Vegetation restoration patterns and their relationships with disturbance on the Giant Panda Corridor of Tudiling, Southwest China

Human activities such as deforestation, cultivation, and overgrazing have contributed to the destruction of forest ecosystems in the upper Minjiang River basin for a long time, which has led to the reduction in forest coverage and biodiversity. On the Giant Panda Corridor of Tudiling in this basin, the effects of the existing disturbance regimes on plant communities after the vegetation restoration in the 1980s were assessed, and the community composition, the species diversity and their relationships with environmental factors significantly associated with the disturbance were analyzed using the transect sampling method, the two-way indicator species analysis (TWINSPAN) and the detrended canonical correspondence analysis (DCCA). The results were as follows: communities could be classified into six types, and species were clustered into four functional groups (responsive to disturbance, retarded disturbance, resistant to intermediate disturbance, and resistant to heavy disturbance) based on both TWINSPAN and DCCA. DCCA with species composition of plots is similar to that with species diversity of plots. The communities were separated into distinct groups along the DCCA axis, and this pattern was significantly correlated with environmental factors. Elevation differences, shape, slope, distance to roads, and the number of paths in the plots had an evident influence on the distribution of the species and communities. Environmental factors including slope, distance to roads, and the number of paths revealed the gradient of disturbance among the communities along the DCCA axis. High disturbance intensity caused significantly lower species diversity and inhibited the regeneration of vegetation compared with the more diverse undisturbed communities. Artificial restoration was more effective than natural restoration in maintaining high species diversity. The process of succession was inhibited in natural restoration because of the failure of tree establishment, growth, and survival during regeneration.     

四川茂县土地岭大熊猫走廊带植被恢复格局及其与干扰的关系

通过样带调查和TWINSPAN、DCCA分析,从植物种、植物群落及其多样性与环境关系方面,研究了岷江上游土地岭大熊猫走廊带恢复植被的干扰状况。结果表明：应用TWINSPAN分类,并结合优势种组成、干扰状况分析及DCCA排序,可将植被划分为6个群落类型,同时划分出响应型、迟钝型、中度干扰忍耐型和重度干扰忍耐型4类干扰响应的植物类型。以样方物种和以样方多样性指数的DCCA分析结果基本一致,物种及群落的空间分布呈明显的聚集格局,反映其与环境因子间的密切关系。DCCA排序图上,海拔差、坡形、与公路距离、坡度及道路条数对群落和物种分布有明显的影响,与干扰相关性最大的坡度、样地道路数目、与公路间的距离3个因子反映了植被的干扰梯度。干扰对土地岭恢复植被影响显著,干扰降低了群落的物种多样性,同时阻碍了演替进程。     

茂县土地岭植被恢复过程中物种多样性动态特征

植被恢复是退化生态系统重建的重要途径,植被恢复过程物种多样性的变化反映了植被的恢复程度.通过群落调查和多样性分析,研究了岷江上游土地岭植被恢复过程中群落物种多样性特征.结果表明： 恢复过程中6类不同类型群落分别表现其对于不同环境特征、干扰及更新方式等的响应;森林是较灌丛更适合当地环境状况的植被类型;人工恢复无干扰和轻度干扰群落的多样性相对较高,是较好的恢复模式.重度干扰使得1年生植物与地下芽植物比例增加,其它口食性较好的多年生草本减少.较强的干扰是群落无法更新、长期处于灌丛阶段且多样性较低的重要原因.本地区人工恢复群落在更新进程和多样性维持上优于自然更新群落,种植华山松加速了本地区植被演替进程.建议以适合恢复区域的多种恢复配置方式进行造林,并避免较强干扰,可以加速群落演替进程并保持恢复群落较高的物种丰富度与多样性.     

木论喀斯特峰丛洼地森林群落空间格局及环境解释

基于广西壮族自治区木论国家级自然保护区典型峰丛洼地景观尺度内不同微生境条件和植物群落类型50个样地 (20 m × 20 m)的系统取样调查, 用二元物种指示方法(TWINSPAN)对样地内胸径(DBH) ≥ 1 cm的木本植物进行分类, 选择10个土壤环境因子和5个空间因子, 利用除趋势典范对应分析(DCCA)研究了森林群落分布的土壤环境与空间格局, 并给予定量化的合理解释。结果如下: 1) TWINSPAN将森林群落划分为11组, 在三级水平上分为4类生态群落类型。2) DCCA第一排序轴集中了排序的大部分信息, 突出反映了各森林群落所在的坡向和土壤主要养分梯度, 沿第一轴从左到右, 坡向由阴转阳, 岩石裸露率越来越高, 土壤主要养分逐渐降低, 森林群落分别出现了由原生性和耐阴性强逐步向阳性先锋树种为主的次生林和人工林变化的格局。3)因子分离分析结果表明, 土壤环境因子对森林群落分布格局的解释能力为39.16%, 其中21.02%单纯由土壤环境因子所引起, 空间因子的解释能力为31.34%, 其中13.16%独立于土壤环境的变化, 18.15%是土壤环境和空间因子相互耦合作用的结果, 不可解释部分达47.66%, 表明喀斯特峰丛洼地森林群落的物种共存受生态位分化理论和中性理论双重控制。     

Factors influencing the distribution and growth of dwarf bamboo, <Emphasis Type="Italic">Fargesia nitida</Emphasis>, in a subalpine forest in Wolong Nature Reserve,southwest China

Dwarf bamboos impose intense resource competition in subalpine coniferous forests, and their exclusive densities have crucial impacts on tree regeneration and understory species diversity. We studied the factors influencing the distribution and growth of dwarf bamboo, Fargesia nitida, in a subalpine forest in southwest China. TWINSPAN, based on an attribute matrix, could divide the subalpine forest into 11 sub-associations, and more clearly reflected ecological functional features of the subalpine forest than analysis based on a species matrix. TWINSPAN was also generally consistent with DCA ordination based on the attribute matrix. DCA and DCCA ordination showed relationships between the distribution of F. nitida population and environment factor. The first DCCA axis showed topography and disturbance gradients (except fallen trees and broken branches); the second DCCA axis showed canopy density and composition gradients. Stepwise multiple regression analyses showed that distribution (culm density and coverage) of F. nitida decreased significantly with landslide and slope aspect, and increased significantly with soil status. The light condition had positive effects on growth and size of bamboo. A stable environment in the northern slope and more broadleaved species dominating in canopy would increase the dwarf bamboo biomass. Thus, the disturbance regimes, the slope aspect and the BA of evergreen conifer trees can provide useful guidelines for the control and management of F. nitida populations, and in helping to understand the succession and regeneration of subalpine forest in this region.     

Quantitative classification and ordination of forest communities in Pangquangou National Nature Reserve

Quantitative analysis of ecological relationships between vegetation and the environment has become an essential means in the field of research of modern vegetation ecology. In this article, based on data from 84 quadrates, forest communities in this reserve were investigated using TWINSPAN, DCA and DCCA. The results will be helpful in the construction and development of Pangquangou National Nature Reserve. Using TWINSPAN, the forest communities were classified into seven types. The distribution pattern of vegetation reflects the comprehensive influence of environments. The results of DCA and DCCA clearly reflect the relationship between the pattern of forest communities and environmental gradients. The ordination result of DCCA indicates that altitude is more important than other environmental factors because the change of altitude gradient will lead to changes in the temperature and humidity gradients. The first of the DCA ordination axes indicates the humidity gradient, and the second indicates the temperature gradient. All these results show that the main factors restricting the distribution of communities in this reserve are temperature and humidity. The ecological meaning of the ordination axis in DCCA is much clearer than that in DCA, and the species-environment correlation of DCCA is more obvious than DCA. The first DCCA axis indicates the altitude gradient among the communities, while the second is the gradient in aspect and slope among the communities. DCCA ordination can simultaneously express similarities of species and environment. Therefore, the quadrat location in the DCCA ordination figure is much closer than in the DCA.     

Quantitative classification and ordination of forest communities in Pangquangou National Nature Reserve

Quantitative analysis of ecological relationships between vegetation and the environment has become an essential means in the field of research of modern vegetation ecology. In this article, based on data from 84 quadrates, forest communities in this reserve were investigated using TWINSPAN, DCA and DCCA. The results will be helpful in the construction and development of Pangquangou National Nature Reserve. Using TWINSPAN, the forest communities were classified into seven types. The distribution pattern of vegetation reflects the comprehensive influence of environments. The results of DCA and DCCA clearly reflect the relationship between the pattern of forest communities and environmental gradients. The ordination result of DCCA indicates that altitude is more important than other environmental factors because the change of altitude gradient will lead to changes in the temperature and humidity gradients. The first of the DCA ordination axes indicates the humidity gradient, and the second indicates the temperature gradient. All these results show that the main factors restricting the distribution of communities in this reserve are temperature and humidity. The ecological meaning of the ordination axis in DCCA is much clearer than that in DCA, and the species-environment correlation of DCCA is more obvious than DCA. The first DCCA axis indicates the altitude gradient among the communities, while the second is the gradient in aspect and slope among the communities. DCCA ordination can simultaneously express similarities of species and environment. Therefore, the quadrat location in the DCCA ordination figure is much closer than in the DCA.     

历山自然保护区猪尾沟森林群落植被格局及环境解释

应用TWINSPAN、DCA和DCCA,从植物种,植物群落与环境的生态关系方面,研究历山自然保护区猪尾沟森林群落的植被分布格局,并给予合理的环境解释。结果如下：（1）采用TWINSPAN数量分类方法,将植被划分为9个群落类型。（2）对于特定的研究区域猪尾沟,制约森林群落类型,植物种分布格局的主要因素是海拔梯度,即水、热两个环境因子。（3）DCCA排序图明显反映出排序轴的生态意义,第一轴基本上突出反映了各植物群落所在环境的海拔梯度,即热量因素,沿第一轴从左到右,海拔逐渐升高,植物群落或植物种对热量要求降低;第二轴主要表现了各植物群落或植物种所在环境的坡度,坡向,即水分和光照因素,沿第二轴从下到上,坡度渐缓,坡向渐向阳。     

秦岭中段松栎混交林群落数量分类与排序

依据陕西省境内秦岭山脉中段设置的34个样地调查资料,从植物物种组成、植物群落与地形因子之间的关系等对该区域松栎混交林群落进行TWINSPAN分类和DCCA排序。结果表明:(1)研究区34个样地共记录维管束植物297种,隶属于77科178属,其中被子植物72科,裸子植物2科,蕨类植物3科;分布较广的植物有:松科、壳斗科、蔷薇科、菊科、禾本科和百合科。(2)TWINSPAN聚类结果将样地群落划分为13个群丛,其中以油松+锐齿槲栎为建群种的群丛最多,占总群丛数量40%,是该区主要的松栎混交林群落类型。(3)样地的DCCA排序结果表明,第一轴明显地反映出群落分布沿海拔、坡位的变化,第二轴主要表现出群落分布沿坡向、坡度的变化趋势;其中海拔、坡度与DCCA一、二轴相关系数分别达到最大值(-0.946 2、-0.795 7),是对该群落分布起决定性作用的因子。(4)研究区主要优势物种的DCCA排序与样地的DCCA排序综合反映出该区松栎混交林群落分布的地形梯度。     

准噶尔盆地典型地段植物群落及其与环境因子的关系

沿88°E线,南北纵穿新疆北部准噶尔盆地,选择环境梯度明显的典型地段,设置33个具有代表性的野外样方,应用TWINSPAN与DCCA分析样方的物种数据和环境数据。研究结果表明:(1)样方TWINSPAN分类结果的第一级分类将分布于流动、半流动沙丘(垄)上的白梭梭群落与固定、半固定沙地上的梭梭群落区分开来,进一步的分类,可将33个样方划分为12个组。35种优势植物种TWINSPAN第1级分类把沙漠内部植物种与外缘物种分开。第2级分类把沙漠内部垄上与垄间植物种以及沙漠外缘旱生、中生和盐生植物种分开。(2)在各种环境因子中,土壤水分与相对高度(或地面活动性)是影响植物群落分布的最主要环境因子,DCCA第一排序轴反映生境水分环境条件,第2轴反映土壤结构梯度的变化。(3)除相对高度(或地面活动性)与土壤水分外,在沙漠南部外缘的山前冲积、洪积扇扇缘,土壤盐分状况亦为植物生长的重要胁迫因子;在沙漠北部外缘的砾石戈壁平原,基质的机械组成对群落分布格局有重要影响;在沙漠内部,土壤质地、地面坡度对植物群落的分布有较大影响。(4)以沙漠为中心的准噶尔盆地地势相对高度与地面活动性、土壤有机质与土壤粘粒、土壤水分与土壤总盐、pH值、有机质、相对高度之间存在显著相关关系。     

亚热带峰丛洼地恢复演替植物群落的数量分类和排序——以广西马山弄拉峰丛洼地为例

采用双向指示种分析法(TWINSPAN)和除趋势对应分析(DCA)对弄拉峰丛洼地恢复演替植物群落进行数量分类和排序。TWINSPAN将20个样方分为10个组,根据植被分类的原则划分为10个群丛,论述了各群丛的群落学特征。20个样方的DCA排序结果反映了恢复演替群落与环境梯度的关系,表明影响群丛分布格局的主导生态因子为恢复时间、人为干扰及露石率。DCA排序将53个种分为4个种组,影响峰丛洼地恢复演替群落及其物种分布格局的主导生态因子为恢复时间、岩性和水分等。各物种在排序轴上的位置反映了种组成员的生态适应性及其在群落中的重要性和更新生态位。     

辽东栎林不同层植物沿海拔梯度分布的DCCA分析

 为研究北京东灵山辽东栎（Quercus liaotungensis）不同层植物的分布与环境因子之间的关系,对东灵山辽东栎林进行了植物群落学调查。沿 海拔梯度在乔木层、灌木层和草本层各调查119个样方,同时调查了每个样方的环境因子如海拔、坡度和坡位。物种数据采用二元属性数据,对 非数值环境因子进行赋值。对东灵山辽东栎林和各环境因子进行去趋势典范对应分析（Detrended canonical correspondence analysis, DCCA）,结果表明：DCCA 第一轴基本上反映了植物群落所处环境的海拔的梯度变化,第二轴基本上反映了坡位的梯度变化。同时发现辽东栎林 大多数植物分布在低海拔区域。乔木层的物种分布比较均匀。草本层的物种分布重叠率是最大的,说明草本植物的生境相似性很高。低海拔区 域的生物多样性要高于高海拔区域的生物多样性。结合环境因子间的相关关系和DCCA排序结果,发现海拔是影响东灵山辽东栎林物种分布的主 要环境因子。     

Effects of grazing and cultivation on forest plant communities in Mount Elgon National Park, Uganda

Plant communities in the montane forest of Mount Elgon National Park were studied in order to assess the impact of grazing and cultivation on species composition. Present and former land uses, tree, shrub and herb species, soil properties and the percentage cover and height of trees, shrubs and herbs were determined in 40 plots. An indirect ordination of these plots showed that species composition was primarily determined by successional stage and agricultural disturbance. In forest plots (ordinated separately) where the widest range of former and current grazing intensities had occurred, evidence of grazing history, soil phosphorus and vegetation height correlated negatively with the strongest ordination axis. Least grazed forest plots had fewer tree seedlings and saplings than more intensively grazed plots. This may be due to the increase in Mimulopsis alpina (Acanthaceae) in less grazed forest where tree regeneration might otherwise be more advanced. Tree seedlings and saplings were uncommon in the forest, rarely exceeding 30cm in height and there was no tree understorey. Although grazing is important for preserving species diversity in Mount Elgon National Park through the maintenance of species-rich grasslands, long-term effects on montane forest communities must be considered in future park management.     

河北小五台山国家级自然保护区森林群落与环境的关系

植物与环境之间的关系是一个复杂的演变过程,运用数量生态学方法探讨森林群落的物种组成、种群的生态特征、不同植物群落与环境之间的关系,有助于保护该区森林群落的稳定性和生物多样性。根据148个森林群落样方数据,选用双向指示种分析(TWINSPAN)和典范对应分析(CCA)方法,对河北小五台山国家级自然保护区森林群落进行分类和排序研究。结果表明:(1)TWINSPAN将该区的森林群落分为20个类型;(2)CCA排序结果较好地反映出群落分布格局与环境梯度的关系,各个森林群落类型在前两轴分异明显,在11个环境因子中,海拔、坡位、凋落层厚度、土壤导电率、土壤温度、土壤湿度、土壤厚度和干扰程度这8个环境因子对森林群落的分布起较大的作用,影响森林群落的分布格局,形成不同的植被类型。(3)乔木层优势种的CCA二维排序图所揭示的环境梯度与群落类型的分布有很大的相似性;t值双序图阐明了海拔、凋落层厚度、土壤温度、干扰程度等环境因子对森林群落乔木层优势种有着重要影响。采用TWINSPAN分类与CCA排序的方法,较好地解释了森林群落与环境因子的关系,为小五台山地区森林生态系统的科学管理和保护提供了理论依据,研究结果也为同类地区森林生态系统研究及保护提供参考和借鉴。     

Vegetation recovery and plant facilitation in a human-disturbed lava field in a megacity: searching tools for ecosystem restoration

Unplanned urban development threatens natural ecosystems. Assessing ecosystem recovery after anthropogenic disturbances and identifying plant species that may facilitate vegetation regeneration are critical for the conservation of biodiversity and ecosystem services in urban areas. At the periphery of Mexico City, illegal human settlements produced different levels of disturbance on natural plant communities developed on a lava field near the Ajusco mountain range. We assessed natural regeneration of plant communities 20 years after the abandonment of the settlements, in sites that received low (manual harvesting of non-timber forest products), medium (removal of aboveground vegetation), and high (removal of substrate and whole vegetation) disturbance levels. We also tested the potential facilitative role played by dominant tree and shrub species. Plant diversity and vegetation biomass decreased as disturbance level increased. Sites with high disturbance level showed poor regeneration and the lowest species similarity compared to the least disturbed sites. Six dominant species (i.e., those with the highest abundance, frequency, and/or basal area) were common to all sites. Among them, three species (the tree Buddleja cordata, and two shrubs, Ageratina glabrata and Sedum oxypetalum) were identified as potential facilitators of community regeneration, because plant density and species richness were significantly higher under their canopies than at open sites. We propose that analyzing community structural traits of the successional vegetation (such as species diversity and biomass) and identifying potential facilitator species are useful steps in assessing the recovery ability of plant communities to anthropogenic disturbances, and in designing restoration strategies.     

Vegetation patterns and ecological factors in the Ili River Valley,Xinjiang, China

The Ili River Valley is located in western Xinjiang as a ‘wet island’ in an arid region, and is rich with unique plant species. In this paper, TWINSPAN (two‐way indicator species analysis) and DCCA (detrended canonical correspondence analysis) were performed to analyze the vegetation patterns and influential factors based on data from a field investigation in the mountainous region of the valley. 259 species were recorded in the 85 plots, up to 235 species all appeared in the herb layer, and species of woody plants were very limited. The species composition varied widely between the northern slope and the southern slope. 35 plots on the northern slope were clustered into 10 groups, and 50 plots on the southern slope were clustered into 11 groupes. The DCCA ordination indicated that elevation as a compound factor was the critical driver of species composition on both the slopes. The vegetation patterns were also related to slope gradient, aspect, soil water, soil pH, organic matter and total nitrogen. Available phosphorus and available potassium were important factors on the southern slope only, maybe because of the appearance of shrubs there. The proportion of variation explained was 49.54% on the northern slope and 41.08% on the southern slope. Edaphic variables were more important than topographical variables on the northern slope, while topographical variables seemed to be more influential on the southern slope.     

安太堡矿区人工植被在恢复过程中的生态关系

采用TWINSPAN、DCA和DCCA,从植物种、植物群落与环境因子关系方面对平朔安太堡矿区的人工植被在恢复过程中的生态关系进行了研究.结果表明,将63个样方划分为12个群落类型,反映了植物群落与环境梯度之间的关系,并列举了各群落的特征.DCA排序图明显反映出排序轴的生态意义,随着复垦时间的增加,土壤含水量也不断升高.DCCA排序进一步表明了土壤有机质含量是所有因子中对植物群落发展起决定性作用的主要环境因素.     

桂西北喀斯特人为干扰区植被自然恢复22年后群落特征

采用全面调查和样方调查的方法，以坡面为尺度，以顶极群落为对照，运用干扰理论和多样性分析方法，研究了桂西北喀斯特4类典型干扰区自然恢复22a之后植被特征及空间分布的变化。结果表明，干扰区的物种多样性丧失严重，共出现维管束植物91科206属241种，仅有自然保护区的26．6％，6种植被类型的顺向演替系列为石漠化稀疏草丛→草丛→灌丛→藤刺灌丛→落叶阔叶林→常绿落叶阔叶混交林片段。随着坡位的上升，群落的高度、盖度、生物量和物种多样性急剧下降。密度则呈少、多、次少的单峰分布状态，各项指标均远低于自然保护区。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，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。此外还针对性地提出了桂西北喀斯特干扰区在不同立地类型上人工与自然相结合的4条植被恢复途径。对因各种人为干扰导致的桂西北喀斯特生态系统处于极度退化状态下的植被恢复建设和生态重建具有重要的理论价值和实际意义。     

Changes in vegetation after 22 years'' natural restoration in the Karst disturbed area in northwestern Guangxi, China

Variations of plant vegetation and spatial distribution were investigated in the areas of 4 types of typical disturbance, which had been under natural restoration for 22 years in the Karst area in northwestern Guangxi while the climax plant community was utilized as control. The slope scale and disturbance theory were used to study the plant diversity in the whole area and selected plots. It is clear that the disturbance had resulted in severe loss of plant species, and only 241 species of vascular plants that belong to 91 families and 206 genera survived in disturbed areas, accounting only for 26.6% of those in the natural reserve area. The consequent succession of 6 types of plant vegetation was sparse grass of rocky desertification, grass, shrub, liana-shrub, deciduous broad-leaved forest and mixed segment of evergreen and deciduous broad-leaved forest. The height, coverage, biomass and species diversity of plants decreased sharply with slope elevating, and the plant density appeared with normal distribution. Compared with the natural reserve area, all indices of plant vegetation in disturbed areas were much worse. Furthermore, different types of disturbance showed various affections on natural vegetative restoration, among which tilling after the whole slope was set on fire caused the worst impact and rocky desertification was the consequence, followed by depasturing after the whole slope was set on fire. Cutting was selective disturbance, and the vegetative restoration in the area with combination of cutting, grazing and setting on fire on the upper slope was relatively fast; however, it was even better in the area with combination of cutting and setting the upper slope on fire. In our studies, 4 strategies for vegetative recovery, using both natural and artificial approaches, were established, which were suitable for the Karst area in northwestern Guangxi.     

Woody plant communities of isolated Afromontane cloud forests in Taita Hills,Kenya

In the Taita Hills in southern Kenya, remnants of the original Afromontane forest vegetation are restricted to isolated mountain peaks. To assess the level of degradation and the need for forest restoration, we examined how forest plant communities and their indicator species vary between and within remnant patches of cloud forest. We used ordinal abundance data to compare plant communities in eight forest fragments. We also analyzed data on the diversity and abundance of trees in 57 0.1 ha plots to compare tree communities within and between the largest two of these fragments, Ngangao (120 ha) and Mbololo (220 ha). The extant vegetation of the Taita Hills at landscape scale consists of secondary moist montane to intermediate montane forest. There was a high species dissimilarity between fragments (69%). Variation in species composition coincided with an abiotic gradient related to elevation. At plot level, secondary successional species and species of forest edges were most abundant and most frequent. Inferred clusters of plots almost entirely coincided with the two forest fragments. Indicator species associated with forest margins and gaps were more frequent in the smaller of the two forest fragments, while indicators for the larger fragment were more typical for less disturbed moist forest. Abiotic site variability but also different levels of disturbance determine site-specific variants of the montane forest. Conservation efforts should not only focus on maintaining forest quantity (size), but also on forest quality (species composition). Late-successional rainforest species are underrepresented in the woody plant communities of the Taita Hills and assisting restoration of viable populations of cloud forest climax tree species is urgently needed.