【作者】 逯军峰；

【导师】 王辉；

【作者基本信息】 甘肃农业大学 ， 水土保持与荒漠化防治， 2007， 硕士

【摘要】 凋落物分解是森林生态系统养分循环中的重要过程,对土壤有机质的形成和养分释放有重要意义,凋落物分解释放的营养元素更是森林维持自身生长的重要物质来源,同时,由凋落物形成的枯枝落叶层是实现森林水源涵养、保持水土的主要作用层。本文通过对甘肃省小陇山地区不同林龄油松人工林(7a生、10a生、16 a生、23 a生、30 a生)和对照(30a生次生锐齿栎林)的凋落量、凋落物现存量、分解速率、枯枝落叶层的持水性能、枯枝落叶层养分含量、土壤理化性质的测定分析,研究不同林龄油松人工林的凋落物变化特征以及对土壤理化性质的影响,结果表明:(1)不同林龄油松人工林的年凋落量在1.957～4.236 t·hm-2之间变化,现存量在12.232～18.788 t·hm-2之间变化;油松人工林的年凋落量、现存量均随着林龄的增加而增加,30a生油松人工林的凋落量最大,而23a生油松人工林的现存量最大;油松人工林的凋落量小于次生锐齿栎林,而现存量大于锐齿栎林。(2)随着油松人工林的生长,凋落物的分解速率逐渐增加;7a生油松人工林枯枝落叶层的分解速率仅为0.160t·hm-2·a,30a生油松人工林枯枝落叶层的分解速率为0.240 t·hm-2·a;但与次生林相比,人工林枯枝落叶层的分解速率仅为次生林的33.6%。可见两种树种凋落物的性质差异显著,改变植被类型对森林生态系统物质循环将造成重大影响。(3)不同林龄油松人工林枯枝落叶层的全N、全P、全K的含量分别在8.56～11.40g·kg-1、0.45～0.63 g·kg-1、0.74～1.23 g·kg-1之间变化,全N、全P、全K的平均储存量分别为158.36㎏·hm-2、8.44㎏·hm-2、15.92㎏·hm-2;30a生油松人工林枯枝落叶层的全N、全P含量最高,而全K含量低于其它林分;油松人工林枯枝落叶层全N、全K储量分别是次生锐齿栎林的1.31、2.99倍,全P的储存量略小于次生锐齿栎林。(4)随着林龄的增加,油松人工林枯枝落叶层的自然含水量与饱和含水量均呈递增趋势且具有较好的拟合关系,两者分别在38.98%～59.22%、246.95%～300.33%之间变化;30a生油松林的自然含水率与饱和持水率分别达到最大值59.22%、300.33%;油松人工林的平均自然含水率略小于次生锐齿栎林,而饱和持水率却显著低于次生锐齿栎林(p<0.001)。(5)油松人工林的土壤理化性质随着林龄的增加而有所改善,有机质在17.5～21.0g·kg-1之间变化、全N在0.92～1.45 g·kg-1之间变化、全K在15.3～21.0g·kg-1之间变化、全P在0.35～0.50g·kg-1之间变化、pH值在6.50～7.08之间变化、田间持水量在18.08～22.81%之间变化、容重在1.06～1.19g·cm-3之间变化;同次生林相比,油松人工林的土壤有机质含量、全N含量、全P含量、田间持水量低,全K含量大致与次生林相近,但容重高于次生锐齿栎林。可见次生锐齿栎林的土壤结构状态和肥力水平要明显好于油松人工林。(6)油松人工林凋落量、现存量、分解率与土壤容重呈负相关,而与土壤全氮、全磷、全钾、田间持水量、pH值呈正相关。更多还原

【Abstract】 The decomposition of forest litters was an important process of nutrient cycling in forest ecosystems and played important role in soil organic matter formation and nutrients released. The nutrition elements released from decomposition in forest litters was an important material sources to vegetation grow. At the same time, Litter layers was main part to keep water and soil. The annual litterfall, pools of litter layers, decomposition rate of forest litters, water holding capacity, the content of main nutrients in litter layers, the physical and chemical properties of forest soil in different plots and the impact of litter on changes of physical and chemistry in Pinus tabulaeformis plantation at different ages in Xiaolong Mountain were studied in the paper. Main results were as follows:(1)The annual litterfall and pools of litter layers was increased with ages, the annual litterfall was rang from 1.957 t?hm-2 to 4.236 t·hm-2, pools of litter layers was rang from 12.232 t?hm-2 to 18.788 t?hm-2, annual litterfall of 30a pinus tabulaeformis plantation had the maximal amount up to 4.236t?hm-2,but the pools of litter layers of 23a pinus tabulaeformis plantation had maximal amount up to 18.788 t?hm-2. the annual litterfall of pinus tabulaeformis plantation was less than secondary forest, but pools of litter layers was more than secondary forest.(2)The decomposition rate of litter was increased with ages. The litter decomposition rate of 7a pinus tabulaeformis plantation was 0.160t·hm-2·a, The litter decomposition rate of 30a pinus tabulaeformis plantation was 0.240t·hm-2·a; the average decomposition rate of litter layers was 33.6% compared with secondary forest. The characteristics of litter quality was different obviously between two trees, To change the type of vegetation has great impact on the material circulation in ecosystem.(3)The content of N ,P ,K in litter layers of pinus tabulaeformis plantation were ranging from 8.56～11.40g·kg-1、0.45～0.63 g·kg-1、0.74～1.23 g·kg-1, respectively. The average reserve of total N, P, K in litter layers were 158.36㎏·hm-2、8.44㎏·hm-2、15.92㎏·hm-2, respectively. The content of N, P in 30a pinus tabulaeformis has maximal amount, but the content of K was less than others. The average reserve of total N, K was 1.31 and 2.99 times than secondary forest, but the average reserve of total P was less than secondary forest.(4)Both water content and saturate water-holding capacity was increased with ages and ranged from 38.98% to 59.22%, 246.95% to 300.33%,respectively,and could be described statistically, the water content and saturate water-holding capacity of 30a pinus tabulaeformis plantation had the maximal amount up to 59.22%、300.33%.The average water content of pinus tabulaeformis plantation was less slightly than secondary forest, but saturate water-holding was more less than secondary forest (p<0.001).(5) The physical and chemical properties were improved with ages, the content of soil organic matter was ranging from 17.5 to 21.0g·kg-1, the content of soil total N ranging from 0.92 to 1.45 g·kg-1, the content of soil total K was ranging from 15.3 to 21.0g·kg-1,the content of soil total P was ranging from 0.35 to 0.50 g·kg-1, pH was ranging from 6.50 to 7.08, field capacity was ranging from 18.08% to 22.81%, soil bulk density was ranging from 1.06 to 1.19g·cm-3.The content of soil organic matter, soil total N, total P, field capacity was less than secondary forest, but the content of soil total K was almost equal to secondary forest and bulk density was more than secondary forest. It was obvious that soil fertility of secondary forest was better than pinus tabulaeformis plantation.(6)The soil factors of soil organic matter, total N, total P, total K, pH, field capacity showed positive correlation with annual litterfall, reserve of litter and decomposition rate, but the factor of soil bulk density showed negative correlation with those factors of forest litter.更多还原