The restoration of biodiversity: where has research been and where does it need to go?

The practice of ecological restoration is a primary option for increasing levels of biodiversity by modifying human-altered ecosystems. The scientific discipline of restoration ecology provides conceptual guidance and tests of restoration strategies, with the ultimate goal of predictive landscape restoration. I construct a conceptual model for restoration of biodiversity, based on site-level (e.g., biotic and abiotic) conditions, landscape (e.g, interpatch connectivity and patch geometry), and historical factors (e.g., species arrival order and land-use legacies). I then ask how well restoration ecology has addressed the various components of this model. During the past decade, restoration research has focused largely on how the restoration of site-level factors promotes species diversity-primarily of plants. Relatively little attention has been paid to how landscape or historical factors interplay with restoration, how restoration influences functional and genetic components of biodiversity, or how a suite of less-studied taxa might be restored. I suggest that the high level of variation seen in restoration outcomes might be explained, at least in part, by the contingencies placed on site-level restoration by landscape and historical factors and then present a number of avenues for future research to address these often ignored linkages in the biodiversity restoration model. Such work will require carefully conducted restoration experiments set across multiple sites and many years. It is my hope that by considering how space and time influence restoration, we might move restoration ecology in a direction of stronger prediction, conducted across landscapes, thus providing feasible restoration strategies that work at scales over which biodiversity conservation occurs.     

People as Ecological Participants in Ecological Restoration

In 1987, Bradshaw proposed that ecological restoration is the ultimate “acid test” of our understanding the functioning of ecosystems ( Bradshaw 1987 ). Although this concept is widely supported academically, how it can be applied by restoration practitioners is still unclear. This is an issue not limited to Bradshaw’s acid test, but moreover, reflects a general difficulty associated with the polarization between conceptual restoration (restoration ecology) and practical restoration (ecological restoration), where each has functioned to certain degree in isolation of the other. Outside of the more obvious pragmatic reasons for the relative independence between ecological restoration and restoration ecology, we propose that a more contentious explanation is that the approach taken toward understanding ecosystem development in restoration ecology is tangential to what actually takes place in ecological restoration. Current paradigms assume that the process of ecosystem development in restoration should follow the developmental trajectories suggested by classical ecological succession models. However, unlike these models, ecosystem development in restoration is, at least initially, largely manipulated by people, rather than by abiotic and biotic forces alone. There has been little research undertaken to explore how restoration activities impact upon or add to the extant ecological processes operating within a restoration site. Consequently, ecological restoration may not be so much an acid test of our understanding the functioning of ecosystems, but rather, an acid test of our understanding mutually beneficial interactions between humans and ecosystems.     

The Two-Culture Problem: Ecological Restoration and the Integration of Knowledge

The terms “ecological restoration” and “restoration ecology” are frequently interchanged. Restoration ecology is the suite of scientific practices that constitute an emergent subdiscipline of ecology. Ecological restoration is the ensemble of practices that constitute the entire field of restoration, including restoration ecology as well as the participating human and natural sciences, politics, technologies, economic factors, and cultural dimensions. This paper is motivated by the concern that the broader practice of restoration may become narrowed over the next decade as a result of zealous attention to scientific and technological considerations, and that restoration ecology will trump ecological restoration. Scientific and technological acumen is necessary for successful restoration, but insufficient. Maintaining a broader approach to restoration requires respect for other kinds of knowledge than science, and especially the recognition of a moral center that is beyond the scope of science to address fully. An example of integrated restoration is presented: the ecological and cultural restoration of Discovery Island (near Victoria, British Columbia, Canada) by the Lekwungen people (Songhees First Nation).     

Balancing economic costs and ecological outcomes of passive and active restoration in agricultural landscapes: the case of Brazil

Forest restoration requires strategies such as passive restoration to balance financial investments and ecological outcomes. However, the ecological outcomes of passive restoration are traditionally regarded as uncertain. We evaluated technical and legal strategies for balancing economic costs and ecological outcomes of passive versus active restoration in agricultural landscapes. We focused in the case of Brazil, where we assessed the factors driving the proportion of land allocated to passive and active restoration in 42 programs covering 698,398 hectares of farms in the Atlantic Forest, Atlantic Forest/cerrado ecotone and Amazon; the ecological outcomes of passive and active restoration in 2955 monitoring plots placed in six restoration programs; and the legal framework developed by some Brazilian states to balance the different restoration approaches and comply with legal commitments. Active restoration had the highest proportion of land allocated to it (78.4%), followed by passive (14.2%) and mixed restoration (7.4%). Passive restoration was higher in the Amazon, in silviculture, and when remaining forest cover was over 50 percent. Overall, both restoration approaches showed high levels of variation in the ecological outcomes; nevertheless, passively restored areas had a smaller percentage canopy cover, lower species density, and less shrubs and trees (dbh > 5 cm). The studied legal frameworks considered land abandonment for up to 4 years before deciding on a restoration approach, to favor the use of passive restoration. A better understanding of the biophysical and socioeconomic features of areas targeted for restoration is needed to take a better advantage of their natural regeneration potential.     

A framework for the practical science necessary to restore sustainable,resilient, and biodiverse ecosystems

Demand for restoration of resilient, self‐sustaining, and biodiverse natural ecosystems as a conservation measure is increasing globally; however, restoration efforts frequently fail to meet standards appropriate for this objective. Achieving these standards requires management underpinned by input from diverse scientific disciplines including ecology, biotechnology, engineering, soil science, ecophysiology, and genetics. Despite increasing restoration research activity, a gap between the immediate needs of restoration practitioners and the outputs of restoration science often limits the effectiveness of restoration programs. Regrettably, studies often fail to identify the practical issues most critical for restoration success. We propose that part of this oversight may result from the absence of a considered statement of the necessary practical restoration science questions. Here we develop a comprehensive framework of the research required to bridge this gap and guide effective restoration. We structure questions in five themes: (1) setting targets and planning for success, (2) sourcing biological material, (3) optimizing establishment, (4) facilitating growth and survival, and (5) restoring resilience, sustainability, and landscape integration. This framework will assist restoration practitioners and scientists to identify knowledge gaps and develop strategic research focused on applied outcomes. The breadth of questions highlights the importance of cross‐discipline collaboration among restoration scientists, and while the program is broad, successful restoration projects have typically invested in many or most of these themes. Achieving restoration ecology's goal of averting biodiversity losses is a vast challenge: investment in appropriate science is urgently needed for ecological restoration to fulfill its potential and meet demand as a conservation tool.     

Structural and functional responses of floodplain vegetation to stream ecosystem restoration

Most river restoration projects have applied relatively small-scale measures focused on improving specific instream conditions, with only limited outcomes for biodiversity in rivers and their adjacent riparian habitats. Here, we investigate the effects of both small- and large-scale restoration projects on floodplain vegetation across 20 European catchments. We focused on the roles of different restoration parameters (i.e., the number, spatial extent and type of restoration measure applied and restoration age) and specific environmental characteristics in regulating changes in plant diversity and trait composition following restoration. Among restoration characteristics, restoration type was the only significant determinant of plant community responses, with stream channel widening having the strongest effects, particularly on the diversity and composition of species traits favoured by increases in physical disturbance (e.g. flooding) and open habitat patch availability (e.g. plant growth form, life strategy and life span). Of the environmental variables, altitude and discharge were positively and most strongly related to responses of both species and trait diversity. Our results emphasise the value of (i) choosing relevant restoration measures that affect environmental conditions of importance for the target organism group and (ii) conducting restoration projects in environmental settings where the likelihood of restoration “success” is maximised.     

Science Driven Restoration: A Candle in a Demon Haunted World—Response to Cabin (2007)

Cabin (2007) asks whether formal science is an effective framework and methodology for designing and implementing ecological restoration programs. He argues that beyond certain ancillary benefits, restoration science has little of practical value to offer the practice of restoration. He goes on to suggest that restoration science most often represents an impediment to restoration practice because an “ivory tower” mentality limits the utility of experiments and diverts research dollars away from answering practical questions. His conclusion is that a nonscientific gardening approach may be more effective at restoring degraded ecosystems. We disagree with this perspective because: (1) restoration science has moved beyond exclusively using “square grids” placed on small patches of land to examine treatment effects on species representation; (2) Cabin’s critique greatly undervalues the contribution of science to restoration practice even where the input of restoration scientists is not directly evident; and (3) the practice of restoration is unlikely to advance beyond small‐scale and truly haphazard successes without well‐designed studies that can provide peer‐reviewed and widely accessible published information on the mechanisms underlying both successes and failures. We conclude that through integration with other disciplines, restoration science increasingly will provide novel approaches and tools needed to restore ecosystem composition, structure, and function at stand to landscape scales. As with the broader role of science in the human enterprise ( Sagan 1996 ), the contribution of restoration science to restoration practice can only grow as the discipline matures.     

半干旱黄土小流域不同恢复方式对生态系统多功能性的影响

在黄土高原大规模退耕还林（草）背景下，植被恢复对生态系统功能会产生极大影响。以往研究多为比较不同恢复方式或植被类型的单一生态系统功能，对生态系统多功能性的研究亟待加强。因此，基于甘肃定西龙滩流域3种恢复方式（天然荒草、自然恢复、人工恢复）6种植被类型（长芒草草地、赖草草地、苜蓿草地、柠条灌丛、油松林、山杏林）38个样地调查数据，选取与土壤养分储存与循环、水源涵养、初级生产力、多样性维持等相关的23个功能指标利用平均值法量化生态系统多功能性。研究结果显示，（1）除营养物转化与循环功能外，其余土壤相关的生态系统功能在不同恢复方式与植被类型间均具有显著性差异（P<0.05）。人工恢复植被的土壤肥力显著高于自然恢复植被；人工恢复植被中土壤肥力从高到低依次为柠条灌丛、苜蓿草地、山杏林、油松林。自然恢复植被的水源涵养功能显著高于人工恢复植被。（2）除植物生长策略外，其余植物相关的生态系统功能在不同恢复方式与植被类型间均具有显著性差异（P<0.05）。人工恢复植被中地上初级生产力从高到低依次为山杏林、油松林、柠条灌丛、苜蓿草地，并显著高于自然恢复植被。人工恢复植被中植物养分吸收能力从高到低依次为苜蓿草地、柠条灌丛、油松林、山杏林，并显著高于自然恢复植被。自然恢复植被的物种多样性显著高于人工恢复植被。（3）生态系统多功能性在不同恢复方式与植被类型间均具有显著性差异（P<0.05）。生态系统多功能性表现为人工恢复植被高于自然恢复植被，但人工恢复植被的水源涵养功能与物种多样性均低于自然恢复植被，不利于生态系统的可持续发展。研究认为，在植被恢复具体实践中，应针对不同的恢复目标，根据各植被类型的功能特征，制定因地制宜的植被恢复战略。     

Plant phenological research enhances ecological restoration

While phenology data (the timing of recurring biological events) has been used to explain and predict patterns related to global change, and to address applied environmental issues, it has not been clearly identified as pertinent for restoration. This opinion article thus aims to raise awareness of the potential of phenology to enhance the quality of restoration projects and ecological restoration theory. We based our analysis on a systematic literature survey carried out in February 2014, searching the words “phenology” or “phenological” in books dealing with restoration, the term “phenolog*” in the journal Restoration Ecology, and the terms “restoration” and “phenolog*” in the database Web of Science until February 2014. We finally selected 149 studies relevant to our goals, and first classified them according to the context in which phenology was addressed. We then analyzed them within the framework of the five key steps of restoration projects: (1) the reference ecosystem; (2) biotic resources; (3) restoration methods; (4) monitoring; and (5) adaptive management. The literature survey showed that phenological information improved decision‐making in the few restoration projects in which it was incorporated. We thus advocate taking phenological data into account at all stages of restoration when appropriate: from the acquisition of baseline data on the reference ecosystem to treatment design, and from restoration action planning and timing to monitoring. Phenological data should at minimum be collected for sown, keystone, dominant, and/or rare species to improve restoration quality. Phenology studies and monitoring should be promoted in future restoration guidelines.     

Developing a vision for improved monitoring and reporting of riparian restoration projects

Representatives from agencies involved in natural resource management in the Murray‐Darling Basin gathered for a workshop in November 2010 to develop a vision for improved monitoring and reporting of riparian restoration projects. The resounding message from this workshop was that the effectiveness of riparian restoration depends on having sound, documented and agreed evidence on the ecological responses to restoration efforts. Improving our capacity to manage and restore riparian ecosystems is constrained by (i) a lack of ecological evidence on the effects of restoration efforts, and (ii) short‐termism in commitment to restoration efforts, in funding of monitoring and in expected time spans for ecosystem recovery. Restoration at the effective spatial scope will invariably require a long‐term commitment by researchers, funding agencies, management agencies and landholders. To address the knowledge gaps that constrain riparian restoration in the Basin, participants endorsed four major fields for future research: the importance of landscape context to restoration outcomes; spatio‐temporal scaling of restoration outcomes; functional effects of restoration efforts; and developing informative and effective indicators of restoration. To improve the monitoring and restoration of riparian zones throughout the Basin, participants advocated an integrated approach: a hierarchical adaptive management framework that incorporates long‐term ecological research.     

Myth‐busting tropical grassy biome restoration

The historical focus in research and policy on forest restoration and temperate ecosystems has created misunderstandings for the restoration of tropical and subtropical old‐growth grassy biomes (TGB). Such misconceptions have detrimental consequences for biodiversity, ecosystem services, and human livelihoods in woodlands, savannas, and grasslands worldwide. Here, we demystify TGB restoration myths to promote a positive agenda to increase the likelihood of success of ambitious landscape‐scale restoration goals of nonforest ecosystems. The 10 TGB restoration myths are: (1) grasslands originate from degraded forests, (2) tree cover is a reliable indicator of habitat quality, (3) planting trees is always good for biodiversity and ecosystem services, (4) grasslands are biodiversity‐poor and provide few ecosystem services, (5) enhancing plant nutrition is needed in restoration, (6) disturbance is detrimental, (7) techniques used to restore temperate grasslands also work for TGB, (8) grasslands represent early stages of forest succession, (9) grassland restoration is only about grasses, and (10) grassland restoration is fast. By demystifying TGB restoration, we hope that policymakers, scientists, and restorationists come to understand and embrace the value of these ecosystems and are motivated to establish policies, standards, indicators, and techniques that enhance the success of TGB restoration. We must abandon misperceptions and misunderstandings of TGB ecology that result in ill‐conceived policies and build an informed and compelling global ecosystem restoration agenda that maintains and improves the well‐being of all inhabitants of grassy biomes.     

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.     

Public Perceptions of the Attractiveness of Restored Nature

Ecological restoration efforts often encounter public resistance. Recreational visitors resist imposition of restoration efforts they fear may result in a visually unattractive area. Public support is, however, essential for restoration efforts on public lands. This study seeks insight into hiker perceptions of perceived attractiveness of nature before and after efforts to restore exotic conifer plantations to native communities containing bog and wet forest communities. Visitors (N = 247) to a Dutch National Park sorted 32 photographs depicting landscapes before and after restoration efforts. Findings show that the most attractive landscape types (bog and wet forest communities containing visible water) are results of restoration efforts and the least attractive landscape types (young deciduous and coniferous forest) are representative of traditional nature before restoration. However, the “middle category” consists of landscape types existing both before and after restoration efforts. Visitors value old coniferous and old deciduous forests as much as products of restoration that lack water. These perceptions are unrelated to either visitor characteristics or the provision of information to visitors explaining restoration goals. The continued existence of resistance to restoration strategies despite their effect on perceived landscape attractiveness implies that the experience of nature has more than only visual dimensions. We expect that more acceptable results of restoration efforts will emerge from the active engagement of the public before restoration practices take place in processes that specifically address feelings of attachment and resistance to change.     

Assessing the Evidence Base for Restoration in South Africa

If restoration is to become effective, able to compete for limited funds and truly adaptive, it must become evidence‐based. Three of the conditions essential for the establishment and advancement of evidence‐based restoration are (1) collection of baseline information; (2) setting clearly defined goals; and (3) relevant and adequate monitoring. Using a literature review, complemented with an online survey, we reviewed 10 restoration programs in South Africa to assess whether current restoration practice meets these conditions. The review showed good collection of baseline information and the setting of restoration goals that span ecological and socioeconomic considerations. However, to a large extent goals were poorly defined, there was more monitoring of inputs than outcomes, and monitoring of ecological indicators was inconsistent. These shortcomings can undermine restoration impacts, as well as the future sustainability of these expensive programs. We conclude with recommendations on how to mainstream the requirements of evidence‐based restoration into current and proposed restoration programs.     

Evaluating where and how habitat restoration is undertaken for animals

Habitat restoration is vital to ameliorate the effects of anthropogenic disturbances on animal habitats. We reviewed the peer‐reviewed literature to examine where and how habitat restoration is undertaken. Our aim was to identify key knowledge gaps as well as research and monitoring needs that can inform future restoration actions. We found: (1) marine and terrestrial actions focus most commonly on restoring vegetation, and freshwater actions focus on restoring the in‐channel habitat; (2) arthropods are the most common focal group; (3) there is often no collection of pre‐restoration data, so certainty in attributing environmental changes to restoration actions is limited; and (4) population and community measures are most commonly used in monitoring programs, which only show if animals are present at restored sites and not whether they are able to grow, survive, and reproduce. We highlight three important considerations for future restoration actions. First, more integration of knowledge among freshwater, marine, and terrestrial systems will help us to understand how, and why, restoration outcomes might vary in different contexts. Second, where possible, restoration projects should be assessed using before‐after‐control‐impact designs, which will provide the strongest evidence if desired restoration responses occur. Third, if the goal of restoration is to develop self‐sustaining breeding populations of target animals, then measures of fitness (i.e. breeding, survival) should be collected. These recommendations will hopefully help guide more effective restoration practices and monitoring in the future.     

植被生态系统恢复及其在华南的研究进展

介绍了恢复生态学常用的理论,并指出恢复生态学研究大多涉及植被生态系统恢复。植被恢复的目标就是要恢复植被的合理结构、功能和动态过程,从而为人类提供生态系统服务。植被恢复可以把区域的地带性植被生态系统作为参考生态系统,但目前的植被恢复工作绝大部分只是恢复了植被生态系统的部分组成、结构和功能。植被生态系统恢复研究主要从退化的原因与过程、恢复的过程与机理,以及从生境恢复、种群恢复、群落恢复、生态系统和景观恢复等不同尺度上的恢复开展。在介绍华南地区的植被生态系统现存问题的基础上,对华南地区开展的植被生态系统恢复,尤其是华南植物研究所(园)开展的植被生态系统恢复研究进行了介绍。最后,提出了华南地区植被生态系统恢复的方向及发展趋势。     

An Ecosystem Model for Exploring Lake Restoration Effects on Fish Communities and Fisheries in Florida

Developing quantitative ecosystem–scale expectations of habitat restoration projects and examining trade‐offs associated with alternative approaches has been a challenge for restoration ecology. Many of the largest freshwater lake restoration projects have occurred in Florida to remediate degradation to vegetated littoral habitats resulting from stabilized water levels, but effects across lake food‐webs have not been assessed. We developed an ecosystem model using Ecopath with Ecosim and Ecospace for a generalized large, eutrophic Florida Lake to explore how simulated restoration activities could influence fish communities with emphasis on sport fish abundance. We modeled three habitat restoration scenarios: (1) “no control,” (2) a “10‐year control” that restored littoral habitat every 10 years, and (3) a “combined control” scenario that restored littoral habitat every 10 years with maintenance controls between 10‐year periods. Our “combined control” scenario provided the largest long‐term habitat restoration benefits for sport fish abundance and the fisheries they support. In Ecospace, we simulated a littoral habitat restoration project that reduced lake‐wide tussock coverage from 30 to 15%. Ecospace predicted positive benefits to sport fish and fisheries following the restoration simulation and highlighted the importance of habitat edge effects, spatial design of habitat restoration projects, and sampling designs for evaluating restoration projects.     

Governance and forest landscape restoration: A framework to support decision-making

Governance challenges are frequently underestimated in forest landscape restoration. Forest restoration practitioners are generally foresters or ecologists and their focus tends to be limited to the specific restoration interventions themselves, such as removing exotic species, protecting sites for natural regeneration and re-planting indigenous trees. Indeed there are many technical challenges, unknowns in technical aspects of forest landscape restoration and knowledge gaps. However, and even more so when dealing with large scales, additional challenges that fall under the governance umbrella such as tenure, policy measures and institutions have a significant impact on restoration, influencing it either positively or negatively. Conversely, the landscape-scale restoration work itself can influence and shape governance arrangements. This paper attempts to explore this wider relationship between large scale forest restoration − and specifically forest landscape restoration (FLR) − and governance. It is intended to assist and provide guidance to forest landscape restoration practitioners, researchers and policymakers on the consideration and importance of governance, and alternative ways in which the two-way relationship (between governance and FLR) plays out. A framework is proposed to support practitioners, researchers and decision-makers to address governance in forest landscape restoration.     

An inventory of continental U.S. terrestrial candidate ecological restoration areas based on landscape context

Landscape context is an important factor in restoration ecology, but the use of landscape context for site prioritization has not been as fully developed. We used morphological image processing to identify candidate ecological restoration areas based on their proximity to existing natural vegetation. We identified 1,102,720 candidate ecological restoration areas across the continental United States. Candidate ecological restoration areas were concentrated in the Great Plains and eastern United States. We populated the database of candidate ecological restoration areas with 17 attributes related to site content and context, including factors such as soil fertility and roads (site content), and number and area of potentially conjoined vegetated regions (site context) to facilitate its use for site prioritization. We demonstrate the utility of the database in the state of North Carolina, U.S.A. for a restoration objective related to restoration of water quality (mandated by the U.S. Clean Water Act), wetlands, and forest. The database will be made publicly available on the U.S. Environmental Protection Agency's EnviroAtlas website ( http://enviroatlas.epa.gov ) for stakeholders interested in ecological restoration.     

长江口潮滩湿地鸟类适栖地营造实验及短期效应

2006～2007年,在总结以往研究的基础上,根据鸟类生态学和生态工程学原理,在长江口崇明岛西端潮滩湿地进行了7hm2(实验工程区和对照区各50%)鸟类适栖地营建实验.结果表明,实验工程区生态系统的生境单元和生物组分(植被、大型底栖动物、鱼类和鸟类等)均发生了明显变化.实验工程区由原来以芦苇群落为主的潮滩湿地变成以明水面、光滩、植被复合结构的湿地鸟类栖息地(明水面面积占40%、浅滩占30%、植被占30%).植被从成片芦苇变为斑块芦苇、灌木丛和其它多类植物并存的格局;大型底栖动物的种类数由开始实验时的下降,逐渐恢复并超过对照区水平,多出约62%;从无纳鱼功能变成有纳鱼功能,秋冬季滞纳鱼类达16种.鸟类群落组成的变化最突出,实验目标鸟类--潮滩湿地鸟(鸻形目Charadriiformes;和鹳形目Ciconiiformes)以及非目标鸟类的种类和数量均明显高于对照区,共记录到56种,比对照区增加了56%.由此说明,本研究的鸟类适栖地营建的生态工程学思路和技术是可行的,在河口湿地生态恢复和重建中具有一定的推广价值.