Ecological research can augment restoration practice in urban areas degraded by invasive species—examples from Chicago Wilderness

Urban biodiversity conservation needs a firm scientific foundation, one that draws upon active and regionally calibrated research programs. Until recently this foundation has not existed. In this paper we examine the way in which the emerging discipline of restoration ecology in an urban context can learn from the experiences of ongoing restoration projects and in turn how novel insights from research of urban soils can help these projects define and reach their goals. Limitations on collaboration between academic researchers and practitioners continues be problematic. We discuss a model whereby this impediment may be removed. A case study of Rhamnus cathartica, an invader of Midwestern woodlands which modifies some important soil ecosystem properties will be used to illustrate the potential for engagement between research and practice.     

《土壤肥料学》课程教学改革思考与实践

适应 2 1世纪的人才培养目标要求 ,结合土壤肥料学的教学特点 ,总结教学内容、教学方法、实验课教学和成绩考核方法等几方面的教改工作实践 ,以期有效提高教学质量。     

Ecology of urban lawns under three common management programs

Turfgrass lawns are a central part of urban and suburban landscapes throughout North America and are often managed using repeated applications of chemical fertilizers and pesticides. These inputs are expensive and may negatively affect ecological processes in lawns. Therefore, we evaluated the influence of three most common lawn care programs on ecological characteristics of turfgrass lawns. Twenty-eight home lawns, separated into 3 groups based on the lawn care program (professional, do-it-yourself [DIY], and no-input), were studied. Data on lawn quality, weed and insect infestation, disease incidence, soil nematode community, soil nitrogen pools, microbial biomass (MBN), and soil organic matter (SOM) were collected. Results indicated that professional lawn care resulted in the highest aesthetic lawn quality mainly due to better weed control, compared to DIY and no-input programs. However, professional and DIY programs negatively affected MBN and SOM pools and enhanced disease (rust) severity. No significant differences in soil nematode population and nematode community indices across the three programs were found, indicating no differences in net ecosystem productivity among the three programs. Overall, soil nematode food web in turfgrass lawns represented a disturbed food web compared to natural grasslands and forest ecosystems, irrespective of the lawn care program used.     

精品课程建设中教材编写的创新思路探索——普通高等教育《土壤学》(“十五”国家级规划)教材的编写体会与实践

作者结合北京市精品课程建设,在组织编写普通高等教育“十五”国家级规划教材《土壤学》的过程中,认为首先应明确教材编写的指导思想,即在课程教材体系上有所创新,在课程教材内容上有所更新,在教学方法和手段上有所革新。同时在贯彻适用性和特色两个原则的基础上,进行了一些编写思路的探索和创新实践,这包括摸清读者底细、确定专业目标、把握课程内涵、了解市场需求,及正确处理好理论与应用、深度与广度、难度与易度、传统与创新、利教与利学、知识传授与技能培养的关系。通过以上步骤,保证了教材的先进性、系统性和特色,并实现了网络教学。     

关于“林业生态工程学”教学的思考

该文分析了目前北京林业大学“林业生态工程学”教学中存在的问题,主要是课程内容较多,又受到其他因素的影响,在有限的教学时数内很难提高教学质量。同时教学实践环节比较薄弱,不能满足社会对学生工作能力的期待。对此,作者在教学内容、教学手段、课堂互动、个性化作业、综合能力培训等方面进行了一些探索,取得了较好的效果。该文提出了进一步教学改革的思路是“以课程设计为主线,围绕设计教授课程”,并沿着“理论—综述—专项规划设计—综合规划设计—评价报告”的路线进行教学。     

渭干河-库车河灌区土壤盐渍化治理对策研究

新疆渭干河-库车河灌区农业生产资源丰富,但也正遭受着土壤盐渍化的严重威胁。对其改良治理巳刻不容缓。根据灌区的盐渍化现状,当前和今后一段时间应着重抓四方面的工作：加强农业水利工程建设,完善排灌系统;大力种植耐盐碱植物;提高土壤肥力,改善土壤结构;采取化学手段,改善土壤理化性质。     

试论李锐小说对人类生存困境的逼视

李锐始终以一种独特的姿态存在于人们的视野中,他的整个小说创作一直是围绕＂从个人出发去追问普遍的人类困境＂这一命题而展开,对于人生困境的无尽展示与言说的背后正包含着对于人生命运无常的追问。从李锐小说所展示的人类生存困境入手,重点考察了从《厚土》到《银城故事》这一时期的创作,梳理了李锐小说中人物的生存困境,进而揭示了人类生存的命运危机。     

Altered resources, disturbance, and heterogeneity: A framework for comparing urban and non-urban soils

We propose a framework of key concepts useful in understanding how urban soils can contribute to general ecological theory. The major factors that can cause urban soils to be different from soils in non-urban ecosystems are identified and related to the familiar state factor approach. We evaluate directly altered resource availability, and the role of stress in mediating resource availability in urban ecosystems. Modified groundwater and stream flow, and atmospheric deposition of nitrogen and base cations are particularly important resource fluxes to soils in urban ecosystems. Disturbance can be conceptualized in the same way in urban as in non-urban ecosystems. However, in addition to biophysical disturbances familiar to ecologists studying wild lands, demographically and socially mediated changes in ecosystem structure must also be considered. These changes include human migration and population structure, institutional shifts, and the effects of human health. Finally, spatial heterogeneity, including fragmentation and differential connectivity, integrates the effects of resources and disturbance, and has an effect on subsequent resource availability and susceptibility to disturbance. Layers of heterogeneity include not only the geomorphic template, but urban climate, biotic composition, buildings and infrastructure, and demographic-social patterns. The complex layering of natural and social factors that constitute urban heterogeneity permit the continuation of important ecological processes, as well as modify ecological fluxes involving soils. We present a modification of the state factor approach as an expanded framework for the study of urban soils. The understanding of urban soils can contribute to general ecological theory by testing the generality of important ecosystem drivers and their linkage with social processes in an under investigated ecosystem type that is increasing in extent and impact worldwide.     

A comparison of soil organic carbon stocks between residential turf grass and native soil

A central principle in urban ecological theory implies that in urbanized landscapes anthropogenic drivers will dominate natural drivers in the control of soil organic carbon storage (SOC). To assess the effect of urban land-use change on the storage of SOC, we compared SOC stocks of turf grass and native cover types of two metropolitan areas (Baltimore, MD, and Denver, CO) representing climatologically distinct regions in the United States. We hypothesized that introducing turf grass and management will lead to higher SOC densities in the arid Denver area and lower densities in the mesic Baltimore area relative to native cover types. Moreover, differences between turf grass soils will be less than differences between the native soils of each metropolitan region. Within Baltimore, turf grass had almost a 2-fold higher SOC density at 0- to 1-m and 0- to 20-cm depths than in rural forest soils, whereas there were no differences with soils of urban forest remnants. Moreover, urban forest remnants had more than 70% higher SOC densities than rural forest soils. Within Denver, turf grass (>25 years of age) had more than 2-fold higher SOC densities than in shortgrass steppe soils, while having similar densities to Baltimore turf grass soils. By contrast, the native soils of Baltimore were almost 2-fold higher than the native steppe grass soils of Denver using SOC densities of remnant forests as representative of native soils in the Baltimore region. These results supported our hypothesis that turf grass systems will be similar in SOC densities across regional variations in climate, parent material, and topography. These similarities are apparently due to greater management efforts in the Denver region to offset the constraint of climate, i.e., anthropogenic factors (management supplements) overwhelmed native environmental factors that control SOC storage.     

Urban soil ecology as a focal point for environmental education

Direct contact with the natural world is an essential element of environmental education and a key to developing environmental literacy and a stewardship ethic. But providing this experience can be challenging in urban environments where many people believe nature only occurs “outside” the city, and urban biota are often unwelcome and perceived in negative terms. Since 80% of the United States’ population lives in or near urban areas, conservation educators and practitioners need to find ways to make nature accessible to this audience, thereby creating a public who can make informed decisions about environmental issues. Soil systems are an important, under-utilized resource for urban environmental education. Soils are ubiquitous and thus easily accessible and their communities can be effective focal points for introducing all levels of ecology, from populations to ecosystems. Soil and litter taxa are also intrinsically interesting, with discoveries of new species still being made in urban areas. By studying urban soil systems, students can develop an enhanced sense of place and an appreciation of the natural world and their connection to it thereby strengthening environmental stewardship. An important role exists for urban ecologists to work with educators to impart enthusiasm for and to augment educators’ understanding of soil systems.