【作者】 金红喜；

【导师】 王刚；

【作者基本信息】 兰州大学 ， 植物生态学， 2012， 博士

【摘要】 过去几十年,全球自然生态系统退化是一个严峻的世界性问题,已引起科学界和各国政府高度重视。如何恢复、重建这些退化生态系统是当前生态学研究领域的前沿和热点之一。生物多样性和生态系统功能是衡量一个退化生态系统恢复重建是否成功的最重要参数,生物多样性增加以及由此带来的生态系统功能改善是人们重点关注的对象。在一个生态系统中,两者的消长有着紧密地联系,多数科学家认为两者之间的关系主要表现为一种渐进饱和趋势,是由物种间相互正作用和抽样效应决定。虽然前人的研究取得了丰硕成果,但目前对生物多样性和生态系统功能在生态恢复建植林(Forests planted for ecosystem restoration; FPER)中的关系缺乏深入认识。本研究以长期受到人类干扰的六盘山自然保护区生态恢复建植林为研究对象,通过野外调查观测、室内分析等方法,对不同恢复阶段、恢复方式、经营管理方式建植林内草本、灌木、乔木物种多样性、生产力以及乔木更新等进行了研究,探讨了恢复时间、方式以及经营管理对建植林中植物物种多样性—生产力关系的影响。结果表明：1)经过近30年的恢复,六盘山国家级自然保护区FPER林内生物多样性增加,生态系统功能逐步完善,生态环境得到显著改良。落叶阔叶林和混交林的植物多样性和生产力显著高于其它类型FPER。草本植物物种多样性、生产力随恢复时间呈递减二次函数变化：y=at2-bt+c,灌木物种多样性、生产力、乔木物种多样性随恢复时间呈递增二次曲线变化：y=-at2+bt+c,但乔木生产力随恢复时间单调递增：y=at+b。2)建植林内,乔木物种多样性随光照条件改良、海拔高度降低、坡度增加而升高,与林地土壤Mg2+、Na+、pH值呈显著正相关关系；乔木生产力随光照强度改良和坡度增加而升高,与林地土壤Mg2+、速效磷、pH值呈显著正相关关系。3)建植林恢复时间不同,植物物种多样性—生产力关系就不同。在恢复时间不足20年的FPER中,草本物种多样性(x)与生产力(y)关系符合递增幂指数函数：y=axb,灌木物种多样性(x)与生产力(y)关系符合递增二次曲线方程：v=ab2-bx+c；在恢复时间20-40年的FPER中,草本、灌木物种多样性(x)与生产力(y)呈递增幂指数函数关系：.y=axb；当FPER恢复时间超过40年时,草本、灌木、乔木物种多样性(x)与生产力(y)之间关系都呈递增幂指数关系：y=axb。随着建植林的恢复时间,植物物种多样性对生产力的正效应在减弱。4)森林恢复方式对植物物种多样性—生产力关系亦有影响。在针叶林和混交林内,物种多样性(x)—生产力(y)关系符合幂指数函数：y=axb；物种多样性变化对针叶林群落生产力影响更大。在阔叶林内,两者之间关系不显著。5)抚育管理方式对林下草本植物物种多样性—生产力关系产生影响。经过间伐的FPER林下草本植物多样性和生产力比未经过间伐的FPER林下草本植物多样性和生产力都要高；在未间伐FPER中,林下草本植物生产力和多样性呈正相关关系;间伐改变了这一关系,使林下草本植物生产力在间伐FPER中随物种多样性增加而降低。SEM (structural equation modeling)模型证明,这种改变主要是因为间伐改变了FPER林下的生境条件和群落结构,从而对林下草本植物物种多样性—生产力关系产生了显著影响。6)相比针阔混交林和针叶林,阔叶林内乔木幼苗密度大、物种丰富、Shannon-Wiener多样性指数高；进一步研究表明,该区FPER林下主要乔木幼苗为辽东栎、少脉椴、桦叶四蕊槭、山杨、红桦、白桦等阔叶树种,很少有油松、华山松等针叶树种幼苗,没有发现华北落叶松幼苗：说明在六盘山自然保护区FPER中,阔叶树种自然更新比针叶树种好,而华北落叶松在该区不能自然更新。阔叶树种幼苗密度、生长状况在阳坡生境下明显优于阴坡生境；而针叶树种幼苗在阴坡的密度、生长状况则好于阳坡。7)在阔叶林内,乔木幼苗密度和多样性指数随恢复年限呈递减趋势；而在针叶林内,乔木幼苗密度、物种丰富度、Shannon-Wiener等多样性指数表现为先增大,后减小趋势,在优势种胸高断面积30-35m2/ha时各项多样性指数达到最高值。更多还原

【Abstract】 Over the past several decades, people have witnessed that the natural ecosystems of the worlds have been increasingly degraded, which has attracted the intense attention from the government and academia. Thus, the restoration and reconstruction of these degraded ecosystems has been an emergent and hot topic in ecology. Biodiversity and ecosystem functioning are among the most important parameters in evaluating the restoration and reconstruction. The increase of the biodiversity and the improvement of ecosystem functioning due to the increasing of biodiversity have been the critical points which people concern. For a given ecosystem, biodiversity and ecosystem functioning are linked closely, and most scientists believe that the ecosystem functioning improves with the increase of the biodiversity at low intensity and saturates at high intensity due to complementarities and sampling effect. So far, the previous achievements have been conspicuous, but the research about the relationship between the biodiversity and ecosystem functioning in forests planted for ecosystem restoration (FPER) is rare. Using observational and investigative methods, we studied herbaceous, shrub, and tree species diversity and productivity, tree seedling diversity in different restoration stages, restoration types, and the management of Liupanshan FPER which had a long history of human disturbance. We also analyzed the effects of restoration time, type and management on the relationship between plant diversity and productivity. The results indicated that:1) After more than30years restorations, the biodiversity has been increased, the ecosystem functioning completed step-by-step, and the ecological environment significantly improved in Liupanshan National Natural Reserve FPER. There were higher plant diversity and productity in deciduous broadleaf forests and mixed forest. The herbaceous species diversity and productivity (y) declined with time(t), and described as a quadratic function. y=at2-bt+c; the shrub species diversity, productivity and tree species diversity ascended, also described as a quadratic function, y=-at2+bt+c:the tree productivity increased with time, and the productivity-time relationship could be best described as a linear function, y=at+b.2) In FPERs. with the amelioration of the light conditions, the increase of slope gradients, and the decrease of elevation, the plant species number increased. The studies also showed that both plant diversity and productivity benefited from higher soil Mg2+and pH. Plant diversity increased with shallow soil Na+, but plant productivity increased with shallow soil available phosphorus.3) There were different relationships between biodiversity and ecosystem functioning in different restored time FPER. In FPER less than20years, the relationships between herbaceous plant diversity (x) and productivity (y) were best described as an exponential growth function,y=axb; the ones for shrub plant diversity (x) and productivity (y) were best described as quadratic growth function. y=ax2-bx+c. In PFER between20-40years, the relationships between herbaceous and shrub plant diversity (x), productivity (y) were best described as an exponential growth function. y=axb; then in PFER more than40years, the relationships between tree, shrub and herbaceous plant diversity (x) and productivity (y) were best described as an exponential growth function, y=axb, by using the Curve Estimation. Moreover, the results showed that such effect of biodiversity on ecosystem functioning was decreasing with restoration times.4) The results from different forest restoration types revealed that the relationship between biodiversity and ecosystem functioning was best described as an exponential growth function, y=axb. in conifer and mixed forests, and the changes of plant diversity have more magnitude effect on ecosystem process in conifer forests than in mixed forests. Such relationships disappeared in the broadleaved forest.5) Tree-thinning affected the relationship between understory herb species diversity and productivity.’Both biodiversity and biomass of understory herb plants were higher in tree-thinned FPER than that in undisturbed FPER, and there was a negative correlation between richness and productivity in the thinning treated communities, whereas a positive correlation was found in undisturbed communities. Structural equation modeling (SEM) suggests that both the community composition and abiotic condition, directly or indirectly changed by tree-thinning, influenced the biodiversity-productivity relationship.6) Our studies also showed that tree seedling density, seedling diversity and Shannon-Wiener richness index were highest in broadleaved forest, and then in P. labulaeformis forest, P. armandii forest, and lowest in L. Principis-rupprechtii forest. The results from investigated tree species seedlings showed that the more popular species were Quercus wuiaishanica, Acer letramerum var. Betulifolium, Tilia paucicostata, Populus davidiana, Betula albo-sinensis, and B. platyphylla; the fewer species were Pinus tabulaeformis, and P. armandii, and there was no L. Principis-rupprechtii seedlings found in every type restoration forest indicating this species failed to regenerated itself in Liupanshan region. The broadleaved seedling density and growth status were better in sunny slope than in shady slope; however, the conifer seedlings were more likely discovered in shady regions.7) In broadleaved forests, tree species seedling density and diversity index were decreasing with time. However, in conifer restoration forests, tree species seedling density, species richness, and Shannon-Wiener index were peaked at the intermediate basal type forests (30～35m2/ha), and then decreased with increasing of the basal area of the predominant species.更多还原