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古尔班通古特沙漠5种植物凋落物分解特征

来源：花匠小妙招时间：2024-11-13 07:01

摘要： 为明确养分受限环境中凋落物的分解特征及调控因素,以古尔班通古特沙漠5种不同生活型植物粗柄独尾草(Eremurus inderiensis)、尖喙牻牛儿苗(Erodium oxyrrhynchum)、芦苇(Phragmites communis)、花花柴(Karelinia caspia)和小果白刺(Nitraria sibirica)为对象,利用分解网袋法,研究了典型植物各器官(叶、茎、根)凋落物的分解过程。结果表明:(1)不同生活型植物各器官凋落物的质量损失过程可以用负指数衰减模型较好地拟合(R2>0.70),经过629 d的分解,物种间及同一植物各器官间凋落物的分解速率存在显著差异,粗柄独尾草和尖喙牻牛儿苗的分解快于芦苇、花花柴和小果白刺,5种植物叶、根凋落物的分解快于茎,而叶和根分解的快慢具有明显的种间差异;(2)凋落物分解过程中N、P养分动态因物种、器官类型而异,5种植物茎凋落物呈现不同程度的养分固持,而粗柄独尾草和尖喙牻牛儿苗的叶、根表现为N、P养分的净释放;(3)初始化学组成对根、茎凋落物分解的影响比叶重要,其中,初始养分含量和难降解成分是限制根分解的主要因子。凋落物初始化学组成是预测温带荒漠凋落物分解的重要因素,而其重要性受植物生活型和器官类型的影响,因此,未来气候变化下,植物物种或植物生物量分配的变化所引起的凋落物质量改变,可能会对荒漠生态系统碳和养分循环产生较大影响。

关键词: 荒漠生态系统, 生活型, 凋落物分解, 分解速率, 养分动态

Abstract: Litter decomposition is one of the key processes in nutrient cycles in temperate deserts. The objectives of this study were to explore the litter decomposition characteristics of four plant life-forms, comprising five typical desert species. Litterbag experiment was carried out to investigate the decomposition characteristics of leaf, stem and root litters of Eremurus inderiensis, Erodium oxyrrhynchum, Phragmites communis, Karelinia caspia and Nitraria sibirica in the Gurbantunggut Desert, northwestern China. Litter mass loss were well described by an exponential decay model (R2>0.70). Decomposition rates were significantly different among species and organs within species. The decomposition rate of E. oxyrrhynchum and E. inderiensis were faster than that of P. communis, K. caspia and N. sibirica after 629 days of decomposition. Leaf and root decomposition were faster than stem, whereas the difference between leaf and root decomposition differed in terms of the plant. In addition, the nutrient release dynamics depended on species and plant organ. Stem generally exhibited nutrient accumulation, while leaf and root of E. inderiensis and E. oxyrrhynchum showed N and P releases. Initial chemical composition was more important in predicting decomposition rates or patterns of stem and root than leaf. Root decomposition was primarily determined by initial nutrient content and the content of recalcitrant compounds of litter. Results suggest that initial chemistry composition plays an important role in litter decomposition in temperate deserts, and the decomposability of desert litters depends on plant life-form and organ. Thus, changes in plant species or in allocation patterns among organs due to litter quality change could have profound effects on carbon and nutrient turnover in desert ecosystems.

Key words: desert ecosystem, life form, litter decomposition, decomposition rate, nutrient dynamics

中图分类号:

Q948.1