【作者】 郭剑芬；

【导师】 杨玉盛；

【作者基本信息】 福建农林大学 ， 水土保持与荒漠化防治， 2003， 硕士

【摘要】 我国中亚热带地区山高坡陡，土壤抗蚀性能差，加上降雨量大且集中，天然林经皆伐、炼山和整地后改为人工林，群落结构简单与树种单一且由于幼林郁闭前水土肥流失较为严重，人工林长期生产力及涵养水源功能的维持日益引起人们关注。枯枝落叶层作为土壤特有的发生层次，是森林生态系统中腐屑食物链的起点，有机碳和养分的储库，并为生态系统的过程提供能量和物质，对维护林地土壤肥力和提高森林生产力具有重要的作用。同时，该层还具有良好涵养水源和保持水土功能。森林生态系统重要组成成分之一的粗木质残体与枯枝落叶层一样，在保持水土和养分及影响土壤发育等方面具有重要的意义。本文以三明格氏栲天然林、格氏栲和杉木人工林及建瓯木荷和杉木人工林为研究对象，对其枯枝落叶层和粗木质残体的生态功能进行较为系统的研究，结果表明： （1）格氏栲天然林、格氏栲人工林和杉木人工林枯枝落叶层现存量分别为8.99、7.56和4.81t·hm^-2；其中叶所占比例分别为64.96％、61.38％和38.05％，枝所占比例分别为31.59％、37.83％和42.62％。三种林分粗木质残体总贮量分别为1.28、0.41和0.21t·hm^-2。格氏栲天然林与人工林枯枝落叶层现存量最大值均出现在春季，而杉木人工林枯枝落叶层现存量最大值出现在夏季。三种林分粗木质残体贮量的季节变化模式均为夏季＞春季＞秋季＞冬季。 （2）格氏栲天然林、格氏栲人工林和杉木人工林不同分解程度枯枝落叶层和粗木质残体的C含量均为L层高于F层。三种林分枯枝落叶层C贮量平均值分别为4.02、3.29和2.28t·hm^-2；格氏栲天然林和人工林与杉木人工林枯枝落叶层C库差异达到显著水平（P＜0.05）。格氏栲天然林粗木质残体C总贮量为0.78t·hm^-2，分别是格氏栲和杉木人工林的4.11倍和7.09倍。枯枝落叶层碳贮量季节变化模式与枯枝落叶层现存量的基本相似。 （3）格氏栲天然林与人工林枯枝落叶层N、P、K平均浓度略高于杉木人工林，而Ca和Mg平均浓度则以杉木人工林枯枝落叶层的为高。未分解层枝的养分浓度基本上小于半分解层，而叶的情况略有不同。格氏栲天然林、格氏栲人工林和杉木人工林枯枝落叶层养分贮量分别为138.42、113.56和72.39kg·hm^-2；除Mg外，格氏栲天然林枯枝落叶层中各种养分贮量均最高。 格氏栲天然林未分解层粗木质残体的N、P、K、Ca、Mg浓度及半分解层N、K、Ca浓度均高于格氏栲和杉本人工林，而格氏栲人工林半分解层粗木质残体的P和Mg浓度均高于其它两种林分。格氏栲天然林粗木质残体养分贮量为14.16kg·hm^-2分别是格氏栲和杉木人工林的4.9倍和14.9倍。三种林分粗木质残体的各元素贮量的大小顺序均为：N＞Ca＞K＞Mg＞P。（4）三种林分枯叶和枯枝水溶性物质和纤维素含量从L层到F层不断下降，而枯枝中 苯醇溶性物质和粗蛋白质含量有所上升。格氏拷天然林枯叶和枯枝水溶性物质、 木质素、粗蛋白质、半纤维素和纤维素总贮量最高，而苯醇溶性物质总贮量以格 氏拷人工林的最高。三种林分F层枯叶和枯枝有机物质的总贮量高于L层。 除半纤维素和纤维素外，三种林分粗木质残体水溶性物质、木质素和粗蛋白 质含量均为L层>F层，而苯醇溶性物质含量为L层<F层.与两种人工林相比， 格氏拷夭然林粗木质残体中各种有机物质贮量均最高。（5）格氏拷天然林、格氏拷人工林和杉木人工林枯叶与粗木质残体的干重热值和去灰 分热值从L层到F层均不断下降。格氏拷天然林枯枝落叶层能量现存量达16125.72 KJ饥一，分别比格氏拷和杉木人工林枯枝落叶层能量现存量高24.290/0$口8L63%。 格氏拷天然林粗木质残体的能量现存量为2389石4 KJ.m.2，分别为格氏拷和杉木人 工林的3.35倍和5.77倍。（6）格氏拷天然林、格氏拷人工林和杉木人工林枯叶和枯枝的最大持水率从L层到F 层逐渐增大，其中格氏拷天然林枯叶和枯枝的平均最大持水率增幅最明显 （56.75%）。三种林分枯枝落叶层持水总量分别为18.78、15.16和9.35 t.hm一，，分 别达自身重量的2.09倍、2.00倍和1.94倍。其中F层叶和枝持水量占林分枯枝落 叶层总持水量的比例分别为67.63%、80.67%和60.86%。（7）杉木人工林中209（处理l）、309（处理2）和409（处理3）原状枯枝落叶截留降 雨量分别t匕木荷人工林的增加16.55%、16.26%和21.17%。在2002年l月一12月 不同降雨情况下，林内和林外微型小区枯枝落叶层减少径流量和泥沙量的效应均 十分显著（尸<0.05）。木荷和杉木人工林林内地表清除枯枝落叶层后产生的地表年 径流深分别为385.62 mm和682.76 mm，是保留枯枝落叶层的1.61倍和1.79倍; 泥沙流失量分别为668.95吨·hm.，和川6.70 ks.hm一，是保留枯枝落叶层的2.46倍 和2.52倍。林外微型小区覆盖1509（处理I）、3009（处理11）和6009（处理111） 木荷原状枯枝落叶产生的地表径流深分别为519.47 mm、417.92nun和351.43 mm，为对照的59.340，0、47.74%和40一50，0;泥沙量分别为2757.07kg·hm”、1746，33 kg·腼一和936.66kg·hm一，为对更多还原

【Abstract】 In the last decades, large-scale native forests have been converted to fast-growing and high yield commercial forest plantations to meet the demands for timber, fuel material, and other forest products. Some silvicultural measures, such as planting pure stands, clear cutting and slash burning, are widely applied during this conversion. Yield decline and land deterioration in such disturbed ecosystem has become serious. In this context, the ecological comparisons between native broadleaved forest and monoculture plantations are necessary in providing the implications for sustainable management. The forest floor is not only storage pools of carbon, nutrient and energy but a central, functional component of forest ecosystems. Coarse woody debris (CWD) also plays a substantial role in several ecological processes in forest ecosystems. However, few studies on forest floor and CWD have been conducted in natural and planted forests under same climatic and edaphic conditions in subtropical China. From 2001, the standing crop and seasonal dynamics of forest floor, its carbon and nutrient stocks, organic chemical properties, energy and water retention ability were studied in a natural forest of Castanopsis kawakamii (NF) and adjacent monoculture plantations of C. kawakamii (CK) and Chinese fir (Cunninghamia lanceolata, CF1) in Sanming, Fujian. In addition, dynamic hydrological role of forest floor, such as rainfall interception, water and soil conservation, was studied in plantations of Schima superba (SS) and Chinese fir (CF2) in Jianou, Fujian. The results showed that:(1) Forest floor masses were 8.99 t-hm-2 in the NF, 7.56 t-hm-2 in the CK and 4.81 t-hm-2 in the CF1 respectively; of the total amount, leaves constituted 64.96%, 61.38% and 38.05% respectively, twigs constituted 31.59%, 37.83% and 42.62% respectively. The average mass of CWD in the NF, CK and CF, were 1.28, 0.41 and 0.21 t-hm-2 respectively. The standing crop of forest floor in the NF and CK showed similar seasonal trend with the maximal value in spring. While for the CF), the forest floor mass peak occurred in summer. The seasonal trend of CWD mass was as follows: summer>spring>autumn>winter.(2) Carbon concentration in the L (litter) layer was higher than that of the F (fragmented) layer. Carbon storage in forest floor of the NF, CK and CFj were 4.02, 3.29 and 2.28 t-hm-2 respectively. Significant difference of stocks of forest floor C was found between NF (or CK) and CF, (P<0.05). Carbon pools in CWD were greatest in the NF, being 4.11 times and 7.09 times as much as that of the CK and the CFi, respectively. Seasonal pattern of C pools in forest floor was similar to that of forest floor masses.(3) Concentrations of N, P and K in forest floors of the NF and CK were higher than those of the CF). In contrast, Ca and Mg concentrations were the highest in the CF|. Twig litter inthe L layer had lower nutrient concentrations than those in the F layer. Nutrient storage in forest floors ranged from 138.42 kg-hm-2 in the NF to 72.39 kg-hm-2 in the CF1. Except for the highest Mg stock in the forest floor of the CK, the amounts of N, P, K and Ca storage were the highest in the forest floor of the NF.The NF had the highest nutrient concentrations of CWD in L layer. While for F layer, P and Mg concentrations of CWD were highest in the CK. Nutrient pools in CWD varied considerably among forests, with greatest values for NF (14.16 kg-hm-2), followed by CK (2.90 kg-hm-2) and CF1 (0.95 kg-hm-2). Nutrient storage in CWD in the three forests followed the sequence of N>Ca >K>Mg>P.(4) Concentrations of water soluble compounds and cellulose in leaf and twig litter of the L layer decreased during the decomposition, while increases of concentrations of alcohol soluble compounds and coarse protein were found in twig litter. Maximum storage of water soluble compounds, lignin, coarse protein, hemicellulose and cellulose were observed in leaf and twig litter of the forest floor in the NF, while the forest floor of the CK had the greatest amount of a更多还原