Predatory pelagic fishes of the Bijagós Archipelago (Guinea-Bissau) show high overlap in diets dominated by sardinella

Knowledge of trophic interactions between the key components of marine communities is required to understand food-web dynamics and develop ecosystem-based management approaches. In West Africa, where fisheries sustain the livelihoods of a significant part of the human population, this understanding is even more urgent, especially in the face of rapidly expanding fisheries and some stock collapses in the region. We studied the feeding ecology of the Crevalle jack Caranx hippos, West African Spanish mackerel Scomberomorus tritor and Guinean barracuda Sphyraena afra in the Bijagós Archipelago, Guinea-Bissau. These are the most abundant pelagic predatory teleost fishes in the area, but little is known about their ecology despite being species with commercial and recreational value, and they likely also play an important role in various African coastal ecosystems. Our findings show a high degree of dietary overlap among these three predator species, despite some degree of segregation by prey size and type. All three predators depend on Sardinella maderensis as the most important prey, which together with other members of the Clupeidae represented 47–96% of the ingested prey items. There was little difference in the diets of the predators between the dry and rainy seasons. These novel findings suggest a ‘wasp-waist’-structured ecosystem in the Bijagós Archipelago in which S. maderensis is the central small-sized pelagic fish species, and stress the need for an ecosystem-based approach to fisheries management in the region, with precautionary measures taken to avoid the overexploitation of clupeids.     

近55 a新疆净生态系统生产力对气候变化的响应

新疆地处干旱和半干旱气候区,明确其生态系统的碳汇大小及其对气候变化的响应对研究中国干旱区植被碳汇及其对陆地碳平衡的贡献具有重要意义。基于最新地面气象观测数据,利用大气植被相互作用模型AVIM2（Atmosphere-Vegetation Interaction Model 2）,在0.05°×0.05°经纬度空间网格上估算分析了1961-2015年新疆净生态系统生产力（NEP）的时空分布特征及其对气候变化的响应。研究结果表明：近55 a新疆NEP平均值为14.4 gC·m^-2,没有明显变化趋势。空间上看,约40%地区的NEP呈下降趋势,主要分布在天山两麓的城市人口聚集区;而60%地区NEP呈上升走势,其主要分布在新疆昆仑山脉、天山山区和人烟稀少的荒漠地区。新疆NEP对降水量变化更为敏感,气温的变化对NEP的影响并不显著。虽然新疆平均碳汇随着年降水量的变化而在源与汇之间波动,但是从多年平均来看,新疆仍然为碳汇区。     

基于生态敏感性和生态系统服务的黑河中游生态功能区划与生态系统管理

生态功能区划是协调生态保护与经济发展的矛盾、实施区域生态系统管理的重要途径。以黑河中游为研究区,基于基础地理信息数据、自然地理数据和土地覆被数据（1986、1995、2000、2010、2011年）,在生态敏感性和生态系统服务重要性分析的基础上,以最小子流域为基本单元,运用二阶聚类法进行生态功能区划;并依据主导生态系统服务对研究区进行分区管理与生态调控。得出结论：（1）黑河中游生态系统类型以荒漠、草地和农田为主,占总面积的90%;森林、水域、城镇与农村居民点零星分布,所占面积不到10%;1986-2010年,农田经历了减少-扩张-再减少的变化,但城镇与农村居民点一直呈现扩张趋势;（2）西北部生态敏感性明显高于东南部,其中极敏感区（约占24%）主要位于张掖-临泽-高台平原北侧、合黎山、祁连山山前戈壁与荒漠、肃南明花区;高度敏感区（约占58%）分布于走廊中部冲洪积平原;（3）各生态系统服务重要性空间分布格局具有一定的相似性,非常重要和极重要综合服务功能区约占3.2%,位于走廊中部的黑河干流缓冲区内;中等和一般重要地区约占20%,分布在山丹和民乐境内祁连山、焉支山、龙首山附近;（4）黑河中游可分为祁连山森林草地生态区、走廊冲洪积平原农田生态区和走廊北部平原灌丛荒漠生态区3个生态区8个生态功能区,依其主导生态系统服务分为生态保育区、生态协调区和生态控制区3类,进而提出了对应的生态系统管理措施。     

Study of Ecological Compensation for Paddy Fields: Oriented towards Eco-environmental Restoration

Agricultural land provides not only food and fiber (an important element of food security), but also serves as a non-market commodity with characteristic externalities and public services. However, there are also many negative impacts on environment of the paddy production. Thus, Payments for paddy ecosystem services encourage farmers to engage in ecological or organic agricultural practices and agro-ecological/environmental supply. However, compared with forest, wetland, and pasture, the eco-function and ecosystem services of paddy fields have gotten insufficient attention. It is necessary to establish an eco-compensation mechanism for paddy fields that boosts behavior that protects farms to benefit the ecosystem. Based on a review of eco-compensation for paddy fields, this paper proposes the policy game framework of eco-compensation for paddy fields, which is oriented to ecological restoration. Secondly, this paper introduces methods for determination of compensation standards, including the cost the farmers’ willingness to accept, and the ecological benefits of adopting environmental friendly farming practices. And finally, this paper puts forward policy recommendations for eco-compensation for paddy ecosystems.     

Considering river structure and stability in the light of evolution: feedbacks between riparian vegetation and hydrogeomorphology

River ecological functioning can be conceptualized according to a four‐dimensional framework, based on the responses of aquatic and riparian communities to hydrogeomorphic constraints along the longitudinal, transverse, vertical and temporal dimensions of rivers. Contemporary riparian vegetation responds to river dynamics at ecological timescales, but riparian vegetation, in one form or another, has existed on Earth since at least the Middle Ordovician (c. 450 Ma) and has been a significant controlling factor on river geomorphology since the Late Silurian (c. 420 Ma). On such evolutionary timescales, plant adaptations to the fluvial environment and the subsequent effects of these adaptations on fluvial sediment and landform dynamics resulted in the emergence, from the Silurian to the Carboniferous, of a variety of contrasted fluvial biogeomorphic types where water flow, morphodynamics and vegetation interacted to different degrees. Here we identify several of these types and describe the consequences for biogeomorphic structure and stability (i.e. resistance and resilience), along the four river dimensions, of feedbacks between riparian plants and hydrogeomorphic processes on contrasting ecological and evolutionary timescales. Copyright © 2014 John Wiley & Sons, Ltd.     

汾河源区生态系统服务价值的时空变化

运用GIS和遥感技术分析了汾河源区宁武县1990、2000、2010年的土地利用/覆被时空变化特征,并参照中国不同陆地生态系统单位面积服务价值,分析了该区域生态系统服务价值的时空变化。结果表明:1990-2010年,研究区生态系统服务价值共损失0.34×10⁸元,且损失量和损失幅度呈增加趋势;研究区东北到西南方向上的大片低海拔区域生态系统服务价值减幅较大,主要与该区域频繁的人类活动有关,而高海拔山区减幅较小或略有增加。气候暖干化、过度放牧和建设用地增加引起的草地和水域减少是导致研究区生态系统服务价值减少的主要原因。     

稻田生态系统服务价值测算方法与应用——以苏州市域为例

对稻田资源的生态服务价值重视不足是稻田保护工作的最大缺陷,导致了稻田资源流失严重。本文以苏州市水稻田为例,运用造林成本法、瑞典碳税法、制氧工业成本法、替代成本法、影子工程法、当量因子法等方法对稻田生态系统各项服务价值进行了测算。结果表明,苏州市域稻田生态系统服务净总价值量为60785.18×10⁵元,单位面积净价值量为73111.84 元/hm²。其中,正面总价值量为68485.93×10⁵元,环境效应负总价值量为7700.75×10⁵元,前者为后者的8.89 倍。从稻田生态系统服务价值各部分的比例看,其实物生产价值远远低于其生态经济价值,表明了作为人工湿地生态系统,稻田生态服务价值对社会经济的可持续发展具有十分重要的作用。研究结果将有助于确定稻田保护经济补偿标准,为各级政府出台相关政策提供思路和依据     

The effects of land consolidation on the ecological connectivity based on ecosystem service value: A case study of Da’an land consolidation project in Jilin province

Land consolidation has a profound impact on landscape patterns and ecological functions at various scales through engineering and biological measures. In recent years, China invests more than 100 billion RMB yuan on land consolidation each year. To understand how land consolidation affects landscape patterns and ecosystems, we investigated the ecosystem service value and the ecological connectivity in a consolidated area of Da’an city from 2008 to 2014 using a revised ecological connectivity index. The results indicated that land consolidation has certain negative influences on the ecosystem services in this area. The total ecosystem service value will decrease by nearly 30% in the late stage of consolidation. This decrease is caused by the loss of ecosystem service of the wetland and grassland, despite a sensible increase of cultivated land. In addition, land consolidation could change the ecological connectivity as well as the land use structure. Up to 85% of the entire area will be in low connectivity in the late stage of consolidation, representing a 6.23% increase in the total coverage compared to pre-consolidation. Finally, the different connectivity landscape and their key areas can be identified by the revised ecological connectivity index effectively. This study is helpful to trace out the relationships between landscape pattern and ecological process, and provides insights for ecological planning and designing of land consolidation in this area. We suggest that more attentions should be paid to improve the quality and ecosystem service value per unit area of the landscape, to establish ecological compensation mechanism of wetland losses, and to create the ecological corridors along the least accumulated impendence surface in the key areas during land consolidation.     

Role of aeolian sediment accretion in the formation of heuweltjie earth mounds,western South Africa

The action of organisms in shaping landforms is increasingly recognized; the field of biogeomorphology and the conceptual framework of ecosystem engineering have arisen in response to the need for integrated studies of the interactions between biotic and abiotic components of landscapes. Pathways by which organisms influence landscape development may be complex. For example, primary change initiated by one biotic element may initiate a cascade of other changes that eventually produce a significant landscape modification. Mound‐like landforms in North America and southern Africa are widely cited examples of biogenic structures, yet there is considerable controversy regarding the processes responsible for their formation. Heuweltjies (Afrikaans for little hills) are circular mounds ranging from 10–30 m diameter and 0.5–2 m height and are widespread in western South Africa. Colonies of the termite (Microhodotermes viator) are typically associated with heuweltjies and some investigators have attributed heuweltjie formation to the direct action of termites in redistributing earthen materials. However, rather than being directly responsible in this way, termites simply create nutrient‐rich islands, which support denser vegetation, thereby inducing the localized accretion of aeolian sediments and upward growth of mounds. Contrasting soil features in heuweltjies in one locale indicate these processes have occurred throughout the late Quaternary. Geographic variation in sizes of mounds is explained in part by the local availability of sediments that can be mobilized and redistributed by the wind. Recognition of the operation of aeolian processes in the formation of heuweltjies has important implications for conservation. Any land use that diminishes the sediment‐trapping effect of vegetation on heuweltjies truncates the very process by which new aeolian materials can accrue and may promote irreversible erosion and landscape degradation. Copyright © 2014 John Wiley & Sons, Ltd.     

Environmental water quantity projections under market-driven and sustainability-driven future scenarios in the Narew basin,Poland

Abstract

The aim of this article is to assess the impact of four scenarios combining possible changes in climate, atmospheric carbon dioxide, land use and water use by 2050, on the specific set of ecologically relevant flow regime indicators that define environmental flow requirements in a semi-natural river basin in Poland. This aim is presented through a modelling case study using the Soil and Water Assessment Tool (SWAT). Indicators show both positive and negative responses to future changes. Warm projections from the IPSL-CM4 global climate model combined with sustainable land- and water-use projections (SuE) produce the most negative changes, while warm and wet projections from the MIROC3.2 model combined with market-driven projections (EcF) gave the most positive changes. Climate change overshadows land- and water-use change in terms of the magnitude of projected flow alterations. The future of environmental water quantity is brighter under the market-driven rather than the sustainability-driven scenario, which shows that sustainability for terrestrial ecosystems (e.g. more forests and grasslands) can be at variance with sustainability for riverine and riparian ecosystems (requiring sufficient amount and proper timing of river flows).

Editor D. Koutsoyiannis

Citation Piniewski, M., Okruszko, T., and Acreman, M.C., 2014. Environmental water quantity projections under market-driven and sustainability-driven future scenarios in the Narew basin, Poland. Hydrological Sciences Journal, 59 (3–4), 916–934.