【作者】 何帆；

【导师】 王得祥；

【作者基本信息】 西北农林科技大学 ， 生态学， 2011， 博士

【摘要】 森林凋落物是指森林生态系统内由生物组分产生并归还到林地表面,通过分解者对其进行物质和能量的转化,维持生态系统内部物质循环的所有有机物质的总称。凋落物对森林生态系统的物质循环、能量流动、森林群落更新以及森林水源涵养、水土保持方面都有着较大的影响。本研究对秦岭林区天然次生油松Pinus tabulaeformis和锐齿栎Quercus aliena. var. acuteserrata林凋落物的储量及其分解状况进行系统研究,对于深入研究和阐明锐齿栎、油松林生态系统的物质循环和养分永续利用途径具有十分重要的意义;可为土壤肥力及林分生产力的维持、森林健康经营管理、天然林保护以及该地区森林资源的有效利用等提供理论和实践依据。研究结果表明:(1)锐齿栎新鲜凋落叶N、P含量均大于油松,两种凋落叶化学性质存在显著性差异(P<0.05)。油松新鲜凋落叶的C/N、C/P、粗纤维/N大于锐齿栎,差异性极显著(P<0.01)。油松、锐齿栎凋落叶分解均呈现出明显的季节性和阶段性特征,凋落叶前1 a干物质损失率分别达到25.20 %和43.77 %,第2 a的干重损失率只有16.20 %和25.33 %。在两个试验年度中6～9月都为凋落叶的迅速分解期,在其它月份保持了较为平稳的分解速度。分解第1 a的6～9月4个月中,油松和锐齿栎凋落叶失重率都在20 %以上,锐齿栎凋落叶失重率最大,为28.97 %,油松凋落叶也达到20.12 %。分解2 a后油松凋落叶的干物质残留率大于锐齿栎,差异显著(P<0.05)。根据Olson分解指数模型,对凋落叶分解95 %被分解所需时间进行的估测结果显示,锐齿栎凋落叶为5.43 a,油松凋落叶为9.87 a。(2)锐齿栎、油松凋落叶C剩余百分率与凋落叶和N、P剩余百分率之间具有显著的二项式回归关系(锐齿栎凋落叶P剩余百分率除外),与凋落叶C/N、C/P呈显著的线性相关关系。将油松凋落叶分别放置于油松林和油松锐齿栎混交林内进行分解,针阔混交林中放置的油松凋落叶分解速率和N、P、C养分释放速度都较油松林中放置的凋落叶更快,在两种林分中分解差异显著(P<0.05)。(3)通过模拟不同温度环境下锐齿栎凋落叶的分解实验表明,25℃温度条件下凋落叶分解和N、P释放速率最高,35℃次之,而15℃环境中凋落叶分解和N、P释放速度最慢。并且当处于25℃的温度环境中时,土壤补充N、P最为迅速,分解90天后,土壤N、P含量分别从3.41 g·kg-1和0.29 g·kg-1上升到了4.61 g·kg-1和0.58 g·kg-1,其他两种温度环境下土壤N、P含量的补充相对缓慢。(4)锐齿栎林年凋落量、凋落物养分含量、养分年回归量均大于油松林,差异性显著(P<0.05)。油松林凋落物储量为30 472.31 kg·hm-2,是锐齿栎的3.4倍,凋落物层N、P、C储量也高于锐齿栎林,两种林分凋落物储量及其养分储量差异均极显著(P<0.01)。油松林内凋落物储量较高主要是油松凋落物较慢的分解速率导致的大量凋落物在林内累积所造成的。(5)锐齿栎和油松林死木质残体储量分别为31 649.33、9 430.75 kg·hm-2。就CWD组成而言,锐齿栎林枯立木和倒木所占的比例基本为1,而油松林中枯立木占据CWD总储量的85.65 %,倒木只占CWD总储量的14.35 %。(6)油松、锐齿栎林细根在分解2 a后,锐齿栎干重残留率和N、P残留率均小于油松细根,差异显著(P<0.05),说明锐齿栎林细根分解速率和养分释放速率均大于油松细根。更多还原

【Abstract】 Forest litter is the general term of all organic matter that producing by the biological components and returning to the woodland surface in forest ecosystem. It maintains the inner material cycle of forest ecosystem through the material and energy transformation of decomposers. Litter has an important significance in the material recycling, energy flow, forest community succession and forest water resource conservation, soil and water conservation of the forest ecosystems.Reserves and decompositions of natural secondary Pinus tabulaeformis litter and Quercus aliena var. acuteserrata litter from Qinling Mountains have been investigated in this study. It has a very important significance in clarifying the material recycling and the sustainable use of Quercus aliena var. acuteserrata and Pinus tabulaeformis. It can also provide theoretical and practical basis for the maintenance of soil fertility and forest productivity, forest health management, natural forest protection and effective utilization of forest resources in this area.The results were obtained as following:(1) There was a significantly different chemical properties of leaf-litters between Pinus tabulaeformis and Quercus aliena var. acuteserrata.The content of N and P in Quercus aliena var. acuteserrata litter were both greater than those in Pinus tabulaeformis leaf-litters. However, the ratio of carbon to nitrogen (C/N), the ratio of carbon to phosphorus (C/P) and the ratio of crude fiber to nitrogen (crude fiber/N) of fresh leaf-litters in Pinus tabulaeformis leaf-litters were all greater than those in Quercus aliena var. acuteserrata leaf-litters, and the difference was significant (P<0.01). The decomposition of leaf-litters in Pinus tabulaeformis and Quercus aliena var. acuteserrata both showed significant seasonal and periodic variations. Loss percentage of dry matters from Pinus tabulaeformis leaf-litters and Quercus aliena var. acuteserrata leaf-litters in the first year were 25.20% and 43.77%, respectively, however, they were only 16.20% and 25.33% in the next year, respectively. It was concluded that the rapid degradation of leaf-litters in the two species was from June to September each year, while the degradation rate was relatively stable in other months. Loss ratio of leaf-litters in Quercus aliena var. acuteserrata was most (28.97%), and those in Pinus tabulaeformis was 20.12% in the first year. Residual percentage of dry matter in Pinus tabulaeformis leaf-litters was much greater than those in Quercus aliena var. acuteserrata leaf-litters after two years (P<0.01). According to Olson decomposition exponential model, the shortest time that the 95 percent leaf-litters could be decomposed was 5.43 years for Q. aliena var. acuteserrata, and 9.87 years for P. tabulaeformis.(2) There were significant binomial regression between the remaining percentage of carbon nutrient (organic carbon) and the remaining percentage of N and P nutrient in Quercus aliena var. acuteserrata leaf-litters and Pinus tabulaeformis leaf-litters. There were significant linear correlation between the remaining percentage of leaf-litters carbon nutrient and C/N, C/P in the two species. When the leaf-litters of Pinus tabulaeformis was placed in Pinus tabulaeformis forest and mixed forest of Pinus tabulaeformis and Quercus aliena var. acuteserrata to be decomposed, the nutrient release rate of N, P, C in the latter were much greater than the former (P <0.01).(3) The decomposition test of Quercus aliena var. acuteserrata leaf-litters under different temperature conditions showed that leaf-litters decomposition rate and N, P nutrients release rate were all highest at 25℃, followed by 35℃, while all those were slowest at 15℃. Leaf-litters was was decomposed rapidly when the soil was added into N, P nutrients at 25℃,and N, P contents in soil increased from 3.41 and 0.29 g·kg-1 to 4.61 and 0.579 g·kg-1, respectively, after decomposing 90 days, however, the supplement rate of N, P contents in soil were relatively slow under other two temperature conditions.(4) The annual amount, nutrient content, nutrient regressed of litter in Quercus aliena var. acuteserrata were all greater than those in Pinus tabulaeformis (P<0.01). Litter reserves in Pinus tabulaeformis was 30 472.31 kg·hm-2, which was 3.4 times as Quercus aliena var. acuteserrata. N, P and C reserves of litter in Pinus tabulaeformis were also higher than those in Quercus aliena var. acuteserrata (P<0.05). The reason that accumulation in Pinus tabulaeformis litter was that the decomposition rate was slow, resulting in a lot of litter accumulating in the Pinus tabulaeformis forest.(5)Woody debris reserves in the two species had 31 649.33 and 9 430.75 kg·hm-2.On CWD composition, snags and fallen trees in natural Quercus aliena var. acuteserrata forests had a same proportion, while the proportion was 85.65% and 14.35% in Pinus tabulaeformis forest, respectively.(6) Decomposition of fine roots in the two species after two years, dry weight residual percentage of fine root and N, P residual percentage were all less than those in Pinus tabulaeformis, (P<0.05). It meant that fine root decomposition percentage and nutrient release percentage in Quercus aliena var. acuteserrata litter were both greater than those in Pinus tabulaeformis.更多还原