【作者】 彭晚霞；

【导师】 王克林；

【作者基本信息】 湖南农业大学 ， 生态学， 2009， 博士

【摘要】 喀斯特峰丛洼地主要分布在我国西南喀斯特南端的斜坡地带,常绿落叶阔叶混交林是该区非地带性的顶极群落,主要分布在木论和茂兰国家级自然保护区,其他大部分森林在人类活动下,发生了不同程度的退化。基于喀斯特峰丛洼地森林动态监测样地和辅助性样地的观测调查和分析,本文系统分析了喀斯特峰丛洼地三种典型森林生态系统胸径≥1 cm木本植物的时空分布格局及维持机制,以期为西南喀斯特峰丛洼地植被迅速恢复和生态重建提供重要的理论依据。主要结论如下:1.喀斯特峰丛洼地森林植物群落种类丰富,随着人工林→次生林→原生林逐渐演替,物种和科的数量明显增加,物种和科优势度越来越不明显,常绿成分逐渐增加,落叶成分相对减少,生活型向多元化发展,结构渐趋合理,生态系统渐趋平衡。2.空间自相关分析、半方差模型及Kriging等值线图均表现出喀斯特常绿落叶阔叶混交林森林具有人工林区、封育区和原生林区性质不同的三大斑块,空间尺度初探效应发现,喀斯特常绿落叶阔叶混交林的空间异质性的采样范围应≥10 hm²,采样间隔10 m基本合适,但要随采样范围的增大而适度增大。3.喀斯特峰丛洼地木论原生林、木连次生林和古周人工林三种典型森林生态系统除Simpson指数和均匀度外其他7个多样性和结构性植被指标在不同的森林类型中其半变异函数的最佳拟合模型均不相同,原生林的所有植被指标均呈强烈的空间自相关,而次生林和人工林呈中等或强烈的空间自相关。原生林森林植被指标的变程较大,人工林次之,次生林的变程最小;分形维数D变化趋势与变程基本一致。4.地形在喀斯特峰丛洼地木论原生林、木连次生林和古周人工林三种森林生态系统中始终处于主导地位,而其他主导因子因森林类型的不同而不同。随原生林→次生林→人工林的退化,植被、土壤、地形之间的相关性越来越弱。5木论原生林沿DCCA第一轴从左到右沿空间因子减小、Fe₂O₃、MnO、Al₂O₃含量的降低及pH、CaO和全氮增加的生态梯度,植物群落由原生林类型逐步向次生人工林过渡;木连次生林沿DCCA第一排序轴从左到右随地形因子降低、Fe₂O₃、MnO、pH增加的生态梯度,植物群落以粉苹婆、假苹婆、红背山麻杆等为先锋种的次生林群落向八角枫、枫香、豆梨、火棘等为先锋种的群落和以白茅为建群种的草丛过渡;古周人工林随着DCCA第一排序轴从左到右随主要养分和水分降低的生态梯度,土壤质量下降,森林群落由次生林群落向人工林群落过渡。6喀斯特峰丛洼地三种典型森林生态系统的土壤环境因子对木本植物分布的解释能力分别为32.59%、30.82%和31.38%,空间因子的解释能力分别为18.79%、17.64%和13.21%,不可解释部分的比例很大,表明在喀斯特峰丛洼地木论原生林、木连次生林和古周人工林三种典型森林生态系统中,除生态位分化理论维持机制外,生物间相互作用和人为干扰等随机因素同样处于重要的地位。7随着群落由草丛→草灌丛→灌丛→藤刺灌丛→乔灌丛→顶极群落的顺向演替和发展,群落的高度、生物量和物种多样性、土壤有机质、养分、阳离子交换量和硅、铁、铝、钛等矿质全量逐步增加,钙、镁全量显著减少,pH值降低。8不同干扰方式对植被自然恢复的影响不同,其中整坡火烧+垦殖的破坏性最大,初步呈现了石漠化景观,整坡火烧+放牧次之,采樵属选择性干扰,采樵+放牧+坡脚火烧的恢复相对较快,没有放牧干扰的采樵+坡脚火烧恢复更好。9.从“人—自然—经济复合生态系统”的观点出发,以干扰程度、群落类型、服务功能、土地退化和贫困状况为指标,提出了喀斯特脆弱生态系统的复合退化模式,建立了喀斯特脆弱生态系统复合退化的控制模型和生态恢复与重建模式。更多还原

【Abstract】 Karst peak-cluster-depression mainly lies in the south slope of karst region in southwest of China.Karst mixed evergreen and deciduous broadleaf forest is an azonal climax community in the area,which is mostly in Mulun National Nature Reserve and Maolan National Nature Reserve.The other forest in the area degenerates in varying degrees due to human activities. Based on the observation,investigation and analysis items in the dynamics sample plots and supplementary plots of forests in karst cluster-peak-depression areas,the paper analyzed the pattern and its maintenance mechanism of woody plants（DBH≥1 cm）,which would provide important theoretical guide to quick vegetation recovery and ecological restoration in karst cluster-peak-depression area in southwest of China.The main results are as followed.（1） There were abundant woody plant species in forests in karst cluster-peak-depression area. In the succession from manmade forest,to secondary forest,to primary forest,species and families increased notably,the predominance of species and families reduced,the composition of evergreen increased gradually and that of deciduous decreased gradually.The variation suggested that the forest vegetation develop towards diverse life forms and reasonable forest structure,and the ecosystems gain more equilibrium.（2） Both semivariagram analysis and Kriging analysis showed that there were three patches of manmade forest,enclosing area and primary vegetation in the 2 hm2 dynamic sample plot of Mulun mixed evergreen and deciduous broadleaf forest in karst cluster-peak-depression area.Scaling effects suggested that the sampling area should be more than 10 hm² and sampling interval of 10 m be feasible,and the interval should increase with the extent of sampling size,aimed to study spatial heterogeneity in the area.（3） The vegetation diversity index and structural index except Simpson index and evenness in the three typical forests in karst cluster-peak-depressions fit different theoretical models of semivariagram.All of these index in Mulun primary forest performed strong spatial autocorrelation and large range,while those in Mulian secondary forest and Guzhou manmade forest performed medium or strong spatial autocorrelation,and with small and less range.The trend of fractal D was in the accordance of range.（4） The results of PCA demonstrated that topography was in the leading factors in the three forests,and other leading factors were different in different forest types.Cluster analysis devised Mulun primary forest,Mulian secondary forest,and Guzhou manmade forest into 5,4, and 4 groups at the gravitative level of 30,respectively.Classical correlation analysis showed that the relationships between vegetation,soil,and topography were in a less close trend with the process of primary forest,to secondary forest,to manmade forest.（5） The vegetation communities in the Mulun primary forest were in the gradual succession from primary forest to secondary forest from the left to fight of the 1^st axis of DCCA（i.e., along the gradient of decrease of topography factors,content of Fe₂O₃,MnO,and Al₂O₃,and increase of pH,CaO and TN）.Those in Mulian secondary forest were in the gradual succession from secondary forest type to communities with pioneer species and grass from the left to right of the 1^st axis of DCCA（i.e.,along the gradient of decrease of topography factors, and the increase of Fe₂O₃,MnO,and pH）.The forest communities in Guzhou manmade forest were in the gradual succession from secondary forest type to manmade forest types from the left to fight of the 1^st axis of DCCA（i.e.,along the gradient of main nutrients and soil water）.（6） Fraction of species abundance variation explained by soil environmental variables in Mulun primary forest,Mulian secondary forest,and Guzhou manmade forest was 32.59%, 30.82%,and 31.38%,respectively.Fraction of species abundance variation explained by topography variables in the three forests was 18.79%,17.64%and 13.21%.The unexplained vegetation variation was large,which hinted that random factors including interaction among creatures and human disturbance took in an important role in the three forests except niche differentiation theory.（7） With the succession from grass,to grass and shrub,to shrub,to liana and shrub,to climax community,The community height,hiomass,diversity,content of soil organic matter, main soil nutrients,CEC,SiO₂,Fe₂O₃,and Al₂O₃ increased,and the pH and content of CaO and MgO decreased.（8） Different disturbance types showed various affections on natural vegetative restoration, among them,tillage after whole slope burned caused the worst impact where rocky desertification was the consequence,followed by depastufing after whole slope burned.While cutting was selective disturbance,the vegetative restoration in the area with combination of cutting,depasturing and slope foot burning was relatively fast,however,it was even better in the area with combination of cutting and slope foot burning.（9） A new model was established to simulate the complex degradation process of vulnerable karst ecosystem based on local human activities,natural environment and economic development by using interruption degrees,community types,service and function of ecosystems,land degradation and poverty as indicators.A controlling model was also established to prevent rocky desertification. @更多还原