【作者】 程煜；

【导师】 洪伟； 吴承祯；

【作者基本信息】 福建农林大学 ， 生态学， 2003， 硕士

【摘要】 森林凋落物是森林生态系统生物产量、养分循环及能量流动研究中的一项重要指标，它是森林生产力的重要组成部分，是林地有机质的主要物质库和维持土壤肥力的基础，是森林生态系统物质循环和能量流动的主要途径，对土壤有机质的形成和养分的释放有着十分重要的意义。在森林凋落物中，落叶是其主要部分，占60％～80％，树叶凋落物的分解是生态系统功能的一个关键成分，其分解过程反映了森林凋落物养分归还土壤的基本特征。森林通过凋落物归还的养分对维持林地的地力具有十分重要的意义，特别是在我国很难做到对林地进行大面积施肥的情况下，凋落物的养分再循环对保持林地的长期生产力显得更为重要。 本文通过对福建省罗卜岩自然保护区内8个具有代表性的闽楠群落结构的调查，分析了亚热带闽楠天然林群落的植被特征和群落结构特征。结果表明，闽楠群落结构分化明显，可分为乔、灌、草三层。植被种类较丰富，乔木层有55个树种、灌木层有82种植物、草本层也有22种，且都发育良好。在乔木层中，以闽楠、青冈栎和檵木为优势种，它们占总物种数的5.5％，重要值却占总数的37.22％，其中闽楠的重要值为28.90％，充分说明闽楠作为群落的建群种，在群落中占有绝对优势。灌木层中重要值位居前五位的有草珊瑚、闽楠幼树、冬青、杜茎山和矩形叶老鼠刺，6.1％的物种占总重要值的24.33％，闽楠幼树的重要值(6.16％)在灌木层中位居第二位，说明闽楠林下更新良好，群落处于稳定增长状态。因群落郁闭度均较大，林内光照较弱，所处地区降水又较多，林内湿度大，因而草本层中蕨类植物较多，群落层间植物发达。群落生长茂盛，外貌呈暗绿色，林相整齐，结构稳定，郁闭度一般在0.8左右，对生境具有良好的适应性。 通过对闽楠天然林林下凋落物现存量的调查，分析了其凋落物层中未分解层和半分解层的储蓄量和含水量。结果表明，在我们调查的8个具典型性的闽楠群落内，林地现存的凋落物中，闽楠凋落物未分解层平均为1.061 435 t/bm~2，占总现存量的32.04％；其它树种未分解凋落物平均为0.860 54 t/hm~2，占总现存量的25.97％；半分解状态凋落物为1.391 185t／hm~2，占总现存量的41.99％，半分解层占有绝对优势。这可能是因样地均处于阳坡(东南坡、西南坡或西坡)，水热状况较好，群落结构稳定，群落内的凋落物分解速度较快。样地内凋落物层平均总持水量达2.318 74t/hm~2，平均持水率高达61.09％，这从一定程度上反映了凋落物层的拦蓄降水、调节森林生态系统水量平衡的生态功能。而且各样地内的未分解层持水量均较少，而半分解层持水量相对都较多，可见相对的半分解层对凋落层的持水蓄水能力的贡献更大。在闽楠林凋落物中，落叶的干重占总凋落物层干重的68.92～99.46％，在凋落层中占有绝对优势。 对闽楠落叶的分解过程进行了系统的研究，并与亚热带几种常用造林树种樟树、竹柏和池杉落叶的分解动态做定量分析比较，同时对它们的凋落物重量的变化过程予以定量化，建立动态模型分析了其动态特征并进行半衰期预测。结果表明：闽楠、 闽棱叶凋落物分解动态及其养分释放规律研究樟树、竹柏和池杉落叶均在分解前期干重下降最快，残留量仅为原来的35．450O一66．950％，到 2002年 9－11月初分解速度减慢，而＊ 月以后速度又有一定程度的上升。与樟树、竹柏和池杉落叶相比，闽桶落叶的分解速度最慢，分解一年时残留量仍占初始重量的52．33％。闽捕落叶分解50％和95％时所需时间都是最长的，分别需要1刀27 a和4．44 a。4个树种的落叶分解速率由大到小依次为：樟树＞竹柏＞池杉＞闽桶。 对闽捕落叶在分解过程中其6种主要养分元素和5种微量元素的含量、释放量及释放速率等规律进行了研究，并与樟树、竹柏和池杉落叶的11种养分元素释放规律作比较，结果表明：在分解初期，闽捕落叶的6种主要元素的总含量为449．632g·xg‘，一年后，只剩下 zoz．v刀 g·xg’，丢失了近刃．svto。闽捕落叶中的 5种微量元素含量的年变化不如主要元素的有规律。在投放时的总含量为55．128g·kg”，分解了一年后，仍有 55．970 g kg”’，几乎无变化。而且在中期其元素总含量还增加了。从叶凋落物营养元素的平均含量来看，在投放初期，闽捕落叶中6种主要元素含量的大小顺序为：有机碳＞N＞Cat K＞P＞Mg。一年后，元素含量的大小顺序变成了：有机碳＞N＞Cat K＞K＞2“Mg。 在分解始期，闽捕落叶中有机碳含量为 421．28 g·kg“‘，除低于池杉落叶中的有机碳含量外，比樟树和竹柏落叶中的都高。一年后闽捕落叶的有机碳含量降为238．95g·kg“’，高于竹柏叶，而低于樟和池杉落叶。闽捕落叶的年释放量为 182．33 g·kg’，与竹柏落叶的较相似。其年最大狰释放率为26．09％。 闽捕落叶中 N含量门．107 g·kg“‘）在分解初期比樟和池杉落叶中的都高，但一年后其含量门．6469·kg”’）却比樟、竹柏和池杉落叶中的都低。闽捕落叶的N年最大富集率为门．97％，最大释放率为22．37％，但樟、竹柏和池杉落叶均出现了富集。闽桶落叶中的 P的初始更多还原

【Abstract】 Litter is a major index in the study of biomass yield, nutrient recycling and energy flow in forestry ecosystem. It has significance to the organic formation and nutrient release because of the follow reasons: major content of the forest productivity; major material pool of forest organic; major course of the material cycling and energy flow in forest ecosystem. Leaves amounts 60%-80% of the litter. Their decomposition is a key factor in the ecosystem functions and the decomposition process reveals the fundamental characteristics of nutrients recycle. In order to remain the sustainable productivity of the forest, it is very important for the nutrient to return to soil through litter, especially the comprehensive fertilization is impossible in our country.The author investigated the structure of 8 representative community in the Luoboyan Natural Reservation in Fujian Province, analyzing characteristics of vegetation and structure of Phoebe bournei community in subtropical natural forest. The result shows that the structure separates obviously into three layers: tree, shrub and herb. There are many species in the vegetation with 55 in the tree layer, 82 in shrub layer, 22 in herb layer. They are all growing healthily. In the tree layer, the dominance species are Phoebe bournei, Cyclobalanopsis glauca, Loropetarum chinense, which accounts for 5.5% of the total species numbers, while the IV (important value) 37.22% of all. In the shrub layer, 6.1% species occupies 24.33%.The young Phoebe bournei is in the second place, which reveals the community is in stable condition because the regeneration is normal. There are more Pteridophyta species in the herb layer and many inter-community species because of the high coverage, more rainfall and high moistening. The community is favorable of the environmental with quick growth, dark-green aspect and stable forest form. Their average crown density is 0.8.The author analyzed the storage amount of the un-decomposing and sub-decomposing layers by investigating the remnant litter under the forest. The result shows that the un-decomposing remnant of Phoebe bournei litter accounts for 32.04% of the total remnant and other species 25.97%; the sub-decomposing has the dominance of 41.99%. The reason may be the sample spots are in good conditions .So the structure is stable and the decomposition rate is high. To some extend, it reflects the facts that the litter has the ecological function of containing rainfall and balancing the water in ecosystem because the total water-holding amount and the average water-holding rate are so high that they reached 2.31874t/hm2 and 61.09% respectively. Moreover, the water holding in the un-decomposition is less and that is relatively more in thesub-decomposition, which reveals the sub-decomposition contributes more to the ability of holding and storing water.By studying apprehensively the process of litter decomposition and comparing quantitatively the other subtropical plantation species, the author quantitatived the mass changes and build the dynamic model to analyze the characteristics and to predict the half-life. The outcome shows that in prophase Phoebe bournei, Cinnamomum camphora, Podocarpus nagi and Taxodium ascendens have lost most of the dry mass, the remnant amount occupied 35.45%-66.95%. During Sep. to Nov. 2002,the rate began to decrease while increased after November. Comparing with the Cinnamomum camphora, Podocarpus nagi and Taxodium ascendens, the decomposition of Phoebe bournei is the slowest and the remnant amount is 52.33% of the original amount after one year. It took 1.027 year and 4.44 year respectively for the litter of Phoebe bournei the longest time to decompose to the extent of 50% and 95%. The rate order of the 4 species decomposition is Cinnamomum camphora > Podocarpus nagi> Taxodium ascendens>Phoebe bournei.Studying on the rules of concentration, releasing amount and releasing rate of 6 major nutrient elements and 5 macronutrient elements in the decomposing process of Phoebe bournei litter and comparin更多还原