摘要:以荒漠草原凋落物为研究对象，通过设置自然降雨（CK）、增雨30%（W）和减雨30%（R）3种水分处理和0（N0）、30（N30）、50（N50）和100 kg hm^-2 a^-1（N100）4种氮素（NH₄NO₃）水平处理，用分解袋法，研究内蒙古短花针茅荒漠草原短花针茅（Stipa breviflora）、冷蒿（Artemisia frigida）、无芒隐子草（Cleistogenes songorica）和木地肤（Kochia prostrata）凋落物分解过程，旨在阐明荒漠草原凋落物分解过程及其对氮沉降和降雨变化的响应特征，为荒漠草原生态系统物质循环过程响应气候变化研究提供基础数据。结果表明：1）经过270 d分解后，短花针茅、冷蒿、木地肤和无芒隐子草干物质残留率分别为69.95%-78.67%、68.89%-79.89%、64.68%-79.23%、66.89%-79.38%，分解速率为木地肤 > 无芒隐子草 > 冷蒿 > 短花针茅。2）氮沉降和降雨对短花针茅和冷蒿凋落物分解速率产生显著影响（P < 0.05），其交互作用对这两种凋落物分解速率不显著（P > 0.05）。氮沉降和降雨以及交互作用均对无芒隐子草和木地肤凋落物分解速率产生显著影响（P < 0.05）。3）单一水分或氮素的添加均提高土壤微生物量碳氮含量，而水氮交互作用下更为显著。4）凋落物分解速率受生物及非生物因子的影响，相关分析表明：冷蒿、无芒隐子草、木地肤与土壤微生物量碳呈极显著正相关（P < 0.01）；冷蒿、木地肤、短花针茅与土壤微生物量氮呈极显著正相关（P < 0.01）；木地肤和短花针茅与土壤含水量呈极显著正相关（P < 0.01）；冷蒿、木地肤、短花针茅与地上生物量呈极显著正相关（P < 0.01）。



Abstract:The objective of this study was to examine the effects of increased nitrogen deposition and changing rainfall patterns on litter decomposition in a desert grassland.Our treatments included three different rainfall patterns (an ambient control, -30% and +30%) and addition of four different levels of nitrogen (an ambient control, 30, 50, and 100 kg hm^-2 a^-1).We used a litterbag method to investigate the litter decomposition process of three dominant species (Stipa breviflora, Artemisia frigida, and Cleistogenes songorica) and another common species (Kochia prostrata) in the context of changing nitrogen deposition levels and rainfall patterns in a desert grassland of Inner Mongolia.This study provides the basic data for research on response to climate change in the material cycle of desert grassland ecosystems.The results showed that:1) After 270 days of decomposition, the dry matter contents of S. breviflora, A. frigida, K. prostrata,and C. songorica were 69.95%-78.67%, 68.89%-79.89%, 64.68%-79.23%,and 66.89%-79.38%,respectively.The rank of the decomposition rate was K. prostrata > C. songorica > A. frigida > S. breviflora. 2)Nitrogen deposition and rainfall significantly affected the decomposition rates of S. breviflora and A. frigida(P < 0.05), but their interactive effects on litter decomposition rates were not significant(P > 0.05).Nitrogen deposition,rainfall,and their interactions significantly influenced the decomposition rates of C. songorica and K. prostrata(P < 0.05). 3)The addition of single moisture or nitrogen level increased the carbon and nitrogen contents of the microorganisms, and the interaction between moisture and nitrogen was more significant.4)The decomposition rate of litters was affected by biotic and abiotic factors.The correlation analysis showed that:A. frigida, C. songorica, and K. prostrata were significantly positively correlated with soil microbial carbon(P < 0.01); A. frigida, K. prostrata, and S. breviflora were significantly positively correlated with soil microbial nitrogen(P < 0.01); K. prostrata, and S. breviflora were significantly positively correlated with soil water content(P < 0.01); and A. frigida, K. prostrata, and S. breviflora were significantly positively correlated with above-ground biomass (P < 0.01).





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