functional parameters may be a more sensitive indicator of environmental change than general parameters. Although fumigation reduced soil microbial biodiversity, there was evidence to suggest that it selected for organisms with particular physiological characteristics. The consequences of this for interpreting biodiversity -function relationships are discussed. The stability of the resulting communities to perturbation was further examined by imposing a transient (brief heating to 40°C) or a persistent (addition of CuSO 4 ) stress. Decomposition of grass residues was determined on three occasions after such perturbations. The soils clearly demonstrated resilience to the transient stress; decomposition rates were initially depressed by the stress and recovered over time. Resilience was reduced in the soils with decreasing biodiversity. Soils were not resilient to the persistent stress, there was no recovery in decomposition rate over time, but the soils with the highest biodiversity were more resistant to the stress than soils with impaired biodiversity. The study of functional stability under applied perturbation is a powerful means of examining the effects of biodiversity.

Comparative study of protozoan communities in full-scale MWTPs in Beijing related to treatment processes

“…The highest species richness as descried above was considered as one of the most important properties for A2O to resist disturbance. That is, the higher degree of redundancy in species, the generally higher degree of stability in biological functions (Griffiths et al, 2000(Griffiths et al, , 2001. The relatively higher species richness of the A2O process (see Fig.…”

Cutting Edge: IL-17–Secreting Innate Lymphoid Cells Are Essential for Host Defense against Fungal Infection

“…Some complex microbial functional traits (e.g., photosynthesis and nitrogen fixation) are strongly linked to specific phylogenetic groups and decreases in microbial diversity have been linked to declines in denitrification, nitrification, and methane oxidation (20,21). For widespread functions like simple carbon substrate degradation, redundancy within the microbiome may mean similar functioning by very different microbial assemblages, reducing the importance of microbial diversity.…”

A study of soil-dynamics based on a simulated drought in an alpine meadow on the Tibetan Plateau

“…There have been several studies which have utilized these concepts to evaluate the perturbation of the stress in the ecosystem or the importance of biodiversity functions (Griffiths et al 2000;Griffiths et al 2001;Tobor-Kaplon et al 2005;Hueso et al 2011). Hereby, we simulated a once-in-a-century extreme drought in the middle period of plant growing season (mid-PGS) in an alpine meadow in the east of the Tibetan Plateau, with which we aspired to address the follow points: 1) how the microbial biomass and soil enzyme activities would respond under the condition of adequate water in an alpine meadow ecosystem on the Tibetan Plateau, 2) how the availability of nutrients (NH 4 + , NO 3 -, PO 4 3-) would change under the extreme conditions of once-in-a-century extreme droughts; 3) how the soil microbial properties such as resistance and resilience would react under such extreme conditions.…”