【作者】 康冰；

【导师】 张广军； 刘世荣；

【作者基本信息】 西北农林科技大学 ， 水土保持与荒漠化防治， 2007， 博士

【摘要】 广西大青山地处亚热带南缘,又与北热带接壤,兼有热带和亚热带气候及植被特征,但达不到二带的典型程度。由于人口超负荷所产生的土地利用变化,大面积天然林遭受严重破坏而呈片断化次生分布,代之为人工纯林,导致森林生产力下降、生物多样性锐减、水土保持等生态服务功能衰退等诸多后果。因此,我们对该区域的退化森林群落的种群关系、结构、生物多样性、演替特征、碳汇生态功能、土壤理化特性等进行研究,以便为退化森林植被及其生态功能的近自然化恢复提供理论依据。主要的研究内容及结果如下:（1）杉木人工林经过13a自然更新过程,林下灌木层植物种有71种,灌木层出现乔木幼树。通过重要值分析,判别了各物种在群落中的地位和作用。用x2统计和r检验研究了该杉木林下灌木层25种主要木本种种间关系,测定它们的种间联结性和相关性,结果清楚地反映了木本植物种间关系以及它们在资源利用和生态特性上的差异。依据分析结果将灌木层25种主要木本植物分成4个种组:Ⅰ.对叶榕（Ficus hispida）+五月茶（Antidesma bunius）+毛桐（Mallotus barbatus）+耳叶榕（Ficus cunia）+水东哥（Saurauia tristyla） +粗糠柴（Mallotus philippinensis）+杜茎山（Maesa japonica）+粗叶榕（Ficus hirta）+山麻杆（Alchornea rugosa）+黄毛榕（Ficus fulva）+白背叶（Mallotus apelta）;Ⅱ柘树（Cudrania tricuspidata）+鸭脚木（Schefflera octophylla）;Ⅲ.杉木（Cunninghamia lanceolata）+大青（Clerodendron cytophyllum）+相思子（Millettia semicastrata）+山石榴（Randia spinosa）+山苍子（Litsea cubeba）+木姜子（Litsea pungens）;Ⅳ.紫金牛（Ardisia japonica）+九节（Psychotria rubra）+山牡荆（Vitex quinata）+风箱树（Cephalanthus occidentalis）+亮叶围涎树（Pithecellobium lucidum）+华腺萼木（Mycetia sinensis）。种组划分的生态指示表明:如果杉木群落中灌木层以种组Ⅲ或Ⅱ的种为优势种,该群落是一个不稳定的过渡类型,最终可能会变化为以这些种为优势的稀疏阔叶林;若以种组Ⅳ为优势种,该群落则是在本地区气候条件下的相对稳定的针叶林群落;以种组I为优势的群落则是乔木层从以针叶树为主、针叶林向针阔混交林的过渡类型。林下灌木种特征值分析及生态种组划分将为该区域同类型森林植被及生态功能近自然恢复改造提供理论依据。（2）对13a生人工马尾松林自然状态林下植被特征调查研究表明,总种有100种,其中灌木种74种,分属41科、63属,占总种数的74.0%;草本26种,分属14科,23属。从植物区系地理分布来看,以热带亚热带成分占优势,温带成分较少。杉木林更新成马尾松林后,无论在水平及垂直分布上,物种多样性和丰富度均降低。灌木层中组成最多的种是大叶藤和长花腺萼木,其次是三叉苦、鸡矢藤、玉叶金花、毛黄肉楠、青冈栎等。林下分布频度最大的草本有弓果黍、乌毛蕨、普通铁线蕨、铁芒萁、扇叶铁线蕨、半边旗等;林地不同坡位灌木、草本生物量分布为坡上部>下部>中部;18种主要木本种群中,长花腺萼木、三叉苦、青冈栎、玉叶金华、毛黄肉楠、无忧花、中平树、破布木等生态位宽度较宽,表明其分布广、数量多、利用资源较充分,对环境的适应性较强。主要木本种群组成的种对中,长花腺萼木-三叉苦、长花腺萼木-青冈栎、三叉苦-青冈栎、玉叶金花-杜茎山、青冈栎-糙叶树、毛黄肉楠-无忧花6对生态位重叠大于0.7,这些种可为同类型林分近自然恢复改造过程中对恢复驱动种及关键种筛选和空间配置提供参考。其他大多数种对生态位重叠较大,表明大多数主要木本种群生态学特性及对环境利用较相似。（3）研究了广西大青山次生林群落经26a自然演替后26a间的种群结构变化规律表明,在减少人为干扰后,次生林片断可通过进展演替实现物种拓殖,物种数目得到有效增加,种间关系变得更为密切,次生林有向原生群落的自然恢复趋向。通过对主要种群类型、重要值、生态位宽度和分布格局的测定,分析了演替过程中各种群内部的消长与分布变化趋势,研究发现阳生性优势种由高集群分布变为随机分布,其生态位宽度减小,中生及阴生性树种则由随机分布逐渐变为高集群分布,生态位宽度增大。树种由32种增加到65种,35种中生及阴生树种为后期侵入种,物种多样性比较丰富;通过对现存种群的种间联结与生态位重叠进行分析,揭示了天然次生演替过程中种间关系的相互适应变化规律。原来阳生性的优势树种,如大叶栎（Castannopsis fleuryi）、大叶山楝（Aphanamixis grandifolia）等,与其他种群的生态位重叠值普遍下降,中生性种群生态位重叠值稍有增加,如柃木（Eurya nitida）、血胶树（Eberhardtia aurata）、广西拟肉豆蔻（Knema guangxiensis）等,中生偏阴生性种群生态位重叠值明显增大,其中一些种,如厚叶琼楠（Beilschmiedia percoriacea）、杨桐（Adinandra millettii）、毛黄肉楠（Actinodaphne pilosa）等,成为群落的建群种和优势种。次生群落种群之间的联结程度加强,一些种从零联结变为高度正联结或负联结,正、负联结性均变得更加紧密,高度正联结的种对占较大比例。种间联结与生态位分析结果基本一致,高度正联结的种群之间生态位重叠值较大,也反映出这些种对生境要求的一致性。次生群落由前期阳生性大叶栎（Castannopsis fleuryi）群落演替为中后期中生性厚叶琼楠（Beilschmiedia percoriacea）群落,群落接近较稳定的中生性气候顶级阶段。次生林群落经26a自然演替后26a间的种群结构变化规律,可为次生林片断的自然有效恢复提供科学参考。（4）研究广西大青山相近立地条件下同龄（26a）的8种典型森林群落的物种丰富度及多样性特征。结果表明:物种多样性的顺序是天然次生林>人工林,次生林乔木层（H>4M）物种较为丰富;几种人工林中,针叶林>常绿阔叶林,针叶林乔木层有一定数量的阔叶树,已经初步向针阔混交林自然演替。两种针叶林中,杉木>马尾松。5种常绿乡土阔叶林不同生长型物种多样性存在差异,就灌木而言,柚木>格木>红椎>火力楠>米老排;就草本而言,格木>米老排>柚木>红椎>火力楠。从不同生长型的物种丰富度指数S来看,所有群落灌木﹥草本,乔木因林型不同各异,人工林中只有马尾松、杉木乔木层有别的物种迁入,但物种丰富度指数S最小,次生林乔木物种丰富度指数大于灌木和草本;从几种群落类型整体来看,次生林乔木、灌木、草本丰富度指数S均最大。人工林中两种针叶林较大,火力楠最小。不同森林群落及不同生长型之间的Margalef丰富度指数Ma及Gleason丰富度指数dGL变化趋势与丰富度S一致。均匀度指数J表现得较为复杂,红椎、格木、米老排林中,草本﹥灌木,说明在这些群落中,灌木虽多,但种的分布并不均匀,而草本相对分布均匀一些。在马尾松群落中尽管乔木丰富度指数最小,但乔木均匀度指数最大。其余群落中均匀度指数J表现出与丰富度指数S一致的规律;杉木、马尾松3个演替发育阶段（7a—13a—23a）的林下灌木、草本的Shannon-Wiener指数H/均从7a到13a逐渐升高, 13a达到最大,到中龄林（23a）后,又逐渐降低,中龄林阶段Shannon-Wiener指数H/高于幼龄林（7a）阶段;马尾松造林密度（n·hm-2）从1350增加到1800时,自然发育14 a后,林下物种丰富度及多样性指数增高,密度为1800时,多样性指数最高,随后密度增加为2100时,林下物种丰富度及多样性指数却呈降低趋势。生物多样性高的森林群落具有复杂的空间结构（水平和垂直分布）与营养结构、稳定的生产力、较强的自我调节恢复及抗干扰能力以及突出的生态服务功能,因此不同森林群落生物多样性时空变化特征对植被自然恢复的状态及进程有显著的指示作用。（5）研究广西大青山典型森林群落演替过程中土壤理化特性及水土保持功能变化。结果表明,不同森林群落类型土壤养分及物理特性存在明显差异（p﹤0.05）。原生性植被遭受破坏并转化为人工植被后,土壤理化特性出现退化的趋势。天然次生林土壤,除全K低于柚木外,其余养分均明显高于所有的人工林。另外,天然次生林群落也具有良好的理化性能,容重较低,空隙度及持水量较高;9种人工林群落相对于撂荒地来说,土壤养分变化有高有低,全N含量呈现增加趋势。柚木、米老排、红椎及杉木×红椎混交林林地富含P。总的来看,两种针叶纯林土壤养分含量较差,但分别与红椎混交后,土壤养分得到了明显改善。常绿阔叶人工纯林土壤有着较为丰富的K。人工林群落中,杉木×红椎混交林群落土壤养分含量最为丰富;9种人工林土壤物理特性差异明显,两种针叶林土壤3个层次容重均最大,但杉木土壤容重低于马尾松,杉木、马尾松分别与红椎混交后,土壤容重均相对减小。5种常绿阔叶人工林中,米老排土壤容重最小,其余4种群落土壤容重差异不大。两种针叶林土壤孔隙度较低,但两种针阔混交林土壤总空隙度较高。5种人工常绿阔叶林的土壤空隙度差异不明显（p>0.05）。人工林群落中,两种针叶纯林持水量较小,两种针阔混交林土壤最大、毛管及最小持水量均高于别的所有人工林群落,说明针阔混交林林下土壤具有较强的蓄水保水能力,可避免或减少因降雨强度大来不及渗透而形成的地表径流,提高了林地的水土保持能力;马尾松、杉木人工纯林自然演替发育过程中（7a—13a—23a）,两种针叶林林地的养分变化趋势基本一致。随着演替,两种林分土壤（0～20cm）有机质、全N、碱解N和盐基总量均呈现明显增加的趋势。随着土层加深,除全K呈现增加的趋势外,其余养分含量均减少,这与地表的凋落物分解状况有关;14a生造林密度(n·hm^-2)分别为1300、1800、2100马尾林地土壤理化特性表现出明显差异（p﹤0.05）。全K含量随着林分密度增加而增高,但有机质、全N和全P含量均是中密度（1800 n·hm-2）林地最高,乔木密度较高的群落相对于稀疏的林分,土壤养分含量更低。中密度林地也有着良好的物理特性,土壤持水量、空隙度都较高,土壤优良的蓄水保水能力可有效缓解地表水对土壤的冲蚀。（6）选取广西大青山3个13a生马尾松、杉木混交林样区,研究其生态系统的碳素积累和分配特征。结果表明,混交林中两个树种的碳素含量各异。马尾松干、根、枝的碳素含量较高,分别为58.6%、56.3%、51.2%,叶和皮含量较低,变化幅度为46.8%～56.3%。各器官中按碳素含量的高低排列顺序为:干>根>枝>皮>叶;杉木皮、叶、干的碳素含量较高,分别为52.2%、51.8%、50.2%,碳素含量从高到低依次为:皮>叶>干>根>枝。从两个树种各器官碳总含量来看,马尾松要高于杉木。灌木层、草本层及地表凋落物层碳素平均含量分别为44.1%、33.0%及48.3%。土壤3个层次（60cm深）碳素含量为1.45%～1.84%,各层次碳素含量分布不均,表层（0～20cm）土壤碳素含量较高。针叶混交林乔木层生物量（t·hm-2）为85.35～101.35,平均为93.83,且均以马尾松生物量居多（占75.7%～82.6%）。混交林生态系统碳库的空间分布序列为土壤层﹥植被层﹥凋落物层。植被层的碳贮量平均为51.91 t·h·m-2,占整个生态系统碳总贮量的29.03%;乔木层碳贮量占整个生态系统的28.36%,占植被层碳贮量的97.7%。乔木层碳贮量中,马尾松占的比例较大,为65.39%。碳贮量在两个树种各器官中的分配,基本与各自的生物量成正比例关系,树干的碳贮量均最高,马尾松、杉木的树干碳贮量分别占各自碳贮量的53.23%、55.57%,树干的碳总贮量占乔木层碳总贮量的54%。其次,两个树种根也占较大比例,树根碳总贮量占乔木层碳总贮量的19.22%。马尾松、杉木枝、皮在各自碳的贮量中分配不同,马尾松枝占的比例要大于皮,而杉木则相反;凋落物层碳贮量平均为3.25 t·hm-2,仅占1.82%;林地土壤层（0～60 cm）碳贮量是相当可观的,平均为123.43 t·hm-2,占69.02%,可见在该区域防止水土流失对碳的固定并避免流失有非常重要的作用。马尾松、杉木混交林年净生产力为11.46 t·hm^-2·a^-1,有机碳年净固定量为5.96 t·hm^-2·a^-1,折合成CO2的量为21.88 t·hm^-2·a^-1。（7）选取广西大青山3个13a生杉木样区,研究其生态系统的碳素积累和分配特征。结果表明,杉木叶、皮、干的碳素含量较高,分别为51.05%、50.18%和48.51%,碳素含量从高到低依次为:叶﹥皮﹥干﹥根﹥枝。灌木层、草本层及地表凋落物层碳素含量分别为43.75%、40.78%及41.87%。土壤3个层次（60cm深）碳素含量为1.14%～2.11%,各层次碳素含量分布不均,表层（0～20cm）土壤碳素含量较高。杉木生态系统碳库的空间分布序列为土壤层﹥植被层﹥凋落物层。植被层的碳贮量平均为44.76 t·hm^-2,占整个生态系统碳总贮量的23.82%,其中乔木层平均碳贮量占整个生态系统的28.37%,占植被层碳贮量的96.07%。碳贮量在各器官中的分配,基本与各自的生物量成正比例关系,树干的碳贮量最高,树干的碳贮量占乔木层碳贮量的58.40%。其次,种根也占较大比例,碳贮量占乔木层碳总贮量的20.09%;凋落物层碳贮量平均为3.48 t·hm-2,仅占1.86%;林地土壤层（0～60 cm）碳贮量是相当可观的,平均为139.27 t·hm^-2,占74.27%,可见防止水土流失对维持森林生态系统碳吸存量、避免碳的流失有非常重要的意义。13a生杉木年净生产力为10.10t·hm^-2·a^-1,有机碳年净固定量为4.67 t·hm^-2·a^-1,折合成CO2的量为17.13 t·hm^-2·a^-1。综上所述,在广西大青山植被恢复过程中,减少人为干扰的情况下,典型森林群落的物种组成、结构、种群关系、土壤理化特性均发生明显改变。随着进展演替,森林群落物种丰富度、生物多样性逐渐增高,种群之间以及种群与环境之间的关系变得密切,土壤理化性能得到改善,森林群落结构趋于稳定,生态功能逐渐增强。但天然地带植被转化为人工植被后,群落物种丰富度及生物多样性降低,地力衰退,稳定性变差、水土保持功能减弱,群落呈现逆向演替的趋势。因此,在植被近自然恢复过程中,以残存的老龄天然次生林为参考,结合自然植被演替特征及种群动态,诱导人工针叶纯林植被进展演替的发生,使得群落逐步演替为针阔混交林。通过分析次生林种群动态及退化的干扰及驱动因子,引导次生林片断向原生顶级群落演替。全面提高该区域退化森林的生产力及水土保持、碳汇等生态服务功能。次生林及人工针叶纯林在封育情形下,群落进展演替明显,逐步演化发育为复杂稳定的结构,因此对次生林和人工针叶纯林实施近自然化恢复是可行的。而常绿阔叶人工林群落进展演替发生比较困难,必须依靠人工改造才可以实现群落结构的复杂和稳定。更多还原

【Abstract】 The study area （106°39′～106°59′E, 21°57′～22°19′N） is located on the south-eastern border in the Guangxi Zhuang Autonomic Region, China. This region belongs to the south-eastern edge of the sub-tropical monsoon climate area. It borders on the north tropical zone in the humid and semi-humid area. Resources such as sunlight, heat, and water are abundant. There are vegetation and climate characteristics between tropical and subtropical in this area , but it was not typical relativing to one of two climate zone.Because of the overcharged population, land use change made the large area natural forest be destructed and distribute fragmentedly, replacing with mass pure coniferous leaved forest.This statement has resulted in worse sequel ,such as productivity decreasing , biodiversity declining ,land degenerating ,ecosystem service such as water and soil conservation,carbon sink etc.declining,we study on the population relation,vegetation structure ,biodiversity, succession sere,carbon sink,soil chemical and physical characteristics of degred forest, in order to proffer academic reference on the semi-natural vegetation restoration and ecological function enhancement. Primary research content and conclusion are as follows:（1）Cunninghamia lanceolata is the main timber tree in the low subtropical area. Because of the simple stand structure and the traditional management focusing only on wood production, the potential consequences of biodiversity loss for ecosystem function and services have received considerable attention in recent years. It is necessary to change stand structure and species composition of Chinese fir plantation in order to increase its species diversity and ecosystem services. The understorey woody plant was beneficial to maintaining site productivity, species diversity and stability of community. Study on the species richeness,interspecific association and correlation could direct the sound practice of vegetation restoration.There were 71 species in shrub layer in Cunninghamia lanceolata plantation after natural succession.The species richness and diversity have increased with slight anthropogenic disturbance. The status and function of understorey woody species were judged by analysis of important Value. Ficus hispida, Cudrania tricuspidata ,Mallotus apelta, Millettia semicastrata etc. were the constructive species; Periploca forrestii,Alangium chinese,Pueraria thunbergiana,Mallotus barbatus etc. were the subdominant species, Clerodendron cytophyllum, Maesa japonica ,Randia spinosa,Litsea cubeba etc. are the companion species ; Viburnum dilatatum, Cayratia japonica ,Rubus palmatus etc. are the rare species. X² statistics and r test were used for testing significance of interspecific association and correlation among 25 main understorey woody plants selecting from the woody population.The results clearly shew their interspecific relationships and their differences in resource utilization. Species-pairs of positive association were in the majority. The most species have accommodated the shady habitat.There was a positive correlation between the important value of species and the interspecific association. The higher important value of the species was, the more close and significant interspecific association was. Based on analytical results of interspecific association and correlation ,25 woody plants in shrub layer could be divided into 4 ecological species groups:Ⅰ.Ficus hispida+Antidesma bunius+Mallotus barbatus+ Ficus cunia+Saurauia tristyla +Mallotus philippinensis+Maesa japonica+Ficus hirta+Alchornea rugosa+Ficus fulva+Mallotus apelta ;Ⅱ. Cudrania tricuspidata+Schefflera octophylla ;Ⅲ. Cunninghamia lanceolata+ Clerodendron cytophyllum+ Millettia semicastrata+ Randia spinosa+ Litsea cubeba+ Litsea pungens;Ⅳ.Ardisia japonica+Psychotria rubra+Vitex quinata+Cephalanthusoccidentalis+Pithecellobium lucidum+Mycetia sinensis.If species groupⅢorⅡwas advantaged species in shrub layer, the community would change from coniferous forest to sparse evergreen broad-leaved forest; For groupⅣ, the community would be relatively stable; For groupⅠ, the coniferous forest would be mixed coniferous-broad leaved forest. The analyse of shrub eigenvalue and classification of ecological species groups would provide a theoretical basis on judging its ecological function,especially water and soil conservation, adjusting the stand structure of plantation and directing the suitable natural vegetation type through the close–natural restoration process. （2）A study on the natural understorey vegetation in artificial masson pine replanted after Chinese fir being cutting down for 13 years indicated that there were 100 species of undergrowth vegetation .There were 74 species of shrub or small arbor, appropriating 74.0 percent of total species,,belonging 41 faculties and 63 categories;the amount of herbs was 26 ,belonging 14 faculties and 23 categories.The tropical and subtropical elements were prominent.The species diversity and richness became decreasing after Masson Pine regenerating from Chinese fir.The analysis of important value shew that the main shrub species or small arbor were Tinomiscium tonkinensis,Mycetia longiflora,Evodia lepta,Paederia scandens,Mussaenda pubuscens,Actinodaphne pilosa,Quercus glauca ,etc. the main herb species were Cyrtococcum patens, Blechnum orientale, Dicranopteris dichotoma, Adiantum flabellulatum, Adiantum edgeworthii, Pteris semipinnata,etc. The biomass of vegetation distributing different position of slope was various, upside>downside>middle part. The niche characteristic of 18 main tree populations in shrub layer was measured,the results shew there was generally very significantly positive correlation between the niche breath and the important value of main woody population.The woody population whose important value higher than others were more adaptable to habitat and their niche breadth was larger than others.The niche overlap of six population counterpart was very large,such as Tinomiscium tonkinensis-Mycetia longiflora, Tinomiscium tonkinensis-Evodia lepta ,Mussaenda pubuscens-Maesa japonica, Quercus glauca-Aphananthe aspera, Actinodaphne pilosa -Saraca chinensis, Evodia lepta-Quercus glaucathese, these species could be the references on selecting and disposing the driving and key species during the natural restoration and reconstruction of the same stand. The niche overlap of major woody population counterpart was larger, which shew that the trend of sharing resource utilization was obvious.（3）The secondary regenerated evergreen broad-leaf forest was fragmentedly distributed after large-scale destruction of the virgin forests in subtropical area. Eco-reconstruction depended largely on the natural restoration capacity and regeneration process, which were rarely studied in Daqingshan, Guangxi. Population dynamics of secondary-growth natural forest over 26 years of successional process were studied for exploring the following questions: （a） What were the variation pattern of population character and interspecific correlation without human disturbance? （b） What was the zonal climax vegetation type?（c） How to restorate the degraded secondary forest effectively? The methodologies of population ecology were employed to measure and analyze the changes in intra-population structure and spatial distribution in terms of the population type, important value, niche breath and distribution pattern. The community investigation took place at the same site in 1980, and the historical data was used as the base of the analysis. The dominated heliophytes at the early successional stage had changed from intense contagious distribution into random distribution and their niche breaths had decreased accordingly. The mesophytes and shade-favorite tree species, however, had the reverse changes from random distribution into highly contagious distribution in concomitance with increasing niche breaths. The number of tree species had risen up from 32 to 65, of which 35 were the late-successional stage species and had rich species diversity.The analysis of niche overlap and interspecific association were made to ascertain the mutual adaptation and evolution of species relations.The results indicated that the values of niche overlap among the light favorite population,such as Castannopsis fleuryi, Aphanamixis grandifolia,etc. and others dropped generally,while the values of niche overlap of mesophytic population, such as Eurya nitida, Eberhardtia aurata, Schefflera octophylla, Knema guangxiensis etc,with others were increased slightly. At the same time, the values of niche overlap of the mesophytes partial to the shade habitats were also enhanced greatly and as the result these species have become dominant species, as the example of Beilschmiedia percoriacea, Adinandra millettii, Actinodaphne pilosa etc. The proportion of species pairs showing positive and negative associations interacted mostly intensively with decline for those species pairs of either no associations or negative associations and increase of the positive associations.The results of interspecific association analysis were consistent with that of niche overlap analysis, i.e., the species pairs with closely positive associations had large niche overlap, indicating that these species tended to utilize environmental resources homogenously. The study suggests that there have been occurring obvious species changes in community during natural restoration process especially for the individual quantities and distributions of many dominant species. All theses results indicated that current communities were developing into the status of increasing ecological stability, as the secondary communities were proceeding close to the zonal climax through the natural succession over 26 years.The study on the population dynamics of secondary-growth natural forest could direct the natural restoration of fragmented secondary forest effectively .（4）We studied the characteristics of species diversity of 8 forest community types, the results shew that the species of secondary forest was much more than that of artificial forest .Among the plantations,the species diversity of coniferous leaved forest was higher than that of the evergreen broad-leaf forest. The coniferous leaved forest tended to needle and broad leaved mixed forest, the species abundance of Chinese fir was higher than that of Pinus massoniana .The shrub species diversity index of native broad-leaved evergreen forests was in the following order: Tectona grandis> Erythrophleum fordii >Castanopsis hystrix>Michelia macclurel >Mytilaria laosensis ,that of herb species was : Erythrophleum fordii > Mytilaria laosensis> Tectona grandis> Castanopsis hystrix>Michelia macclurel . The understory species richness indexes（S） of two coniferous leaved forest were higher than other plantations; According to the various growth forms,shrub species abundance indexes of all forest were higher than that of herb species ,tree species of secondary forest was richer than that of shrub or herb species,the arbor species abundance indexes of all plantations was lower than other life form;The species Margalef indexes （Ma） and Gleason indexes（dGL） were intensive relative to richness indexes（S）. The evenness indexes（J） shew complex orders, shrub species evenness indexes were lower in Castanopsis hystrix, Erythrophleum fordii and Mytilaria laosensis communities,although the shrub species was richer than herb species.J of other forest was relative to S;The Shannon-Wiener indexes（H/） of two coniferous leaved forest increased over 7～13a succession stages , after 13 years , the Shannon-Wiener indexes（H/） decreased contrarily;With the 14 years natural growth Pinus massoniana tree density increasing from 1350n·hm^-2 to 1800 n·hm^-2, undestory species diversity indexes increased .As the tree density increasing to 2100 n·hm-2, the species richness and diversity indexes decreased.The plant community with high species diversity had complex space and nutrition structure, stable productivity, relatively intensive capacity of self regulation and anti-interference and prominent ecosystem servise, so the species diversity characteristics of various plant communities could direct the goal and effect of natural vegetation restoration.（5）Soil chemical and physical properties were studied during the successional stages of typical forest community in Dangqingshan in Guangxi .The results shew that the difference of various forest was significant （p﹤0.05）. After the original forest being cutting down, the soil degraded. Except for the total K,the nutrient content of natural forest was higher than that of all plantations ,in addition ,the soil physical capability was better, with higher soil saturated water capacity , total porosity and capillary porosity ,lower bulk density, so the secondary forest soil could saturate overmuch ground runoff and prenvent soil erosion effectively.In view of precipitous slope, intensive rainfall, thin soil and imestone terrain,if the soil was eroded , basement rock was easy bare ,vegetation was very difficult recovering , rocky desertification occurred on the lime rock in succession.So the secondary forest was very useful of soil erosion and rocky desertification prevention;The soil nutrient content of artificial vegetation fluctuated relativing to the abandoned land,the total N content increased after artificial reforestation, the soil P were rich in Tectona grandis, Michelia macclurel, Castanopsis hystrix,mixed forest of Chinese fir and Castanopsis hystrix.The soil nutrient contents of two coniferous leaved forest were lower than that of broad-leaved evergreen forest, after mixing with the evergreen broad leaved trees, the soil nutrient content increased .The soil chemical and physical traits developed during the succession from coniferous forest to coniferous broad leaved mixed forest.There were abundant K in the broadleaved forest soil.The total porosity of evergreen broad leaved forest were no significant （P﹥0.05）;With the natural succession （7a—13a—23a） of two coniferous forest types, the soil （0～20cm） organic matter ,total N, available N and soil CEC increasing ;Soil properties of Pinus massoniana was intensive related to the tree density.With the tree density increasing,total K accumulated .Contents of organic matter,total K and P were higher in the middle density forest soil with higher soil saturated water capacity, total porosity and capillary porosity,the superior function of keeping and storing water could prenvent the erosion of surface soil in middle density forest .Vegetation restoration was very significant of preventing water loss and soil erosion.（6）Carbon accumulation and distribution of the 13 years old Pinus massoniana and Cunninghamia lanceolata mixed plantation in Daqingshan,Guangxi were studied with 3 sampling plots.The results shew that the carbon contents varied with tissues and tree species, but the total carbon contents of Pinus massoniana were higher than that of Cunninghamia lanceolata. The average tissue carbon contents of Pinus massoniana were: wood （58.6%） > root （56.3%） > branch （51.2%） > bark （49.8%） > leaf （46.8%）. While Cunninghamia lanceolata were: bark （52.2%） > leaf （51.8%） > wood （50.2%） > root （47.5%） > branch （46.7%）. The carbon contents of soil （in depth of 60cm） ranged from 1.45% to 1.84%, with an average of 1.70%. The carbon content was higher in the surface soil （0～20cm） than in the deep layer （below 20cm）. The average carbon content percentage was greatest for trees （51.1%）, followed by litters （48.3%）, shrub （44.1%） and herb （33.0%）. The biomass of trees in the three plots ranged from 85.35 t·hm-2 to 101.35 t·hm-2, with the average of 93.83 t·hm-2, in which 75.7%～82.6% was accounted for Pinus massoniana. The biomass of the understory was 2.1～3.95 t·hm-2, with an average of 2.72 t·hm-2, while the standing stock of ground litter was 5.49～7.91 t·hm-2, with an average of 6.75 t·hm-2.The carbon storage of the mixed plantation was greatest in soil layer （69.02%）, so water and soil conservation was significant of the carbon sink in forest ecosystem,followed by vegetation （29.03%） and standing litter （1.82%）. The carbon storage of tree layer occupied 28.36% of total ecosystem and 97.7% of vegetation layer. Of total carbon storage in tree layer, Pinus massoniana took up 65.39%. The tissue carbon storages were positively related to the amounts of their corresponding biomass. Trunk accumulated the highest carbon storage, comprising 53.23% of the overstorey trees in Pinus massoniana and 55.57% in Cunninghamia lanceolata, respectively. Root made up about 19.22% of total tree carbon. The annual net productivity of mixed plantation was 11.46 t·hm^-2·a^-1, sequestering carbon of 5.96 t·hm^-2·a^-1, which was equvalent to fixing CO2 of 21.88 t·hm^-2·a^-1 . It was indicated that plantation was an important sink of atmospheric CO2.（7）Carbon accumulation and distribution were studied in plantation of Chinese fir forest ecosystem in Daqingshan ,Guangxi.The results shew that the average carbon concentrations in all organs Was in the following order:leaf（51.05%）> bark（50.18%）> wood（48.51%）> root（47.65%）> branch（46.21%）.The carbon concentrations of soil （to 60cm） ranged from 1.14% to 2.11% ,with an average of 1.66%.Carbon concentrations of surface soil（to 20cm） was higher than the other layer. The average carbon concentrations in different layers was in the order as: trees （49.7%）> shrub （43.75%） >standing litters （43.75%）>herb （40.78%）. The carbon storage order forest ecosystem was soil layer>vegetation >standing litter. Of total average carbon, 23.82% was distributed by vegetation component, 74.27% by soil （60cm depth）, only 1.86% by standing ground litter layer. The carbon storage of tree layer occupied 22.94% of total ecosystem and 96.07% of vegetation layer. The carbon storage in different organs was positively related to the biomass of corresponding organs. Trunk accumulated the highest carbon storage, comprising 58.40% of carbon storage in tree layer. Root made up 20.09% of total tree carbon.The annual net productivity of forest plantation was 10.10t·hm^-2·a^-1,stored carbon up to 4.67 t·hm^-2·a^-1,amounted CO2 to 17.13 t·hm^-2·a^-1 . Forest was a important sink of atmospheric CO2.Sum up, if reducing the anthropogenic disturbance during the natural vegetation restoration, the vegetation composition, structure, population relationship, carbon sink,soil chemical and physical characteristics developed evidently. With progressive succession, the forest community species richness and diversity increased gradually, interspecific association and correlation became intensive, soil chemical and physical capability had improved, forest community tended to stabile stages.On the other hand,as native vegetion converting into the various palantation,retrogressive succession occurred ,as a result,the species richness and diversity decreased reversely , the stand structure was simplified ,the ecosystem service function declined. Land use change was the main intrusive factors of the forest degradation in this study area .So we can reference to the old aged natural secondary forest, natural successional traits and population dynamics to accelerate the progressive succession in order to tend to the original plant community finally. The vegetation restoration aimed to enhance the productivity and ecosystem foundation completely, especially the water and soil conservation and carbon storage .With closing mountains to facilitate forestation,the secondary and coniferous leaved plantation developed gradually,the structure of community became complex and stable,so near-natural restoration of secondary and coniferous leaved plantation was feasible with abundant water and heat resources.While the ever green broad leaved plantation was difficult to cause progressive succession,the artificial reconstruction was necessary up to the stable and complex stand structure.更多还原