Restoration and Rehabilitation of Degraded Ecosystems in Arid and Semi-Arid Lands. II. Case Studies in Southern Tunisia, Central Chile and Northern Cameroon

A model of ecosystem degradation and three possible responses to it—restoration, rehabilitation, and real-location—is applied to ongoing projects in the arid mediterranean region of southern Tunisia, the subhumid mediterranean region of central Chile, and the semiarid tropical savannas of northern Cameroon. We compare both nonhuman and human determinants of ecosystem degradation processes in these contrasted regions, as well as interventions being tested in each. A number of quantifiable “vital ecosystem attributes” are used to evaluate the effects of ecosystem degradation and the experimental responses of rehabilitation on vegetation, soils and plant-soil-water relations. We argue that attempts to rehabilitate former ecosystem structure and functioning, both above- and below ground, are the best way to conserve biodiversity and insure sustainable long-term productivity in ecosystems subjected to continuous use by people in arid and semi-arid lands of “the South.” The success of such efforts, however, depends not only on elucidating the predisturbance (or slightly disturbed) structure and function of the consciously selected “ecosystem of reference,” but also on understanding and working with the socioeconomic, technical, cultural, and historical factors that caused the degradation in the first place.     

A conceptual framework for urban ecological restoration and rehabilitation

Urban greenspace has gained considerable attention during the last decades because of its relevance to wildlife conservation, human welfare, and climate change adaptation. Biodiversity loss and ecosystem degradation worldwide require the formation of new concepts of ecological restoration and rehabilitation aimed at improving ecosystem functions, services, and biodiversity conservation in cities. Although relict sites of natural and semi-natural ecosystems can be found in urban areas, environmental conditions and species composition of most urban ecosystems are highly modified, inducing the development of novel and hybrid ecosystems. A consequence of this ecological novelty is the lack of (semi-) natural reference systems available for defining restoration targets and assessing restoration success in urban areas. This hampers the implementation of ecological restoration in cities. In consideration of these challenges, we present a new conceptual framework that provides guidance and support for urban ecological restoration and rehabilitation by formulating restoration targets for different levels of ecological novelty (i.e., historic, hybrid, and novel ecosystems). To facilitate the restoration and rehabilitation of novel urban ecosystems, we recommend using established species-rich and well-functioning urban ecosystems as reference. Such urban reference systems are likely to be present in many cities. Highlighting their value in comparison to degraded ecosystems can stimulate and guide restoration initiatives. As urban restoration approaches must consider local history and site conditions, as well as citizens’ needs, it may also be advisable to focus the restoration of strongly altered urban ecosystems on selected ecosystem functions, services and/or biodiversity values. Ecosystem restoration and rehabilitation in cities can be either relatively inexpensive or costly, but even expensive measures can pay off when they effectively improve ecosystem services such as climate change mitigation or recreation. Successful re‐shaping and re-thinking of urban greenspace by involving citizens and other stakeholders will help to make our cities more sustainable in the future.     

Vital Landscape Attributes: Missing Tools for Restoration Ecology

Twenty-three “vital ecosystem attributes” (VEAs) were previously proposed to aid in quantitative evaluation of whole ecosystem structure, composition, and functional complexity over time. We here introduce a series of 16 quantifiable attributes for use at a higher spatial scale and ecological organizational level, the landscape. “Vital landscape attributes” (VLAs) should be useful in evaluating the results of ecological restoration or rehabilitation undertaken with a landscape perspective, provided that clear definitions and boundaries are agreed upon for the different spatial and ecological entities involved. Like VEAs, VLAs should be sensitive to changes wrought by human as well as to nonhuman factors leading to ruptures in flow processes or vegetation “switches.” They should be applicable over a wide range of landscape types and therefore aid in conducting rigorous interlandscape comparisons. We present three groups of VLAs: (1) landscape structure and biotic composition, (2) functional interactions among ecosystems within the landscape, and (3) degree, type, and causes of landscape fragmentation and degradation. Ecotones between ecosystems are touched upon by several different VLAs. Because conflicting terminology abounds in this area, we append a glossary defining the problematic terms used.     

Rehabilitation of Tropical Lands: A Key to Sustaining Development

Land rehabilitation is proposed as a management strategy to reverse the negative consequences of tropical deforestation and land degradation. We first define the concepts associated with ecosystem modification—conversion, damage, and degradation—and those associated with ecosystem repair—restoration, rehabilitation, and reclamation. We then present a scheme of sustainable land use in the tropics, with illustrations of how rehabilitation and restoration activities fit into the overall scheme of the use of land. Because damaged lands cannot contribute effectively to sustained economic development, land rehabilitation is a necessary step for increasing the chances of attaining sustainability. Approaches for rehabilitating ecosystems are discussed, including the management of stressors and subsidies in relation to their point of interaction in the ecosystem. Finally, we illustrate the concepts of ecosystem rehabilitation of damaged, degraded, and derelict lands with examples of case studies from dry to humid life zones in island and continental situations throughout the tropics. The case studies demonstrate that opportunities for success exist, even with severely degraded lands, but a considerable amount of research remains to be done before we have a full understanding of the complexity of the task facing us.     

The SER Standards,cultural ecosystems,and the nature‐culture nexus—a reply to Evans and Davis

Evans and Davis claim the SER Standards use a “pure naturalness” model for restoration baselines and exclude most cultural ecosystems from the ecological restoration paradigm. The SER Standards do neither. The SER Standards consider both “natural” ecosystems (that are unequivocally not cultural) and “similar” cultural ecosystems as suitable reference models. Furthermore, Evans and Davis propose assessing whether a cultural ecosystem exhibits “good, bad, or neutral impacts from humans on ecosystems” as the basis for reference models. We argue that such an approach would overlook the indispensability of native ecosystem benchmarks to measure human impacts and provide a springboard for social‐ecological restoration.     

Restoration of Biodiversity and Ecosystem Services on Agricultural Land

Cultivation and cropping are major causes of destruction and degradation of natural ecosystems throughout the world. We face the challenge of maintaining provisioning services while conserving or enhancing other ecosystem services and biodiversity in agricultural landscapes. There is a range of possibilities within two types of intervention, namely “land sharing” and “land separation”; the former advocates the enhancement of the farmed environment, but the latter a separation between land designated for farming versus conservation. Land sharing may involve biodiversity-based agricultural practices, learning from traditional farming, changing from conventional to organic agriculture and from “simple” crops and pastures to agro-forestry systems, and restoring or creating specific elements to benefit wildlife and particular services without decreasing agricultural production. Land separation in the farmland context involves restoring or creating non-farmland habitat at the expense of field-level agricultural production—for example, woodland on arable land. Restoration by land sharing has the potential to enhance agricultural production, other ecosystem services and biodiversity at both the field and landscape scale; however, restoration by land separation would provide these benefits only at the landscape scale. Although recent debate has contrasted these approaches, we suggest they should be used in combination to maximize benefits. Furthermore, we suggest “woodland islets”, an intermediate approach between land abandonment and farmland afforestation, for ecological restoration in extensive agricultural landscapes. This approach allows reconciliation of farmland production, conservation of values linked to cultural landscapes, enhancement of biodiversity, and provision of a range of ecosystem services. Beyond academic research, restoration projects within agricultural landscapes are essential if we want to halt environmental degradation and biodiversity loss.     

Are Socioeconomic Benefits of Restoration Adequately Quantified? A Meta‐analysis of Recent Papers (2000–2008) in Restoration Ecology and 12 Other Scientific Journals

Many ecosystems have been transformed, or degraded by human use, and restoration offers an opportunity to recover services and benefits, not to mention intrinsic values. We assessed whether restoration scientists and practitioners use their projects to demonstrate the benefits restoration can provide in their peer‐reviewed publications. We evaluated a sample of the academic literature to determine whether links are made explicit between ecological restoration, society, and public policy related to natural capital. We analyzed 1,582 peer‐reviewed papers dealing with ecological restoration published between 1 January 2000 and 30 September 2008 in 13 leading scientific journals. As selection criterion, we considered papers that contained either “restoration” or “rehabilitation” in their title, abstract, or keywords. Furthermore, as one‐third of the papers were published in Restoration Ecology, we used that journal as a reference for comparison with all the other journals. We readily acknowledge that aquatic ecosystems are under‐represented, and that the largely inaccessible gray literature was ignored. Within these constraints, we found clear evidence that restoration practitioners are failing to signal links between ecological restoration, society, and policy, and are underselling the evidence of benefits of restoration as a worthwhile investment for society. We discuss this assertion and illustrate it with samples of our findings—with regards to (1) the geographical and institutional affiliations of authors; (2) the choice of ecosystems studied, methods employed, monitoring schemes applied, and the spatial scale of studies; and (3) weak links to payments for ecosystem service setups, agriculture, and ramifications for public policy.     

景观生态恢复与重建是区域生态安全格局构建的关键途径

生态恢复与重建是跨尺度、多等级的问题,其主要表现层次应是生态系统（生物群落）、景观,甚至区域,而不能仅仅局限于生态系统。景观的恢复与重建是针对景观退化而言,景观退化从表现形式上可分为景观结构退化与景观功能退化。景观结构退化即景观破碎化,是指景观中各生态系统之间的各种功能联系断裂或连接度(connectivity)减少的现象;而鲜受重视的景观聚集（aggregation）在很多情况下同样具有造成景观退化的负面效应。景观功能退化是指与前一状态相比,由于景观异质性的改变导致景观的稳定性与服务功能等的衰退现象。景观恢复是指恢复原生生态系统间被人类活动终止或破坏的相互联系;景观生态建设应以景观单元空间结构的调整和重新构建为基本手段,包括调整原有的景观格局,引进新的景观组分等,以改善受胁或受损生态系统的功能,提高其基本生产力和稳定性,将人类活动对于景观演化的影响导入良性循环。二者的综合,统称为景观生态恢复与重建,是构建安全的区域生态格局的关键途径。其目标是建立一种由结构合理、功能高效、关系协调的模式生态系统（model ecosystem）组成的模式景观（model landscape）,以实现生态系统健康、生态格局安全和景观服务功能持续,以3S(RS,GPS,GIS)技术为支撑的GAP(ageographic approach to protect biological diversity)分析将为大尺度景观恢复的诊断、评价、规划提供重要的手段。景观中某些关键性点、位置或关系的破坏对整个生态安全具有毁灭性的后果,研究景观层次上的生态恢复模式及恢复技术、选择恢复的关键位置、构筑生态安全格局已成为景观生态学家关注的焦点。     

Restoration Ecology to the Future: A Call for New Paradigm

The discipline of restoration ecology has grown remarkably in the past decades, providing new ideas and opportunities for conserving biological diversity, managing ecosystems, and testing ecological theories. On the other side, its past‐oriented, static, and idealistic approach has been criticized for subjectivity in determining restoration goals, inapplicability to dynamic ecosystems, and inability for restoring certain irreversible losses. Moreover, unpredictable sustainability of the restored ecosystems, which were modeled after its historical fidelity, adds our skepticism under the changing environment. This paper calls for a new paradigm of ecological restoration to the future. A future‐oriented restoration should (1) establish the ecosystems that are able to sustain in the future, not the past, environment; (2) have multiple alternative goals and trajectories for unpredictable endpoints; (3) focus on rehabilitation of ecosystem functions rather than recomposition of species or cosmetics of landscape surface; and (4) acknowledge its identity as a “value‐laden” applied science within economically and socially acceptable framework. Applicability of ecological theories to restoration practice is also discussed in this paper.     

Mangrove Restoration: Do We Know Enough?

Mangrove restoration projects have been attempted, with mixed results, throughout the world. In this paper, I first examine goals of existing mangrove restoration projects and determine whether these goals are clear and adequate, and whether or not they account for the full range of biological diversity and ecological processes of mangrove ecosystems. Many restored mangrove forests resemble forest plantations rather than truly integrated ecosystems, but mangrove plantations can be a first step toward mangrove rehabilitation. Mangrove restoration projects that involve associated aquaculture or mariculture operations tend to be more likely to approximate the biological diversity and ecological processes of undisturbed mangrove ecosystems than are projects that focus only on the trees. These integrated restoration projects also provide a higher economic return than do silvicultural projects alone. Second, I briefly assess whether existing ecological data are sufficient to undergird successful restoration of mangal and define criteria for determining whether or not a mangrove ecosystem has been restored successfully. These criteria include characteristics of vegetation (forest) structure, levels of primary production, composition of associated animal communities, and hydrology. Finally, I suggest ways to improve mangrove restoration projects and identify key research needs required to support these efforts. Ecological theories derived from other wetland and upland systems rarely have been applied to either “basic” or “applied” mangrove forest studies, to the detriment of restoration projects, whereas lessons from restoration of the relatively species‐poor mangrove ecosystems could be beneficially applied to restoration projects in other contexts. An international database of mangrove restoration projects would reduce the likelihood that unsuccessful restoration projects would be repeated elsewhere. Clear criteria for evaluating success, greater accessibility of information by managers in the developing world, intensified international cooperation, and application of relevant ecological theories will improve the success rate of mangrove restoration projects.     

淡水湖泊生态系统退化驱动因子及修复技术研究进展

目前我国多数淡水湖泊污染、退化问题非常严重,诸多修复技术也已初见成效。影响淡水湖泊生态系统退化的驱动因子众多,既有生物因素也有非生物因素,它们之间相互联系,相互作用,且作用机理错综复杂。首先介绍了淡水湖泊生态系统退化的含义及形式;其次,分析、总结了淡水湖泊生态系统退化的驱动因子,从退化的生态学完整性意义和退化修复的技术手段上看,淡水湖泊生态系统主要受物理、化学和生物三大驱动因子影响,且基本遵循"环境变化-驱动力-压力(阈值)-状态-响应"原理;再次,在厘清湖泊生态系统退化驱动原理的基础上,从淡水湖泊生态系统功能模块和湖泊生态系统修复实践经验总结的角度出发,构建了淡水湖泊生态系统修复模块技术体系,并就湖泊富营养化和湖滨湿地生态系统退化修复的技术进行了讨论和对比;最后,对淡水湖泊生态系统修复的环境变化驱动因子的作用机制、作用途径和修复技术的长效机制等方面进行了展望。     

生态系统退化程度诊断：生态恢复的基础与前提

 生态系统退化程度诊断是进行生态恢复与重建的基础和前提。然而目前的生态系统化程度诊断大多停留在定性的水平,如何对退化生态系统的退化程度进行定量的诊断就成为恢复生态学与生态恢复实践所面临的一个迫切且十分关键的问题。在综述前人研究的基础上,比较系统地论述了生态系统退化程度诊断的一系列问题：绘制了描述生态系统退化程度的概念模型;认为在实践中退化程度诊断的参照系统可以选择相应的受人类或自然干扰程度比较轻的“自然生态系统”;归纳了生态系统退化程度诊断的生物途径、生境途径、生态过程途径、生态系统功能/服务途径、景观途径;把诊断方法分为单途径单因子诊断法、单途径多因子诊断法、多途径综合诊断法;分析了生态系统退化程度诊断的可能指标（体系）;给出了生态系统退化程度诊断的策略与流程,并对生态系统退化程度诊断及生态恢复过程中应注意的事项进行了讨论。建议我国加强典型生态系统退化程度的综合诊断研究。     

The Semiglades: The Collision of Restoration,Social Values,and the Ecosystem Concept

Defining success targets in restoration and how social values affect them are two commonly discussed issues in restoration today. We believe that how success is commonly defined—with vague terms such as “healthy ecosystem” or cited as a return to a previous, historic state—needs to be reevaluated. With the increasing number of novel ecosystems, there is an increasing conflict between the ecosystem concept, social values, and restoration. This arises from the fact that ecosystems are defined by the values of the scientists describing them, necessarily constraining the ecosystem to a generally static concept. It is not directly the concept, but how it is perceived through our filter of social values that represses the creativity and innovation needed in restoration today. Within restoration, we feel that the ecosystem concept does a disservice by ignoring the increasing number of novel systems, and that hinders real progress in a time when hesitation can be costly. To best illustrate this, we offer the example of restoration of the Florida Everglades and how it has become a novel system in pattern and process. We suggest renaming the Everglades “The Semiglades” in hopes of opening a dialog to expose social/ecosystem biases and include novel landscapes in management and planning.     

Fostering sustainable land restoration through circular economy‐governed transitions

Soil and land are critical common pool resources offering a multitude of ecosystem services (ES) and presently affected by degradation and unplanned exploitation. The present article therefore attempts to elucidate the importance of circular economy in boosting land restoration and realization of several sustainable development goals through efficient waste recycling and clean energy production from degraded lands combined with policy restructuring for aligning circularity with restoration. Integrative policy frameworks targeting a “sustainable restoration economy” can help improve the cost feasibility of restoration projects through circularization of resource value chains besides enhancing social welfare and ecological vitality.     

The age of restoration: challenges presented by dryland systems

Intact drylands are highly evolved and complex ecosystems, which allow them to be productive despite harsh environmental conditions. However, drylands are particularly susceptible to degradation, even after minor disturbance events. Conditions for natural plant recruitment in dryland systems are spatially and temporally irregular, which can create challenges for restoration. Large-scale restoration and rehabilitation of dryland ecosystems have become a global concern, prompted by ever-increasing anthropogenic pressure and associated degradation of these natural systems worldwide. The success of plant reestablishment programs in these regions is closely linked to both ecological and socioeconomic opportunities and limitations. This special issue brings together papers that discuss the roles which ecological and socioeconomic factors play in influencing dryland ecosystem restoration outcomes. We aim to (1) highlight the current status of recovery efforts taking place across a range of dryland ecosystems, emphasize advances in the region-specific understanding of plant community development, and (2) provide comparisons between the primary drivers and limitations to restoration that exist across dryland systems.     

Stretch Goals and Backcasting: Approaches for Overcoming Barriers to Large-Scale Ecological Restoration

The destruction and transformation of ecosystems by humans threatens biodiversity, ecosystem function, and vital ecosystem services. Ecological repair of ecosystems will be a major challenge over the next century and beyond. Restoration efforts to date have frequently been ad hoc, and site or situation specific. Although such small‐scale efforts are vitally important, without large‐scale visions and coordination, it is unlikely that large functioning ecosystems will ever be constructed by chance through the cumulative effects of small‐scale projects. Although the problems of human‐induced environmental degradation and the need for a solution are widely recognized, these issues have rarely been addressed on a sufficiently large‐scale basis. There are numerous barriers that prevent large‐scale ecological restoration projects from being proposed, initiated, or carried through. Common barriers include the “shifting baseline syndrome,” the scale and complexity of restoration, the long‐term and open‐ended nature of restoration, funding challenges, and preemptive constraint of vision. Two potentially useful approaches that could help overcome these barriers are stretch goals and backcasting. Stretch goals are ambitious long‐term goals used to inspire creativity and innovation to achieve outcomes that currently seem impossible. Backcasting is a technique where a desired end point is visualized, and then a pathway to that end point is worked out retrospectively. A case study from the Scottish Highlands is used to illustrate how stretch goals and backcasting could facilitate large‐scale restoration. The combination of these approaches offers ways to evaluate and shape options for the future of ecosystems, rather than accepting that future ecosystems are victims of past and present political realities.     

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.     

Learning from scientific literature: Can indicators for measuring success be standardized in “on the ground” restoration?

The Society for Ecological Restoration (SER) Primer identifies key ecosystem attributes for evaluating restoration outcome. Broad attribute categories could be necessary due to the large variety of restoration projects, but could make overall evaluations and assessments challenging and might hamper the development of sound and successful restoration. In this study we carry out a systematic review of scientific papers addressing evaluation of restoration outcome. We include 104 studies published after 2010 from Europe or North America, representing different types of restoration projects in terrestrial and freshwater ecosystems. We explore the main ecological and socioeconomic attributes used to evaluate restoration outcome, and related indicators and specific methods applied to measure this, in relation to ecosystem and type of restoration project. We identify a wide range of indicators within each attribute, and show that very different methods are employed to measure them. This complexity reduces the opportunity for meaningful comparison and standardization of evaluation of restoration outcome, within and between ecosystems. Socioeconomic indicators are rarely used to evaluate restoration outcome, and studies including both ecological and socioeconomic indicators are nearly absent. Based on our findings we discuss whether standardization and streamlining of indicators is useful to improve the evaluation of “on the ground” restoration, or if this is not appropriate given the diversity of goals and ecosystems involved. Species‐specific traits are used in many projects and should be considered as an addition to the original SER attributes. Furthermore, we discuss the potential for restoration evaluation that encompasses not only assessment of ecological but also socioeconomic indicators.     

The potential of earthworms to restore ecosystem services after opencast mining – A review

Opencast coal mining has several environmental impacts, which require land rehabilitation when mining operations are finished. For that reason, restoration after such extractive industries’ work is common and has been well studied. However, many ecological restoration schemes do not examine to what extent complete and functioning ecosystems have been restored above and below ground. While the aim should be to restore functioning ecosystems, most restoration plans focus only on vegetation and above ground macro-fauna.Among the potential species that are likely to be important early in mine land restoration, earthworms are particularly good candidates. They provide several ecosystem services that are likely to accelerate soil restoration, improve primary production and facilitate the restoration of a functional ecosystem in mining areas. These services include the following: increase in topsoil fertility, food for a wide range of predators and recycling of waste organic materials on rehabilitated areas.Here, we outline some of the challenges specifically facing opencast mining restoration and describe how the ecosystem services provided by earthworms may address some of these challenges.     

Ensuring the adaptive potential of Coastal wetlands of India- the need of the hour for sustainable management

India is endowed with a variety of coastal wetlands viz., mangroves, seagrasses, saltmarshes, coral reefs, lagoons and tidal flats, and the country is also a signatory to the Ramsar Convention on Wetlands and the Convention of Biological Diversity, besides having a robust framework of laws and policies, governing the wetland conservation. However, the conservation strategies can better be improved in the context of increasing pressures and threats and limited success of restoration/rehabilitation. Land conversion and ecological degradation of coastal wetlands are the stressors, associated with rapid coastal developmental activities and climate change. The coastal wetlands require desired habitat niche and hence, the conversion of coastal wetlands to other land uses (including agricultural and urban lands) may lead to permanent loss, whereas ecologically degraded coastal wetlands may be resilient if supported by effective protection measures. Preventing the habitat conversion and maximizing the adaptive potential (viz., the ability of populations or species to adapt to rapid environmental change with minimal disruption) by preserving the ecological health are the need of the hour to safeguard the existing coastal wetlands and sustain the provisional ecosystem services offered by them rather than short-term increase in area by unproductive restoration/rehabilitation efforts. Since coastal wetlands are flow through ecosystems, preserving the hydrological connectivity, facilitating the connectivity between adjacent ecosystems and protection of natural corridors are potential strategies that are required to enhance the adaptive potential of coastal wetlands. This analysis calls for site-specific, long-term and integrated ecosystem-based protection, management and rehabilitation strategies based on scientific principles and enforcing the effective legislative measures to regularize the coastal developmental activities in India.