State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, The Chinese Academy of Sciences, Beijing, China.
PLoS One. 2012;7(4):e35165. doi: 10.1371/journal.pone.0035165. Epub 2012 Apr 5.
Global 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 FINDINGS: To 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/SIGNIFICANCE: Increased 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.
全球气候变化预计将刺激净初级生产力的增加，从而增加土壤碳（C）的输入。增加的 C 输入以及可能增加的降水可能会影响土壤微生物过程和植物生长。
方法/主要发现：为了研究 C 和水分添加对土壤微生物特性和植物生长的影响，我们在中国东北温带草原进行了为期两年的实验。我们发现，土壤 C 和水分添加显著影响微生物特性并刺激植物生长。C 添加显著增加了土壤微生物生物量和活性，但对微生物群落结构的影响有限。水分添加在第一年显著增加了土壤微生物活性，但第二年对水分的响应减少了。微生物活性的水分变化可归因于土壤氮（N）有效性的降低和土壤微生物群落结构的转变。然而，在两年的 C 添加期间，水分添加对土壤微生物活性没有影响，这可能是因为 C 添加缓解了土壤微生物的养分限制。此外，C 和水分添加相互作用影响植物功能群组成。水分添加显著增加了 C 添加处理中草和草本植物生物量的比例，但在环境 C 水平下仅显示出较小的影响。我们的研究结果表明，土壤微生物活性和植物生长受到养分（C 和 N）和水分供应的限制，并强调了养分供应在调节温带草原土壤微生物和植物对潜在增加降水的响应中的重要性。
结论/意义：增加的土壤 C 输入和降水将对温带草原的土壤微生物特性和植物生长产生显著影响。这些发现将提高我们对土壤微生物和植物对间接和直接气候变化影响的响应的理解。
