河岸带生态系统植被与土壤对水文变化的响应研究进展

河岸带的植被与土壤是生态系统重要组成部分,对于维持河岸带的生态健康、生态系统服务与可持续性具有至关重要的作用。水文变化是河岸带生态系统的首要干扰因子,系统总结了水文变化对河岸带植被的特征以及植被形态、群落分布、繁殖、生存策略的影响,并阐述了河岸带水文和植被对土壤氮磷迁移转化的影响机制。根系作为土壤与植物地上部分之间物质、能量流动与信号传导的关键纽带,目前对根系的研究还较欠缺,需要加强水文变化对河岸带湿地植物根系形态、结构、功能特征的影响机理研究,以及湿地植物对水文变化的适应机制和耐受阈值方面的探究。在微观方面,应加强水文变化与植被等多因素耦合对土壤氮磷迁移转化过程的机理研究。河流形态和土壤的多样性决定着河岸带水文作用特征的复杂性,今后需注重河岸带个性特征与水文响应的关系研究。河岸带是横向的水陆生态过渡带和河流上下游的纵向生态廊道,亟需综合考虑和模拟流域土壤、植被与水文、人类活动之间的耦合关系,预测未来气候与社会经济情境下的河岸带生态系统演变规律,为河岸带生态系统的生态调节、生物多样性保护与生态恢复等提供理论依据与技术支撑。     

图们江流域河流生态系统健康评价

河流是重要的自然生态系统,也是重要的生态廊道之一,图们江流域河流生态系统的健康状况,对维护跨国界流域的水环境的管理和可持续发展有着重要的意义。基于河流水文、河流形态、河岸带状况、水体理化参数以及河流生物5个层面选取22个指标构建了图们江流域河流生态系统健康评价指标体系,运用层次分析法和加权平均法对其进行了健康评价。评价结果表明,虽然该地区处于"健康"级别,但也有28%的地区处于"亚健康"状态。河流健康综合指数(RHI`)与河流生物指标、水体理化指标、河流形态指标、河岸带指标等4项呈显著相关(P0.05),相关系数依次为0.847、0,757、0.740、0.547。研究结果表明图们江流域水生生物的生存环境遭到严重破坏、水体污染严重,河岸带生态退化、城市化影响严重等一系列影响河流健康的问题。     

河岸带研究及其退化生态系统的恢复与重建

河岸带是指水陆交界处的两边,直至河水影响消失为止的地带。河岸带是湿地的重要组成部分,在流域生态系统中发挥着重要的作用,具有较大的生态、社会、经济和旅游价值。河岸带研究以生态学、水文学和地貌学炎基础,涉及多种学科和技术方法。由于自然和人为因素的影响,退化河岸带的生态恢复与重建较为复杂,通过安徽潜山县潜水退化河岸带滩地近6a的生态恢复与重建试验,研究结果表明：恢复与重建后的河岸带滩地生态系统的生物多样性和稳定性增加;土训结构和养分条件得到改善,其中,小于0.002mm的粘粒含量的平均值由恢复前的4.53％,上升到恢复后的11.71％,土壤容重由恢复前的1.455g/cm^2下降到恢复后的1.2g/cm^2,土壤有机质的平均值由恢复前的1.25g/kg上升到恢复后的9.44g/kg;河滩地泥沙淤积量增加;植物抗风浪作用增强,有效地保护了河岸,改善了河岸带地区的小气候。河岸带研究在我国起步较晚,因此,今后应加强河岸带的管理和对退化河岸带生态系统的恢复与重建工作,使河岸带生态系统可持续地为人类提供丰富多样的生产、生活和观光旅游产品。     

流域径流泥沙对多尺度植被变化响应研究进展

植被变化与流域水文过程构成一个反馈调节系统,是目前生态水文学研究的重点对象.由于植被自身的生长发育以及受自然因素和人为干扰的作用,植被变化具有多尺度性;由于受流域水文环境的异质性和水文通量的变化性的影响,流域水文过程也同样具有多尺度性.因此,只有通过对不同尺度生态水文过程分析,才能揭示流域径流泥沙对植被变化的响应机理.从不同时空尺度回顾了植被生长、植被演替、植被分布格局变化、造林以及森林经营措施等对流域径流泥沙影响的主要研究成果;概括了目前研究采用的3种主要方法,即植被变化对坡面水流动力学影响的实验室模拟、坡面尺度和流域尺度野外对比观测实验以及水文生态模型模拟方法;分析了植被变化与径流泥沙响应研究要考虑的尺度问题,从小区尺度上推至流域尺度或区域尺度时应考虑不同的生物物理控制过程.研究认为,要确切理解植被与径流泥沙在不同时空尺度的相互作用,必须以等级生态系统的观点为基础,有效结合生态水文与景观生态的理论,从地质-生态-水文构成的反馈调节入手,系统地理解植被变化与径流泥沙等水分养分之间的联系及反馈机制,建立尺度转换的基础.同时,作为有效的研究工具,今后水文模型的发展应更加注重耦合植被生理生态过程以及景观生态过程,从流域径流泥沙对多尺度植被变化水文响应的过程与机制入手,为植被恢复与重建、改善流域水资源状况和流域生态环境奠定基础.     

广西桂林漓江河岸带植被配置类型与退化机制研究

河岸带植被结构与组成等配置状况直接影响其稳定河岸、净化水质、生物多样性、生物栖息地以及旅游景观等重要功能。查明漓江河岸带主要植被配置类型及其各自退化表现、原因与恢复途径, 是开展河岸带退化植被恢复的基础与前提。该研究通过野外实地调查与测量, 对漓江桂林-阳朔河段 51 个河岸带断面的地形、土壤、植被等进行了系统调查, 分析了河岸带植被退化的主要表现、主导干扰因素, 并通过流域与河岸带尺度综合的角度 , 提出了漓江河岸带植被恢复的思路。从岸坡地形与植被组合出发, 按照自然、近自然、人工等干扰程度 , 广西漓江河岸带可划分为江心洲宽滩地疏林灌草自然型、丘陵陡坡林灌草自然型、平原农田缓坡灌草近自然型、平原滩地林草近自然型、聚落阶地疏灌林草人工-自然混合型、城镇岸坡林草人工型等 6 种典型植被配置模式。漓江河岸带植被退化主要表现为多样性差、景观破碎、生态功能弱 , 而城镇、交通、旅游等不合理开发建设是主导性的干扰因素。从生态稳定和景观美观的角度 , 提出了漓江河岸带植被恢复与优化的思路, 以期为广西漓江河岸带生态修复提供科学依据。     

基于多水文改变指标评价东江流域河流流态变化及其对生物多样性的影响

新丰江、枫树坝和白盆珠3座大型水库的建立对东江流域河道流量和河流流态过程有了较大改变,威胁河道下游生态系统的健康。基于广义指标生态剩余和生态赤字评价了东江流域受水库影响后流域生态需水需求目标总的盈余和缺失变化过程,基于IHA32指标计算的Do和DHRAM评价了水库对下游河段河流水文过程总的改变程度以及威胁河道生态系统健康的风险性大小,并进一步分析了对河道生物多样性的影响。研究结果如下:(1)水库对流量历时曲线(FDC)有显著影响,曲线上部下降,尾部上升,尤其体现在秋季和冬季。降水对年与夏季生态剩余影响较大,水库对各季节生态剩余和生态赤字均有较大影响:秋季和冬季生态赤字几乎为0,生态剩余显著增加。生态剩余和生态赤字与大部分IHA中32个指标具有很强的相关性,可作为衡量东江流域年和季节径流变化的生态指标。(2)龙川、河源、岭下和博罗4站点总体改变程度分别为58.48%、54.04%、54.32%和52.47%。河流流态变化导致总季节生态剩余增加并维持在较高水平,进一步引起河流生物多样性下降,并维持在较低水平。龙川和河源两站河流流态的变化对河流生态系统造成了高风险性影响,岭下和博罗两站则为中等风险。     

南亚热带退化生态系统恢复和重建的生态学理论和应用

退化生态系统的恢复与重建是一项十分复杂的系统工程,其功能和动态过程涉及物质、能量、空间、时间和多样性等基本的生态变量。在南亚热带的气候生态因子中,既有光、温、水充裕的有利一面,也有秋旱、台风和暴雨等不利的因素,但总的来说,影响退化生态系统恢复的主导生态因子是土壤因子,如土壤肥力和土壤水份。极度退化的生态系统的恢复与重建,第一步就是控制水土流失,提高土壤肥力和土壤理化结构,这还需要工程措施和生物措施相结合．退化生态系统的植被的恢复与重建,最有效和最省力的是顺从生态系统的演替发展规律来进行,生态系统演替理论是指导退化生态系统重建的重要的理论基础．退化生态系统恢复与重建的优化结构的构建,依赖于对空间、生物、能量生态学原理的理解。种群密度制约、种群空间分布格局、边缘效应、生态位分化、食物链、生物多样性等原理均对生态系统结构的构建有指导意义．而生态系统的群体发展,则受物质定律的影响．     

梯级开发对河流生态系统和景观影响研究进展

作为水资源和水能开发利用的主要方式,河流梯级开发在满足国民经济各部门对河流水资源开发的要求和推动流域社会经济持续发展的同时,也对整个流域生态系统产生了不可避免的人为影响.本文根据河流梯级开发的过程和流域生态系统的特征,分别综述了梯级开发对坝址区生态系统、流域库区小气候、河岸带生态系统、水生态系统、河流湿地和流域景观生态的主要影响,并提出了研究展望,如加强梯级开发对各生态因子影响后的连锁反应和累积效应研究;在水库群运行和联合调度时期,应加强正负生态效应综合影响作用的研究以及不同时空尺度条件下对流域生态系统演替发展和稳定等方面的研究.     

长江流域生态系统水文调节服务空间特征及影响因素:基于子流域尺度分析

水文调节服务是流域生态系统所提供的重要服务之一,认识流域生态系统水文调节服务空间变异规律及其驱动力,对于流域生态系统保护与恢复、合理开发利用水资源具有重要意义。以洪涝灾害频发的长江流域为对象,运用变异系数法和多元统计方法,在子流域尺度上研究了长江流域生态系统水文调节服务空间特征及影响因素。结果表明,长江流域子流域生态系统水文调节服务呈现出明显的空间异质性,水利工程密集、自然植被覆盖率高达71%的金沙江和汉江水系各子流域水文调节服务最强,降雨与径流变异系数差为0.477;农田和人口密集的嘉陵江水系各子流域水文调节服务最弱,降雨与径流变异系数差为-0.474,其他子流域水文调节服务作用不明显。影响水文调节服务的主要因素是:水库库容、自然植被面积比例、农田面积比例、单位面积人口数,其中:水库库容和自然植被面积比例对水文调节服务具有正向促进作用,农田面积比例和单位面积人口对水文调节服务的作用正好相反。水库库容对子流域生态系统水文调节服务空间异质性的贡献最大(58.85%)。上述结果有助于科学认识长江流域生态系统水文调节服务空间分异规律,可为制定不同子流域生态保护与恢复措施、提升子流域生态系统水文调节服务提供科学依据。     

强度干扰后退化森林生态系统中保留木的生态效应研究综述

保留木是指森林生态系统受到强度干扰后所存留的树木,保留木对退化森林生态系统结构与功能的维持和恢复具有多方面的生态效应。在生态系统的尺度上总结了退化森林生态系统中保留木的各种生态效应,主要包括保留木对非生物因子和生物因子(附生生物多样性、动物活动和动物多样性、树木更新、空间结构)的影响。森林生态系统经营中,"绿树保留"的经营方式是基于保留木生态效益的实践应用,它可有效减少采伐对生态系统结构和功能所造成的损失。并将有助于深入理解受到强度干扰后森林生态系统中保留木的多种生态效应,可为退化森林生态系统的恢复与重建提供理论依据。     

Riparian Restoration in the Western United States: Oveview and Perspecive

This historical and conceptual overview of riparian ecosystem restoration discusses how riparian ecosystems have been defined, describes the hydrologic, geomorphic, and biotic processes that create and maintain riparian ecosystems of the western USA, identifies the main types of anthropogenic desturbances occurring in these ecosystems, and provides an overview of restoration methods for each disturbance type. We suggest that riparian ecosystems consist of two zones: Zone I occupies the active floodplain and is frequently inundated and Zone II extends from the active floodplain to the valley wall. Successful restoration depends n understanding the physical and biological processes that influence natural riparian ecosystems and the types of disturbance that have degraded riparian areas. Thus we recommend adopting a process-based approach for riparian restoration. Disturbances to riparian ecosystems in the western USA result from streamflow modifications by dams, reservoirs, and diversions; stream channelization; direct modification of the riparian ecosystem; and watershed disturbances. Four topics should be addressed to advance the state of science for restoration of riparian ecosys-tems: (1) interdisciplinary approaches, (2) a unified framework, (3) a better understanding of fundamental riparian ecosystem processes, and (4) restoration po-tential more closely related to disturbance type. Three issues should be considered regarding the cause of the degraded environment: (1) the location of the causative disturbance with respect to the degraded riparian area, (2) whether the disturbance is ongoing or can be elim-inated, and (3) whether or not recovery will occur nat-urally if the disturbance is removed.     

Restoration and management of riparian ecosystems: a catchment perspective

1. We propose that strategies for the management of riparian ecosystems should incorporate concepts of landscape ecology and contemporary principles of restoration and conservation. A detailed understanding of the temporal and spatial dynamics of the catchment landscape (e.g. changes in the connectivity and functions of channel, riparian and terrestrial components) is critical. 2. This perspective is based upon previous definitions of riparian ecosystems, consideration of functional attributes at different spatial scales and retrospective analyses of anthropogenic influences on river catchments. 3. Restoration strategies must derive from a concise definition of the processes to be restored and conserved, recognition of social values and commitments, quantification of ecological circumstances and the quality of background information and determination of alternatives. 4. The basic components of an effective restoration project include: clear objectives (ecological and physical), baseline data and historical information (e.g. the hydrogeomorphic setting and the disturbance regime), a project design that recognizes functional attributes of biotic refugia, a comparison of plans and outcomes with reference ecosystems; a commitment to long-term planning, implementation and monitoring and, finally, a willingness to learn from both successes and failures. 5. Particularly important is a thorough understanding of past natural disturbances and human-induced changes on riparian functions and attributes, obtained by a historical reconstruction of the catchment.     

Resilience,Restoration, and Riparian Ecosystems: Case Study of a Dryland,Urban River

Resilient systems can absorb disturbance and persist despite variability as long as the capacity of the system to adapt is not exceeded. Riparian plant communities of dryland alluvial rivers are expected to be naturally resilient systems because they persist in the highly variable floodplain. River modification has altered the flow regime on many dryland rivers, in some cases exceeding the adaptive capacity of the riparian vegetation, but these changes may be readily reversible. The Salt River in Phoenix, Arizona has been impounded, dewatered, channelized, but also re‐watered with urban effluent and storm drain runoff. To determine whether riparian vegetation is resilient to these various perturbations, paired comparisons were made in the vegetation and seed bank between a non‐diverted reference reach, a diverted reach, and a re‐watered urban reach. In the diverted reach, composition had shifted to that of a stress tolerant xeroriparian shrubland with low diversity in both the seed bank and extant vegetation. Most surprisingly, few differences were observed in the composition and structure of the vegetation and soil seed banks between the reference reach and the urban reach, particularly in the wet patches, suggesting that hydric riparian plant communities have the capacity to adapt to these modified conditions. These results provide support for a process‐oriented approach to restoration on the Salt River and other urban dryland rivers using patches of persisting vegetation as models for achievable restoration targets.     

Multiscale Patterns of Riparian Plant Diversity and Implications for Restoration

Planning riparian restoration to resemble historic reference conditions requires an understanding of both local and regional patterns of plant species diversity. Thus, understanding species distributions at multiple spatial scales is essential to improve restoration planting success, to enhance long‐term ecosystem functioning, and to match restoration planting designs with historic biogeographic distributions. To inform restoration planning, we examined the biogeographic patterns of riparian plant diversity at local and regional scales within a major western U.S.A. drainage, California's Sacramento—San Joaquin Valley. We analyzed patterns of species richness and complementarity (β‐diversity) across two scales: the watershed scale and the floodplain scale. At the watershed scale, spatial patterns of native riparian richness were driven by herbaceous species, whereas woody species were largely cosmopolitan across the nearly 38,000 km² study area. At the floodplain scale, riparian floras reflected species richness and dissimilarity patterns related to hydrological and disturbance‐driven successional sequences. These findings reinforce the importance of concurrently evaluating both local and regional processes that promote species diversity and distribution of native riparian flora. Furthermore, as restoration activities become more prevalent across the landscape, strategies for restoration outcomes should emulate the patterns of species diversity and biogeographic distributions found at regional scales.     

深圳市植被受损分级评价及其与景观可达性的关系

植被受损评价及其受损成因分析是快速城市化地区生态保护和管理工作的重要基础研究课题。以深圳市2007年航空影像数据、2007年IRS卫星数据以及1 ∶ 10万电子地形图为基础数据,建立植被受损以及人为活动强度空间特征的表征方式,通过叠图分析及统计分析建立两者之间的响应关系,用以揭示人为活动对植被的影响程度及方式。进行了深圳市植被受损情况分级评价和景观可达性分级评价;然后通过两种分级评价结果的Pearson相关性分析和叠图统计分析,解析植被受损与景观可达性空间分异特征之间的关系。研究结果表明,深圳市人为干扰表现为人造纯林和生态风景林的营建、果园的种植以及极端机械干扰3种类型,受损程度可以分成6级。景观可达性能够定量化描述人为活动强度的空间分异特征,全区可达性程度可以分成5级。叠图分析结果显示,景观可达性水平与植被受损程度之间为正相关关系,相关系数为0.794。利用本研究方法还可以有效解析植被受损程度与人为活动空间分异特征之间的关联细节。     

Disturbances and species distribution of the riparian vegetation of a Rift Valley stream

The Njoro River riparian vegetation species composition, distribution, disturbances and uses are presented and discussed. Montane Juniperus procera-Olea europaea spp. africana and submontane Acacia abyssinica forests were identified as the main riparian vegetation groups. Approximately 55% of the riparian vegetation species are used for herbal medicine, treating more than 330 health problems, and only 11% of the plants are edible. Albizzia gummifera in the Syzygium cordatum-Pittosporum abyssinicum-Hibiscus diversifolius forest is cut selectively for herbal medicine preparations. Disturbances on the riparian vegetation zone are broadly classified as those induced by man, livestock and wildlife. Comprehensive effects of disturbance included loss of vegetation vertical strata, increase/decrease of species diversity, introduction of alien plant species, and reduction of plant sizes and vegetation hectarage. The effects of grazing on the vegetation were severe around livestock watering points. Grazing and browsing by wildlife were the main disturbances of the vegetation near the Njoro River estuary at the Lake Nakuru National Park. Periodic flooding, as a natural disturbance, regulates growth and survival of vegetation at the Lake Nakuru drawdown. Quantification of species diversity and the extent of disturbance by humans and livestock is important for future management of the vegetation and, consequently, the river.     

Development of Vegetation and Aquatic Habitat in Restored Riparian Sites of California's North Coast Rangelands

The preponderance of short‐term objectives and lack of systematic monitoring of restoration projects limits opportunities to learn from past experience and improve future restoration efforts. We conducted a retrospective, cross‐sectional survey of 89 riparian revegetation sites and 13 nonrestored sites. We evaluated 36 restoration metrics at each site and used project age (0–39 years) to quantify plant community and aquatic habitat trajectories with a maximum likelihood model selection approach to compare linear and polynomial relationships. We found significant correlations with project age for 16 of 21 riparian vegetation, and 11 of 15 aquatic habitat attributes. Our results indicated improvements in multiple ecosystem services and watershed functions such as diversity, sedimentation, carbon sequestration, and available habitat. Ten riparian vegetation metrics, including native tree and exotic shrub density, increased nonlinearly with project age, while litter and native shrub density increased linearly. Species richness and cover of annual plants declined over time. Improvements in aquatic habitat metrics, such as increasing pool depth and decreasing bankfull width‐to‐depth ratio, indicated potentially improved anadromous fish habitats at restored sites. We hypothesize that certain instream metrics did not improve because of spatial and/or temporal limitations of riparian vegetation to affect aquatic habitat. Restoration managers should be prepared to maintain or enhance understory diversity by controlling exotic shrubs or planting shade‐tolerant native species as much as 10 years after revegetation.     

Effects of Stream Restoration on Woody Riparian Vegetation of Southern Appalachian Mountain Streams,North Carolina,U.S.A

Riparian revegetation, such as planting woody seedlings or live stakes, is a nearly ubiquitous component of stream restoration projects in the United States. Though evaluations of restoration success usually focus on in‐stream ecosystems, in order to understand the full impacts of restoration the effects on riparian ecosystems themselves must be considered. We examined the effects of stream restoration revegetation measures on riparian ecosystems of headwater mountain streams in forested watersheds by comparing riparian vegetation structure and composition at reference, restored, and degraded sites on nine streams. According to mixed model analysis of variance (ANOVA), there was a significant effect of site treatment on riparian species richness, basal area, and canopy cover, but no effect on stem density. Vegetation characteristics at restored sites differed from those of reference sites according to all metrics (i.e. basal area, canopy cover, and species composition) except species richness and stem density. Restored and degraded sites were structurally similar, with some overlap in species composition. Restored sites were dominated by Salix sericea and Cornus amomum (species commonly planted for revegetation) and a suite of disturbance‐adapted species also dominant at degraded sites. Differences between reference and restored sites might be due to the young age of restored sites (average 4 years since restoration), to reassembly of degraded site species composition at restored sites, or to the creation of a novel anthropogenic ecosystem on these headwater streams. Additional research is needed to determine if this anthropogenic riparian community type persists as a resilient novel ecosystem and provides valued riparian functions.