An Ecological Basis for Managing Giant Sequoia Ecosystems

A strategy for management of giant sequoia groves is formulated using a conceptual framework for ecosystem management recently developed by Region Five of the USDA Forest Service. The framework includes physical, biological, and social dimensions. Environmental indicators and reference variability for key ecosystem elements are discussed in this paper. The selected ecosystem elements include: 1) attitudes, beliefs, and values; 2) economics and subsistence; 3) stream channel morphology; 4) sediment; 5) water; 6) fire; 7) organic debris; and 8) vegetation mosaic. Recommendations are made for the attributes of environmental indicators that characterize these elements. These elements and associated indicators will define and control management activities for the protection, preservation, and restoration of national forest giant sequoia ecosystems.     

加强水土保持 防止生态恶化

本文论述了水土水流失对生态环境的影响和对农业生产的危害，阐明增强环境意识，加强水土保持时防止生态恶化，是我国振兴农业的重要性与紧迫性的任务。     

生态文明与农业发展

农业作为国民经济的基础,是生态文明的重要内容,其文明程度直接体现生态文明程度.生态文明建设给农业经营提出了更高的要求,也为农业生产的发展指明了方向.充分认识生态文明建设与农业生产的关系,加强农业相关人员的生态文明教育和农业环保法制建设,实施更加科学、文明的农业经营方式将对促进农业的可持续发展和生态文明建设发挥积极的作用.     

Experimental and Ecological Implications of Evening Bird Surveys in Stream-Riparian Ecosystems

Stream-riparian ecosystems are dynamic and complex entities that can support high levels of bird assemblage abundance and diversity. The myriad patches (e.g., aquatic, floodplain, riparian) found in the riverscape habitat mosaic attract a unique mixture of aquatic, semiaquatic, riparian, and upland birds, each uniquely utilizing the river corridor. Whereas standard morning bird surveys are widely used across ecosystems, the variety of bird guilds and the temporal habitat partitioning that likely occur in stream-riparian ecosystems argue for the inclusion of evening surveys. At 41 stream reaches in Vermont and Idaho, USA, we surveyed bird assemblages using a combination of morning and evening fixed-width transect counts. Student’s paired t-tests showed that while bird abundance was not significantly different between morning and evening surveys, bird assemblage diversity (as measured by species richness, Shannon-Weiner’s index, and Simpson’s index) was significantly higher in the morning than in the evening. NMS ordinations of bird species and time (i.e., morning, evening) indicated that the structure of morning bird assemblages was different from that of evening assemblages. NMS further showed that a set of species was only found in evening surveys. The inclusion of evening counts in surveying bird assemblages in stream-riparian ecosystems has important experimental and ecological implications. Experimentally, the sole use of morning bird surveys may significantly underestimate the diversity and misrepresent the community composition of bird assemblages in these ecosystems. Ecologically, many of the birds detected in evening surveys were water-associated species that occupy high trophic levels and aerial insectivores that represent unique aquatic-terrestrial energy transfers.     

Major Ecosystems in China: Dynamics and Challenges for Sustainable Management

Ecosystems, though impacted by global environmental change, can also contribute to the adaptation and mitigation of such large scale changes. Therefore, sustainable ecosystem management is crucial in reaching a sustainable future for the biosphere. Based on the published literature and publicly accessible data, this paper discussed the status and trends of forest, grassland, and wetland ecosystems in China that play important roles in the ecological integrity and human welfare of the nation. Ecological degradation has been observed in these ecosystems at various levels and geographic locations. Biophysical (e.g., climate change) and socioeconomic factors (e.g., intensive human use) are the main reasons for ecosystem degradation with the latter factors serving as the dominant driving forces. The three broad categories of ecosystems in China have partially recovered from degradation thanks to large scale ecological restoration projects implemented in the last few decades. China, as the largest and most populated developing nation, still faces huge challenges regarding ecosystem management in a changing and globalizing world. To further improve ecosystem management in China, four recommendations were proposed, including: (1) advance ecosystem management towards an application-oriented, multidisciplinary science; (2) establish a well-functioning national ecological monitoring and data sharing mechanism; (3) develop impact and effectiveness assessment approaches for policies, plans, and ecological restoration projects; and (4) promote legal and institutional innovations to balance the intrinsic needs of ecological and socioeconomic systems. Any change in China’s ecosystem management approach towards a more sustainable one will benefit the whole world. Therefore, international collaborations on ecological and environmental issues need to be expanded.     

Denitrification Distributions in Four Valley and Ridge Riparian Ecosystems

/ Denitrification in riparian ecosystems can reduce the amount ofnitrogen transported from farm fields to streams. In this study, we examinedenitrification in four riparian ecosystems common to the Valley and Ridgephysiographic province in Pennsylvania, USA. The sites exhibit differentvegetation, are underlain by different rock types, and are downgradient offarm fields. Mean site denitrification rates ranging from 0.6 to 1.9 &mgr;gN/kg soil/day were measured using intact core incubation techniques. Thethree riparian sites covered with grass each exhibited greaterdenitrification rates than the wooded site. Denitrification rate wascorrelated with moisture content but not with nitrate-N or organic carboncontents. Denitrification rates were greatest near the soil surface and atpositions nearest the stream. Rates decreased uniformly with distance awayfrom the stream and also with depth in the soil for each site. While patternsof nitrate-N, moisture, and organic carbon content differ among the sites,their combined effects on denitrification support the observed, consistentdenitrification rate pattern.KEY WORDS: Denitrification; Riparian ecosystems     

Comparative Analysis of New Zealand and US Approaches for Agricultural Nonpoint Source Pollution Management

The role of the central government in New Zealand is generally limited to research and policy development, and regional councils are responsible for most monitoring and management of the problem. The role of the federal government in the United States includes research and monitoring, policy development, and regulation. States also have a significant management role. Both countries rely on voluntary approaches for NPS pollution management. Very few national water quality standards exist in New Zealand, whereas standards are widely used in the United States. Loading estimates and modeling are often used in the United States, but not in New Zealand. A wide range of best management practices (BMPs) are used in the United States, including buffer strips and constructed/engineered wetlands. Buffer strips and riparian management have been emphasized and used widely in New Zealand. Many approaches are common to both countries, but management of the problem has only been partly successful. The primary barriers are the inadequacy of the voluntary approach and the lack of scientific tools that are useful to decision-makers. More work needs to be performed on the evaluation of approaches developed in both countries that could be applied in the other countries. In addition, more cooperation and information/technology transfer between the two countries should be encouraged in the future.     

惠来县景观格局与动态变化分析

在GIS技术和卫星遥感资料的支持下,利用景观格局分析软件FRAGSFATS3．3分析了揭阳市惠来县1994-2001年的土地景观格局的动态变化,并分别在类型水平上和景观水平上选择了部分景观指数。计算结果表明,破碎度趋向加深,景观结构和斑块形状复杂性增加（尤以林地和其它用地严重）;景观稳定性增加,优势度减少;景观多样性有所提高,受人类干扰程度加深,说明惠来县城市化速度快,处于城市发展的初期;各景观要素又有不同的景观动态特征。     

现代农作物废弃物的生态效应及资源化利用

通过分析我国农业废弃物对生态环境的影响以及农业废弃物资源化开发的现状,阐述了农业废弃物资源化开发利用存在的问题。提出生物技术、绿色工艺及开发节能环保建材等无害处理农业废弃物新途径,指出发展循环农业的有效模式,即建立生态农业多途径循环开发模式,植物、动物和微生物资源组成的“三维结构”的绿色新型农业,建立和推广生态型家庭经济模式,为推进农产品高效流通,促进农产品深度综合开发提供借鉴。     

生态移民在保护自然生态环境中的重要作用及实施建议

在西部大开发中,生态环境保护与建设要先行,而生态移民则是落实该项政策的一项极重要措施。将自然保护区、交通和通讯不发达的边缘区、生态环境脆弱区和地质灾区的农牧民,移往自然环境条件较好,公路交通及通讯发达,接近城镇的地区,不但可改善和提高这些居民的生活水平,更重要的是对迁出区的自然生态环境保护,特别是珍稀野生动植物的生存和自然繁殖有十分积极的作用。而工业生产移民则是环境保护必要手段。该项政策的实施,不但具有重大社会政治、生态环境及经济效益,而且在我国自然保护史上是个重大创举。     

Stream Invertebrate Communities, Water Quality, and Land-Use Patterns in an Agricultural Drainage Basin of Northeastern Nebraska, USA

We used invertebrate bioassessment, habitat analysis, geographic information system analysis of land use, and water chemistry monitoring to evaluate tributaries of a degraded northeast Nebraska, USA, reservoir. Bimonthly invertebrate collections and monthly water chemistry samples were collected for two years on six stream reaches to identify sources contributing to reservoir degradation and test suitability of standard rapid bioassessment methods in this region. A composite biotic index composed of seven commonly used metrics was effective for distinguishing between differentially impacted sites and responded to a variety of disturbances. Individual metrics varied greatly in precision and ability to discriminate between relatively impacted and unimpacted stream reaches. A modified Hilsenhoff index showed the highest precision (reference site CV = 0.08) but was least effective at discriminating among sites. Percent dominance and the EPT (number of Ephemeroptera, Plecoptera, and Trichoptera taxa) metrics were most effective at discriminating between sites and exhibited intermediate precision. A trend of higher biotic integrity during summer was evident, indicating seasonal corrections should differ from other regions. Poor correlations were evident between water chemistry variables and bioassessment results. However, land-use factors, particularly within 18-m riparian zones, were correlated with bioassessment scores. For example, there was a strong negative correlation between percentage of rangeland in 18-m riparian zones and percentage of dominance in streams (r ² = 0.90, P < 0.01). Results demonstrate that standard rapid bioassessment methods, with some modifications, are effective for use in this agricultural region of the Great Plains and that riparian land use may be the best predictor of stream biotic integrity.     

四川盆地农业自然环境质量评价

本文用一种综合、定量的方法，评价了四川盆地农业自然环境的现状质量，得到了较之传统的定性描述更为科学、直观的评价结果。评价结果显示，四川盆地农业自然环境质量只属中等水平，而不是通常所言“农业自然条件优越”；１３０个县中只有１５个的质量属良好，它们呈岛状分布；自然潜力质量与生态质量往往不匹配，因为人在开发利用自然资源的时候，往往造成生态质量的下降。     

环境友好农业生产的生态补偿机制探索与实践

围绕中德技术合作＂中国华北地区集约化农业的环境战略＂项目实施过程中,为鼓励农民采用节水、节肥、节药环境友好方式生产安全优质设施蔬菜,减轻农业面源污染,保护农业生态资源与环境而开展的生态补偿的实践进行论述,结合项目的实践从补偿原则、补偿对象、补偿标准、补偿形式、补偿环节、补偿监管等方面进行了探讨。笔者认为,建立健全农业生态环境补偿制度符合世界贸易组织农业协议绿箱政策,有利于推动环境友好技术的应用。环境友好农业生产的生态补偿应以项目（政府）补贴为主导,以农民自愿为前提,以骨干农户、农民专业合作社为主要补偿对象,以技物结合为主要补偿形式,以兼顾生态、经济和社会效益为目标。     

农业利用有机废弃物的生态工程

本文运用生态工程将农业利用有机废弃的主要用途划分为作饲料，肥料，能源，培养料和多层次循环利用５种方式，论述了中国农业利用有机废弃物的历史，现状与水平，对农业利用作秸秆，畜禽粪便，沼气发酵余物和机的主要秣工程技术。     

Legitimizing Fluvial Ecosystems as Users of Water: An Overview

We suggest that fluvial ecosystems are legitimate users of water and that there are basic ecological principles guiding the maintenance of long-term ecological vitality. This article articulates some fundamental relationships between physical and ecological processes, presents basic principles for maintaining the vitality of fluvial ecosystems, identifies several major scientific challenges and opportunities for effective implementation of the basic ecological principles, and acts as an introduction to three specific articles to follow on biodiversity, biogeochemistry, and riparian communities. All the objectives, by necessity, link climate, land, and fresh water. The basic principles proposed are: (1) the natural flow regime shapes the evolution of aquatic biota and ecological processes, (2) every river has a characteristic flow regime and an associated biotic community, and (3) aquatic ecosystems are topographically unique in occupying the lowest position in the landscape, thereby integrating catchment-scale processes. Scientific challenges for the immediate future relate to quantifying cumulative effects, linking multidisciplinary knowledge and models, and formulating effective monitoring and assessment procedures. Additionally, forecasting the ecological consequences of changing water regimes is a fundamental challenge for science, especially as environmental issues related to fresh waters escalate in the next two to three decades.     

天然气长输管道建设对生态环境的影响及防范措施

针对天然气长输管道建设影响面广、介质危险性大的特点,从对土地利用方式、土壤环境、林业生态系统、农业生态系统、野生动植物、景观、地质等方面分析施工期的环境影响。提出预防、减缓、植被恢复、管理、风险防范等方面的生态保护措施,特别给出了林地生态系统、农田生态系统、野生动物、土壤的具体保护措施;从加强环境管理、加强施工人员的环保意识、加强野生动物保护的宣传力度方面提出了针对性的管理措施。     

基于生态足迹的新疆可持续发展评价

生态足迹是分析国家或地区自然资源可持续利用的重要指标.利用FAO数据、新疆统计年鉴等自然资源生产与消费数据、人口数据,采用可变世界单产法计算了2000-2009年新疆生态足迹.结果表明:从2000-2009年间,新疆的人均生态足迹显著上升,生态赤字有逐渐加大的趋势.生态协调系数DS显示,新疆的资源利用超出生态环境的承载范围,其发展模式是不可持续的.     

Assessing the Effectiveness of Winter Cover Crops for Controlling Agricultural Nutrient Losses

A nutrient loss reduction strategy is necessary to guide the efforts of improving water quality downstream of an agricultural watershed. In this study, the effectiveness of two winter cover crops, namely cereal rye and annual ryegrass, is explored as a loss reduction strategy in a watershed that ultimately drains into a water supply reservoir. Using a coupled optimization-watershed model, optimal placements of the cover crops were identified that would result in the tradeoffs between nitrate-N losses reduction and adoption levels. Analysis of the 10%, 25%, 50%, and 75% adoption levels extracted from the optimal tradeoffs showed that the cover crop placements would provide annual nitrate-N loss reductions of 3.0%–3.7%, 7.8%–8.8%, 15%–17.5%, and 20.9%–24.3%, respectively. In addition, for the same adoption levels (i.e., 10%–75%), sediment (1.8%–17.7%), and total phosphorus losses (0.8%–8.6%) could be achieved. Results also indicate that implementing each cover crop on all croplands of the watershed could cause annual water yield reduction of at least 4.8%, with greater than 28% in the months of October and November. This could potentially be detrimental to the storage volume of the downstream reservoir, especially in drought years, if cover crops are adopted in most of the reservoir's drainage area. Evaluating water yield impacts, particularly in periods of low flows, is thus critical if cover crops are to be considered as best management practices in water supply watersheds.     

The Concept of Habitat Diversity Between and Within Ecosystems Applied to River Side-Arm Restoration

Since returning an ecosystem to its pristine state may not be realistic in every situation, the concept of habitat diversity is proposed to help decision-makers in defining realistic restoration objectives. In order to maintain habitat diversity and enhance the long-term success of restoration, process-oriented projects should be preferred to species-oriented ones. Because the hydrogeomorphological processes that influence biodiversity operate at different spatiotemporal scales, three scales are considered: river sectors, floodplain waterbodies, and mesohabitats within each waterbody. Based on a bibliographical review, three major driving forces are proposed for incorporation into the design of restoration projects: (1) flow velocity and flood disturbances, (2) hydrological connectivity, and (3) water supply. On the sector scale, increased habitat diversity between waterbodies can be achieved by combining various intensities of these driving forces. On the waterbody scale, increased habitat diversity within the ecosystem can be achieved by varying water depth, velocity, and substrate. The concept is applied to a Rhône River sector (France) where three terrestrialized side arms will be restored. Two were designed to be flood scoured, one having an additional supply of groundwater, the other being connected to the river at both ends. The third cannot be scoured by floods because of upstream construction and would be supplied by river backflow through a downstream connection. Habitat diversity within the ecosystem is exemplified on one side arm through the design of a sinuous pathway combined with variation of water depth, wetted width, and substrate grain size. Self-colonization of the side arms is expected owing to the restoration of connectivity to upstream sources of potential colonizers.