Threats and opportunities for freshwater conservation under future land use change scenarios in the United States

Freshwater ecosystems provide vital resources for humans and support high levels of biodiversity, yet are severely threatened throughout the world. The expansion of human land uses, such as urban and crop cover, typically degrades water quality and reduces freshwater biodiversity, thereby jeopardizing both biodiversity and ecosystem services. Identifying and mitigating future threats to freshwater ecosystems requires forecasting where land use changes are most likely. Our goal was to evaluate the potential consequences of future land use on freshwater ecosystems in the coterminous United States by comparing alternative scenarios of land use change (2001–2051) with current patterns of freshwater biodiversity and water quality risk. Using an econometric model, each of our land use scenarios projected greater changes in watersheds of the eastern half of the country, where freshwater ecosystems already experience higher stress from human activities. Future urban expansion emerged as a major threat in regions with high freshwater biodiversity (e.g., the Southeast) or severe water quality problems (e.g., the Midwest). Our scenarios reflecting environmentally oriented policies had some positive effects. Subsidizing afforestation for carbon sequestration reduced crop cover and increased natural vegetation in areas that are currently stressed by low water quality, while discouraging urban sprawl diminished urban expansion in areas of high biodiversity. On the other hand, we found that increases in crop commodity prices could lead to increased agricultural threats in areas of high freshwater biodiversity. Our analyses illustrate the potential for policy changes and market factors to influence future land use trends in certain regions of the country, with important consequences for freshwater ecosystems. Successful conservation of aquatic biodiversity and ecosystem services in the United States into the future will require attending to the potential threats and opportunities arising from policies and market changes affecting land use.     

Towards an urban marine ecology: characterizing the drivers,patterns and processes of marine ecosystems in coastal cities

Human population density within 100 km of the sea is approximately three times higher than the global average. People in this zone are concentrated in coastal cities that are hubs for transport and trade – which transform the marine environment. Here, we review the impacts of three interacting drivers of marine urbanization (resource exploitation, pollution pathways and ocean sprawl) and discuss key characteristics that are symptomatic of urban marine ecosystems. Current evidence suggests these systems comprise spatially heterogeneous mosaics with respect to artificial structures, pollutants and community composition, while also undergoing biotic homogenization over time. Urban marine ecosystem dynamics are often influenced by several commonly observed patterns and processes, including the loss of foundation species, changes in biodiversity and productivity, and the establishment of ruderal species, synanthropes and novel assemblages. We discuss potential urban acclimatization and adaptation among marine taxa, interactive effects of climate change and marine urbanization, and ecological engineering strategies for enhancing urban marine ecosystems. By assimilating research findings across disparate disciplines, we aim to build the groundwork for urban marine ecology – a nascent field; we also discuss research challenges and future directions for this new field as it advances and matures. Ultimately, all sides of coastal city design: architecture, urban planning and civil and municipal engineering, will need to prioritize the marine environment if negative effects of urbanization are to be minimized. In particular, planning strategies that account for the interactive effects of urban drivers and accommodate complex system dynamics could enhance the ecological and human functions of future urban marine ecosystems.     

基于元胞自动机的城市空间动态模拟

城市空间动态的模拟与预测可以为城市可持续发展规划与管理提供重要的参考依据。SLEUTH元胞自动机模型在城市空间模拟中较强的适用性和可移植性,该模型通过对历史数据的蒙特卡洛迭代自动寻找城市增长误差最小的参数组合,解决了传统元胞自动机模型中转换规则不易确定的问题。以武汉市为研究案例,运用SLEUTH模型进行了城市空间动态模拟与情景预测。2007年至2011年的城市空间模拟结果显示,模拟结果与实际历史数据可以获得良好的空间匹配度,Lee-Sallee形状指数均在0.6以上,显示SLEUTH元胞自动机模型经过本地化校正后具有较强的适用性和满意的模拟精度。进而,设置了现状趋势、基本保护、严格保护等3种情景对武汉2025年城市空间动态进行了预测,结果显示,各情景模式下城市居住用地均明显增长,农业用地、林地、水域等均有所减少;现状趋势情景和基本保护情景下农田、林地、水域减少的幅度较大,会加剧区域的生境破碎、耕地功能下降、水资源匮乏、湖滨湿地萎缩等生态问题,说明这两种情景不能有效满足城市生态系统健康和可持续发展的需要。严格保护情景下,城市居住用地扩张的程度得到了明显的控制,水域和林地得到了有效的保护,对于重要的自然生态系统组分保护及其服务能力维持可以起到显著作用。     

The impact of projected increases in urbanization on ecosystem services

Alteration in land use is likely to be a major driver of changes in the distribution of ecosystem services before 2050. In Europe, urbanization will probably be the main cause of land-use change. This increase in urbanization will result in spatial shifts in both supplies of ecosystem services and the beneficiaries of those services; the net outcome of such shifts remains to be determined. Here, we model changes in urban land cover in Britain based on large (16%) projected increases in the human population by 2031, and the consequences for three different services--flood mitigation, agricultural production and carbon storage. We show that under a scenario of densification of urban areas, the combined effect of increasing population and loss of permeable surfaces is likely to result in 1.7 million people living within 1 km of rivers with at least 10 per cent increases in projected peak flows, but that increasing suburban 'sprawl' will have little effect on flood mitigation services. Conversely, losses of stored carbon and agricultural production are over three times as high under the sprawl as under the 'densification' urban growth scenarios. Our results illustrate the challenges of meeting, but also of predicting, future demands and patterns of ecosystem services in the face of increasing urbanization.     

闽三角城市群生态安全格局构建及城镇扩展模拟

在快速城镇化背景下，构建生态安全格局并探讨城镇用地扩展格局已成为保障区域生态安全和缓解生态保护与土地开发矛盾的重要手段。以闽三角城市群为例，基于景观安全格局原理和ArcGIS空间分析法，从综合水安全、生物保护安全、地质灾害安全以及游憩安全四个方面叠加构建"底线安全格局-缓冲安全格局-最优安全格局"三种不同安全水平的综合生态安全格局；然后结合SLEUTH模型，将不同生态安全格局情景作为约束条件融入其排除图层，对研究区2015-2030年的城镇用地空间扩展进行多情景模拟。研究表明：①底线安全格局、缓冲安全格局以及最优安全格局的面积为9305.51、7576.28、3482.73 km²，分别占闽三角城市群总面积的36.89%、30.03%、13.81%；②三种生态安全格局情景模拟下城镇用地均呈增长趋势，但增长速度均小于历史用地的增长速度，高安全格局约束下的新增城镇用地面积和增长速度均最小，表明将生态安全格局作为城镇发展的约束条件，在城镇土地开发中能够增强对生态空间的保护力度，维护区域生态安全，控制城镇蔓延。相关研究成果可为城镇开发边界管控与国土空间规划的编制提供技术支撑与决策辅助。     

Ecosystem engineering impact of Limnoperna fortunei in South America

Limnoperna fortunei, or golden mussel, has invaded aquatic ecosystems in the Americas following it introduction from Southeast Asia. It is not only an aggressive invasive species, it is also a very effective ecosystem engineer, altering both ecosystem structure and function, and causes great ecological and economic impacts. This paper describes its impact as an ecosystem engineer (on benthic communities and the water column). A review of the existing scientific literature is presented, and the impact and the mechanisms by which the golden mussel modifies, maintains, and creates new environmental conditions in the invaded South American inland freshwater environments are analyzed. Understanding the ecosystem engineering roles of L. fortunei is important for its management and/or control in the invaded areas, and in cases of future invasions.     

全球环境变化对典型生态系统的影响研究:现状、挑战与发展趋势

随着全球环境变化和人类活动对生态系统影响的日益加深,生态系统结构和功能发生强烈变化,生态系统提供各类资源和服务的能力在显著下降。在这种背景下,全面认识生态系统的结构功能与全球环境变化的关系已成为当前生态学研究的热点之一。本文综述了全球环境变化对典型生态系统(包括森林生态系统、河口湿地生态系统、城市生态系统)影响以及全球环境变化适应的研究现状,分析研究面临的困难及挑战。在此基础上,提出对未来研究发展趋势的展望。在森林生态系统与全球环境变化研究上,未来应重视能更好模拟现实情景的、多因子、长期的全球环境变化控制试验,并注重不同生物地球化学循环之间的耦合作用。在湿地生态系统与全球环境变化研究上,未来应加强氮沉降、硫沉降及盐水入侵对湿地生态系统碳氮循环的影响,明晰滨海湿地的蓝碳功能,加强极端气候和人类干扰影响下湿地生态系统结构和功能变化及恢复力的研究。在城市生态系统与全球环境变化研究上,未来应深化城市生物地球化学循环机制研究,实现城市生态系统的人本需求侧重与转向,并开展典型地区长期、多要素综合响应研究。在全球环境变化适应研究上,未来应构架定量化、跨尺度的适应性评价体系,加强典型区域/部门的适应性研究以及适应策略实施的可行性研究,注重适应与减缓对策的关联研究及实施的风险评估。期望本综述为我国生态系统与全球环境变化研究提供一些参考。     

区县生态系统健康评价方法——以东莞市各镇区为例

现有城市生态系统健康研究多集中在城市及城市群层面，未能深入探究城市内部特征。鉴于此，聚焦区县生态系统健康状况，进一步探究城市内部的健康分布特征；提出了"发展水平-服务功能-抵御干扰-自我维育"四维区县生态系统健康评价框架，并建立了相应的多层级指标体系，构建了区县生态系统健康评价模型；在分析区县生态系统健康变化过程及空间分异特征的基础上，识别区县生态系统健康的主要贡献因子。针对东莞各镇区的研究结果表明：1995-2015年间，各镇区生态系统健康状态总体趋于恶化，其中西南地区生态系统的退化比东南地区更为明显。自我维育对各镇区生态系统健康变化具有重要影响，主要瓶颈在于快速发展过程中土地资源的稀缺及较低的利用效率。对区县生态系统健康的研究可以帮助决策者了解城市生态系统复杂的内部特征，在此基础上更好地平衡区域发展、维护城市生态系统健康。     

Spatial and temporal population change in the Tehran Metropolitan Region and its consequences on urban decline and sprawl

In the last three decades, Tehran has experienced urban sprawl and decline. The aim of this study is to look into the process of urban sprawl as a spatial and visual manifestation of Tehran's periphery expansion between 1976 and 2016. In relation to population growth and Tehran's urban decline and sprawl, four major urban development stages were investigated: urbanization, counter-urbanization, ex-urbanization, and re-urbanization. As a result, data analysis required the application of the Distributional Model, Moran's Spatial Correlations at both the global and local levels, and G general statistics. The Shannon Entropy and Holdren models are then used to measure the degree of metropolitan region urban sprawl over the course of the study period. Between 1976 and 2016, the population of Tehran city and the Tehran Metropolitan Region (TMR) increased dramatically, with Tehran city continuing to increase from 2.7 to 8.73 million, Tehran periphery cities increasing from, 417,000 to 7.24 million, and the TMR continuing to increase from 3.13 to 15.98 million. These changes would manifest spatially as urban sprawl and decline. The study's findings revealed a link between the TMR's pattern and manner of sprawl development and urban deterioration. As a result, future research on well-adjusted and planned TMR development will be available.     

关于蝗虫多样性与草原生态系统可持续发展的若干科学问题

蝗虫多样性既是草原生态系统演化的产物 ,反过来也影响着草原生态系统的结构与功能。蝗虫多样性状况与草原生态系统的持续发展有着密切的关联 ,这其中的科学问题包括 :(1 )蝗虫多样性及其空间变异机理 ;(2 )蝗虫多样性对草原生态系统过程的影响 ;(3 )蝗虫多样性空间格局与草原生态系统演化中的自然和人文因素的关联 ;(4 )蝗虫种群暴发的多样性阈值与草原生态系统的调控 ;(5 )蝗虫多样性和稳定性与草原生态系统的健康等。深入发掘生物多样性所包含的科学内涵 ,将一个物种的多样性与生态系统的结构和功能耦合起来研究 ,从重要物种蝗虫的生物多样性入手 ,深入探讨草原生态系统的持续发展问题 ,将为减少或减轻我国西部草原蝗灾发生提供科学的支持     

Evaluation of global warming impacts on the carbon budget of terrestrial ecosystems in monsoon Asia: a multi-model analysis

This study assesses the potential impacts of future global warming on the carbon budget of terrestrial ecosystems across monsoon Asia using the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP) dataset. We used simulation results of two emission pathways (RCP2.6 and RCP8.5), climate projections of five climate models, and seven terrestrial biome models to analyze the changes in net primary production and carbon stocks in the South, Southeast, and East Asian subregions during the period 1981–2099. The simulations indicated that by the end of the 21st century, net primary production would increase by 9–45 % and ecosystem carbon storage would increase by 42–86 Pg C. The clearest climatic impacts were found when using the adaptation-oriented emission scenario (RCP8.5), which assumes a greater CO₂ increase and a larger change in climatic conditions. Substantial disparities in temporal trajectories and spatial patterns were found in the estimated changes, owing to the uncertainties in the emission scenarios, climate projections, and ecosystem models. We attempted to derive consistent patterns throughout the simulations to specify potential hotspots of climatic impacts (e.g., soil carbon change in the southern Tibetan Plateau). Finally, we discuss changes to the climatic characteristics in the study region (e.g., a change in the rainy season), the implications for ecosystem services, and the need for collaborative field monitoring studies.     

Does Urban Sprawl Impact on Self-Rated Health and Psychological Distress? A Multilevel Study from Sydney, Australia

Mental health can be influenced by a number of neighbourhood physical and social environmental characteristics. We aimed to determine whether urban sprawl (based on population density) in Sydney, Australia, is associated with self-rated health and psychological distress. We used a cross-sectional multilevel study design. Individual level data on self-rated health and psychological distress were obtained from the 2006 and 2007 NSW Population Health Survey. We did not find significant associations between urban sprawl and self-rated health and psychological distress after controlling for individual and area level covariates. However, positive neighbourhood factors were generally associated with better self-rated health and lower psychological distress but few of these associations were statistically significant.     

城市生态景观建设的指导原则和评价指标

在人口膨胀和快速城市化的全球化背景下,构建人与自然和谐的生态景观是城市景观规划和设计的基本美学观和价值观.缺乏统一的指导原则和评价标准使得城市生态景观建设出现了很多问题,也限制了生态景观的进一步推广和实践.基于文献调研和专家咨询的方式,归纳了城市生态景观的基本内涵和指导原则,并提出了针对性的评价指标.通过问卷调查的方式,获取了170余份有效问卷,据此分析公众对城市生态景观的理解和需求.可以依据该结果为城市生态景观的定量评价提供初步的权重值,为进一步完善生态景观建设的理论和方法提供了参考和依据.     

间套作种植提升农田生态系统服务功能

间套作是指在同一块土地上同时种植两种或两种以上的作物,能够充分利用有限资源,提升单位面积物质产出,同时还具有多重其他生态效益,是一种基于生物多样性的可持续农业发展范式.生态系统服务是评价生态系统功能的重要突破口,也是当前生态学领域研究的热点问题.从生态系统服务的角度论述间套作种植提升农田生态系统服务功能,并从物质产出、土壤肥力维持、生物多样性保护、水土保持、病虫草害和有害污染物控制等方面论述了间套作种植提升农田生态系统功能的实践及机制.在此基础上,构建了间套作农田生态系统服务功能评价的理论框架和指标体系,并提出了间套作种植农田生态系统未来应加强的研究方向.     

The trade-off between housing density and sprawl area: Minimising impacts to forest breeding birds

Increasing housing density is generally assumed to confer negative effects on forest breeding birds. This implies we should build at low density over the landscape to conserve these species. However, for a given human population, low-density development must cover a large area, resulting in sprawl. A pertinent question is then: at what housing density are the impacts of a given human population on forest biodiversity minimised? For a given human population, it is unclear whether the impacts on forest biodiversity are less where housing density is high and sprawl area is small or where housing density is low and sprawl area is large. We addressed this question using the abundance, species richness and evenness of forest birds in Ottawa, Ontario and Gatineau, Quebec, Canada. First, we counted breeding birds at 22 sites representing a range of housing densities. We then used these empirical measurements to estimate forest bird abundance, species richness and evenness in four hypothetical development scenarios representing the trade-off between housing density and sprawl area. With the exception of the Undeveloped scenario (i.e., continuous forest), forest birds and forest interior birds were most abundant in the Compact scenario and most speciose in the Semi-compact scenario, whereas forest edge birds were most abundant and speciose in the Dispersed scenario. All three bird groups were most even in the Compact scenario. We conclude that compact housing development (building at high density over a small area) minimises the impacts of a given human population on forest breeding birds.     

Effects of decadal experimental drought and climate extremes on vegetation growth in Mediterranean forests and shrublands

Increased drought combined with extreme episodes of heatwaves is triggering severe impacts on vegetation growth, particularly for plant communities in arid and semiarid ecosystems. Although there is an abundance of short‐term field drought experiments in natural ecosystems, remaining knowledge gaps limit the understanding and prediction of vegetation growth to ongoing and future climate scenarios. Here, we assessed the impacts of long‐term (1999–2016) experimental drought (ca. ?30% rainfall) on the vegetation growth of a Mediterranean high (H) and low (L)‐canopy forests and an early‐successional shrubland, as indicated by above‐ground biomass increment (ABI) and standing density, respectively. We found habitat context (impact of historical climate change, soil depth and successional status) of the study sites significantly affected the magnitude of climate impacts; there were synergistic effects of experimental drought and meteorological drought (Standardised Precipitation–Evapotranspiration Index, SPEI) as well as extreme dry years on vegetation growth. Long‐term experimental drought decreased the ABI for the two forest canopy types and the standing density for the shrubland. Water availabilities in winter–spring (SPEIs) were positively correlated with the ABI and standing density. Moreover, experimental drought decreased the vegetation growth in extreme dry years for the shrubland. We propose that future work not only study the vegetation dynamics with physiological, phenological and demographical changes in long‐term processes and across climate gradients, but also should explore the changes of multiple functions simultaneously (e.g. multifunctionality) under long‐term processes and extremes. This type of analysis of long‐term data is essential to understand and predict biodiversity loss, composition shifts, declines in ecosystem function and carbon budgets at temporal and spatial scales, to enable policy makers to design and implement strategies for the maintenance of sustainable ecosystem function under future climate change scenarios.     

North Sea cod and climate change – modelling the effects of temperature on population dynamics

In order to examine the likely impacts of climate change on fish stocks, it is necessary to couple the output from large‐scale climate models to fisheries population simulations. Using projections of future North Sea surface temperatures for the period 2000–2050 from the Hadley General Circulation Model, we estimate the likely effects of climate change on the North Sea cod population. Output from the model suggests that increasing temperatures will lead to an increased rate of decline in the North Sea cod population compared with simulations that ignore environmental change. Although the simulation developed here is relatively simplistic, we demonstrate that inclusion of environmental factors in population models can markedly alter one's perception of how the population will behave. The development of simulations incorporating environment effects will become increasingly important as the impacts of climate change on the marine ecosystem become more pronounced.     

Top 10 Principles for Designing Healthy Coastal Ecosystems Like the Salish Sea

Like other coastal zones around the world, the inland sea ecosystem of Washington (USA) and British Columbia (Canada), an area known as the Salish Sea, is changing under pressure from a growing human population, conversion of native forest and shoreline habitat to urban development, toxic contamination of sediments and species, and overharvest of resources. While billions of dollars have been spent trying to restore other coastal ecosystems around the world, there still is no successful model for restoring estuarine or marine ecosystems like the Salish Sea. Despite the lack of a guiding model, major ecological principles do exist that should be applied as people work to design the Salish Sea and other large marine ecosystems for the future. We suggest that the following 10 ecological principles serve as a foundation for educating the public and for designing a healthy Salish Sea and other coastal ecosystems for future generations: (1) Think ecosystem: political boundaries are arbitrary; (2) Account for ecosystem connectivity; (3) Understand the food web; (4) Avoid fragmentation; (5) Respect ecosystem integrity; (6) Support nature’s resilience; (7) Value nature: it’s money in your pocket; (8) Watch wildlife health; (9) Plan for extremes; and (10) Share the knowledge.     

The effects of urbanization on pollinators and pollination: A meta-analysis

Urbanization is increasing worldwide, with major impacts on biodiversity, species interactions and ecosystem functioning. Pollination is an ecosystem function vital for terrestrial ecosystems and food security; however, the processes underlying the patterns of pollinator diversity and the ecosystem services they provide in cities have seldom been quantified. Here, we perform a comprehensive meta-analysis of 133 studies examining the effects of urbanization on pollinators and pollination. Our results confirm the widespread negative impacts of urbanization on pollinator richness and abundance, with Lepidoptera being the most affected group. Furthermore, pollinator responses were found to be trait-specific, with below-ground nesting and solitary Hymenoptera, and spring flyers more severely affected by urbanization. Meanwhile, cities promote non-native pollinators, which may exacerbate conservation risks to native species. Surprisingly, despite the negative effects of urbanization on pollinator diversity, pollination service measured as seed set is enhanced in non-tropical cities likely due to abundant generalists and managed pollinators therein. We emphasize that the richness of local flowering plants could mitigate the negative impacts of urbanization on pollinator diversity. Overall, the results demonstrate the varying magnitudes of multiple moderators on urban pollinators and pollination services and could help guide conservation actions for biodiversity and ecosystem function for a sustainable future.     

Recent evolutionary history predicts population but not ecosystem‐level patterns

In the face of rapid anthropogenic environmental change, it is increasingly important to understand how ecological and evolutionary interactions affect the persistence of natural populations. Augmented gene flow has emerged as a potentially effective management strategy to counteract negative consequences of genetic drift and inbreeding depression in small and isolated populations. However, questions remain about the long‐term impacts of augmented gene flow and whether changes in individual and population fitness are reflected in ecosystem structure, potentiating eco‐evolutionary feedbacks. In this study, we used Trinidadian guppies (Poecilia reticulata) in experimental outdoor mesocosms to assess how populations with different recent evolutionary histories responded to a scenario of severe population size reduction followed by expansion in a high‐quality environment. We also investigated how variation in evolutionary history of the focal species affected ecosystem dynamics. We found that evolutionary history (i.e., gene flow vs. no gene flow) consistently predicted variation in individual growth. In addition, gene flow led to faster population growth in populations from one of the two drainages, but did not have measurable impacts on the ecosystem variables we measured: zooplankton density, algal growth, and decomposition rates. Our results suggest that benefits of gene flow may be long‐term and environment‐dependent. Although small in replication and duration, our study highlights the importance of eco‐evolutionary interactions in determining population persistence and sets the stage for future work in this area.