Soil microbial community composition as affected by restoration practices in California grassland

Abstract

Agricultural practices have strong impacts on soil microbes including both the indices related to biomass and activity as well as those related to community composition. In a grassland restoration project in California, where native perennial bunchgrasses were introduced into non-native annual grassland after a period of intensive tillage, weeding, and herbicide use to reduce the annual seed bank, microbial community composition was investigated. Three treatments were compared: annual grassland, bare soil fallow, and restored perennial grassland. Soil profiles down to 80 cm in depth were investigated in four separate layers (0-15, 15-30, 30-60, and 60-80 cm) using both phospholipid ester-linked fatty acid (PLFAs) and ergosterol as biomarkers in addition to microbial biomass C by fumigation extraction. PLFA fingerprinting showed much stronger differences between the tilled bare fallow treatment vs. grasslands, compared to fewer differences between restored perennial grassland and annual grassland. The presence or absence of plants over several years clearly distinguished microbial communities. Microbial communities in lower soil layers were little affected by management practices. Regardless of treatment, soil depth caused a strong gradient of changing habitat conditions, which was reflected in Canonical Correspondence Analysis of PLFAs. Fungal organisms were associated with the presence of plants and/or litter since the total amount and the relative proportion of fungal markers were reduced in the tilled bare fallow and in lower layers of the grassland treatments. Total PLFA and soil microbial biomass were highly correlated, and fungal PLFA biomarkers showed strong correlations to ergosterol content. In conclusion, microbial communities are resilient to the grassland restoration process, but do not reflect the change in plant species composition that occurred after planting native bunchgrasses.

Growth, nutrition, and soil respiration of a mycorrhiza-defective tomato mutant and its mycorrhizal wild-type progenitor

“…This is not unexpected given that microbial biomass and total PLFA have been found to be highly correlated with each other (Potthoff et al 2006). As in a previous study, PLFA analysis showed little difference in soil microbial communities between the two tomato genotypes (Cavagnaro et al 2006).…”

Agricultural Management and Labile Carbon Additions Affect Soil Microbial Community Structure and Interact with Carbon and Nitrogen Cycling

“…The composition and activity of the soil microbial community is influenced by ecosystem state factors (e.g., climate, soil type), plant species composition and, farming practices in agroecosystems [9][10][11]. Organic management practices using diverse rotations and additions of organic residues affect microbial community structure over the long term through buildup of soil organic matter (SOM) and changes in SOM chemistry [6,7,[12][13][14].…”

“…Organic management practices using diverse rotations and additions of organic residues affect microbial community structure over the long term through buildup of soil organic matter (SOM) and changes in SOM chemistry [6,7,[12][13][14]. In addition, greater crop diversity alters plant litter inputs and can presumably increase the number of ecological niches available for soil microbes [7,11]. The structure of microbial communities can in turn have important implications for the rates of soil processes.…”

Microbial Community Structure of Paddy Soil Under Long-term Fertilizer Treatment Using Phospholipid Fatty Acid (PLFA) Analysis

“…Environmental conditions and perturbations are likely to affect population structures and their functions in soils which may in turn result in a change of overall soil properties (Widmer et al, 2000). Understanding the microbial ecology of soil is increasingly recognized as important for the restoration and sustainability of ecosystems (Steenwerth et al, 2002;Potthoff et al, 2006). Soil microbial parameters are probably the earliest indicators of soil quality used.…”