降水量变化及氮添加下荒漠草原土壤有机碳及其易分解组分研究  

Soil organic carbon and its easily decomposed components under precipitation change and nitrogen addition in a desert steppe in northwest China

作　　者：马煦晗 黄菊莹 余海龙[2] 韩翠 李冰[1] MA Xu-Han;HUANG Ju-Ying;YU Hai-Long;HAN Cui;LI Bing(Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwestern China,Key Laboratory of Restoration and Reconstruction of Degraded Ecosystems in Northwestern China of Ministry of Education,School of Ecology and Environment,Ningxia University,Yinchuan 750021,China;School of Geography and Planning,Ningxia University,Yinchuan 750021,China)

机构地区：[1]西北土地退化与生态恢复国家重点实验室培育基地,西北退化生态系统恢复与重建教育部重点实验室,宁夏大学生态环境学院,银川750021 [2]宁夏大学地理科学与规划学院,银川750021

出　　处：《植物生态学报》2024年第8期1065-1077,共13页Chinese Journal of Plant Ecology

基　　金：宁夏自然科学基金(2022AAC02012);国家自然科学基金(32160277和32371632)。

摘　　要：土壤有机碳(C)库在稳定陆地C循环和调节全球气候等方面扮演着重要角色。该研究基于2017年设立于宁夏荒漠草原的降水量变化(-50%、-30%、自然、+30%、+50%)及氮(N)添加(0和5 g·m^(-2)·a^(-1))的两因素野外实验,探讨了处理4年后,0-60 cm土壤有机C特征(含量、储量、组分)的变化规律和影响因素,以期为科学预测全球变化下半干旱区草原C汇功能提供数据支撑。N添加对土壤有机C特征影响较小。相比之下,降水量改变了有机C特征,且其影响程度依赖于N水平和土层深度。就整个0-60 cm而言,与自然降水量相比,0 g·m^(-2)·a^(-1)N添加下,增减降水量对有机C特征影响较小;5 g·m^(-2)·a^(-1)N添加下,减少30%降水量显著提高了易氧化有机C和溶解性有机C含量,增加30%降水量显著提高了颗粒有机C和轻组有机C含量。有机C含量及其储量与土壤含水量、纤维二糖水解酶、碱性磷酸酶活性正相关,与土壤NO3--N含量负相关。易氧化有机C、颗粒有机C和轻组有机C含量与土壤亮氨酸氨基肽酶活性正相关,与微生物生物量N含量负相关。溶解性有机C和微生物生物量C含量则与以上3个指标呈相反的关系。研究结果表明,N添加下,降水量改变对土壤有机C含量及其储量影响较小,但适度增减降水量会通过改变土壤含水量、N有效性、酶活性以及植物群落优势度等途径降低有机C稳定性,从而导致荒漠草原土壤C排放风险增加。Aims Soil organic carbon(C)pool plays an important role in regulating terrestrial C cycle and global climate,etc.The purpose of this study is to furnish data that will facilitate the scientific prediction of the C sink function of the grasslands in semi-arid regions under global change.Methods Based on a two-factor field experiment of precipitation change(-50%,-30%,natural,+30%,+50%)and nitrogen(N)addition(0 and 5 g·m^(-2)·a^(-1))established in 2017 in a desert steppe in Ningxia,we explored the response patterns and driving factors of soil organic C characteristics(content,storage,and components)in 0-60 cm soils after 4 years of treatments.Important findings N addition had little effects on soil organic C characteristics.In contrast,precipitation exerted a significant influence on soil organic C characteristics,with the magnitude of the effect contingent up on the N level and soil depth.In the absence of N addition,both increasing and decreasing precipitation had a minimal impact on organic C characteristics across the whole 0-60 cm depth.In contrast,a 30%reduction in precipitation led to a significant increase in the content of easily oxidized organic C and dissolved organic C,while a 30%increase in precipitation resulted in a significant increase in the content of particulate organic C and light fraction organic C under 5 g·m^(-2)·a^(-1) N addition.The content of soil organic C and its storage were positively correlated with soil water content,cellobiohydrolase activity and alkaline phosphatase activity.Conversely,they were negatively correlated with soil NO3--N.The content of easily oxidized organic C,particulate organic C and light fraction organic C was found to be positively correlated with soil leucine aminopeptidase activity and the Simpson dominance index,while negatively correlated with microbial biomass N content.Dissolved organic C and microbial biomass C content showed the opposite relationship with the three indices above.These findings indicate that alterations in precipitation levels exert min

关 键 词：半干旱区 降水格局 氮沉降 土壤碳排放 土壤碳稳定性 

分 类 号：S812.2[农业科学—草业科学]