Novel and designed ecosystems

Growing attention to novel and designed ecosystems, and the confusion that follows from the overlap of these distinct ecosystem approaches, risks a loss of focus on ecological values at the core of restoration ecology. Novel ecosystems originate in ecosystems that are transformed beyond which the practical efforts of conventional restoration are feasible. They are also self‐sustaining in the sense that they take time to form, and do not typically receive regular management. In this respect, they arise differently than designed ecosystems, which are assembled with specific goals in mind and are often heavily managed. Designed (or engineered) ecosystems comprise a variety of ecological approaches including reclamation (return a degraded ecosystem to productive capacity), green infrastructure, and agroecological systems. There are three elements that distinguish novel and designed ecosystems. Designed ecosystems typically require intensive intervention to create them, and ongoing management to sustain them; novel ecosystems do not. Second, the human intentions behind designed and novel ecosystems are usually different. Designed ecosystems exist in the service of human interests, including specific services (e.g. filtration, cooling, nature appreciation), aesthetics, and shifting value commitments toward green infrastructure; novel ecosystems arise typically through inadvertent human activity. Third, designed and novel ecosystems have different developmental pathways. Historical ecosystems are the starting point for restored, hybrid, and novel ecosystems; designed ecosystems are intentionally created. Designed ecosystems stand apart as providing a new origin for ecosystems of the future, including those that become novel ecosystems.     

A triage framework for managing novel,hybrid, and designed marine ecosystems

The novel ecosystem (NE) concept has been discussed in terrestrial restoration ecology over the last 15 years but has not yet found much traction in the marine context. Against a background of unprecedented environmental change, managers of natural marine resources have portfolios full of altered systems for which restoration to a previous historical baseline may be impractical for ecological, social, or financial reasons. In these cases, the NE concept is useful for weighing options and emphasizes the risk of doing nothing by forcing questions regarding the value of novelty and how it can best be managed in the marine realm. Here, we explore how the concept fits marine ecosystems. We propose a scheme regarding how the NE concept could be used as a triage framework for use in marine environments within the context of a decision framework that explicitly considers changed ecosystems and whether restoration is the best or only option. We propose a conceptual diagram to show where marine NEs fit in the continuum of unaltered to shifted marine ecosystems. Overall, we suggest that the NE concept is of interest to marine ecologists and resource managers because it introduces a new vocabulary for considering marine systems that have been changed through human actions but have not shifted to an alternate stable state. Although it remains to be seen whether the concept of marine NEs leads to better conservation and restoration decisions, we posit that the concept may help inform management decisions in an era of unprecedented global marine change.     

米草属植物入侵的生态后果及管理对策

生物入侵是全球变化的重要组成部分,可能对入侵地造成严重的经济和生态后果,所以评价外来种入侵的生态后果是入侵生态学研究的核心问题之一。本文以米草属(Spartina)植物为例,综述了其对入侵地区自然环境、生物种群、群落和生态系统的影响;结合国际上对米草属入侵种的管理策略,讨论了我国米草属植物管理中的一些重要问题。     

Grasshopper （Orthoptera： Acrididae） biodiversity and grassland ecosystems

Interesting results may arise by combining studies on the structure and function of ecosystems with that of biodiversity for certain species. Grasshopper biodiversity is the result of the evolution of grassland ecosystems; however, it also impacts on the structure and the function of those ecosystems. We consider there to be a close relationship between the health of grassland ecosystems and grasshopper biodiversity. The main problems involved in this relationship are likely to include： （i） grasshopper biodiversity and its spatial pattern; （ii） the effect of grasshopper biodiversity on the ecological processes of grassland ecosystems; （iii） the biodiversity threshold of grasshopper population explosions; （iv） the relationship between grasshopper biodiversity and the natural and human factors that affect grassland ecosystems; and （v） grasshopper biodiversity and the health of grassland ecosystems. The solutions to these problems may provide sound bases for controlling disasters caused by grasshoppers and managing grassland ecosystems in the west of China. In this paper, we introduced two concepts for grasshopper biodiversity, that is, ＂spatial pattern＂ and ＂biodiversity threshold＂. It is helpful to understand the action of the spatial pattern of grasshopper biodiversity on the ecological processes of grassland ecosystems and the effect of this spatial pattern on the health of those ecosystems, owing to the fact that, in the west of China, grasslands are vast and grasshoppers are widely distributed. Moreover, we inferred that the change in the level of component richness at each type of grasshopper biodiversity can make an impact on grassland ecosystems, and therefore, there is likely to be a threshold to grasshopper biodiversity for the stability and the sustainability of those ecosystems.     

河流生态系统健康研究现状与展望——基于文献计量研究

河流生态系统健康是生态系统服务供给和流域可持续发展的基础,亟需从其内涵、影响、评价等方面进行系统归纳。运用文献计量梳理国内外文献,归纳了河流生态系统健康在河流自身、人类需求、管理目标3个方面的内涵;并从人类活动、土地利用、河流生境、水质、水量、气候变化等几个方面归纳了影响河流生态系统健康的主要因素和机理;明确了现有的河流生态系统健康评价方法,包括指示生物法、综合指标法、数学模型法等,总结了它们的优缺点和适用范围。最后,从河流生态系统健康的概念内涵、评价指标和水陆耦合等方面提出了存在的问题,建议进行流域整体的河流生态系统健康评价、跨区域的综合评价对比、多学科评价指标、河流廊道等几个方面的深入研究。     

Do experiments exploring plant diversity–ecosystem functioning relationships inform how biodiversity loss impacts natural ecosystems?

An enormous recent research effort focused on how plant biodiversity (notably species richness) influences ecosystem functioning, usually through experiments in which diversity is varied through random draws of species from a species pool. Such experiments are increasingly used to predict how species losses influence ecosystem functioning in ‘real’ ecosystems. However, this assumes that comparisons of experimental communities with low vs high species richness are analogous to comparisons of natural communities from which species either have or have not been lost. I explore the validity of this assumption, and highlight difficulties in using such experiments to draw conclusions about the ecosystem consequences of biodiversity loss in natural systems. Notably, these experiments do not mimic what happens in real ecosystems either when local extinctions occur or when species losses are offset by gains of new species. Despite limitations, this single experimental approach for studying how biodiversity loss affects ecosystems has often been advocated and implemented at the expense of other approaches; this limits understanding of how natural ecosystems respond to biodiversity loss. I conclude that a broader spectrum of approaches, and more explicit consideration of how species losses and gains operate in concert to influence ecosystems, will help progress this field.     

The emergence of the social‐ecological restoration concept

Many ecosystems in the world are the result of a close interaction between local people and their environment, which are currently recognized as social‐ecological systems (SoES). Natural catastrophes or long‐standing social and political turmoil can degrade these SoES to a point where human societies are no longer autonomous and their supporting ecosystems are highly degraded. Here, we focus on the special case of the restoration of SoES that we call social‐ecological restoration (SoER), which is characterized as a restoration process that cannot avoid simultaneously dealing with ecological and social issues. In practice, SoER is analogous in many ways to the general principles of ecological restoration, but it differs in three key aspects: (1) the first actions may be initially intended for human groups that need to recover minimum living standards; (2) the SoER process would often be part of a healing process for local people where cultural values of ecosystems play an essential role; and (3) there is a strong dependency on external economic inputs, as the people belonging to the SoES may be incapable of reorganizing themselves on their own and supporting ecosystems can no longer self‐recover. Although it might not be desirable or necessary to call all restoration projects with a social component an SoER, the use of this concept may help in defining early restoration targets that may prevent conflicts among users in the long term. From the perspective of other disciplines, SoER would be more appropriately perceived as programs of “social‐ecological recovery” in the long term.     

湖泊-流域生态系统管理的内容与方法

在流域生态系统管理研究综述的基础上,对湖泊一流域生态系统管理的概念进行了界定,对水环境管理、综合流域管理与流域生态系统管理之间的差异进行了对比分析。确定了生态系统生态学、流域生态学、生态系统健康和流域方法为湖泊．流域生态系统管理的理论基础,生态系统方法和流域分析为其方法学基础。在上述分析的基础上,提出了湖泊．流域生态系统管理的6个主要步骤：研究范围界定、基础信息收集与基本生态学问题的分析和评价、管理目标设定、系统综合、生态系统综合评价、适应性管理;识别出湖泊-流域生态系统管理中的3个关键问题：①生态系统管理中的不确定性和障碍分析;②流域土地利用变化对湖泊水质和生态系统的影响;③流域生态子系统与社会子系统的关联。     

Resource subsidies between stream and terrestrial ecosystems under global change

Streams and adjacent terrestrial ecosystems are characterized by permeable boundaries that are crossed by resource subsidies. Although the importance of these subsidies for riverine ecosystems is increasingly recognized, little is known about how they may be influenced by global environmental change. Drawing from available evidence, in this review we propose a conceptual framework to evaluate the effects of global change on the quality and spatiotemporal dynamics of stream–terrestrial subsidies. We illustrate how changes to hydrological and temperature regimes, atmospheric CO₂ concentration, land use and the distribution of nonindigenous species can influence subsidy fluxes by affecting the biology and ecology of donor and recipient systems and the physical characteristics of stream–riparian boundaries. Climate‐driven changes in the physiology and phenology of organisms with complex life cycles will influence their development time, body size and emergence patterns, with consequences for adjacent terrestrial consumers. Also, novel species interactions can modify subsidy dynamics via complex bottom‐up and top‐down effects. Given the seasonality and pulsed nature of subsidies, alterations of the temporal and spatial synchrony of resource availability to consumers across ecosystems are likely to result in ecological mismatches that can scale up from individual responses, to communities, to ecosystems. Similarly, altered hydrology, temperature, CO₂ concentration and land use will modify the recruitment and quality of riparian vegetation, the timing of leaf abscission and the establishment of invasive riparian species. Along with morphological changes to stream–terrestrial boundaries, these will alter the use and fluxes of allochthonous subsidies associated with stream ecosystems. Future research should aim to understand how subsidy dynamics will be affected by key drivers of global change, including agricultural intensification, increasing water use and biotic homogenization. Our conceptual framework based on the match–mismatch between donor and recipient organisms may facilitate understanding of the multiple effects of global change and aid in the development of future research questions.     

Functional traits,the phylogeny of function,and ecosystem service vulnerability

People depend on benefits provided by ecological systems. Understanding how these ecosystem services – and the ecosystem properties underpinning them – respond to drivers of change is therefore an urgent priority. We address this challenge through developing a novel risk‐assessment framework that integrates ecological and evolutionary perspectives on functional traits to determine species’ effects on ecosystems and their tolerance of environmental changes. We define Specific Effect Function (SEF) as the per‐gram or per capita capacity of a species to affect an ecosystem property, and Specific Response Function (SRF) as the ability of a species to maintain or enhance its population as the environment changes. Our risk assessment is based on the idea that the security of ecosystem services depends on how effects (SEFs) and tolerances (SRFs) of organisms – which both depend on combinations of functional traits – correlate across species and how they are arranged on the species’ phylogeny. Four extreme situations are theoretically possible, from minimum concern when SEF and SRF are neither correlated nor show a phylogenetic signal, to maximum concern when they are negatively correlated (i.e., the most important species are the least tolerant) and phylogenetically patterned (lacking independent backup). We illustrate the assessment with five case studies, involving both plant and animal examples. However, the extent to which the frequency of the four plausible outcomes, or their intermediates, apply more widely in real‐world ecological systems is an open question that needs empirical evidence, and suggests a research agenda at the interface of evolutionary biology and ecosystem ecology.     

Riparian vegetation diversity along regulated rivers: contribution of novel and relict habitats

1. The creation and maintenance of spatial and temporal heterogeneity by rivers flowing through floodplain landscapes has been disrupted worldwide by dams and water diversions. Large reservoirs ( novel ecosystems ) now separate and isolate remnant floodplains ( relict ecosystems ). From above, these appear as a string of beads, with beads of different sizes and string connections of varying lengths.
2. Numerous studies have documented or forecast sharp declines in riparian biodiversity in relict ecosystems downstream from dams. Concurrently, novel ecosystems containing species and communities of the former predam ecosystems have arisen along all regulated rivers. These result from the creation of new environments caused by upper reservoir sedimentation, tributary sedimentation and the formation of reservoir shorelines.
3. The contribution of novel habitats to the overall biodiversity of regulated rivers has been poorly studied. Novel ecosystems may become relatively more important in supporting riverine biodiversity if relict ecosystems are not restored to predam levels. The Missouri River of the north-central U.S.A. is used to illustrate existing conditions on a large, regulated river system with a mixture of relict and novel ecosystems.     

The ‘Design’ of Mediterranean Landscapes: A Millennial Story of Humans and Ecological Systems during the Historic Period

What makes the structure and dynamics of coupled natural and human systems difficult to interpret in the Mediterranean is the extreme diversity in space and time of both environments and human societies. The succession of civilizations that waxed and waned in the Mediterranean Basin over several millennia has had great impacts on biota and ecosystems everywhere in the basin. A complex ‘coevolution’ has been claimed to shape the interactions between ecosystem components and human societies. Two opposing schools of thought traditionally have considered the consequences of human pressures on Mediterranean ecosystems. The ‘Ruined Landscape’ or ‘Lost Eden theory’ argues that human action resulted in a cumulative degradation and desertification of Mediterranean landscapes. The second school argues that humans actually contributed to keeping Mediterranean landscapes diverse since the last glacial episode. With this debate in mind, I show the following: (1) One cannot understand the components and dynamics of current biodiversity in the Mediterranean without taking into account the history of human-induced changes; (2) The various systems of land use and resource management that provided a framework for the blossoming of Mediterranean civilizations also had profound consequences on the distribution and dynamics of species, communities, and landscapes; (3) The processes of domestication of plant and animal species, which first occurred in the eastern Mediterranean area some 10,000 years ago, contributed to the increase of certain components of biodiversity at several spatial scales. Positive and negative feedback cycles between cultural practices and natural systems at the local and regional levels have kept ecosystems robust and resilient; (4) Assuming that human action can, to a certain extent, be considered a large-scale surrogate for natural sources of ecosystem disturbance, such patterns give support to the diversity-disturbance hypothesis—specifically, intermediate levels of disturbance have promoted biological diversity; (5) Intraspecific adaptive variation increased as a result of human-induced habitat changes over millennia, resulting in bursts of differentiation during the later Holocene of local ecotypes and gene pools of domesticated and wild plant and animal species, with region-specific characters fitting them to local climate and environmental conditions. High intraspecific adaptive variation also arose from earlier natural processes of the Pleistocene, mainly from a combination of periodic refugia formation and climate dynamics. During the Holocene, the main sources of disturbance came increasingly from humans, specifically from the coupled cultural and natural modifications of community and landscape structure. It is concluded that a high degree of resilience of Mediterranean ecosystems resulted in a dynamic coexistence of human and natural living systems, which in some cases provided stability, while fostering diversity and productivity (Blondel and Aronson, 1999). The word “design” used in the title and elsewhere in this paper metaphorically indicates that the long-lasting influence of human impacts resulted in an unintentional shaping of individual components of landscapes.     

Functional links and robustness in food webs

The robustness of ecosystems to species losses is a central question in ecology, given the current pace of extinctions and the many species threatened by human impacts, including habitat destruction and climate change. Robustness from the perspective of secondary extinctions has been addressed in the context of food webs to consider the complex network of species interactions that underlie responses to perturbations. In-silico removal experiments have examined the structural properties of food webs that enhance or hamper the robustness of ecosystems to species losses, with a focus on the role of hubs, the most connected species. Here we take a different approach and focus on the role of the connections themselves. We show that trophic links can be divided into functional and redundant based on their contribution to robustness. The analysis of empirical webs shows that hubs are not necessarily the most important species as they may hold many redundant links. Furthermore, the fraction of functional connections is high and constant across systems regardless of size and interconnectedness. The main consequence of this scaling pattern is that ecosystem robustness can be considerably reduced by species extinctions even when these do not result in any secondary extinctions. This introduces the possibility of tipping points in the collapse of ecosystems.     

How complete is our knowledge of the ecosystem services impacts of Europe's top 10 invasive species?

Invasive non-native species have complex multilevel impacts on their introduced ecosystems, leading to far-ranging effects on fundamental ecosystem services, from the provision of food from that system, to human health and wellbeing. For this reason, there is an emerging interest in basing risk assessments not only on the species' ecological and economic impacts, but also on the effects related to ecosystem services. We investigated the quality and extent of baseline data detailing the effects that the top 10 of the ‘worst’ invasive species in Europe are having on their adopted ecosystems. The results were striking, as the 10 species showed a wide range of impacts on ecosystem services, a number of which were actually positive for ecosystems and human well-being. For instance, the bivalve Dreissena polymorpha is a prolific biofouler of pipes and boats, but it can improve water quality through its filtration of nuisance algae, a valuable effect that is often overlooked. We found that negative effects, particularly economic ones, were often assumed rather than quantitatively evidenced; for example, the cost of crop damage by species such as Myocastor coypus and Branta canadensis. In general, the evidence for impacts of these ‘worst’ invaders was severely lacking. We conclude that invasive species management requires prioritization, which should be based on informed and quantified assessment of the potential ecological and economic costs of species (both positive and negative), considered in the proper context of the invader and ecosystem. The Millennium Ecosystem Approach provides a useful framework to undertake such prioritization from a new perspective combining ecological and societal aspects. However, standard guidelines of evaluation are urgently needed in order to unify definitions, methods and evaluation scores.     

Acid rain and its effects on sediments in lakes and streams

Wet and dry deposition of acidic substances, which are emitted to the atmosphere by human activities, have been falling on increasingly widespread areas throughout the world in recent decades. As a result, annual precipitation averages less than pH 4.5 over large areas of the Northern Temperate Zone, and not infrequently, individual rainstorms and cloud or fog-water events have pH values less than 3. Concurrently, thousands of lakes and streams in North America and Europe have become so acidified that they no longer support viable populations of fish and other organisms.Acid deposition may affect sediments in lakes and streams in a variety of ways. In particular, the sediment-water exchange of metals, sulfur, nitrogen and phosphorus, microbial processes, growth of periphyton and macrophytes, and benthic invertebrates may be affected.Overall, the effects of acid deposition on lake and stream ecosystems are the result of numerous and complex biogeochemical interactions, including catchment characteristics, flow path and residence time of water, and lake-basin morphometry and acid neutralization capacity of both aquatic and terrestrial (catchment) ecosystems.Suggestions for future research are given.     

Modeling the trophic effects of marine protected area zoning policies: A case study

Marine protected areas (MPAs) are increasingly being recognized as an alternative management tool for conserving marine resources and ecosystems. By integrating organism dispersal rates, ecosystem interactions and fishing effort dynamics, ECOSPACE, a spatially explicit ecosystem-based modeling tool, allowed us to compare the ecological consequences of alternative MPA zoning policies within the proposed Gwaii Haanas National Marine Conservation Area, located off the west coast of British Columbia, Canada. The desired effects of MPAs include higher fishery yields, the conservation of biodiversity, and/or the preservation of intact ecosystems. However, ECOSPACE predicts that when MPAs are small, species interactions and movements may make these objectives difficult to achieve. ECOSPACE suggests that the effects of MPAs are reduced at their boundaries where fishing effort is predicted to concentrate. Furthermore, top predators may become more abundant within MPAs, which could lead to a depression of their prey species and a subsequent increase of species at even lower trophic levels. Trophic cascade patterns and density gradients across boundaries are nontrivial departures from our simple expectations of how MPAs protect areas and will force us to reconsider what constitutes effective conservation. Our ECOSPACE model indicates that the establishment of multi-use buffer zones may help alleviate these realistic but worrisome ecological predictions. When coupled with an overall reduction in harvest pressure, ECOSPACE suggests that a MPA with a large core `no-take' zone and large buffer will result in the greatest increase in organism biomass. The use of marine zoning may be an effective management tactic to reduce social conflict and conserve marine ecosystems.     

磷的生物有效性对山地生态系统的影响

磷(P)的生物有效性对山地生态系统的发育和稳定至关重要。由于大气CO_2浓度升高和N沉降增加,生态系统C、N和P的化学计量比失衡,P的生物有效性受到更多关注。近年来山地系统中P的研究不断深入,2004—2013年间ISI Web of Knowledge中相关研究论文几乎是此前近百年的3倍。总结了山地生态系统中P的生物有效性的特点及其对植物物种多样性和初级生产力的影响。山地生态系统P的生物有效性因垂直高差和地形梯度空间变异明显,快速物质运移和生物过程是控制山地生态系统P的生物有效性的关键因素。P的生物有效性可以影响山地生态系统物种多样性和初级生产力,其对初级生产力的限制存在于全球范围内的山地生态系统。当P的生物有效性发生改变时,山地生态系统的结构越复杂,其植物物种多样性和初级生产力的响应可能会越平缓。全球变化的重要驱动因子(如增温和N沉降增加)可以直接或间接地改变山地生态系统P的生物有效性,因此需要在山地生态系统中加强长期监测和养分控制实验,并结合新型P分析技术,以期认识山地生态系统P的生物有效性的现状、变化趋势和对生态系统的影响,从而为适应全球变化背景下山地生态系统养分状况的改变提供依据。     

Optimal Investment in Multi-species Protection: Interacting Species and Ecosystem Health

This article uses an ecological-economic approach to study optimal investment in multi-species protection when species interact in an ecosystem. The analysis is based on a model of stochastic species extinction in which survival probabilities are interdependent. Individual species protection plans can increase a species survival probability within certain limits and contingent upon the existence or absence of other species. Protection plans are costly and the conservation budget is fixed. It is assumed that human well-being depends solely on the services provided by one particular species, but other species contribute to overall ecosystem functioning and thus influence the first species survival probability. One result is that it may be optimal to invest in the protection of those species that do not directly contribute to human well-being, even if biological conservation decisions are exclusively derived from such a utilitarian framework. Another result is that the rank ordering of spending priorities among different species protection plans, as obtained under the assumption of independent species, may be completely reversed by taking species interaction into account. The conclusion is that effective species protection should go beyond targeting individual species, and consider species relations within whole ecosystems as well as overall ecosystem functioning. Ecosystem health is identified as a necessary prerequisite for successful species protection in situ.     

Climate change, biotic interactions and ecosystem services

Climate change is real. The wrangling debates are over, and we now need to move onto a predictive ecology that will allow managers of landscapes and policy makers to adapt to the likely changes in biodiversity over the coming decades. There is ample evidence that ecological responses are already occurring at the individual species (population) level. The challenge is how to synthesize the growing list of such observations with a coherent body of theory that will enable us to predict where and when changes will occur, what the consequences might be for the conservation and sustainable use of biodiversity and what we might do practically in order to maintain those systems in as good condition as possible. It is thus necessary to investigate the effects of climate change at the ecosystem level and to consider novel emergent ecosystems composed of new species assemblages arising from differential rates of range shifts of species. Here, we present current knowledge on the effects of climate change on biotic interactions and ecosystem services supply, and summarize the papers included in this volume. We discuss how resilient ecosystems are in the face of the multiple components that characterize climate change, and suggest which current ecological theories may be used as a starting point to predict ecosystem-level effects of climate change.