Responses of morphological and physiological traits to herbivory by snails of three invasive and native submerged plants

3种入侵和本地沉水植物形态和生理性状对螺类牧食的响应 沉水植物水盾草(Cabomba caroliniana)已成为中国太湖流域的优势入侵水生植物。与外来物种的原产地环境相比,引入地新环境中存在的专食性天敌较少。外来物种可能会逃避其原产地环境中的天敌牧食,又因为它们的适口性相对较差,从而导致在引入地外来物种通常比本地物种遭受的牧食者影响更低(天敌逃逸假说)。本研究的目的是比较水盾草与共生的本地沉水植物对本地牧食者的响应。我们进行了一个中宇宙尺度实验,研究了水盾草和两种共生的本地沉水植物黑藻(Hydrilla verticillata)和穗花狐尾藻(Myriophyllum spicatum)对两种本地广食性腹足纲螺类萝卜螺(Radix swinhoei)和环棱螺(Sinotaia quadrata)的牧食响应。记录了它们的形态性状指标(总生物量、冠根比和相对生长率)和生理性状指标(叶片总非结构性碳、木质素和纤维素)。研究结果表明,环棱螺对3种沉水植物性状指标的影响较少。随着本地广食性螺类萝卜螺数量的增加,黑藻和穗花狐尾藻大部分植物性状发生了改变,而水盾草的植物性状表现出相对稳定的趋势。水盾草对萝卜螺的牧食更具抵抗力,这与天敌逃逸假说的假设一致。这一发现说明牧食性螺类促进了水盾草的入侵,这可能会改变沉水植物群落中的物种组成。     

Ecological restoration of rich fens in Europe and North America: from trial and error to an evidence‐based approach

Fens represent a large array of ecosystem services, including the highest biodiversity found among wetlands, hydrological services, water purification and carbon sequestration. Land‐use change and drainage has severely damaged or annihilated these services in many parts of North America and Europe; restoration plans are urgently needed at the landscape level. We review the major constraints on the restoration of rich fens and fen water bodies in agricultural areas in Europe and disturbed landscapes in North America: (i) habitat quality problems: drought, eutrophication, acidification, and toxicity, and (ii) recolonization problems: species pools, ecosystem fragmentation and connectivity, genetic variability, and invasive species; and here provide possible solutions. We discuss both positive and negative consequences of restoration measures, and their causes. The restoration of wetland ecosystem functioning and services has, for a long time, been based on a trial‐and‐error approach. By presenting research and practice on the restoration of rich fen ecosystems within agricultural areas, we demonstrate the importance of biogeochemical and ecological knowledge at different spatial scales for the management and restoration of biodiversity, water quality, carbon sequestration and other ecosystem services, especially in a changing climate. We define target processes that enable scientists, nature managers, water managers and policy makers to choose between different measures and to predict restoration prospects for different types of deteriorated fens and their starting conditions.     

Procreative and performative kinship among residents in Victorian caravan parks

Recent senior anthropologists have heralded a new era where performative social and cultural kinship may eclipse procreational ‘biological kinship’ in contemporary western society. This article takes research on permanent residents in caravan parks as an extreme case that may act as an exemplar for future western contexts. Between 2003 and 2008, interviews with caravan‐park managers, 50 interviews with park residents and short field stays at 17 outer Melbourne and rural Victorian caravan parks, provided multi‐sited ethnographic material for analysis. I argue that contemporary contexts for relatedness give scope for creative development of social performative ties with ‘ex’ spouses and in‐laws, friends and pets. ‘Biological’ kin and family with a material dimension remain central, however, and a response to family need or rupture is often the broadening of the procreative kin links between grandparent and grandchild and between siblings. Childhood institutionalisation and divorce in particular, contributed to pathways towards caravan park housing. Other kin‐based motivations include finding safe accommodation for wives; providing housing for young adult males after injury and family divorce; and arranging for housing succession for children. Ideas of blood and folk biology demonstrate considerable resilience in contemporary kinship arrangements.     

Hydrological responses of a valley‐bottom wetland to land‐use/land‐cover change in a South African catchment: making a case for wetland restoration

Valley‐bottom wetlands are valuable assets as they provide many ecosystem services to mankind. Despite their value, valley‐bottom wetlands are often exploited and land‐use/land‐cover (LULC) change results in trade‐offs in ecosystem services. We coupled physically based hydrological modeling and spatial analysis to examine the effects of LULC change on water‐related ecosystem services in the Kromme catchment: an important water‐providing catchment for the city of Port Elizabeth. LULC scenarios were constructed to match 5 different decades in the last 50 years to explore the potential effects of restoring the catchment to different historic benchmarks. In the Kromme catchment, valley‐bottom wetlands have declined by 84%, driven by key LULC changes: an increase in irrigated land (307 ha) and invasion by alien trees (336 ha). If the wetlands were restored to the relatively pristine extent and condition of the 1950s, riverflow could increase by approximately 1.13 million m³/a, about 6% of the current supply to Port Elizabeth. Wetland restoration would also significantly improve the catchment's ability to absorb extreme rainfall events, decreasing flood damage. We conclude that in the face of the water scarcity in this region, all ecosystem services, particularly those related to water flow regulation, should be taken into account by decision makers in charge of land zonation. Zonation decisions should not continue to be made on the basis of provisioning ecosystem services alone (i.e. food provision or dam yield). We recommend prioritization of the preservation and restoration of valley‐bottom wetlands providing water‐related ecosystem services to settlements downstream.     

Understory vegetation as an indicator for floodplain forest restoration in the Mississippi River Alluvial Valley,U.S.A.

In the Mississippi River Alluvial Valley (MAV), complete alteration of river‐floodplain hydrology allowed for widespread conversion of forested bottomlands to intensive agriculture, resulting in nearly 80% forest loss. Governmental programs have attempted to restore forest habitat and functions within this altered landscape by the methods of tree planting (afforestation) and local hydrologic enhancement on reclaimed croplands. Early assessments identified factors that influenced whether planting plus tree colonization could establish an overstory community similar to natural bottomland forests. The extent to which afforested sites develop typical understory vegetation has not been evaluated, yet understory composition may be indicative of restored site conditions. As part of a broad study quantifying the ecosystem services gained from restoration efforts, understory vegetation was compared between 37 afforested sites and 26 mature forest sites. Differences in vegetation attributes for species growth forms, wetland indicator classes, and native status were tested with univariate analyses; floristic composition data were analyzed by multivariate techniques. Understory vegetation of restoration sites was generally hydrophytic, but species composition differed from that of mature bottomland forest because of young successional age and differing responses of plant growth forms. Attribute and floristic variation among restoration sites was related to variation in canopy development and local wetness conditions, which in turn reflected both intrinsic site features and outcomes of restoration practices. Thus, understory vegetation is a useful indicator of functional progress in floodplain forest restoration.     

Barriers to Promoting Eco‐Industrial Parks Development in China

For at least the past two decades, eco‐industrial parks (EIPs) have been promoted as policy and commercial instruments for achieving industrial sustainable development. Yet, few EIPs have seen successful operational implementation, especially if they begin as standard industrial parks. Rapid economic growth, commensurate with increasing environmental damage in China, has resulted in officials’ further pursuing EIP policy as a significant element of the broader circular economy and ecological modernization efforts. This article examines the barriers for EIP development from industrial park senior manager perspectives. Using resource dependence theory and the resource‐based view as theoretical lenses, we investigate the external and internal barriers for EIP development in 51 Chinese industrial parks. A number of barriers are identified and grouped through a factor analysis. Cluster analysis is utilized to help categorize and evaluate the perceived levels of barriers and hardships experienced by various senior officials that manage the EIPs. It is found that few respondents encounter no significant barriers. Barriers related to technological development and capacity building are the most prevalent. These results highlight the relative importance of various activities that may be necessary by policy makers and other stakeholders to overcome the barriers. For example, cooperation in developing technological solutions for EIPs seems to be a major thrust that should be pursued by EIP development stakeholders. Other policy and managerial insights based on the general findings of this study are also presented.     

Large amounts of labile organic carbon in permafrost soils of northern Alaska

Permafrost‐affected soils of the northern circumpolar region represent 50% of the terrestrial soil organic carbon (SOC) reservoir and are most strongly affected by climatic change. There is growing concern that this vast SOC pool could transition from a net C sink to a source. But so far little is known on how the organic matter (OM) in permafrost soils will respond in a warming future, which is governed by OM composition and possible stabilization mechanisms. To investigate if and how SOC in the active layer and adjacent permafrost is protected against degradation, we employed density fractionation to separate differently stabilized SOM fractions. We studied the quantity and quality of OM in different compartments using elemental analysis, ¹³C solid‐phase nuclear magnetic resonance (¹³C‐NMR) spectroscopy, and ¹⁴C analyses. The soil samples were derived from 16 cores from drained thaw lake basins, ranging from 0 to 5500 years of age, representing a unique series of developing Arctic soils over time. The normalized SOC stocks ranged between 35.5 and 86.2 kg SOC m^?3, with the major amount of SOC located in the active layers. The SOC stock is dominated by large amounts of particulate organic matter (POM), whereas mineral‐associated OM especially in older soils is of minor importance on a mass basis. We show that tremendous amounts of over 25 kg OC per square meter are stored as presumably easily degradable OM rich in carbohydrates. Only about 10 kg OC per square meter is present as presumably more stable, mineral‐associated OC. Significant amounts of the easily degradable, carbohydrate‐rich OM are preserved in the yet permanently frozen soil below the permafrost table. Forced by global warming, this vast labile OM pool could soon become available for microbial degradation due to the continuous deepening of the annually thawing active layer.     

城市公园景观秋冬季动态热效应

在北京市3个公园中选择裸地、道路、林地、草地4种主要景观类型,通过2013年10月、11月、12月的实地监测数据,定量揭示不同景观类型地表温度、近地表空气温度和湿度的日间变化特征,并分析日间温湿度的均值、幅度大小、空气温湿度的匹配程度。4种景观类型日间地表和空气温度均呈单峰变化趋势,裸地、道路、林地、草地的地表温度最高值分别出现在14:00、12:00、14:00、12:00,空气温度最高值则都在14:00,相对湿度最大值出现在8:00,最小值在14:00。从日间均值来看,地表温度为裸地道路草地、林地,裸地的日均空气温度最高,4种景观的相对湿度差异不显著。从日间变化幅度来看,所有景观类型的地表温度均明显大于空气温度,尤其是裸地和道路的日间变化比林地和草地更加明显。通过定量分析4种景观类型的日间热环境动态变化,可以为城市热环境改善、景观设计和生态规划提供科学依据。     

黑河下游湿地土壤有机氮组分剖面的分布特征

结合野外调查,用Bremner法研究了黑河下游湿地不同土壤类型的有机氮组分,结果表明:在0—50 cm土层,5种土壤有机氮均以酸解性氮为主,占全氮的71.04%—81.79%。泥炭土、沼泽土、草甸土、亚高山草甸土所含的酸解氮、非酸解氮和酸解氮组分氨态氮、氨基酸态氮、氨基糖态氮含量的剖面分布总体上均随土层深度的增加而呈降低趋势,而风沙土却相反,上述有机氮组分呈升高趋势。5种土壤酸解氮及其组分氨态氮、氨基酸态氮、氨基糖态氮占全氮比例的剖面分布总体上均随土层深度的增加而呈降低趋势,而非酸解氮却呈升高趋势。5种土壤酸解未知态氮含量及占全氮比例均在剖面分布上无明显特征。在0—30 cm各相同土层内,5种土壤酸解氮各组分含量及占全氮比例的大小顺序均为氨基酸态氮氨态氮未知态氮氨基糖态氮;而在30—50 cm土层,5种土壤酸解氮各组分含量及占全氮比例的大小顺序均无明显特征。此外,黑河下游湿地土壤干化、沙化过程中,表层0—10 cm土壤有机氮组分含量变化明显,其中土壤氨态氮对生态环境变化最为敏感。     

中国内陆湿地生态系统服务价值评估——以71个湿地案例点为数据源

湿地生态系统为人类生存和发展提供了多种服务功能,不仅包括水资源、水产品等直接输出功能,还包括调蓄洪水、净化水质、调节大气成分等调节服务功能和文化服务功能。通过对已经发表湿地生态系统服务功能价值评价相关的文献进行搜集和整理,得到全国71个湿地案例点的价值评价数据,在此基础上对湿地生态系统各项服务功能在全国各区域的生态系统价值量进行对比分析。全国湿地价值评价结果显示,按照各项服务功能按照价值量高低排序依次为调节气候调蓄洪水涵养水源净化水质保持土壤产品输出固碳释氧生物栖息地旅游休闲科研教育。在对全国湿地进行分区分析得知,东北平原及山区、东部地区和青藏高原地区在各项调节、供给服务功能方面发挥着显著的积极作用,这3个区域同时也是我国湿地的密集分布区。结合不同地理分区下的湿地生态系统服务功能价值量特点,可以实现区域发展与湿地生态环境研究的协同发展,并能够为湿地的保护和建设起到科学、合理的参考方案。