滇池湖滨带优势湿地挺水植物分解特征研究

Decomposition characteristics of common wetland emergent plants in Dianchi lakeside

关键词:  挺水植物, 分解动态, 湖滨带, 枯落物, 生境

Key words:  emergent plants, decomposition of dynamic, lakeside, litter, habitat

摘要:

湿地挺水植物是维持湿地生态系统功能的重要载体,其分解过程是物质能量循环的必要环节。为了更全面地了解湿地凋落物的分解特征,该研究选取九种滇池湖滨带优势湿地挺水植物,采集生长旺季、立枯阶段、倒伏阶段、沉水阶段共4个阶段的叶枯落物样品,在3.5 a的培养期内测定了叶枯落物分解速率及3大类指标(16种理化指标),分析了分解速率和理化指标的动态变化及其相关性、物种种类与分解阶段对各指标变异的贡献度。结果表明:(1)分解速率(k)范围为0.43 ～ 1.41 a^-1,其中茭草分解最快(k=1.41 a^-1),再力花分解最慢(k=0.43 a^-1)。(2)物理性状中的比叶面积、穿刺力度、干物质量在培养期内分别呈“持续上升”“持续下降”和“先升后降”的变化趋势; 养分元素指标主要呈现“释放-富集”“富集-释放”和“净释放”3种变化模式; 涉碳化合物指标中,木质素表现为“富集-释放”“富集-释放-富集”和“富集”模式,纤维素与半纤维素表现为“富集-释放”的变化规律。(3)叶枯落物分解速率与初始物理指标(比叶面积、穿刺力度、干物质量)和初始涉碳化合物指标(纤维素、半纤维素)的相关性最高。(4)13种指标在培养期内的动态变化由分解阶段主导,3种指标由物种种类主导。其中,比叶面积、穿刺力度、干物质量、碳、钾、钙、硫、铁等在不同植物的分解过程中表现出相似的规律,可作为研究挺水植物枯落物分解的关键指示性指标。该研究表明,不同植物的分解速率不同,物理和涉碳化合物指标是调控分解速率的主要因子; 通过揭示不同湿地挺水植物的分解规律,为进一步开展枯落物分解预测提供重要理论参考。

Abstract:

Wetland emergent plants are important carriers for maintaining the functions of wetland ecosystems, and the decomposition process is a necessary part of the material energy cycle. In order to fully understand the decomposition characteristics of wetland litter, we selected nine dominant wetland emergent plants in Dianchi lakeside and collected the leaf litter samples in four stages from living to death, including vigorous growth season, standing dead stage, lodging stage, and submerged stage. We measured the leaf litter decomposition rate and sixteen physical and chemical indexes during the 3.5 a period. We analyzed the dynamic changes of decomposition rate and physical and chemical indicators, as well as their correlation, and we calculated the contribution of species and decomposition stages to the variation of each indicators. The results were as follows:(1)Decomposition rates(k value)ranged from 0.43 a^-1 to 1.41 a^-1, among which Zizania latifolia decomposed the fastest(k=1.41 a^-1), Thalia dealbata decomposed the slowest(k=0.43 a^-1).(2)Specific leaf area, puncture strength and dry matter amount showed a trend of “continuous increase” “continuous decrease” and “first increase and then decrease”, respectively. Nutrient element indexes mainly presented “release-enrichment”“enrichment-release” and “net release” modes. Among the key carbon-related indexes, lignin showed the trend in “enrichment-release”“enrichment-release-enrichment” and “enrichment”, respectively. Cellulose and hemicellulose showed “accumulation-release” changes.(3)Leaf litter decomposition rate had the highest correlation with initial physical indexes(i.e., specific leaf area, puncture strength, amount of dry matter)and initial carbon-related indexes(i.e., cellulose, hemicellulose).(4)Dynamic changes of thirteen indexes during the incubation period were mainly dominated by the decomposition stage, and three indexes were dominated by species. Among them, specific leaf area, puncture strength, amount of dry matter, carbon, potassium, calcium, sulfur, iron and other indexes have consistency in the decomposition dynamics of different emergent plants. Therefore, it can be used as key indexes for emergent plant litter decomposition. This study indicates that the decomposition rates of different plants are different, and physical and carbon-related compound indicators are the main factors regulating the decomposition rate, the decomposition law of wetland emergent plants is revealed to provide crucial theoretical reference for further predicting litter decomposition of wetland emergent plants.