亚热带稻田弃耕湿地土壤因子对植物群落结构的影响

采用冗余分析法对弃耕一年稻田湿地生态系统的植物群落与土壤因子进行了分析.结果表明：在亚热带湿地生态系统中,土壤水分条件、有效钾、有效磷和pH是影响物种分布的最主要土壤因子.试验区的主要植物物种可以划分为3个物种组:丁香蓼-水竹叶物种组(组1)、牛鞭草-圆叶节节菜-稻槎菜物种组(组2)和小白酒草-辣蓼-双穗雀稗物种组(组3).其中,组1主要分布于土壤有效钾含量较高的区域;组2主要分布于阶段性淹水区域;组3主要分布于排水区域,且与土壤有效磷和pH呈正相关.物种多样性与土壤pH、植被地上生物量与土壤全钾含量呈显著正相关,均匀度与土壤有效氮含量呈显著负相关,与其他指标的相关性均不显著.     

Plant community complexity in the arid valley of Minjiang River, southwestern China

Biocomplexity theory is becoming increasingly important in understanding natural vegetation dynamics and interrelation among all components of the ecosystem. In this study, based on the field investigation of plant species and environmental factors (altitude, microtopography, soil water content, and soil nutrients) in an arid valley of the upper reaches of Minjiang River, Sichuan Province, southwestern China, plant community complexity and its relationship with environmental factors, community diversity, species evenness and richness were studied. Both total and structural complexities of the communities showed a “high- low-high” tendency with the increase in altitude of the area, which meant that the complexity of communities was the highest at the sites of low and high altitude, whereas it was the lowest at the sites of intermediate altitude. It was found that the total community complexity had significant quadratic correlations with soil organic matter (SOM) content, total nitrogen (N), hydrolyzable N, soil water content, and available potassium (K), whereas it had no significant correlations with soil total K, total phosphorus (P), available P, and pH value. The total community complexity positively correlated with community diversity, species evenness and species richness, whereas the structural complexity negatively correlated with the community evenness. Of the two components of the total community complexity, namely, the structural complexity and the structural diversity, the structural complexity was more sensitive than the structural diversity to the changes of species in the community, which was not only related to the community evenness but also to the community richness. The relative contribution of both the structural complexity and the structural diversity to the total complexity would be different for different study areas or ecosystems.     

上海世界博览会园区内及周边地区鸟类多样性及其影响因子

2006年3-9月,对上海世博园区及周边地区鸟类资源进行普查,并对鸟类数量、种类和环境因子相关性进行研究。结果表明,该区域内现有鸟类10目27科67种,其群落多样性指数为3.46。运用概率统计方法分析了鸟类群落结构和分布特征,并将鸟类群落指数与园林绿地的8项环境指标进行分析,表明鸟类的种数、数量以及多样性指数与公园的面积、水域面积、形状指数、生境种类呈极显著相关;鸟类多样性、均匀性指数与树种总数呈显著相关;鸟类种数与环境中的位置条件有关。同时,就世博园区绿地建设中的引鸟工程,提出了5点建议。     

线虫群落对抚顺煤矸石山周边土壤可溶性盐污染的响应

于2006年5月对抚顺西露天矿西舍场煤矸石山周边的次生盐渍化样地进行可溶性盐含量和土壤线虫调查,经淘洗-过筛-离心漂浮法提取土壤线虫,应用线虫多样性指数和功能类群指数研究该区域土壤线虫群落的特征及差异。研究结果表明,抚顺西露天矿西舍场矸石山周围环境受到了煤矸石风化产生的以硫酸钠为主的可溶性盐污染, 但污染程度不高,土壤整体健康状况良好;共鉴定出线虫29属,其中Acrobeloides、Cervidellus 和Mesorhabtidis为优势属,随采样点距矸石山距离的增加线虫优势属也有所变化;研究区域中食细菌线虫和植物寄生线虫的绝对丰度高于食真菌线虫和捕食-杂食线虫的绝对丰度;土壤pH、矿化度、HCO₃^-、Cl^-、SO₄^2-、NO₃^-与线虫生态指数间存在显著相关关系。因此,通过开展线虫群落对土壤可溶性盐污染的响应研究,能为促进土壤生态系统健康发展提供科学依据。     

庙岛群岛典型植物群落物种、功能、结构多样性及其对环境因子的响应

海岛植被在全球生物多样性研究中起重要作用,研究海岛植被多样性对于理解海陆相互作用下植物群落的多样性维持机制有重要意义.本研究以庙岛群岛的麻栎群落、刺槐群落、黑松群落、荆条群落4种典型植物群落为对象,采用物种多样性指数、功能多样性指数和结构多样性指数,在群落尺度上探讨了海岛典型植物群落物种、功能、结构多样性间的关系及其对环境因子的响应.结果表明: 黑松群落的物种丰富度与Rao指数高于刺槐群落与麻栎群落,而结构多样性却较低;荆条灌丛的物种、结构多样性均低于森林群落,而功能多样性高于部分森林群落.物种丰富度与Rao指数以及树高多样性间呈显著正相关,与功能均匀度呈显著负相关.结构多样性主要由坡度决定且与坡度呈负相关;功能均匀度与坡度呈正相关,而功能异质性、功能离散度和物种多样性则更多地受土壤理化性质的影响,与土壤容重及土壤总碳呈正相关,与土壤含水率呈负相关.总体而言,庙岛群岛的植物群落多样性格局既有与大陆植被相似的特征,但也有其海岛特殊性.     

铅锌矿渣场植被自然演替与基质的交互效应

矿业废弃地生态系统自然恢复的植被演替过程与机理是生态恢复研究的重要内容之一.以空间代替时间的方法,选择立地条件基本一致的4个不同自然恢复年限铅锌矿区为对象,研究黔西北土法炼锌渣场废弃地植被自然演替与矿渣基质理化性质的交互效应.结果表明： 随着堆置时间的增加,矿渣基质的营养条件明显得到改善,全氮、全磷和全钾含量极显著增加, pH上升,电导率下降,容重降低,有效铅和镉显著降低. 同时,随着恢复时间的增长,植物群落的物种丰富度、多样性指数和均匀度也相应提高.植物群落组成以多年生草本植物为主,植物群落演替在前20年较为缓慢,30年后植被群落盖度可达到53%,超过40年盖度可达87%.矿渣理化性质与物种多样性显著相关,典型变量分别是全氮、全磷和全钾;物种多样性指数与有效铅和镉呈显著负相关.土法炼锌渣场废弃地植被自然演替过程在30年后速度加快,植被生长的限制因子是营养供给不足和重金属的有效性高.     

新疆阜康绿洲荒漠过渡带植物群落物种多样性与土壤环境因子的耦合关系

对新疆阜康绿洲荒漠过渡带植物群落4个物种多样性指数和3层土壤19个指标进行回归分析,结果表明,土壤酸碱度,全盐量,Cl^-,K^ Na^ ,Mg^2 ,土壤有机质,全N和速效P与物种多样性有显著相关关系（P＜0．05）。酸碱度和有机质与多样性的最好拟合为二项式,即高的物种多样性出现在梯度中间位置。其余6个指标与物种多样性为显著线形负相关关系。表明全盐量,Cl^-,K^ Na^ ,Mg^2 含量越多,物种多样性越小,全N和速效P与均匀度均呈显著负相关,表明全N和速效P含量上升,均匀度显著下降,植物个体数与土壤水盐的回归分析表明,植物多度受土壤水分和盐分影响显著（P＜0．01）。     

山西五鹿山森林群落木本植物功能多样性

通过选取群落中木本植物种子的扩散方式、传粉方式、植株高度和盖度等13个功能性状,计算出群落的6个功能多样性指数:功能性状距离、功能性状平均距离、功能体积、功能均匀度、功能分散指数和Rao二次熵指数,结合群落物种丰富度指数、Shannon-Wiener指数和物种均匀度指数对山西五鹿山森林群落木本植物功能多样性进行研究。结果表明:(1)功能性状距离、功能性状平均距离、功能体积与物种丰富度、Shannon-Wiener指数显著正相关;功能均匀度与Shannon-Wiener指数、物种均匀度指数显著正相关;功能分散指数、Rao二次熵指数与物种均匀度指数、Shannon-Wiener指数显著正相关;(2)功能多样性的差异很大程度上是由于物种差异所引起的;(3)6个功能多样性指数可分为三类:功能性状距离、功能性状平均距离、功能体积为功能丰富度指数;功能均匀度为功能均匀度指数;功能分散指数和Rao二次熵指数为功能离散度指数。该分类结果符合指数的计算方法和生态学意义,以及相互独立的标准。     

稀土尾矿土壤细菌群落结构对植被修复的响应

选用赣州-安远稀土弃废尾矿及其不同植被修复的堆浸田为研究对象,调查废弃尾矿及6种不同植被修复方案下土壤理化性质的变化,并利用变性凝胶梯度电泳(DGGE)技术,分析土壤微生物群落结构对植被修复的响应。结果表明:与未修复尾矿土壤相比,经不同植被修复后的土壤理化性质均得到明显改良,其中土壤含水量、有机质含量均比未修复尾矿土壤增加2—3倍。微生物群落结构分析表明,植被修复后土壤微生物群落与废弃尾矿土壤微生物群落亲缘度仅为0.21,表明植被修复后,土壤微生物群落结构发生了明显变化,且微生物多样性、均匀度、丰富度与未修复尾矿土壤相比均有了明显的提高。而在不同植被修复方案中,以湿地松和山胡椒为优势群落的两种植被修复方案对土壤改良效果最为明显,这两种修复方案不仅能显著改善土壤的固水性、有机质含量,并且对微生物群落的改善作用也最为显著。典范对应分析表明,废弃尾矿土壤微生物群落结构受土壤p H影响最为显著,而植被修复后土壤微生物群落的环境影响因子则转变为含水量、有机质、有机碳及总磷含量。进一步揭示了微生物在植被修复过程中所起到的重要作用,并为矿山生态重建过程中的土壤改良工作提供了丰富的理论依据。     

秦岭皇冠暖温带落叶阔叶林灌木层结构与物种多样性

灌木是森林生态系统中的重要组成部分,探究灌木层的物种组成、结构和空间分布可以为进一步阐明森林物种共存、生物多样性维持和群落演替机制奠定基础。本研究分析了秦岭皇冠25 hm²森林样地灌木层的物种组成、空间分布以及物种多样性。结果表明: 样地内灌木独立个体共20716株(分枝10463个),隶属于28科45属54种。灌木层优势种的优势度不明显,重要值均＜10。灌木层植被的径级结构为倒“J”型;灌木在样地内呈聚集分布且空间分布存在明显的海拔差异。样地内个体数最多的9种灌木的径级结构和空间分布与灌木层整体情况一致。随着海拔升高,Shannon多样性指数(H)和Simpson优势度指数(D)变化不显著,而Pielou均匀度指数(E)降低。多样性指数H、D、E随乔木层优势种个数增加而降低,E随亚乔木层优势种个数增加而升高。多样性指数H、D、E与土壤全磷呈显著负相关;H与土壤pH呈显著正相关,E与土壤全钾呈显著正相关。本研究区灌木层物种丰富,结构稳定,更新良好;灌木层的物种多样性主要受到乔木层优势种个数和土壤pH、全磷的影响。     

Diversity of the understory vascular vegetation in 40 year-old and old-growth forest stands on Vancouver Island,British Columbia

Abstract. We studied plant diversity of the understory vascular vegetation in 40 yr-old plantations (immature stands) and old-growth forest stands on southwestern Vancouver Island, British Columbia, Canada. Site-specific comparisons using several indices of species diversity were made between: (1) immature stands segregated according to the canopy cover and dominant canopy tree species; and (2) immature and old-growth stands. There were no significant differences (P < 0.05) among immature stands in species richness (S) and the Shannon-Wiener index (H′), in relation to the canopy cover or in S, H′ and evenness (E) in relation to the dominant canopy tree species. Using the same indices, the plant diversity varied with edaphic conditions (represented by five site associations) and time (represented by two developmental stages). At both stand- and site levels, plant diversity increased with increasing soil moisture, from slightly dry to moist sites, and with increasing plant-available soil nitrogen in both immature and old-growth stands; and the plant diversity of immature stands across the sites studied was considerably lower than in old-growth stands, regardless of site association. The indices of plant diversity, floristic similarity indices, and species turnover rates indicated that the immature stands had their plant diversity at a minimum, but a drastic loss of diversity expected in the stem exclusion stage had not materialized. We attributed decline in plant diversity to the absence of old-growth structural features in immature stands. Several measures to foster the stand-level diversity were proposed.     

Effects of plant diversity, plant productivity and habitat parameters on arthropod abundance in montane European grasslands

Arthropod abundance has been hypothesized to be correlated with plant diversity but the results of previous studies have been equivocal. In contrast, plant productivity, vegetation structure, abiotic site conditions, and the physical disturbance of habitats, are factors that interact with plant diversity, and that have been shown to influence arthropod abundance. We studied the combined effect of plant species diversity, productivity and site characteristics on arthropod abundance in 71 managed grasslands in central Germany using multivariate statistics. For each site we determined plant species cover, plant community biomass (productivity), macro- and micronutrients in the soil, and characterized the location of sites with respect to orographic parameters as well as the current and historic management regimes. Arthropods were sampled using a suction sampler and classified a priori into functional groups (FGs). We found that arthropod abundance was not correlated with plant species richness, effective diversity or Camargo's evenness, even when influences of environmental variables were taken into account. In contrast, plant community composition was highly correlated with arthropod abundances. Plant community productivity influenced arthropod abundance but explained only a small proportion of the variance. The abundances of the different arthropod FGs were influenced differentially by agricultural management, soil characteristics, vegetation structure and by interactions between different FGs of arthropods. Herbivores, carnivores and detritivores reacted differently to variation in environmental variables in a manner consistent with their feeding mode. Our results show that in natural grassland systems arthropod abundance is not a simple function of plant species richness, and they emphasize the important role of plant community composition for the abundance patterns of the arthropod assemblages.     

新薛河底栖动物物种多样性与功能多样性研究

研究功能多样性与物种多样性关系及其随环境梯度的变化规律,有助于理解生物在群落中的共存机制;然而,二者间关系的研究在淡水生态学中尚鲜见报道。通过对新薛河典型河段(A缓流河段、B断流河段、C有机污染河段、D对照河段、E人为干扰河段)底栖动物季节性调查,就物种多样性和功能多样性时空动态及关系进行了研究。结果表明:在空间序列上,物种多样性指数在B河段均最低,表明间歇性断流对物种多样性影响重大。功能丰富度在D河段最高,A河段最低;功能均匀度在A河段高于其他河段;功能分离度在A、B河段最高,D河段最低。在时间序列上,物种丰富度和Shannon指数均值在10月份最低,4月份最高;均匀度指数在12月份最低,10月份最高。3个功能多样性指数于各季节间差异显著、相互独立,主要受水文条件和底栖动物生活史影响。相关分析表明,功能多样性指数间无显著相关性;功能丰富度同物种丰富度和Shannon指数相关显著,功能均匀度同物种均匀度相关显著。逐步回归分析发现,功能丰富度受物种丰富度和Shannon指数影响显著,功能均匀度受物种均匀度影响显著;功能多样性和物种多样性指数间拟合度总体不高。研究结果进一步表明:相对物种多样性,功能多样性对生境梯度变化响应更加全面。     

Spatial heterogeneity of soil nutrients and plant species in herb-dominated communities of contrasting land use

Recent interest in spatial pattern in terrestrial ecosystems has come from an awareness of the intimate relationship between spatial heterogeneity of soil resources and maintenance of plant species diversity. Soil and vegetation can vary spatially in response to several state factors of the system. In this study, we examined fine-scale spatial variability of soil nutrients and vascular plant species in contrasting herb-dominated communities (a pasture and an old field) to determine degree of spatial dependence among soil variables and plant community characteristics within these communities by sampling at 1-m intervals. Each site was divided into 25 1-m² plots. Mineral soil was sampled (2-cm diameter, 5-cm depth) from each of four 0.25-m² quarters and combined into a single composite sample per plot. Soil organic matter was measured as loss-on-ignition. Extractable NH₄ and NO₃ were determined before and after laboratory incubation (28 days at 27°C) to determine potential net N mineralization and nitrification. Cations were analyzed using inductively coupled plasma emission spectrometry. Vegetation was assessed using estimated percent cover. Most soil and plant variables exhibited sharp contrasts between pasture and old-field sites, with the old field having significantly higher net N mineralization/nitrification, pH, Ca, Mg, Al, plant cover, and species diversity, richness, and evenness. Multiple regressions revealed that all plant variables (species diversity, richness, evenness, and cover) were significantly related to soil characteristics (available nitrogen, organic matter, moisture, pH, Ca, and Mg) in the pasture; in the old field only cover was significantly related to soil characteristics (organic matter and moisture). Both sites contrasted sharply with respect to spatial pattern of soil variables, with the old field exhibiting a higher degree of spatial dependence. These results demonstrate that land-use practices can exert profound influence on spatial heterogeneity of both soil properties and vegetation in herb-dominated communities.     

Ecological potentials of biodiversity modelled from information entropies: Plant species diversity of North-Central European forests as an example

The paper deals with the hypothesis that ecosystems have well-defined potentials of biodiversity. These potentials can be quantified as information entropy of the corresponding ecosystem type. The hypothesis is verified for the diversity of plant species.

A vegetation database of North-Central European forests containing more than 12000 relevés is analyzed computationally. The samples are classified into ecosystem types that are homogeneous with respect to vegetation patterns, ecological site factors, and, implicitly, with respect to ecosystem processes. Growing numbers of relevés are selected randomly from the representatives of different ecosystem types and investigated mathematically.

Shannon information (product of logarithmic species number and evenness) obeys a hyperbolic saturation equation approaching a finite value on infinite area. This asymptotic limit defines the ecological potential of species diversity. Within a given plant-geographical region, it is determined by ecological site factors like climate and soil controlling interrelations between plants. Competition relationships and hence potentials of phytodiversity are altered by management significantly. The curve of evenness versus area size is hump-shaped. Maximum evenness is proportional to the ecological potential of species diversity. The area size where evenness attains its maximum can be interpreted as the minimum area of the respective forest type. The ecological potentials of plant species diversity modelled from information entropies correspond to vegetation patterns consisting of a limited number of plant species. These vegetation patterns are closely related to ecosystem processes like nutrient cycling, plant nutrition, evapotranspiration, microbial processes, or net-primary production. Revealing the relationships between vegetation patterns and ecosystem processes allows scaling functional information from local measurement scales up to regional scales.

It is suggested to explore genetic, proteomic, and species data in order to derive comprehensive ecological potentials of biodiversity on various levels from population to landscape. The expected results could improve the understanding of the relationship between biodiversity and ecosystem functioning as well as the sustainability of ecosystem management.     

Non-native fishes and native species diversity in freshwater fish assemblages across the United States

The proliferation of non-native species in North American freshwater ecosystems is considered a primary threat to the integrity of native community structure. However, a general understanding of consistent and predictable impacts of non-native species on native freshwater diversity is limited, in part, because of a lack of broad-scale studies including data from numerous localities across multiple drainages. This study uses data from 751 localities collected during the United States Geological Survey (USGS) National Water Quality Assessment (NAWQA) program to examine the influence of non-native fish species on native freshwater fish assemblages across the United States. In general, no significant differences in native fish richness and diversity measures were detected between sites with only native species and sites containing non-native species. However, at sites with non-native species, the number of non-native species present was negatively correlated with native species richness and Shannon diversity and positively correlated with native evenness. Non-native piscivores were negatively correlated with native species richness and Shannon diversity and positively correlated with native evenness. Native piscivores were positively correlated with native richness and diversity and negatively correlated with native evenness at sites with only native species. Our results suggest that from a superficial perspective, native species richness and diversity are not different among sites with and without non-native species. However, when patterns of native species richness and diversity are examined at sites containing non-native species, correlations between non-native and native species richness and diversity imply the expected negative effect of invasive taxa. Additionally, non-native piscivores appear to have a significant negative effect on native taxa and possibly represent a novel selective force on naive native prey.     

Factors affecting species diversity of plant communities and the restoration process in the loess area of China

The Loess Plateau of China is a special region that has suffered from soil erosion and water loss for a long time. Ecological restoration is an urgent task for this region. This study aims to characterize the variation in the vegetation restoration process on the abandoned croplands in the loess area. A series of quadrats were set up in different restoration stages in the Yancun watershed, Shanxi Province, an area of typical loess hills and gullies. Species and environmental data were recorded in each quadrat. Multivariate analysis and indices for species richness, diversity and evenness were used in the analysis. A series of plant community stages with different composition, structure and environments were identified by clustering analysis (UPGMA). These communities included three main restoration stages, grassland stage, scrubland stage and forest stage, and nine sub-stages, i.e. nine associations. Canonical correspondence analysis (CCA) showed that time since abandonment was the key factor for the restoration process, and the first CCA axis was effectively a time gradient. Elevation, soil type, slope and aspect were also important in the restoration process in the loess area. Species richness and diversity increased, and evenness decreased in the restoration process. The variation of species richness and diversity significantly correlated with time since abandonment, elevation and soil type. Time since abandonment is most important to the restoration process and species diversity is the main indicator of community changes in restoration in the Loess Plateau. For effective management, abandoned lands should be kept from disturbance.     

恒湖农场茶叶港草洲枯水期湿地植物与土壤关系及种群生态位分析

湿地植物与土壤关系问题一直就是生态学研究的热点,也是湿地植物种群生态位研究的基础。基于鄱阳湖典型湿地-|恒湖农场茶叶港草洲19个样地20种植物重要值组成的样地-|物种矩阵,用等级聚类分析中的Ward法(离差平方和法)将研究区植物划分为灰化薹草(Carex cinerascens)群落、虉草(Phalaris arundinacea)群落及南荻(Triarrhena lutarioriparia)群落3个群落类型。通过Spearman秩相关分析检验物种多样性指数(Shannon-Wiener多样性指数H'、物种丰富度指数S和Pielou均匀度指数J)与土壤因子(土壤pH值、电导率、含水量和有机质)的相关性,结果发现研究区植物物种的Shannon-Wiener多样性指数H'、物种丰富度指数S与土壤pH值分别为显著(P0.05)和极显著(P0.01)正相关关系,而与土壤有机质分别达到显著(P0.05)和极显著(P0.01)负相关水平,Pielou均匀度指数J与土壤因子相关性不明显。利用RDA(冗余分析)排序分析研究区植物物种分布与土壤p H值、电导率、含水量、有机质的关系,结果发现土壤pH值、土壤有机质与研究区植物物种分布关系最为密切(P=0.042,0.048),可以看成是关键控制因子。基于对研究区植物物种分布影响较大的土壤pH值及有机质环境因子,将其分别划分为10个梯度等级,分析植物种群生态位。发现研究区优势种灰化薹草、虉草生态位宽度较大,蚊母草(Veronica peregrina)、荇菜(Nymphoides peltata)等生态位宽度较小,生态位重叠值整体保持在较低水平,说明物种在土壤pH值和土壤有机质两个环境梯度上生态位分化明显。     

岷江干旱河谷植物群落的复杂性

通过对岷江干旱河谷植被及环境因子的系统取样调查,研究了该地区植物群落复杂性及其与环境因子的关系,探讨了群落复杂性与多样性、均匀度、物种丰富度之间的关系.随着海拔的增加,群落总复杂性和结构复杂性均表现为“高-低-高”的变化趋势,表明高海拔和低海拔段有较高的复杂性,中海拔段复杂性较低;位于干旱河谷核心区的样带3、4较北部过渡区样带1、2和南部过渡区样带5、6有着较低的群落总复杂性;不同坡位、坡形及坡向,群落总复杂性和结构复杂性,均表现为上坡位＞下坡位＞中坡位,凹坡＞平破＞凸坡,阴坡＞半阴半阳坡＞阳坡.华帚菊-小黄素馨灌丛的总复杂性最高,西南野丁香灌丛、驼绒藜灌丛的总复杂性最低,橿子栎灌丛和群小花滇紫草灌丛的结构复杂性较高; 群落总复杂性与有机质、全N、土壤含水量、水解N、速效K呈现出显著的二次曲线关系,与全K、全P、速效P、pH值没有明显的相关关系.总复杂性与多样性、均匀度、物种丰富度的关系密切,均呈现显著的线性正相关关系.均匀度和结构复杂性呈现极显著的线性负相关,表明结构复杂性随均匀度的增加而减小.作为群落总复杂性与多样性的区分,结构复杂性对群落内物种数的变化较为敏感,不仅与均匀度有关,还与群落物种数量有关.结构复杂性和多样性作为群落总复杂性的两个组成部分,对总复杂性的影响随着研究区域和群落的不同而不同.     

青土湖不同年限退耕地植被物种多样性及土壤酶活性研究

采用时空替代法,对甘肃省民勤县青土湖不同年限退耕地(退耕1 a、2 a、4 a、8 a、13 a、20 a、30 a、40 a)的植被演替特征、土壤酶活性进行调查,以耕地为对照(CK),分析植被群落与土壤酶活性的相关性,以揭示其变化规律及其驱动机制,为青土湖区及其相似地区退耕地生态系统修复及生态环境建设提供理论基础。结果表明：(1)青土湖在退耕40 a自然恢复过程中,9个样方中共出现16科32属42种植物,物种构成表现为：多数种归于少数科,大部分植物种为单属单科。(2)随着退耕年限的增加,群落优势种由草本植物逐渐转化成灌木植物,植物种由退耕初期(1 a或2 a)的19种降低到退耕4 a的14种、退耕20 a的13种、退耕30 a的5种;退耕30 a时耐盐碱灌木植物盐爪爪成为该地的优势种,其重要值达到52.862,但退耕40 a时优势种盐爪爪的重要值降为36.008。(3)随着退耕年限增加,植物Margalef丰富度指数呈波动式下降的趋势;Shannon多样性指数和Pielou均匀度指数总体趋势呈先增加后减小,再逐渐趋于稳定;Simpson优势度指数整体变化幅度较小,最终呈稳定的趋势。(4)在不同土层(0~20 cm和20~40 cm)中,4种土壤酶活性随退耕年限增加总体表现出先升高后下降再逐渐趋于稳定的趋势,均在退耕8 a后显著下降,且磷酸酶和脲酶活性均显著低于蔗糖酶和过氧化氢酶活性;与对照样地(CK)相比,磷酸酶活性与脲酶活性均随退耕年限增加而下降;土壤磷酸酶、蔗糖酶和脲酶活性均随土层加深而降低。(5)相关分析结果显示,0~20 cm土层中,物种数与土壤蔗糖酶活性、磷酸酶活性以及脲酶活性均呈显著正相关关系;20~40 cm土层中,物种数与土壤脲酶活性呈极显著正相关关系,与土壤过氧化氢酶活性呈显著负相关关系;Margalef丰富度指数与0~20 cm土层的磷酸酶活性和蔗糖酶活性均呈显著正相关关系,与脲酶活性呈极显著正相关关系;20~40 cm土层中,Margalef丰富度指数与脲酶活性呈极显著正相关关系;Shannon多样性指数、Pielou均匀度指数和Simpson优势度与4种土壤酶活性间相关性较低且均不显著。研究认为,在青土湖区退耕地植被自然演替过程中,植物群落变得比较单一,物种多样性逐年降低,脲酶活性对物种多样性起着关键性作用。