Political ecology: a synthesis and search for relevance to today's ecosystems conservation and development

Africa is facing problems of deforestation, desertification, loss of soil fertility, loss of wildlife habitats and biodiversity, and the deterioration of aquatic ecosystems and lack of accessible, good quality water. Governments have formulated policies, enacted legislation and established various institutions addressing these issues. African countries are yet to arrest the environmental problems they are facing, due to, among others, the ineffectual theoretical analysis of the problem of ecosystems degradation. This study argues for the adoption of the political ecological framework in the analysis of sociopolitical sources, conditions and ramifications of ecosystems change and also highlights the explanatory power of this conceptual framework as far as the explanation of the problem of ecosystems degradation is concerned, and shows how it can enable us deal with the multi-layered causality rather than the symptoms of the problem of ecosystems change.     

The physics and ecology of mining carbon dioxide from the atmosphere by ecosystems

Reforesting and managing ecosystems have been proposed as ways to mitigate global warming and offset anthropogenic carbon emissions. The intent of our opinion piece is to provide a perspective on how well plants and ecosystems sequester carbon. The ability of individual plants and ecosystems to mine carbon dioxide from the atmosphere, as defined by rates and cumulative amounts, is limited by laws of physics and ecological principles. Consequently, the rates and amount of net carbon uptake are slow and low compared to the rates and amounts of carbon dioxide we release by fossil fuels combustion. Managing ecosystems to sequester carbon can also cause unintended consequences to arise. In this paper, we articulate a series of key take‐home points. First, the potential amount of carbon an ecosystem can assimilate on an annual basis scales with absorbed sunlight, which varies with latitude, leaf area index and available water. Second, efforts to improve photosynthesis will come with the cost of more respiration. Third, the rates and amount of net carbon uptake are relatively slow and low, compared to the rates and amounts and rates of carbon dioxide we release by fossil fuels combustion. Fourth, huge amounts of land area for ecosystems will be needed to be an effective carbon sink to mitigate anthropogenic carbon emissions. Fifth, the effectiveness of using this land as a carbon sink will depend on its ability to remain as a permanent carbon sink. Sixth, converting land to forests or wetlands may have unintended costs that warm the local climate, such as changing albedo, increasing surface roughness or releasing other greenhouse gases. We based our analysis on 1,163 site‐years of direct eddy covariance measurements of gross and net carbon fluxes from 155 sites across the globe.     

Sentinel systems on the razor's edge: effects of warming on Arctic geothermal stream ecosystems

The Earth is experiencing historically unprecedented rates of warming, with surface temperatures projected to increase by 3–5 °C globally, and up to 7.5 °C in high latitudes, within the next century. Knowledge of how this will affect biological systems is still largely restricted to the lower levels of organization (e.g. species range shifts), rather than at the community, food web or ecosystem level, where responses cannot be predicted from studying single species in isolation. Further, many correlational studies are confounded with time and/or space, whereas experiments have been mostly confined to laboratory microcosms that cannot capture the true complexity of natural ecosystems. We used a ‘natural experiment’ in an attempt to circumvent these shortcomings, by characterizing community structure and trophic interactions in 15 geothermal Icelandic streams ranging in temperature from 5 °C to 45 °C. Even modest temperature increases had dramatic effects across multiple levels of organization, from changes in the mean body size of the top predators, to unimodal responses of species populations, turnover in community composition, and lengthening of food chains. Our results reveal that the rates of warming predicted for the next century have serious implications for the structure and functioning of these fragile ‘sentinel’ ecosystems across multiple levels of organization.     

The fundamental processes in ecology: a thought experiment on extraterrestrial biospheres

Ecological science is often organised as a hierarchical series of entities: genes, individuals, populations, species, communities, ecosystems and biosphere. Here, I consider an alternative process‐based approach to ecology, and analyse the nature of the fundamental processes in ecology. These fundamental processes are discussed in the context of the following question:‘for any planet with carbon‐based life, which persists over geological time scales, what are the minimum set of ecological processes that must be present?‘I suggest that the following processes would be present on any such planet: energy flow, multiple guilds, ecological tradeo ffs leading to within‐guild biodiversity, ecological hypercycles, merging of organismal and ecological physiology, carbon sequestration and possibly photosynthesis. Nutrient cycling is described as an emergent property of these fundamental processes. I discuss reasons why a biosphere based on a single species with no nutrient cycling is very unlikely to exist. I also describe the concept of ‘Gaian effect’. This suggests that some processes will always tend to extend the lifespan of a biosphere in which they develop (positive Gaian effect) while others could either increase or decrease (negative Gaian effect) such a lifespan. These ideas are discussed in the context of astrobiology, ecosystem services, conservation biology and Gaia theory.     

景感生态学在流域生态系统保护与修复实践中的应用——以大凌河流域北票段为例

生态系统保护与修复已成为我国生态文明建设的一项核心内容,自2016年以来,在全国24个省（自治区、直辖市）已开展了25个山水林田湖草生态保护修复工程试点工程。以大凌河流域北票段为研究区,探讨了景感生态学理论在山水林田湖草生态系统保护与修复实践中的应用。基于景感生态学理论,构建大凌河流域北票段生态系统保护与修复综合治理框架,以保持、改善和提升生态系统服务,实现可持续发展为目标,构建了"一中心、二重点、五要素、六工程"的生态系统保护与修复景感空间体系,并基于此将大凌河流域北票段生态系统保护与修复分为5个重要治理区域,形成"一带四区"的生态安全格局,提出了应用景感生态学理论,构建区域居民的共同行为规范,引导并实现人类对自然生态系统的有利影响,进一步提升生态系统保护与修复效果的对策建议。通过大凌河流域北票段的分析案例,以景感营造的理念开展区域生态系统保护与修复顶层设计,为促进区域可持续发展提供思路和途径。     

论21世纪生态学的新使命--演绎生态系统在地球表面系统过程中的作用

地球表面系统包括大气圈的对流层、水圈、生物圈和岩石圈的地壳部分 ,是“地球系统”中与人类当前生存关系最密切、最直接的部分。地球表面系统是一个反馈和控制系统 ,生物圈 ,尤其是人类表现出越来越重要的作用。地球表面系统研究使生态学与地学各学科领域相整合。在此新的整合研究中 ,不同生态系统类型成果的“整合”和向区域、流域尺度应用的“尺度转化”,以及生态过程与各地学过程的“整合”成为难点。文章介绍了地球表面系统的国际研究计划、研究状况和技术手段 ,总结了我国目前的研究进展、存在的问题 ,指出演绎生态系统在地球表面系统过程中的作用是本世纪生态学的重要任务 ,并提出了推动我国该领域发展的相关建议     

Pollination by nocturnal Lepidoptera,and the effects of light pollution: a review

1. Moths (Lepidoptera) are the major nocturnal pollinators of flowers. However, their importance and contribution to the provision of pollination ecosystem services may have been under‐appreciated. Evidence was identified that moths are important pollinators of a diverse range of plant species in diverse ecosystems across the world. 2. Moth populations are known to be undergoing significant declines in several European countries. Among the potential drivers of this decline is increasing light pollution. The known and possible effects of artificial night lighting upon moths were reviewed, and suggest how artificial night lighting might in turn affect the provision of pollination by moths. The need for studies of the effects of artificial night lighting upon whole communities of moths was highlighted. 3. An ecological network approach is one valuable method to consider the effects of artificial night lighting upon the provision of pollination by moths, as it provides useful insights into ecosystem functioning and stability, and may help elucidate the indirect effects of artificial light upon communities of moths and the plants they pollinate. 4. It was concluded that nocturnal pollination is an ecosystem process that may potentially be disrupted by increasing light pollution, although the nature of this disruption remains to be tested.     

Managing biological control services through multi‐trophic trait interactions: review and guidelines for implementation at local and landscape scales

Ecological studies are increasingly moving towards trait‐based approaches, as the evidence mounts that functions, as opposed to taxonomy, drive ecosystem service delivery. Among ecosystem services, biological control has been somewhat overlooked in functional ecological studies. This is surprising given that, over recent decades, much of biological control research has been focused on identifying the multiple characteristics (traits) of species that influence trophic interactions. These traits are especially well developed for interactions between arthropods and flowers – important for biological control, as floral resources can provide natural enemies with nutritional supplements, which can dramatically increase biological control efficiency. Traits that underpin the biological control potential of a community and that drive the response of arthropods to environmental filters, from local to landscape‐level conditions, are also emerging from recent empirical studies. We present an overview of the traits that have been identified to (i) drive trophic interactions, especially between plants and biological control agents through determining access to floral resources and enhancing longevity and fecundity of natural enemies, (ii) affect the biological control services provided by arthropods, and (iii) limit the response of arthropods to environmental filters, ranging from local management practices to landscape‐level simplification. We use this review as a platform to outline opportunities and guidelines for future trait‐based studies focused on the enhancement of biological control services.     

The predatory Chironomidae of an iron-rich stream: feeding ecology and food web structure

Abstract. 1. Three species of Tanypodinae (Chironomidae) were found in an acid and iron-rich stream in southern England. Maximum abundance was achieved in summer and they were sparse at other times. Individuals were aggregated on the stream bed and were overrepresented in accumulations of leaf litter.
2. The diets of all three species consisted of a mixture of prey (prominently detritivorous chironomid larvae) and detritus. More detritus and fewer prey were taken in winter than in summer.
3. When comparing large tanypod species with small and, intraspecifically, late instars with early, the proportion of guts containing prey increased with increasing body size.
4. Stonefly larvae were more prominent in the diet of Zavrelimyia barbatipes (Kieffer) in summer than in winter but for the other two species the reverse was true. A bigger proportion of Trissopelopia longimana (Staeger) guts contained prey in early summer than in August whereas more Macropelopia goetghebueri (Kieffer) guts contained prey in August. This was apparently a consequence of seasonal differences in the distribution of body size among the populations of these two species.
5. The stream contains two further common predators, Plectrocnemia conspersa (Curtis) and Sialis fuliginosa Pict. These are important predators of tanypod larvae but might also compete with them since they severely deplete populations of prey taken in common.
6. Analysis of the food-web in Broadstone Stream reveals remarkably high values of connectance (C and C_max) and of species richness times connectance (SC_max). Such characteristics are theoretically associated with fragile and dynamically unstable food webs, and may be found in 'constant' environments. There is also an apparently unusual prevalence of omnivory in the community.     

Contribution of nematodes to the structure and function of the soil food web

As carbon and energy flow through the soil food web they are depleted by the metabolic and production functions of organisms. To be sustained, a "long" food web, with a large biomass at higher trophic levels, must receive a high rate of rhizodeposition or detrital subsidy, or be top-populated by organisms of slow growth and long life cycle. Disturbed soil food webs tend to be bottom heavy and recalcitrant to restoration due to the slow growth of upper predator populations, physical and chemical constraints of the soil matrix, biological imbalances, and the relatively low mobility and invasion potential of soil organisms. The functional roles of nematodes, determined by their metabolic and behavioral activities, may be categorized as ecosystem services, disservices or effect-neutral. Among the disservices attributable to nematodes are overgrazing, which diminishes services of prey organisms, and plant-damaging herbivory, which reduces carbon fixation and availability to other organisms in the food web. Unfortunately, management to ameliorate potential disservices of certain nematodes results in unintended but long-lasting diminution of the services of others. Beneficial roles of nematodes may be enhanced by environmental stewardship that fosters greater biodiversity and, consequently, complementarity and continuity of their services.     

Connecting ecology to daily life: how students and teachers relate food webs to the food they eat

This study used sociocultural learning theory to better understand how middle and high school environmental science and biology students and pre- and in-service science teachers connect the daily life activity of eating to the food web model learned in school. We sought to understand how student and teacher perceptions of the environment and their experiences influenced their responses to interview questions regarding this topic. Findings, based on transcribed interviews with 54 study participants, indicate that three quarters of teachers and students were unable to connect the food they eat with ecosystem food webs. Even so, many respondents particularly those from elite public schools, did not demonstrate common food web misconceptions identified by other researchers, instead showing a sophisticated understanding of food web interactions. These findings indicate that even though participants were proficient in their school science understanding of food web interactions, they did not readily think about how their everyday out of school activities, like eating, relate to those interactions. This may be representative of a more general disconnect between formal ecology instruction and daily life activities. We provide several recommendations for how this disconnect can be remedied in our classrooms.     

A review on the effects of nitrogen and phosphorus addition on tree growth and productivity in forest ecosystems

Nitrogen (N) and phosphorus (P) inputs induced by anthropogenic activities and atmospheric N and P deposition have largely increased the availability of soil N and P in terrestrial ecosystems, which have considerably affected terrestrial carbon cycling processes. Tree growth and productivity in forest ecosystems play an important role in global carbon cycling, and determine the magnitude and direction of terrestrial carbon sequestration. Currently, a large number of field manipulation experiments have been conducted to investigate the effects of N and/or P addition on tree growth and forest productivity, but the results from these studies were inconsistent. Such inconsistent results might be affected by multiple factors, including biological, environmental and experimental variables. Here, we reviewed the present research status of the effects of N and P addition on tree growth and forest productivity in forest ecosystems based on three aspects, including the number of publications and experiments with field N and P addition, and the global distributions of these experiments. Then, we summarized the methods for assessing tree growth and forest productivity at ecosystem level in forest ecosystems, including relative growth rate and absolute increment. According to the related results, we reviewed the regulating factors that affect tree growth and productivity, and the potential mechanisms for such factors, including climate, tree size and stand age, plant functional traits (including type of tree-associated mycorrhizal fungi, N-fixation property of trees, and conservative and acquisitive functional traits), plant-microbe interaction, ambient nutrient (i.e., N and P) deposition rate, and experimental variables. Finally, we summarized the current studies, and pointed out five aspects that are urgently needed to provide further insights in future studies, including the physiological mechanism of how tree growth responds to N and P addition, the tradeoff and allocation among growth of various parts of tree under N and P addition, the role of plant functional traits in regulating and predicting the responses of tree growth to N and P addition, how the competition among trees regulates the responses of tree growth to N and P addition, and conducting long-term and coordinated distributed field experiments investigating the effects of N and P addition on tree growth and forest productivity at the global scale.     

生态学的科学概念及其演变与当代生态学学科体系之商榷

生态学既是生物学的分支学科,也是环境科学、地球系统科学的重要组成部分,其研究成果可直接服务于植物、动物、微生物的生物多样性保护、生物资源利用及生物产业管理等应用领域.生态系统概念将经典生态学或者基础生态学研究扩展到了生态系统生态学或者生态系统科学的新阶段,奠定了大尺度及全球生态环境科学研究的理论基础,促进了生物学、地理...     

Comparative and Experimental Approaches to the Study of Microbial Food Webs

ABSTRACT The study of microbial food webs is dominated by field measurements of microbial standing stocks and rate processes and to a lesser extent by laboratory studies. These approaches reflect the concerns of microbial ecologists to assess accurately the capabilities of microorganisms and to compare microbial processes to other ecosystem parameters. These approaches have led to enormous advances in understanding microbial food webs. Reconciling our expanding knowledge with general questions about the significance and representation of microbial food webs in ecosystem studies requires additional approaches including comparative studies and field experiments. Comparative studies, analyses of microbial stocks or rates across a wide range of ecosystems, lead to quantitative models of microbial processes. These models facilitate testing of hypotheses at a very general level, allow the comparison of different stocks or rate processes across a gradient of systems, and detect unusual situations or outlier systems. Field experimental manipulations offer the advantages of working with intact natural communities, of direct evaluation of results with statistical methods, and of testing important qualitative hypotheses. Both comparative and field manipulation studies have led to important advances in the study of microbial food webs and should be expanded.     

氮磷添加对树木生长和森林生产力影响的研究进展

人为活动所导致的氮、磷输入和大气氮、磷沉降使生态系统中的氮、磷可利用性大幅提高, 对陆地生态系统的碳循环过程产生了显著影响。树木生长和森林生产力在全球碳循环中发挥着重要作用, 它决定着陆地碳固存的大小和方向。目前, 在全球范围内开展了很多氮、磷添加调控树木生长和森林生产力的野外控制实验, 但是研究结果并不一致, 受到多种生物、环境和实验处理条件等因素的影响。该文从野外氮添加和磷添加实验的文献数量、实验数量及其全球空间分布三个方面概述了氮、磷添加对树木生长和森林生产力影响的研究现状, 并总结了氮、磷添加实验中树木生长和森林生产力的评估方法, 包括相对生长速率和绝对增长量。基于相关的研究结果, 阐述了氮、磷添加影响树木生长和森林生产力的调控因素及其潜在影响机制, 包括气候、树木径级与林龄、植物功能性状(共生菌根类型、树木固氮属性和保守性与获得性性状)、植物和微生物相互作用关系、区域养分沉降速率和实验处理条件等。最后, 基于当前的研究进行了系统总结, 并指出今后需要加强的几个方面的研究, 以期为后续研究提供参考: 树木生长响应氮、磷添加的生理学机制, 树木各部分生长对氮、磷添加响应的权衡与分配, 植物功能性状在调节与预测树木生长响应氮、磷添加中的作用, 树木之间的竞争关系如何调控氮、磷添加对树木生长的影响, 以及开展长期的和联网的氮、磷添加对树木生长和森林生产力影响的野外控制实验。     

Industrial Ecosystems and Food Webs: An Expansion and Update of Existing Data for Eco‐Industrial Parks and Understanding the Ecological Food Webs They Wish to Mimic

Cyclical industrial networks are becoming highly desirable for their efficient use of resources and capital. Progress toward this ideal can be enhanced by mimicking the structure of naturally sustainable ecological food webs (FWs). The structures of cyclic industrial networks, sometimes known as eco‐industrial parks (EIPs), are compared to FWs using a variety of important structural ecological parameters. This comparison uses a comprehensive data set of 144 FWs that provides a more ecologically correct understanding of how FWs are organized than previous efforts. In conjunction, an expanded data set of 48 EIPs gives new insights into similarities and differences between the two network types. The new information shows that, at best, current EIPs are most similar to those FWs that lack the components that create a biologically desirable cyclical structure. We propose that FWs collected from 1993 onward should be used in comparisons with EIPs, given that these networks are much more likely to include important network functions that directly affect the structure. We also propose that the metrics used in an ecological analysis of EIPs be calculated from an FW matrix, as opposed to a community matrix, which, to this point, has been widely used. These new insights into the design of ecologically inspired industrial networks clarify the path toward superior material and energy cycling for environmental and financial success.     

景观生态学:海洋生态系统研究的一个新视角

全球海洋生态系统作为异质性的复杂巨系统是一类景观生态系统 ,具有明显的等级结构 ,因此 ,景观生态学的原理和方法完全可以应用到海洋生态学的研究中来。生态系统的尺度限制了海洋生态学向更加宏观的方向进一步发展 ,在景观的水平上 ,运用景观生态学的理论和方法可以更好地在多个尺度上开展深入广泛的研究。本文不仅讨论了海洋景观的空间异质性 ,而且就海洋景观生态学的若干研究方向进行了探讨。     

基于景感生态学的城市生态空间服务提升研究——以北京市顺义区为例

景感生态学思想融合自然要素、物理感知、心理认知等方面,并服务于土地利用与建设。北京市在迈向建设国际一流的和谐宜居之都目标过程中,极为重视城市居民对城市生态空间的感知和互动,充分体现了将城市生态空间与人居环境质量和心理健康耦合分析的景感生态学的理念。从结合景感生态学中景感营造的思想和顺义区生态规划实践的角度出发,分析了顺义区生态空间景观格局和视觉空间格局。结果表明,顺义区的森林、草地、湿地等斑块相对比较破碎,中心城区的森林、绿地较少;顺义区具有中等以下绿视率的路段长度占比近60%,中等以上水平尤其是较高水平绿视率的路段较少,具有较大的通过景感营造提升生态服务的空间。进而以提升顺义区的城市生态空间服务为目标,总结出了生态空间景观格局优化、视觉空间格局优化、生态空间科学规划及管控、生态系统服务综合提升4个核心愿景,并基于这4个愿景提出了针对性的景感营造措施。     

Climate change and freshwater ecosystems: impacts across multiple levels of organization

Fresh waters are particularly vulnerable to climate change because (i) many species within these fragmented habitats have limited abilities to disperse as the environment changes; (ii) water temperature and availability are climate-dependent; and (iii) many systems are already exposed to numerous anthropogenic stressors. Most climate change studies to date have focused on individuals or species populations, rather than the higher levels of organization (i.e. communities, food webs, ecosystems). We propose that an understanding of the connections between these different levels, which are all ultimately based on individuals, can help to develop a more coherent theoretical framework based on metabolic scaling, foraging theory and ecological stoichiometry, to predict the ecological consequences of climate change. For instance, individual basal metabolic rate scales with body size (which also constrains food web structure and dynamics) and temperature (which determines many ecosystem processes and key aspects of foraging behaviour). In addition, increasing atmospheric CO₂ is predicted to alter molar CNP ratios of detrital inputs, which could lead to profound shifts in the stoichiometry of elemental fluxes between consumers and resources at the base of the food web. The different components of climate change (e.g. temperature, hydrology and atmospheric composition) not only affect multiple levels of biological organization, but they may also interact with the many other stressors to which fresh waters are exposed, and future research needs to address these potentially important synergies.     

Response diversity determines the resilience of ecosystems to environmental change

A growing body of evidence highlights the importance of biodiversity for ecosystem stability and the maintenance of optimal ecosystem functionality. Conservation measures are thus essential to safeguard the ecosystem services that biodiversity provides and human society needs. Current anthropogenic threats may lead to detrimental (and perhaps irreversible) ecosystem degradation, providing strong motivation to evaluate the response of ecological communities to various anthropogenic pressures. In particular, ecosystem functions that sustain key ecosystem services should be identified and prioritized for conservation action. Traditional diversity measures (e.g. ‘species richness’) may not adequately capture the aspects of biodiversity most relevant to ecosystem stability and functionality, but several new concepts may be more appropriate. These include ‘response diversity’, describing the variation of responses to environmental change among species of a particular community. Response diversity may also be a key determinant of ecosystem resilience in the face of anthropogenic pressures and environmental uncertainty. However, current understanding of response diversity is poor, and we see an urgent need to disentangle the conceptual strands that pervade studies of the relationship between biodiversity and ecosystem functioning. Our review clarifies the links between response diversity and the maintenance of ecosystem functionality by focusing on the insurance hypothesis of biodiversity and the concept of functional redundancy. We provide a conceptual model to describe how loss of response diversity may cause ecosystem degradation through decreased ecosystem resilience. We explicitly explain how response diversity contributes to functional compensation and to spatio‐temporal complementarity among species, leading to long‐term maintenance of ecosystem multifunctionality. Recent quantitative studies suggest that traditional diversity measures may often be uncoupled from measures (such as response diversity) that may be more effective proxies for ecosystem stability and resilience. Certain conclusions and recommendations of earlier studies using these traditional measures as indicators of ecosystem resilience thus may be suspect. We believe that functional ecology perspectives incorporating the effects and responses of diversity are essential for development of management strategies to safeguard (and restore) optimal ecosystem functionality (especially multifunctionality). Our review highlights these issues and we envision our work generating debate around the relationship between biodiversity and ecosystem functionality, and leading to improved conservation priorities and biodiversity management practices that maximize ecosystem resilience in the face of uncertain environmental change.