Success of Active Revegetation after Tamarix Removal in Riparian Ecosystems of the Southwestern United States: A Quantitative Assessment of Past Restoration Projects

Invasion by the non‐native tree Tamarix has led to implementation of restoration projects aimed at maintaining the ecological integrity of many riparian communities in the southwestern United States. These restoration efforts may include Tamarix removal, manipulation of hydrologic regimes, and active revegetation of native species. The goal of this study was to determine which site characteristics are correlated with restoration success, defined in terms of reductions of undesirable species such as Tamarix and establishment of desirable, native species. To accomplish this, vegetative and environmental data were collected at 28 sites in the southwestern United States where active revegetation was completed after Tamarix removal. These data were incorporated into regression tree models with predictor variables that included number of years since removal (1–18 years) and multiple management, climate, soils, and hydrological variables to determine success of Tamarix control, revegetation success, and general plant community responses. Our results suggest that there are easily measurable site characteristics that are associated with greater native cover and richness, planting success, and Tamarix control. Close proximity to perennial water, sufficient precipitation, recent flooding, and good drainage as well as coarser soil texture, and lower soil pH all favored native species. Overall, those site characteristics associated with native species success were the same as those related to lower Tamarix cover. These quantitative models are intended to assist researchers and land managers to design more effective riparian restoration efforts in this critical arid lands ecosystem.     

A functional trait perspective on plant invasion

Background and Aims

Global environmental change will affect non-native plant invasions, with profound potential impacts on native plant populations, communities and ecosystems. In this context, we review plant functional traits, particularly those that drive invader abundance (invasiveness) and impacts, as well as the integration of these traits across multiple ecological scales, and as a basis for restoration and management.

Scope

We review the concepts and terminology surrounding functional traits and how functional traits influence processes at the individual level. We explore how phenotypic plasticity may lead to rapid evolution of novel traits facilitating invasiveness in changing environments and then ‘scale up’ to evaluate the relative importance of demographic traits and their links to invasion rates. We then suggest a functional trait framework for assessing per capita effects and, ultimately, impacts of invasive plants on plant communities and ecosystems. Lastly, we focus on the role of functional trait-based approaches in invasive species management and restoration in the context of rapid, global environmental change.

Conclusions

To understand how the abundance and impacts of invasive plants will respond to rapid environmental changes it is essential to link trait-based responses of invaders to changes in community and ecosystem properties. To do so requires a comprehensive effort that considers dynamic environmental controls and a targeted approach to understand key functional traits driving both invader abundance and impacts. If we are to predict future invasions, manage those at hand and use restoration technology to mitigate invasive species impacts, future research must focus on functional traits that promote invasiveness and invader impacts under changing conditions, and integrate major factors driving invasions from individual to ecosystem levels.     

Riparian Butterfly (Papilionoidea and Hesperioidea) Assemblages Associated with Tamarix-Dominated, Native Vegetation–Dominated, and Tamarix Removal Sites along the Arkansas River, Colorado, U.S.A.

We studied butterfly assemblages at eight riparian sites over five years. Sites included Tamarix spp.–dominated riparian areas; sites where mechanical means or biological control agents (Diorhabda elongata deserticola) were used to limit Tamarix; sites that were mixtures of native woody vegetation (e.g., Populus and Salix) and Tamarix; and native vegetation sites. We identified a gradient in butterfly community composition that changed from treated Tamarix sites, through mixed vegetation, to native vegetation sites. Tamarix sites had lower butterfly metric (riparian butterfly index [RBI]) values than did native vegetation sites. The RBI is based on a combination of richness measures and the presence of specific species and groups of butterflies. There was no significant change in the RBI over sampling periods at any sites, including both Tamarix eradication sites. The RBI at sites where Tamarix control took place did not approach restoration goals based on values at unimpacted sites. Positive effects on riparian butterfly assemblages were not linked to any Tamarix control efforts, nor did we detect a decline from initial butterfly metrics at Tamarix sites. Direct ordination provided information on environmental variables, such as amount of nectar and herbaceous plant richness, which may be important in riparian restoration efforts.     

植物功能性状、功能多样性与生态系统功能: 进展与展望

植物功能性状与生态系统功能是生态学研究的一个重要领域和热点问题。开展植物功能性状与生态系统功能的研究不仅有助于人类更好地应对全球变化情景下生物多样性丧失的生态学后果,而且能为生态恢复实践提供理论基础。近二十年来,该领域的研究迅速发展,并取得了一系列的重要研究成果,增强了人们对植物功能性状-生态系统功能关系的认识和理解。本文首先明确了植物功能性状的概念, 评述了近年来植物功能性状-生态系统功能关系领域的重要研究结果, 尤其是植物功能性状多样性-生态系统功能关系研究现状; 提出了未来植物功能性状与生态系统功能关系研究中应加强植物地上和地下性状之间关系及其与生态系统功能、植物功能性状与生态系统多功能性、不同时空尺度上植物功能性状与生态系统功能, 以及全球变化和消费者的影响等方面。     

利用农业生物多样性持续控制有害生物

农业生物多样性对保障全球粮食安全和农业可持续发展至关重要.人类在多样性的形成上发挥了关键作用,人类结合自然进化创造了遗传多样性、物种多样性和生态系统多样性.农业生物多样性发挥了很多社会经济和环境功能:保障粮食安全;维持农业生态系统可持续发展;赋予农村经济适变性.但当前人类毁灭农业生物多样性的速度更为惊人.在总结石油农业单一化种植的生态负效应、传统农业提倡“天人合一”的生态正效应的基础上,分析讨论了利用农业生物多样性持续控制有害生物的必要性和可行性,从生态系统多样性、物种多样性和种内遗传多样性3个层次,归纳了构建和恢复农田生物多样性的基本方法.基于病理学、生态学、营养学和生理学等学科领域,从群体异质效应、稀释效应、微生态效应、诱导抗性效应、物理阻隔效应、生理学效应和化感效应等7个方面,归纳了利用农业生物多样性持续控制有害生物的基础原理.寻求低投入、高效益、多样化和可持续的农业生产系统是当今世界许多科学家、决策者和生产者共同关心的问题.农业生物多样性具有重要的生态作用,在现代农业框架下,是合情合理构建持续、稳定、健康、高产的农田生态系统,持续控制有害生物的金钥匙.为此必须加强四方面的课题研究:各种作物之间的相生相克关系及其作用机理;各种有害生物的主要天敌种类、生物学、生态学特性及其适生环境;利用农业生物多样性全面、持续控制有害生物的农业生产模式;与其相配套的农艺措施与农业机械.     

基于植物多样性的生态系统恢复动力学原理

生态系统恢复动力学是生态学的重要问题.本研究利用岛屿生物地理学、植物群落演替、生物多样性维持机制及生态系统功能等有关理论,推导了生态系统恢复动力学模型,并用半湿润常绿阔叶林次生演替阶段数据作了初步验证.基于动力学模型讨论了动力学原理.结果表明,生态系统恢复的动力学过程决定于生态系统恢复力F1、干扰力F2和环境阻力F3的综合作用.植物多样性恢复速度的变率与植物种丰富度呈反比,与生态系统恢复总动力F呈正比.生态系统恢复力F1和环境阻力F3是初始物种丰富度s0、特定地理区域资源环境状况的函数.干扰力是干扰强度系数b和物种丰富度s的函数.当生态系统存在有害干扰的条件下,物种丰富度不能达到生态系统最高物种丰富度sm.动力学模型显示,初始物种丰富度s0越小,生态系统恢复过程越具有逻辑斯蒂性.建立了生态系统恢复力、环境阻力和干扰力的计算模型和植物多样性、干扰对生态系统恢复的作用模型.生态系统恢复动力模型显示,植物多样性能增加生态系统恢复力,促进生态系统稳定性.     

Jump‐starting coastal wetland restoration: a comparison of marsh and mangrove foundation species

During coastal wetland restoration, foundation plant species are critical in creating habitat, modulating ecosystem functions, and supporting ecological communities. Following initial hydrologic restoration, foundation plant species can help stabilize sediments and jump‐start ecosystem development. Different foundation species, however, have different traits and environmental tolerances. To understand how these traits and tolerances impact restoration trajectories, there is a need for comparative studies among foundation species. In subtropical and tropical climates, coastal wetland restoration practitioners can sometimes choose between salt marsh and/or mangrove foundation species. Here, we compared the early life history traits and environmental tolerances of two foundation species: (1) a salt marsh grass (Spartina alterniflora) and (2) a mangrove tree (Avicennia germinans). In an 18‐month study of a recently restored coastal wetland in southeastern Louisiana (USA), we examined growth and survival along an elevation gradient and compared expansion and recruitment rates. We found that the rapid growth, expansion, and recruitment rates of the salt marsh grass make it a better species for quickly establishing ecological structure at suitable elevations. The slower growth, limited expansion, and lower recruitment of the mangrove species show its restricted capacity for immediate structural restoration, especially in areas where it co‐occurs with perennial salt marsh species. Our findings suggest that the structural attributes needed in recently restored areas can be achieved sooner using fast‐growing foundation species. Following salt marsh grass establishment, mangroves can then be used to further assist ecosystem development. This work highlights how appropriate foundation species can help jump‐start ecosystem development to meet restoration objectives.     

Inoculation with native soil improves seedling survival and reduces non-native reinvasion in a grassland restoration

Losses of grasslands have been largely attributed to widespread land-use changes, such as conversion to row-crop agriculture. The remaining tallgrass prairie faces further losses due to biological invasions by non-native plant species, often with resultant ecosystem degradation. Of critical concern for conservation, restoration of native grasslands has been met with little success following eradication of non-native plants. In addition to the direct and indirect effects of non-native invasive plants on beneficial soil microbes, management practices targeting invasive species may also negatively affect subsequent restoration efforts. To assess mechanisms limiting germination and survival of native species and to improve native species establishment, we established six replicate plots of each of the following four treatments: (1) inoculated with freshly collected prairie soil with native seeds; (2) inoculated with steam-pasteurized soil with native seeds; (3) noninoculated with native seeds; or (4) noninoculated/nonseeded control. Inoculation with whole soil did not improve seed germination; however, addition of whole soil significantly improved native species survival, compared to pasteurized soil or noninoculated treatments. Inoculation with whole soil significantly decreased reestablishment of non-native invasive Bothriochloa bladhii (Caucasian bluestem); at the end of the growing season, plots receiving whole soil consisted of approximately 30% B. bladhii cover, compared to approximately 80% in plots receiving no soil inoculum. Our results suggest invasion and eradication efforts negatively affect arbuscular mycorrhizal hyphal and spore abundances and soil aggregate stability, and inoculation with locally adapted soil microbial communities can improve metrics of restoration success, including plant species richness and diversity, while decreasing reinvasion by non-native species.     

Resilience and restoration of tropical and subtropical grasslands,savannas, and grassy woodlands

Despite growing recognition of the conservation values of grassy biomes, our understanding of how to maintain and restore biodiverse tropical grasslands (including savannas and open‐canopy grassy woodlands) remains limited. To incorporate grasslands into large‐scale restoration efforts, we synthesised existing ecological knowledge of tropical grassland resilience and approaches to plant community restoration. Tropical grassland plant communities are resilient to, and often dependent on, the endogenous disturbances with which they evolved – frequent fires and native megafaunal herbivory. In stark contrast, tropical grasslands are extremely vulnerable to human‐caused exogenous disturbances, particularly those that alter soils and destroy belowground biomass (e.g. tillage agriculture, surface mining); tropical grassland restoration after severe soil disturbances is expensive and rarely achieves management targets. Where grasslands have been degraded by altered disturbance regimes (e.g. fire exclusion), exotic plant invasions, or afforestation, restoration efforts can recreate vegetation structure (i.e. historical tree density and herbaceous ground cover), but species‐diverse plant communities, including endemic species, are slow to recover. Complicating plant‐community restoration efforts, many tropical grassland species, particularly those that invest in underground storage organs, are difficult to propagate and re‐establish. To guide restoration decisions, we draw on the old‐growth grassland concept, the novel ecosystem concept, and theory regarding tree cover along resource gradients in savannas to propose a conceptual framework that classifies tropical grasslands into three broad ecosystem states. These states are: (1) old‐growth grasslands (i.e. ancient, biodiverse grassy ecosystems), where management should focus on the maintenance of disturbance regimes; (2) hybrid grasslands, where restoration should emphasise a return towards the old‐growth state; and (3) novel ecosystems, where the magnitude of environmental change (i.e. a shift to an alternative ecosystem state) or the socioecological context preclude a return to historical conditions.     

Public Values for River Restoration Options on the Middle Rio Grande

River restoration is a widespread phenomenon. This reflects strong public values for conservation, though missing are studies explicitly justifying restoration expenditures. Public restoration benefits are not well quantified, nor are public preferences among diverse activities falling into the broad category “restoration.” Our study estimates public values for restoration on the Middle Rio Grande, New Mexico. Stakeholder meetings and public focus groups guided development of a restoration survey mailed to Albuquerque area households. Four restoration categories were defined: fish and wildlife; vegetation density; tree type; and natural river processes. Survey responses supplied data for both choice experiment (CE) and contingent valuation (CV) analyses, two established environmental economics techniques for quantifying public benefits of conservation policies. Full restoration benefits are estimated at over $150 per household per year via the CE and at nearly $50 per household per year via CV. The CE allows value disaggregation among different restoration categories. The most highly valued category was tree type, meaning reestablishing native tree dominance for such species as Cottonwood (Populus deltoides) and eradicating non‐native trees such as Saltcedar (Tamarix ramosissma). The high public values we have found for restoration offer economic justification for intensive riparian management, particularly native plant‐based restoration in the Southwest.     

Ecological restoration of rich fens in Europe and North America: from trial and error to an evidence‐based approach

Fens represent a large array of ecosystem services, including the highest biodiversity found among wetlands, hydrological services, water purification and carbon sequestration. Land‐use change and drainage has severely damaged or annihilated these services in many parts of North America and Europe; restoration plans are urgently needed at the landscape level. We review the major constraints on the restoration of rich fens and fen water bodies in agricultural areas in Europe and disturbed landscapes in North America: (i) habitat quality problems: drought, eutrophication, acidification, and toxicity, and (ii) recolonization problems: species pools, ecosystem fragmentation and connectivity, genetic variability, and invasive species; and here provide possible solutions. We discuss both positive and negative consequences of restoration measures, and their causes. The restoration of wetland ecosystem functioning and services has, for a long time, been based on a trial‐and‐error approach. By presenting research and practice on the restoration of rich fen ecosystems within agricultural areas, we demonstrate the importance of biogeochemical and ecological knowledge at different spatial scales for the management and restoration of biodiversity, water quality, carbon sequestration and other ecosystem services, especially in a changing climate. We define target processes that enable scientists, nature managers, water managers and policy makers to choose between different measures and to predict restoration prospects for different types of deteriorated fens and their starting conditions.     

演替理论与植被恢复

《昆明-蒙特利尔全球生物多样性框架》提出要高质量保护和恢复各30%的土地,最大化地实现保护生物多样性和缓解气候变化的目标,而演替理论和植被恢复可以为实现30%的保护和恢复目标服务。演替理论是植被生态学中的核心理论,演替是指在一个地点上由一群不同物种组成的生命体的结构或组成随时间而变化的过程; 植被恢复是以植物种植、配置为主,恢复或重建植物群落或天然更新恢复植物群落的过程,植被恢复是生态系统结构和功能从简单到复杂、从低级向高级变化的过程,最终目的是建立健康稳定的植物群落。演替是植被恢复的基础,植被恢复被视为对演替过程的操纵,以达到恢复受损植被生态系统的目标。演替理论可以指导植被恢复,而植被恢复对演替理论的发展有益。演替按裸地性质可以分为原生演替和次生演替,有研究建议将恢复过程视为第三演替,这将有助于理解通过人为干预促进植被恢复成功的管理选择,特别是通过强调退化生态系统中的环境和生物遗存的管理选择。此外,该文还提出了植被恢复理论和演替理论未来可能重点关注的科学和技术问题。     

A potential novel source of information for screening and monitoring the impact of exotic plants on ecosystems

Exotic invasive species often affect the pools and fluxes of carbon, nutrient elements, and energy, but there are few sources of information that permit these effects to be anticipated. Some plant traits, such as growth rates and tissue nutrient content, are known to influence the ecosystem process, but information about these traits is often not available. I propose that plant secondary chemistry may be a useful trait for assessing the likelihood of ecosystem (and community) impacts. Information about such traits is readily available from several sources, rendering it a good candidate for screening and monitoring programs. Plant secondary chemicals affect a variety of ecosystem processes, largely through their direct and indirect impacts on soil microbial community composition and function. They also have well-known effects on human physiology, as evidenced in the numerous plant-derived bioactive compounds used for their medicinal and other physiological effects. There is a large amount of information available about plant secondary chemistry due to its role in herbal medicine, dietary supplements and the emerging field of nutraceuticals. This information includes databases and traditional texts in ethnobotany, plant chemistry, and alternative medicine. I review evidence that secondary compounds are widespread in invasive species and affect soil microbial communities and microbially-mediated ecosystem processes. Invasion ecology may profit from collaborations with a novel group of scientists, including those in ethnobotany, nutraceuticals, plant chemistry and alternative medicine.     

Planning Riparian Restoration in the Context of Tamarix Control in Western North America

Throughout the world, the condition of many riparian ecosystems has declined due to numerous factors, including encroachment of non‐native species. In the western United States, millions of dollars are spent annually to control invasions of Tamarix spp., introduced small trees or shrubs from Eurasia that have colonized bottomland ecosystems along many rivers. Resource managers seek to control Tamarix in attempts to meet various objectives, such as increasing water yield and improving wildlife habitat. Often, riparian restoration is an implicit goal, but there has been little emphasis on a process or principles to effectively plan restoration activities, and many Tamarix removal projects are unsuccessful at restoring native vegetation. We propose and summarize the key steps in a planning process aimed at developing effective restoration projects in Tamarix‐dominated areas. We discuss in greater detail the biotic and abiotic factors central to the evaluation of potential restoration sites and summarize information about plant communities likely to replace Tamarix under various conditions. Although many projects begin with implementation, which includes the actual removal of Tamarix, we stress the importance of pre‐project planning that includes: (1) clearly identifying project goals; (2) developing realistic project objectives based on a detailed evaluation of site conditions; (3) prioritizing and selecting Tamarix control sites with the best chance of ecological recovery; and (4) developing a detailed tactical plan before Tamarix is removed. After removal, monitoring and maintenance as part of an adaptive management approach are crucial for evaluating project success and determining the most effective methods for restoring these challenging sites.     

Ecological Restoration Treatments Increase Butterfly Richness and Abundance: Mechanisms of Response

Few ecosystem restoration studies evaluate whether arthropods are important components of ecosystem recovery. We tested the hypothesis that ponderosa pine restoration treatments would increase adult butterfly species richness and abundance as a direct result of increased understory diversity and abundance. To examine mechanisms that potentially affect adult butterfly distribution, we quantified host plant frequency, nectar plant abundance, and insolation (light intensity) in restoration treatment and control forests. This study is unique, because this is the first invertebrate monitoring in ponderosa pine forest restoration treatments in the U.S. Southwest and also because these treatments are the first replicated ponderosa pine restoration treatments at a landscape scale. Three patterns emerged: (1) butterfly species richness and abundance were 2 and 3 times greater, respectively, in restoration treatment units than in paired control forests 1 year after treatment, and 1.5 and 3.5 times greater, respectively, 2 years after treatment, ordination of control and treatment sampling units using butterfly assemblages showed significant separation of control and restoration treatment units after restoration treatment; (2) host plant and nectar plant species richness showed little difference between treated and control forests even 2 years after treatment; and (3) insolation (light intensity) was significantly greater in treated forests after restoration. We suggest that changes in the butterfly assemblage may occur due to light intensity effects before plant community changes occur or can be detected. Butterfly assemblage differences will have additional cascading effects on the ecosystem as prey for higher trophic levels and through plant interactions including herbivory and pollination.     

Phytometers are underutilised for evaluating ecological restoration

Ecological restoration increases, but evaluation of restoration efforts is inadequate because reliable performance indicators are lacking. As plants are important actors in ecological restoration, we suggest that they be used as metres, i.e. phytometers, of restoration success. Phytometer plants are transplanted to different conditions to integrate measures of the prevailing conditions. We analysed 109 studies for the use of phytometers and especially their applicability to evaluate ecological restoration. Most studies employed single species and life-stages and focused on habitat conditions and environmental impacts. Most experiments were conducted on grasslands in moist temperate regions. Growth was the dominant response variable, in long-term studies often combined with reproductive output and plant survival. Only five studies specifically evaluated ecological restoration, implying that its potential is not yet realised. We found phytometers promising in evaluating restoration outcomes given that they are easy to measure, can provide rapid results, and serve as integrative indicators of environmental conditions with the ability of covering many aspects of plant life and ecosystem processes. To evaluate restoration success with high resolution and generality, we suggest a combination of different phytometer species, life-forms and life-stages, and experimental periods >1 year to reduce effects of transplantation and between-year variation and to account for time lags in ecological processes and changes after restoration.     

Integrating trait‐based empirical and modeling research to improve ecological restoration

A global ecological restoration agenda has led to ambitious programs in environmental policy to mitigate declines in biodiversity and ecosystem services. Current restoration programs can incompletely return desired ecosystem service levels, while resilience of restored ecosystems to future threats is unknown. It is therefore essential to advance understanding and better utilize knowledge from ecological literature in restoration approaches. We identified an incomplete linkage between global change ecology, ecosystem function research, and restoration ecology. This gap impedes a full understanding of the interactive effects of changing environmental factors on the long‐term provision of ecosystem functions and a quantification of trade‐offs and synergies among multiple services. Approaches that account for the effects of multiple changing factors on the composition of plant traits and their direct and indirect impact on the provision of ecosystem functions and services can close this gap. However, studies on this multilayered relationship are currently missing. We therefore propose an integrated restoration agenda complementing trait‐based empirical studies with simulation modeling. We introduce an ongoing case study to demonstrate how this framework could allow systematic assessment of the impacts of interacting environmental factors on long‐term service provisioning. Our proposed agenda will benefit restoration programs by suggesting plant species compositions with specific traits that maximize the supply of multiple ecosystem services in the long term. Once the suggested compositions have been implemented in actual restoration projects, these assemblages should be monitored to assess whether they are resilient as well as to improve model parameterization. Additionally, the integration of empirical and simulation modeling research can improve global outcomes by raising the awareness of which restoration goals can be achieved, due to the quantification of trade‐offs and synergies among ecosystem services under a wide range of environmental conditions.     

Informing management decisions for ecological networks,using dynamic models calibrated to noisy time‐series data

Well‐intentioned environmental management can backfire, causing unforeseen damage. To avoid this, managers and ecologists seek accurate predictions of the ecosystem‐wide impacts of interventions, given small and imprecise datasets, which is an incredibly difficult task. We generated and analysed thousands of ecosystem population time series to investigate whether fitted models can aid decision‐makers to select interventions. Using these time‐series data (sparse and noisy datasets drawn from deterministic Lotka‐Volterra systems with two to nine species, of known network structure), dynamic model forecasts of whether a species’ future population will be positively or negatively affected by rapid eradication of another species were correct > 70% of the time. Although 70% correct classifications is only slightly better than an uninformative prediction (50%), this classification accuracy can be feasibly improved by increasing monitoring accuracy and frequency. Our findings suggest that models may not need to produce well‐constrained predictions before they can inform decisions that improve environmental outcomes.     

Deploying microbes as drivers and indicators in ecological restoration

Ecosystem degradation is a major environmental threat. Beyond conservation, restoration of degraded ecosystems is a prerequisite to reinstate their ability to provide essential services and benefits. Most of the restoration efforts focus on aboveground restoration, that is, plants, under the assumption that establishment of plant species will reestablish the faunal and microbial species. While this may be true for some cases, it is not a general rule. Reestablishment of microbial communities by dedicated efforts is also necessary for successful restoration, as cycling of essential nutrients for plant growth and decomposition of organic matter is dependent on them. The role of microbial fertilizers and efficient organisms used in agriculture needs to be explored in restoration. Testing of symbiotic interactions between potential plant growth-promoting Rhizobacteria and plants native to a degraded ecosystem can be conducted and utilized for successful establishment of plant species. However, utmost care must be taken while introducing new microbial species or non-native plant species to an area, as they can adversely affect the resident microbial community. Techniques like phospholipid fatty-acid analysis can be used for taxonomic identification of large microbial groups in non-degraded reference ecosystems before introducing microbial species into a degraded ecosystem. For use of microbes in restoration, more studies on microbe-plant interactions need to be conducted. For use of Soil Microbial Community (SMC) as indicators of restoration, their role and function in the ecology of the area need to be elucidated by employing all the available techniques.     

湖泊水位变动对水生植被的影响机理及其调控方法

水位的高低及其变动范围、频率、发生的时间、持续的时长和规律性等是影响湖泊水生植被的核心因子.水位变动有短期、年内季节性和年际变动3种,对湖泊水生植被有不同的影响机理.水位短期变动通过对水体中的悬浮物、透明度、光衰减系数等的影响而对水生植被产生作用;周期性的年内季节性和年际水位变动可对水生植被的生态适宜性产生影响,并进而改变其时空分布;长期的高水位和低水位以及非周期性的水位季节变动会破坏水生植被长期以来对水位周期性变化所产生的适应性,从而影响了植被的正常生长、繁衍和演替.植被的极端深度和物种多样性是水位调控的核心表征指标,可通过经验数据分析法、生态模型法和参照法等方法来确定湖泊的适宜水位变动范围和时间.研究对象选择、研究方法、管理中的应用以及重要环境变化所产生的影响等是今后相关研究的核心问题.