【作者】 杨占彪；

【导师】 王刚；

【作者基本信息】 兰州大学 ， 生态学， 2009， 博士

【摘要】 本文对六盘山自然保护区4种不同类型森林群落：华北落叶松林(Form．Larixprincipis-rupprechtii)、油松林(Form．Pinus tabulaeformis)、华北落叶松+辽东栎林(Form．Larix principis-rupprechtii+Quercus liaotungensis)、辽东栎+少脉椴+山杨林(Form．Quercus liaotungensis+Tilia paucicostata+Populus davidiana)的更新特征进行了研究，并根据国际恢复生态学会(SER)提出的部分评价生态恢复成功的标准，对退化土地上三种人工恢复措施进行了生态恢复评价。同时研究了华北落叶松人工林林与天然次生林交错带对更新的影响；人为干扰对华北落叶松人工林更新的影响。最后对华北落叶松天然更新的影响因素进行了探讨。主要研究结果如下：1．不同类型森林群落中，阔叶林和针阔混交林中幼苗丰富度、多样性指数和幼苗密度较高；其出现的树种总数也高于华北落叶松和油松人工林。华北落叶松林中，除辽东栎以外，幼苗密度较高的树种主要是耐荫树种，如桦叶四蕊槭、茶条槭、五尖槭。而针阔混交林和阔叶林中以动物为传播途径的物种增多。五个主要优势种中，辽东栎和油松可以在任何森林群落中定居生长，并且更新个体较充足。华北落叶松在任何群落中都没有更新幼苗，随着演替的进行，这个物种会逐渐被其他种群替代。对于针阔混交林，随着华北落叶松比例的增加，林下幼苗丰富度和幼苗密度减小。当针阔树种的比例接近1时林下幼苗丰富度和多样性较大。建议在人工造林时，针叶树种比例不能过大。2．通过对灌木地种植华北落叶松(LS)、灌木地种植油松(PS)和稀疏林地种植华北落叶松(LO)的三种不同恢复措施评价结果显示：这三种恢复措施在一定程度上促进了本地物种的入侵，增加了物种多样性和土壤养分含量。表明人为有目的的种植后期演替物种能够绕过退化土地上的早期演替阶段，加速了演替过程，因此其恢复措施是可行的。然而，LS和PS中由于林分密度过大，导致入侵的本地物种数量少于LO中；同时LS和PS的物种多样性、幼苗密度、幼苗多样性和土壤养分含量明显小于LO。和参照相比，L0的物种组成、物种多样性和土壤养分含量具有极高的相似性。结果表明，该恢复措施比较成功，并且加快了群落的演替近30年。由于LS和PS林分密度过大，在自疏阶段或出现较大程度自然干扰之前，物种多样性将不会有明显的增加。为了保护生物多样性，必须提前进行人工间伐，减小林地密度，改善环境条件，促进物种丰富度和多样性的增加。华北落叶松由于在当地不能天然更新，因此该物种终将会被本地物种替代。而油松因为能够进行天然更新，所以该群落具有较高的恢复潜力；随着演替的进行，本地物种的入侵，该群落最终会形成针阔混交林的较稳定群落。在L0中，虽然有少数树种缺失，但随着林内环境条件的改善，这些树种将很快入侵该群落。而从森林生态系统对人类服务的角度出发，有必要在华北落叶松死亡或收获木材后进行补植以弥补华北落叶松不能天然更新的不足。3．华北落叶松林和阔叶林形成的交错带内幼苗密度和幼苗丰富度略低于阔叶林，却明显高于华北落叶松林。而交错带内幼苗多样性指数和均匀度指数在三个群落中表现最高，不同幼苗种类表现出比较均匀分布的特征。交错带内较大径级的更新幼苗比例相对于相邻群落有所增加，说明幼苗在交错带内能够快速的生长，建议造林措施以不同群落交错的方式代替大面积的纯林种植。4．重度间伐林地(＜650 stems／ha)和中等面积(mean：114．62 m~2)的林窗内幼苗丰富度、多样性指数以及幼苗密度最大；幼树的丰富度、多样性指数和幼苗密度的最大值出现在重度间伐林地和大面积林窗内。重度间伐林地和中等面积、大面积林窗内幼苗在各个径级都有分布。幼树的平均树高和胸径随着干扰强度的增加而增加。幼苗与生境条件的相关分析表明，光照、枯枝落叶层厚度是影响间伐林地幼苗生长的主要因素。而大面积林窗内草本盖度明显影响着幼苗的丰富度和密度。林分密度管理和创建林窗能够增加林分结构异质性，从而提供适宜的环境条件，促进幼苗存活和生长。然而，轻度间伐林地和小面积林窗由于周围树木林冠的扩展，林冠空隙很容易再次郁闭，从而不能形成长期的资源和环境的异质性。因此，对华北落叶松人工林进行间伐时，强度不能过于太小。同时，对间伐过的林地进行多次间伐，有利于形成林分年龄结构的差异，从而构成较复杂的林分结构。5．通过播种华北落叶松种子和种植2年生华北落叶松幼苗并观测种子萌发率和幼苗成活率表明：华北落叶松不能在六盘山自然保护区天然更新的主要原因是刚萌发的幼苗不能成功越冬。同时光照条件、土壤水分、枯枝落叶层等环境条件也共同作用限制种子的萌发和幼苗存活。不同时期种植的幼苗存活率不存在显著差异，表明2年生华北落叶松幼苗能够顺利越冬。更多还原

【Abstract】 Regeneration and assessment of restoration in four different forest communitieswas studied in this research.These communities include:Form.Larixprincipis-rupprechtii,Form.Pinus tabulaeformis,Form.L.principis-rupprechtii+Quercus liaotungensis,and Form.Q.liaotungensis+Tiliapaucicostata+Populus davidiana.Furthermore,the effects of ecotone and harvest onforest regeneration were studied.Finally,this research also studied the effect factor onregeneration ofL.principis-rupprechtii.The main results are as follows:1.Seedling richness,diversity index and seedling density were higher inbroadleaved forest and conifer-broadleaved mixed forest than coniferous forests.Species number was higher in broadleaved forest and conifer-broadleaved mixedforest than in coniferous forests.The major species was shade-tolerant species in L.principis-rupprechtii forest,such as Acer tetramerum Pax var.betulifolium,Acermaximowiczii,and Acer ginnala.The number of animal-dispersed species increased inconifer-broadleaved mixed forest and broadleaved forest.Q.liaotungensis and P.tabulaeformis can re-establish in evey communities,andthere was large number of their seedlings.There was not L.principis-rupprechtiiseedling in four communities.This result suggests that the population of L.principis-rupprechtii will be replaced by other populations.With the increase ofproportion of L.principis-rupprechtii,seedling richness and seedling densitydecreased.Seedling richness and density was highest when proportion of conifer andbroadleaved species was equal.2.After assessing the success of three restoration projects:planting Larixprincipis-rupprechtii (LS) and Pinus tabulaeformis (PS) on shrubland,and planting L.principis-rupprechtii on open forest land (LO),the results show that all threerestoration plantings facilitated the re-establishment of native species,increased thespecies diversity and soil nutrient contents.The results Suggests that plantinglate-successional species bypassed the early successional stages of restoration andaccelerated the succession process.Thus,it shows the ecological feasibility ofrestoration efforts.However,the reestablishment of native species in LS and PS was poorer than LObecause of the excessive stand density.Species diversity,seedling number,and seedling diversity were significantly higher in LO than in LS and PS.Soil nutrientwas also significantly higher in the LO treatment.The vegetation composition,speciesdiversity,and soil nutrient in LO,however,were more similar to these in the reference.This result indicated that planting L.principis-ruppreehtii on open forest standappears to be successful,and has accelerated the succession process for approximately30 years.For long-term restoration,in LS and PS,species richness and diversity will notincrease significantly until the self-thinning stage or the occurrence of naturaldisturbance,because excessive stand density greatly impedes the regeneration ofnative species.Thus,selective thinning is necessary for future forest management,andL.principis-rupprechtii forest will be replaced by native species in the future.In LO,although few native species still disappear,they will reestablish with improve ofenvironmental condition.Furthermore,post-planting activities are required aftertimber harvesting or the natural mortality of the species to make up the failureregeneration ofL.principis-rupprechtii.3.Although seedling richness and seedling density were lower in ecotone thanbroadleaved forest,seedling diversity index and evenness index was higest amongthree communities.Seedling richness,diversity index,evenness index and seedlingdensity were lowest in coniferous forest.The proportion of seedling in larger size washigher in ecotone than in broadleaved forest and coniferous forest.This result showsthat ecotone improved the growth of seedling and suggests that it is required toreplace the large area pure forest by small patches.4.Seedling richness,seedling diversity index and seedling density were highest inheavy thinned stands (＜650 stems/ha) and medium gaps (mean:114.62 m2).Saplingrichness,diversity index,and density were highest in heavy thinned stands and largergaps.In heavy thinned stands,medium gaps and large gaps,tree seedling distributedat all size classes.With the enhancement of disturb intensity,the average height andDBH of sapling increased.There was the significant positive relationship betweenlight and seedling richness,diversity and density in thinned stands.However,litterdepth impeded the increase of seedling richness,diversity and density.Moreover,herbaceous cover was the important factor,which impeded the increase of seedlingrichness and seedling density in large gaps.Increasing vertical and horizontal structural heterogeneity within stands,density management and creating gaps support the suitable environmental condition forseedling survival and growth.However,canopy openness will be filled quickly byexpansion of neighboring trees in light thinned stands and small gaps.As a result,those stands can not support long-term structural and environmental heterogeneity.Thus,the better development of understory vegetation and regeneration require moreintensive density management and variable density thinning.Activities on severaldisturbances are favorable for age and structural heterogeneity of forest.Moreover,the high competition from herbaceous has impeded the survival and growth ofseedling in large gaps.It is necessary to cut herbaceous regularly.5.The results of experiment about sowing seed and planting seedling of L.principis-rupprechtii by different treatments shows seedling can’t survival duringwinter,which is the major reason of L.principis-rupprechtii can’t regenerate inLiupan Mountain Natural Reserve.At the same time,light level,soil water content,and depth of litter also impede the seed germination and seedling survival.Furthermore,there was significant difference in seedling survival rate of 2 years oldbetween different planting times.This result suggests that 2-year seedling can survivalsuccessfully during winter.更多还原