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.     

植被(植物群落)稳定性研究评述

稳定性是植物群落结构与功能的一个综合特征。本文对影响植被稳定性的主要干扰因索、群落多样性(复杂性)与稳定性的关系、植被稳定性的判定与测度指标、稳定性的机制等方面的研究进展进行了阐述。指出应加强干扰对植被稳定性影响及提高干旱区人工植被稳定性的技术措施的的研究,以指导自然植被的保护利用和人工植被的建设,对植被稳定性机制的认识需要从植物群落内部的生物学生态学过程方面进行深入研究。     

种子大小及其命运对植被更新贡献研究进展

种子是种子植物的繁殖体.种子对后代的资源投入将会直接影响后代的适合度进而影响到植被群落的更新.一般较大种子物种在种子萌发和幼苗生长阶段是具有较大优势的;但较小种子物种在逃避被动物采食和形成持久的土壤种子库成为植被更新的后备动力方面具有较大的优势.在不同的选择压力下,不同大小种子在以后的生活史中具有不同的命运,对植被的更新也具有不同的贡献.本文主要从种子大小和种子的传播散布、种子萌发、种子存活以及种子土壤库等方面综述了国外关于种子大小及其以后命运对植被更新贡献的研究结果,并对国内的相关研究提出了一些建议：种子生态学研究需要结合群落特点以及微环境等,开展从种子生产到幼苗更新全过程的系统性研究,为植物物种多样性保育和退化植被恢复方面提出有科学依据的管理措施.     

林窗干扰与森林群落演替

林窗干扰是影响森林群落演替的一个重要因素。该文从林窗干扰和森林群落演替理论及林窗对森林群落微环境、植物入侵和定居、群落结构、群落演替的影响等方面简要介绍了当前国内外有关林窗干扰与森林群落演替的研究现状和研究前景。     

四川峨眉山珙桐群落的初步研究

本文通过对峨眉山珙桐群落分布、生境条件、区系组成、群落外貌和结构等方面的分析,认为该群落的性质是一种典型的中亚热带中山山地常绿、落叶阔叶混交林植被;适宜分布于温暖、潮湿、雨量充沛、云雾多、日照少、山势陡峻、沟谷切割很深的地段;群落中植物种类丰富,区系组成复杂,古老植物较多,从区系地理成分的分析反映出该区域植被具有中国—日本植物区系的基本特征。 该群落的自然更新是通过种子繁殖和萌蘖等方式的互补来实现,从而使其成为较稳定的群落。但目前该群落正遭到较严重的破坏,应采取人工辅助更新等切实措施加以保护。     

干旱区荒漠景观的植被自然更新机制初探

根据实地调在和参阅资料．依山前洪积扇、河流沿岸阶地、沙丘及丘间低地、戈壁、盐沼的景观斑块,初步探讨干旱区植被的自然更新机制。干旱区的高温干燥、温差强烈、风蚀沙埋已成为植物繁衍后代的动力;萌蘖、劈裂、地下茎萌生等多种繁殖方式．使荒漠植物在严酷的条件下实现自然更新,形成以母株为中心的母系居群。地貌形态和种子传播动力决定了群落外形。在干旱区,以种子繁殖的植物之种子成熟期与年内的丰水期相吻合,有利于植被更新．只有在连续2年降水较大时（超过多年平均降水量）,沙丘和丘间地,戈壁植被的自然更新才可能发生;河流沿岸植被的自然更新受地下水影响最明显;湖盆盐碱地植被带有水生植被的痕迹,自然更新相对较难;景观斑块镶嵌分布．形成微环境均异的廊道．有利于植被的自然更新。     

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。     

鸟类栖木在森林植被恢复中的生态意义

鸟类传播种子对于植物种群自然更新及群落演替具有重要的生态意义,鸟类栖息的树木具有富集种子雨功能,在山体滑坡区及废弃矿区等干扰生境中人工设置鸟类栖木,可以增加鸟类传播的种子雨输入,丰富土壤种子库,尤其食果鸟类可以传播那些处于群落演替中期至后期的乔、灌木树种,能够促进受干扰地区森林植被的演替进程.5·12汶川大地震对地震灾区造成了大面积的山体滑坡和严重的植被破坏,在地震灾区森林植被的生态恢复工作中,一些地区可以采用人工设置鸟类栖木方法,充分利用山体滑坡区周围残余森林的丰富种子源及众多食果鸟类,促进灾区森林植被的自然恢复.     

植被群落特征对城市生态系统服务的影响研究进展

生态空间（林地、灌木、草地、水体）所产生的生态系统服务极大的改善了人类的生存环境，在城市绿地破碎化日益严重、绿地质量逐渐降低、乡土植物逐渐减少、入侵风险逐渐加剧等生态背景下，如何维持稳定而持续增长的城市生态系统服务供给，一直困扰着当下从事城市生态学领域研究的学者和城市管理者。植被群落作为城市绿地系统的基本组成单元，在绿地破碎化趋势下，可作为研究内容来探讨城市生态系统服务维持或提升策略；植被群落泛指城市中常见的、具有明显边界的、按照一定分布规则的植物群落单元，既包括道路绿地、居住区绿地、公园绿地等，也包括城市郊野自然林地。但对植被群落生态功能的研究也多停留在对某一生态问题的简单相关性研究，缺乏系统性和整体性。从微观层面的植被群落角度，整合相关文献研究，介绍了受植被群落特征影响的6种典型城市生态系统服务，综述了植被群落特征对这6种城市生态系统服务的影响机理，对植被群落特征因子进行总结、归类，从树种特性、垂直结构、水平结构、其他4个角度构建了"植被群落特征因子对城市生态系统服务影响关系表"。最后面向典型生态系统服务提升提出了城市低质量植被群落地区的营建和更新原则，以期为今后城市园林部门、规划部门制定城市绿地系统规划提供基础性技术支撑。     

塔克拉玛干沙漠南缘自然植被的水分状况及其恢复

塔克拉玛干沙漠南缘 (以下简称塔南 )是我国土地沙漠化最严重的地区之一 ,其主要原因是因为塔南绿洲边缘的自然植被遭到严重破坏。自然植被的恢复有赖于对主要植被类型生物学特性的了解 ,于 1 998～2 0 0 1年在位于塔南策勒绿洲边缘进行的中国 -欧盟合作研究项目 ( ERBIC1 8CT980 2 75 ) ,目的是探索塔南绿洲边缘自然植被可持续管理的生态学基础。通过对几种优势植物叶片 (或同化枝 )水分关系、气体交换、以及群落特性等方面的综合研究 ,得出了以下结论 :( 1 )塔南绿洲边缘的自然植被皆为隐域性植被 ,主要优势种为 :胡杨、柽柳、骆驼刺以及少量的灰杨 ,这种植物是依靠河流的地表水而发生 ,依靠河流地下水补给而生存 ;( 2 )由于缺乏充分的地表水的补给 ,现存的自然植被几乎不能实现自然更新 ;完全破坏后的自然植被已无自然恢复的可能性 ,必须使用人工辅助方法进行恢复 ;( 3)塔南绿洲边缘主要优势植物叶片 (或同化枝 )清晨水势和气体交换研究结果表明 ,依赖地下水生存的几种植物在整个生长季节没有发生严重的水分胁迫 ,保护和恢复绿洲边缘自然植被的必要条件是保持地下水位的相对稳定 ,禁止对地下水的过度开采。     

苔藓植物对植物天然更新的影响

种子是天然更新的基础,幼苗和幼树的生长是天然更新过程中最敏感的阶段。苔藓植物作为许多生态系统的主要地被物,在维管植物天然更新过程中发挥着不容忽视的作用。在许多植被类型中,都有发育良好的苔藓群落,大量的研究证明它们的存在影响到维管植物的萌发、建成和生长,并且可能进一步影响到物种的共生,有一些种类甚至可能指示树种的更新。本文就苔藓植物对物种更新早期阶段的作用和影响进行了综述。包括苔藓植物的生理特性造成的微气候变化;苔藓群落对种子传播、萌发及幼苗建成的影响。并讨论了苔藓植物与更新物种的种间关系及其对幼苗生长的化感作用。     

木本植物萌枝生态学研究进展

综述了萌枝的生物学特征、个体生活史策略、生物地理学特征,以及对种群和群落特征的影响.已有的研究虽然在干扰与萌枝关系、萌枝生活史策略等领域取得了众多成果,但生态学意义远未揭示清楚,尤其是萌枝对种群、群落结构和动态的影响还需要深入探索.我国在重视萌枝生态理论研究的基础上,应加强理论和植被恢复及生态系统管理实践相结合的研究.     

Is long‐term protection useful for the regeneration of disturbed plant communities in dry areas?

In dry areas, natural plant communities are mainly affected by climatic stress and human disturbances – overgrazing, ploughing and biomass harvesting – that accelerate their degradation. Management techniques, including creation of national parks (fencing), are needed to conserve natural resources/biodiversity. The long‐term effects of protection on the plant communities should be monitored. This study assessed the results of long‐term protection on the composition and diversity of the natural plant communities of Sidi Toui National Park (southern Tunisia) using the point‐quadrat method and ecological indicators of the ecosystem structure. Comparison of these indicators for the period 1990–2011 inside (fenced) and outside (disturbed) the Park showed that regeneration of natural vegetation increased during the first decade of the fencing period (1990–2001), but declined during the period (2008–2011). After a long period of fencing, plant tufts were bigger and aged, and the ecosystem dynamics decreased. In the absence of animal activities, the hardpan at the soil surface impedes seedling emergence. This suggests that long‐term fencing is not recommended for conserving floral diversity in dryland ecosystems. To ensure and maintain the regeneration of these ecosystems, fencing periods alternating with controlled grazing (by introducing wild herbivores) are recommended.     

草地生态学领域空斑研究进展

空斑(gap)是近几十年来草地生态学领域的重点研究对象之一,在草地植被更新、群落结构和草地生态系统物种多样性维持方面起着重要作用。本文在介绍空斑的概念、功能分类和形成的基础上,总结分析了国内外对空斑的研究现状,发现目前对草地空斑的研究主要集中在空斑大小、空斑类型对物种更新以及空斑对群落结构和物种多样性影响等方面,而对空斑小环境和土壤的研究较少,对空斑内生理生态学、机理和机制性的问题尚缺乏深入探讨;建议在今后加强对空斑内环境变化、空斑内物种的生理生态学特性和物种对空斑更新的响应机制等方面的研究。     

The disturbance and vegetation dynamics: a review and an alternative framework

Disturbances are common phenomena that occurs in nature and significantly affects the dynamics of vegetation and plant populations. This paper shows that despite considerable progress in the theory of disturbances, for different authors the notion of disturbance has different meanings. The differences follow from an alternative understanding of the term, assumption of the holistic or reductionistic concept of the study or different approaches to equilibrium and non-equilibrium in nature. Different theoretical and methodological assumptions taken when analysing vegetation changes under the effect of disturbances allow relative arbitrariness in the interpretation of results. However, not all biotic interactions and ecological processes taking place in plant communities can be identified as disturbances. The effects of disturbances should be described on the basis of an objective assessment of what is normal for the functioning and stabilisation of a community as well as what disturbs and disrupts this equilibrium. Moreover, assuming the equivalent treatment of ecological systems, the interaction of the disturbing factors should be related to a specific level of life organisation (an individual, population or community), which would permit unambiguous discernment of the disturbance effects and finally generalise its effects on different levels of the hierarchical structure of vegetation.     

Response of two oligohaline marsh communities to lethal and nonlethal disturbance

Severity is recognized as an important attribute of disturbance in many plant communities. However, the effects of disturbances of different severity on patterns of regeneration in oligohaline marsh vegetation have not been experimentally examined. In these communities, a critical difference in the effects of disturbance severity may be whether the vegetation dies as a result of the disturbance or is merely damaged and hence capable of resprouting. We described the regeneration of vegetation in two Louisiana marsh community types, one dominated by Sagittaria lancifolia L. and the other by Spartina patens (Ait.) Muhl., following three levels of disturbance: no disturbance, a nonlethal disturbance, and a lethal disturbance. In the nonlethal disturbance, aboveground vegetation was clipped to simulate common disturbances such as fire and herbivory that remove aboveground vegetation but leave rhizomes intact. In the lethal disturbance vegetation was killed using herbicide to simulate disturbances causing plant mortality such as wrack deposition, sedimentation, scouring, and flooding following fire or herbivory. Regeneration was assessed over a 2-year period by measuring plant species richness, relative abundance, relative dominance, cover, and final biomass. To elucidate mechanisms for observed responses of vegetation, the species composition of the seed bank, light penetration, water level, salinity, and soil redox potential were evaluated. Despite differences in the structure of undisturbed vegetation in the two community types, they exhibited the same overall pattern of regeneration. Following nonlethal disturbance, the dominant species resprouted and quickly reestablished the structure of the vegetation. In contrast, recolonization following lethal disturbance occurred primarily via seedling recruitment, which resulted in marked shifts in community structure that persisted throughout the study. While the two communities responded similarly overall to disturbance, the response of individual species was not uniform; abundance, dominance, biomass, or cover increased for some species but decreased for others in response to disturbance. Seed bank species occurred in the vegetation following lethal disturbance in the Spartina community and in both disturbed and undisturbed plots in the Sagittaria community, indicating that the seed bank is a source of propagules for regeneration and maintenance of oligohaline marshes. Of the environmental variables measured, light level was most closely related to the effect of disturbance severity on community structure. Our results suggest that lethal and nonlethal disturbances have differential effects on regeneration of vegetation that can create pattern in oligohaline marshes communities. Received: 29 September 1997 / Accepted: 12 May 1998     

亚高山森林生态系统过程研究进展

亚高山森林是以冷、云杉属为建群种或优势种的暗针叶林为主体的森林植被。亚高山森林在庇护邻近脆弱生态系统、保育生物多样性、涵养水源、碳吸存和指示全球气候变化等方面具有十分重要且不可替代的作用和地位,其多样化的植被和土壤组合为研究生态系统过程提供了天然的实验室。亚高山森林的群落演替与更新、生物多样性保育、水文生态过程、生物元素的生物地球化学循环以及亚高山森林生态过程对气候变化的响应等研究已取得了明显的进展。但有关全球变化条件下的亚高山森林土壤生物多样性和冬季生态学过程等研究明显不足。全球气候变化背景下的冬季生态学过程、极端灾害事件对亚高山森林生态系统过程的影响、亚高山森林生物多样性的保育机制、亚高山森林土壤生物多样性与生态系统过程的耦合机制等可能是未来研究的前沿科学问题。     

Are plant functional types relevant to describe degradation in arid,southern Tunisian steppes?

Abstract. In the Tunisian arid zone disturbances (e.g. overgrazing and agriculture) and stresses (e.g. aridity, low fertility) drive changes in the structure and functioning of rangelands, with a decrease in perennial plant cover, changes in floristic composition and erosion. Long‐term monitoring requires (1) an understanding of the dynamics of vegetation change and associated ecological processes and (2) identification of relevant indicators. Using data from the arid zone of southern Tunisia we tested the hypothesis that plant functional response types could be used to address these two goals. We identified plant functional response types in response to a gradient of soil and vegetation types characterized by changes in perennial plant cover, dominant species and associated soil types. Vegetation samples were stratified by contrasted vegetation patch types with varying perennial plant cover (1.6 to 22%). We focused our analysis of trait responses within dwarf–shrubs, which are the dominants in typical steppe ecosystems of south Tunisia. Available trait data concerned morphology (plant height, leaf type), regeneration (dispersal mode, phenology and regeneration mode) and grazing value. Although we found it difficult to recognize ‘indicator response types’ that could be used directly to monitor changes in community composition, we were able to identify plant response syndromes that are relevant to long‐term vegetation changes, and in particular degradation processes, in the region. Two main response types were identified: the decreaser type, made up of small or medium chamaephytes with high grazing palatability and the increaser type with medium to tall chamaephytes and low grazing palatability. These response types are proposed as key elements in a state‐and‐transition model of vegetation dynamics in the context of agropastoral disturbances and climatic and edaphic stresses.     

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.