鄱阳湖湿地优势植物枯落物的分解速率及碳、氮、磷释放动态特征

植物枯落物分解对生态系统碳通量和养分循环有至关重要的作用，这一过程主要由3个相互作用的因素决定，即化学（枯落物理化特性）、物理（气候和环境）以及生物（参与枯落物分解的微生物和无脊椎动物）因素。在气候和立地环境条件相同的情况下，枯落物质量是制约分解的内在因素。在鄱阳湖湿地开展了野外定位观测实验，采用分解袋技术研究了鄱阳湖湿地优势植物芦苇（Phragmite）、南荻（Triarrhena lutarioriparia）和薹草（Carex.cinerascens Kükenth）枯落物分解速率及碳（C）、氮（N）、磷（P）元素释放动态特的征差异性。结果表明，在0-150 d内三种植物枯落物的干物质分解速率和残留率以及碳相对归还指数（CRRI）、氮相对归还指数（NRRI）、磷相对归还指数（PRRI）差异性都极其显著。在0-150 d内分解速率都是芦苇的最大，薹草的次之，南荻最小。分解进行150 d后，芦苇、南荻和薹草枯落物干物质残留率依次约为56.57%、67.99%和60.88%，CRRI依次约为57.44%、34.58%和41.75%，NRRI依次约为50.71%、-22.66%、和23.18%，PRRI依次约为88.91%、79.27%和85.63%。用Olson负指数衰减模型拟合方程预测芦苇、南荻、薹草枯落物分解完成50%所需的时间大约依次为184 d、249 d和210 d，分解完成95%所需的时间依次为795 d、1078 d和908 d。芦苇和薹草枯落物碳、氮和磷在分解过程中都表现出净释放模式，而南荻枯落物的碳和磷也一直表现为净释放模式，但是氮一直表现为净积累模式。芦苇分解过程中的营养释放作用最强，而南荻群落对氮的吸收和富集效应最强。研究表明植物种类及基质物质量对枯落物分解及其养分释放有很强的调控作用。今后的研究应考虑不同物种枯落物混合时的分解过程以及分解过程中的微生物因素，以便能揭示植物群落物种多样性及微生物活动在湿地生物地球化学循环中的调控作用机制，以期为鄱阳湖湿地碳、氮和磷的生物地球化学循环提供更新的认识，为鄱阳湖湿地的科学管理、保护与恢复提供科学依据。

Dynamic characteristics of the decomposition rate and carbon, nitrogen and phosphorus release of the dominant plants in Poyang Lake Wetland

Litter decomposition is an important ecological process in global carbon (C) and nutrient cycling. This process is mainly determined by three factors of interaction, namely, chemical (physical and chemical properties of litter), physical (climate and environment), and biological (microorganisms and invertebrates involved in the decomposition of litter) factor. Under the same climate and site environment, the quality of litter is the internal factor that restricts decomposition. This study aims to investigate the decomposition rate and dynamic characteristic difference of carbon, nitrogen, phosphorus release from the litter of Phragmite, Triarrhena lutarioriparia, Carex. cinerascens Kükenth in Poyang Lake wetland, using decomposition bag technique. The results showed that there were significant differences of the dry mass remaining rates, decomposition rates, and carbon relative return index (CRRI), nitrogen relative return index (NRRI), phosphorus relative return index (PRRI) between three types of plants litter within 0-150 d. The decomposition rate of Phragmite was the highest, followed by Carex. cinerascens litter, and decomposition rate of Triarrhena lutarioriparia was the smallest. After 150 days of decomposition, the dry mass remaining rates of Phragmite, Triarrhena lutarioriparia Carex. cinerascens were about 56.57%, 67.99%, and 60.88%. The CRRIs of the three plants were 57.44%, 34.58% and 41.75%, the NRRIs of them were 50.71%, -22.66%, and 23.18%, and the PRRIs of them were 88.91%, 79.27% and 85.63%, respectively. The simulation results of Olson negative exponential model estimated that it would cost 184, 249 and 210 days respectively for decomposing 50% of Phragmite, Triarrhena lutarioriparia, Carex. cinerascens litter and about 759, 1078 and 908 days for 95% of them. The C, N, P of Phragmite and Carex. cinerascens litter showed a net release pattern within 150 days, while the C and P of Triarrhena lutarioriparia litter also showed a net release pattern, but N always showed a net accumulation pattern. Our studies showed that the plant species and the physical and chemical properties of litter had a strong regulatory effect on the decomposition and the release of nutrients. Our future studies should consider the decomposition process of different species litter mixing and the microbial factors in the decomposition process, so as to reveal the regulation mechanism of plant community species diversity and microbial activities in wetland biogeochemical cycle. In order to provide a renewed understanding for the biogeochemical cycle of C, N, and P in Poyang Lake wetland, and to provide scientific basis for scientific management, protection and restoration of Poyang Lake wetland.