摘要:橡胶树凋落叶在橡胶林生态系统养分循环中起着重要的作用，研究凋落叶的分解和养分释放特性及其影响因素，对资源的循环利用及指导高效施肥具有重要意义。在海南省天然橡胶主产区选取橡胶林地进行凋落叶原位分解试验，研究坡度和埋深对橡胶树凋落叶干物质分解特性、养分元素释放规律及其物质成分红外光谱特征的影响。结果表明，凋落叶分解速率明显受到坡度和深度的影响；分解9个月后，干物质残留率高低顺序为坡地覆盖（39.6%） > 平地覆盖（26.8%） > 平地埋深（11.2%） > 坡地埋深（6.9%）；凋落叶的损失符合Olsen指数衰减模型（P < 0.01），各处理凋落叶干物质分解95%所需要的时间分别为29.3、20.5、12.8和13.2个月；各处理C/N比从最初的25.1下降到12.7、14.4、16.2和16.9。分解期间各处理养分残留率差异显著（P < 0.05）；分解9个月后，坡地覆盖处理S-I养分元素C、N、P、K、Ca、Mg的残留率最高，分别为10.9%、21.6%、10.7%、9.7%、10.4%、7.9%，而坡地埋深处理S-Ⅱ最低，分别为3.8%、6.5%、3.4%、2.3%、0.8%、2.1%。傅里叶红外光谱（FTIR）分析显示，凋落叶分解前后在3387 cm^-1、1734 cm^-1处的吸收峰强度明显减弱，表明纤维素、半纤维素、木质素、多糖、脂肪族等碳水化合物遭到分解；1050 cm^-1处的吸收峰向低频方向位移了17 cm后变为1033 cm^-1，表明分解破坏了凋落叶原有的可溶性糖和纤维素C-C键和C-O键伸缩振动。综上所述，埋深处理有利于加速凋落叶物质分解和养分元素释放速率；建议橡胶树生产中将凋落叶与表土混合或压青处理，提高橡胶林养分循环效率。



Abstract:Leaf litter plays an important role in nutrient recycling in rubber ecological systems. Studying the decomposition characteristics of dry matter and nutrient release and their effects has important significance for resource utilization and the management of high efficiency fertilization. A decomposing-bag experiment was conducted in a rubber forest at the main production areas of natural rubber trees in Hainan Province, China. The objectives were to study the effects of slope and depth on the characteristics of dry matter decomposition, nutrient release, and FTIR (fourier transform infrared spectroscopy) of leaf litter. The results showed that the decomposition rates were significantly affected by varying degrees of slope and depth. The dry matter remaining rates between different treatments were in the following order:covered slopes (39.6%) > covered flatland (26.8%) > buried flatland (11.2%) > buried slopes (6.9%). Leaf litter loss agreed with an Olsen exponential attenuation model (P < 0.01). The time required for 95% leaf litter decomposition was 29.3, 20.5, 12.8, and 13.2 months, and the C/N ratios decreased from the initial 25.1 to 12.7, 14.4, 16.2, and 16.9 after 9 months, for the above treatments, respectively. The nutrient remaining rates were significantly different (P < 0.05) among different treatments during the decomposition stage. After 9 months, the nutrient remaining rate for C, N, P, K, Ca, and Mg on the covered slope was higher than that in other treatments, at 10.9%, 21.6%, 10.7%, 9.7%, 10.4%, and 7.9%, respectively; but that in the buried slopes was lower than that in the other treatments, at 3.8%, 6.5%, 3.4%, 2.3%, 0.8% and 2.1%, respectively. Analysis of the FTIR spectroscopy characteristics of leaf litter showed the absorption peak strength at waves of 3387 cm^-1 and 1734 cm^-1, which obviously became weak after 9 months of decomposition, thus proving the decomposition and transformation of carbohydrates, i.e. cellulose, hemicellulose, lignin, polysaccharide, and fatty acid group compounds. The absorption peak at 1050 cm^-1 shifted to 17 cm at low frequency and then changed to 1033 cm^-1, suggesting that decomposition destroyed the original soluble sugar and cellulose C-C and C-O bond stretching vibration. In conclusion, buried leaf litter could contribute to mass loss and nutrient release. Therefore, we suggest that the litter of rubber forests should be mixed with soil or buried in green manuring pits to improve the recycling efficiency of rubber plantation systems.





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