【微生物群落对降水量变化的响应】Patrick O. Sorensen Matthew J. Germino Kevin P. Feris. Microbial community responses to 17 years of altered precipitation are seasonally dependent and coupled to co-varying effects of water content on vegetation and soil C.Soil Biology and BiochemistryVolume 64 September 2013 Pages 155–163

Abstract

Precipitation amount and seasonal timing determine the duration and distribution of water available for plant and microbial activity in the cold desert sagebrush steppe. In this study we sought to determine if a sustained shift in the amount and timing of precipitation would affect soil microbial diversity community composition and soil carbon (C) storage. Field plots were irrigated (+200 mm) during the dormant or growing-season for 17 years. Microbial community responses were assessed over the course of a year at two depths (15–20 cm 95–100 cm) by terminal restriction fragment length polymorphism (T-RFLP) along with co-occurring changes in plant cover and edaphic properties. Bacterial richness Shannon Weaver diversity and composition in shallow soils (15–20 cm) as well as evenness in deep soils (95–100 cm) differed across irrigation treatments during July. Irrigation timing affected fungal community diversity and community composition during the dormant season and most strongly in deep soils (95–100 cm). Dormant-season irrigation increased the ratio of shrubs to forbs and reduced soil C in shallow soils by 16% relative to ambient conditions. It is unclear whether or not soil C will continue to decline with continued treatment application or if microbial adaptation could mitigate sustained soil C losses. Future changes in precipitation timing will affect soil microbes in a seasonally dependent manner and be coupled to co-varying effects of water content on vegetation and soil C.

【CARD-FISH分析土壤微生物】Masayuki Ushio Kobayashi Makoto Jonatan Klaminder Shin-ichi Nakano. CARD-FISH analysis of prokaryotic community composition and abundance along small-scale vegetation gradients in a dry arctic tundra ecosystem.Soil Biology and Biochemistry