典型荒漠植物凋落物分解及养分动态研究

Study on Dynamic Status of Litter Decomposition and Nutrients of Typical Desert Plants

采用分解网袋法,对古尔班通古特沙漠南缘粗柄独尾草(Eremurus inderiensis)、尖喙牻牛儿苗(Erodiumoxyrrhynchum)和沙漠绢蒿(Seriphidium santolinum)3种荒漠植物叶、茎和根的分解、养分释放特性进行了研究。结果表明:叶片、茎、根系的质量损失过程均符合指数衰减模型。经过364 d的分解,粗柄独尾草叶、粗柄独尾草根、尖喙牻牛儿苗叶、尖喙牻牛儿苗茎、尖喙牻牛儿苗根、沙漠绢蒿茎、沙漠绢蒿根的失重率分别为41.96%、81.94%、42.18%、29.32%、47.02%、20.66%和20.71%;3种植物根、茎、叶的分解速率存在显著差异,分解速率依次为:粗柄独尾草根>叶;尖喙牻牛儿苗根>叶>茎;沙漠绢蒿根>茎。在整个分解过程中,N和P含量总的趋势表现为释放,叶、根凋落物质量损失与初始N、P含量显著负相关,非生物因素对其分解有重要影响。

As one of the most important ecosystem processes, litter decomposition is closely related to plant nutri- ents, ecosystem productivity and carbon and nutrient cycling, particularly to soil organic carbon pool-size and its stabilization. During last decades, numerous studies on litter decomposition in moist environment was conducted However, there was few information about litter decomposition in arid area. Litter decomposition in arid area is dif- ferent from that in moist environment owing to severe natural climate, such as sporadic rainfall, intense solar radia- tion, long-term drought and serious water loss and soil erosion. In recent studies, it was found that there is a dis- crepancy between simulated decomposition rates and measured ones in arid area. It is considered that ephemeral plants are important for net primary productivity in some deserts, and particularly for soil carbon input. The aims of this study are to investigate the dynamic status of litter decomposition of three typical desert species. Litter bag method was used to investigate the decomposition rate and nutrient release of roots, stems and leaves of Eremurus inderiensis, Erodium oxyrrhynchum and Seriphidium santolinum. Mass loss curves of leaves, stems and roots of these species were well described by an exponential decay model. Mass loss rates of leaves and roots of E. inderien- sis, leaves, stems and roots of E. oxyrrhynchum, stems and roots of S. santolinum were 41.96% , 81.94% , 42.18% , 29.32%, 47.02% , 20.66% and 20.71% respectively. During the 364-day decomposition in field, the decomposition rates were different from different species litters, and they were in an order of roots 〉 leaves of E. inderiensis, roots 〉 leaves 〉 stems of E. oxyrrhynchum and roots 〉 stems of S. santolinum. N and P release was observed throughout the decomposition process, N and P contents in litters were negatively correlated with mass loss. In addition, decomposition rate was significantly different at different decomposition stages. In conclusion, the decomposition rates of litters of desert ephemeral plants were high, and the decomposition time and litter types are the important factors of decomposition in arid area.