降水变化和养分添加对呼伦贝尔草甸草原土壤呼吸的影响

Effects of precipitation change and nutrient addition on soil respiration in Hulunber meadow steppe

土壤呼吸是陆地生态系统碳循环的重要组成部分,研究土壤呼吸对降水变化和养分沉降的响应有助于评估全球变化对生态系统碳循环的影响。然而,目前降水变化和养分沉降对土壤呼吸的交互影响研究相对较少。本研究以呼伦贝尔草甸草原为对象,通过增减雨和养分添加,模拟研究降水变化和养分沉降及其交互对草甸草原土壤呼吸的影响及其机制。结果表明:增雨对土壤呼吸没有显著影响,干旱显著降低了土壤呼吸;养分添加对土壤呼吸有一定的抑制作用,但其与降水变化的交互作用不显著。增雨显著增加了土壤湿度,但对土壤温度没有显著影响;相反,干旱显著降低了土壤湿度,增加了土壤温度;养分添加显著增加了可溶性无机碳、无机氮和地上净初级生产力,降低了土壤湿度。土壤呼吸与土壤湿度、微生物生物量碳、微生物生物量氮呈显著正相关,而与土壤温度呈显著负相关;土壤湿度、土壤温度、微生物生物量碳和微生物生物量氮可以分别解释土壤呼吸56.3%、26%、16.6%和19.6%的变异,表明土壤水分是调控土壤呼吸的关键因子。本研究有助于增强对全球变化背景下草甸草原土壤呼吸的理解和认识。

Soil respiration is an important part of terrestrial carbon cycling.Understanding its response to precipitation changes and nutrient addition can help to assess how global changes affect terrestrial carbon cycling.However,few studies have focused on the interactive effects of precipitation change and nutrient deposition on soil respiration.We conducted a field-manipulated experiment with increasing or decreasing precipitation and adding nutrient to simulate precipitation change and nutrient deposition on a meadow steppe in Hulunber,to explore the main and interactive effects of those two global change factors on soil respiration and the underlying mechanisms.The results showed that increasing precipitation did not affect soil respiration,while drought significantly reduced soil respiration.Nutrient addition had a limiting inhibitory effect on soil respiration,but its interaction with changing precipitation was not significant.Increasing precipitation significantly increased soil moisture,but did not affect soil temperature.Drought significantly reduced soil moisture and increased soil temperature.Nutrient addition significantly increased soluble inorganic carbon,inorganic nitrogen,and aboveground net primary productivity,and reduced soil moisture.Soil respiration was negatively correlated with soil temperature,but positively correlated with soil moisture,microbial biomass carbon and microbial biomass nitrogen.Soil moisture,soil temperature,microbial biomass carbon and microbial biomass nitrogen explained 56.3%,26%,16.6%,and 19.6%of the variation in soil respiration,respectively,indicating that soil moisture was the key factor regulating soil respiration.These findings may facilitate the understanding of soil respiration in meadow steppe under scenarios of global change.