Abstract
BackgroundGlobal climatic change is generally expected to stimulate net primary production, and consequently increase soil carbon (C) input. The enhanced C input together with potentially increased precipitation may affect soil microbial processes and plant growth.Methodology/Principal FindingsTo examine the effects of C and water additions on soil microbial properties and plant growth, we conducted an experiment lasting two years in a temperate steppe of northeastern China. We found that soil C and water additions significantly affected microbial properties and stimulated plant growth. Carbon addition significantly increased soil microbial biomass and activity but had a limited effect on microbial community structure. Water addition significantly increased soil microbial activity in the first year but the response to water decreased in the second year. The water-induced changes of microbial activity could be ascribed to decreased soil nitrogen (N) availability and to the shift in soil microbial community structure. However, no water effect on soil microbial activity was visible under C addition during the two years, likely because C addition alleviated nutrient limitation of soil microbes. In addition, C and water additions interacted to affect plant functional group composition. Water addition significantly increased the ratio of grass to forb biomass in C addition plots but showed only minor effects under ambient C levels. Our results suggest that soil microbial activity and plant growth are limited by nutrient (C and N) and water availability, and highlight the importance of nutrient availability in modulating the responses of soil microbes and plants to potentially increased precipitation in the temperate steppe.Conclusions/SignificanceIncreased soil C input and precipitation would show significant effects on soil microbial properties and plant growth in the temperate steppe. These findings will improve our understanding of the responses of soil microbes and plants to the indirect and direct climate change effects.
Highlights
Human activity is altering the global atmosphere and climate in multiple ways
Interactive Effects of Combined C and Water Additions Our results showed that no water effects on soil microbial activity and community structure were visible under C addition during the two years (Fig. 3E, F; Fig. 4G, H), this is likely because C input alleviates energy and nutrient limitation to soil microbes
With a field manipulative experiment, this study showed that enhanced soil C input and water addition affected soil microbial processes and stimulated plant growth in the temperate steppe
Summary
The increase in atmospheric CO2 concentration contributes to rising global temperatures and precipitation over some areas, including northeastern China [1,2]. Anticipated global warming and elevated atmospheric CO2 concentration are generally assumed to increase primary production in most terrestrial ecosystems [3,4,5]. Much more plant residues will be incorporated into soil organic matter. There is still a large uncertainty about how increased litter input and precipitation would affect soil microbial properties and plant growth. Global climatic change is generally expected to stimulate net primary production, and increase soil carbon (C) input. The enhanced C input together with potentially increased precipitation may affect soil microbial processes and plant growth
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