Developing a complementary framework for urban ecology

Cities are characterized by dynamic interactions between socio-economic and biophysical forces. Currently more than half of the global population reside in cities which influence the global biogeochemical cycles and climate change, substantially exacerbating pressures on urban pollution, water quality and food security, as well as operating costs for infrastructure development. Goods and services such as aesthetic values, water purification, nutrient recycling, and biological diversity, that urban ecosystems generate for the society, are critical to sustain. Urban planners are increasingly facing the considerable challenges of management issues for urban ecosystems. Poor understanding of the complementary roles of urban ecology in urban infrastructure, and the functioning of ecosystems and ecological resilience of a complex human-dominated landscape has impeded effective urban planning over time, resulting in social disharmony. Here a complementary framework for urban ecology is proposed, in which ecosystems interact with land use, architecture and urban design – “E-LAUD” – affecting ecosystem and human health, and building on the concept that land uses in urban green areas, road-strips, wetlands, ‘habitat islands’ and urban architecture could synergistically benefit when clustered together in different combinations of urban landscapes. It is proposed that incorporation of the E-LAUD framework in urban planning forms the context of a new interdisciplinary research programme on ecological resilience for urban ecosystems and helps promote ecosystem services.     

当代中国农村家庭结构变化的原因分析

当今我国处于社会转型期,自给自足的小农经济转向社会主义市场经济,这成为农村家庭变化的动力,促使传统的农村家庭转向现代家庭,家庭结构也随之发生明显的变化,对整个社会的经济、政治、文化都会有深远的影响.本文主要从家庭模式、家庭功能等角度来阐述家庭结构从传统走向现代的动因,有助于我们充分地认识我国农村的深层结构,为政府决策机构制定正确的方针、路线和政策提供参考.     

Simulation of corn yields in the Upper Great Lakes Region of the US using a modeling framework

We examined the utility of a site-based simulation model for corn (MAIZE) applied to the Upper Great Lakes Region (UGLR) of the United States for 1992–1996. To evaluate model outputs, we used a modeling applications system integrative framework (MASIF) to simulate corn yields in the UGLR. We divided the region into two ecological zones (upper UGLR-1 and lower UGLR-2) and compared MAIZE and USDA National Agriculture Statistics Service (NASS) yield estimates in each zone. There was greater agreement between MAIZE and NASS yields at lower yield values. As NASS yields increased, MAIZE yields also increased, but to a greater extent than did NASS yields. We conducted a mean spatial analysis of maize yield from 1992 to 1996. We also conducted a spatial analysis of 1994, 1995 and 1996. There are both spatial and temporal differences when yields are mapped.     

我国林业经济增长整合模式分析

在概述了经济增长模式理论的基础上,分析了林业经济增长的动力因素。 以系统论的观点提出了以林业资本、人力、技术、制度为动力因素,四者之间相互作用的林业经济增长整合模式框架。     

已形成产业化格局的苍溪毛兔业

苍溪县近年来抓住毛兔产业西移的契机 ,采取增投入、普科技、抓饲料、建市场、扶龙头、强领导等措施大力发展长毛兔。一个市场牵龙头 ,龙头连基地 ,基地带农户的大产业 ,大规模 ,大流通 ,大市场 ,大效益的毛兔产业化发展格局已基本形成。 1 999年底 ,全县存栏毛兔 2 0 1 5万只 ,产毛 95 8吨 ,兔业产值达 1 6亿元 ,占牧业总产值的 2 9 4 % ,兔业创税 1 0 0 0余万元。通过养兔 ,全县已有 8 5万余农户摆脱贫困 ,走上了富裕之路     

Effects of biodegradable mulch on soil quality

Biodegradable plastic films are desirable alternatives to traditional black polyethylene plastic for use as mulches in agroecosystems. Efforts are ongoing to engineer biodegradable plastic mulches that could be incorporated into the soil at the end of the crop season, and decomposed by microorganisms, ultimately to CO₂, H₂O, and biomass. Whether changes in soil quality occur during or following biodegradation is unknown. An 18-month study evaluated the effects on soil quality following burial of four potentially biodegradable mulches and a no mulch control in high tunnel and open field tomato production systems across three geographically distinct locations (Knoxville, TN; Lubbock, TX; Mount Vernon, WA). The mulch treatments included: two starch-based mulches (BioAgri^® Ag-Film and BioTelo Agri); one experimental 100% polylactic acid mulch (Spunbond-PLA-10); one cellulose-based mulch (WeedGuardPlus; positive control); and a negative control (no mulch). The soil management assessment framework (SMAF) was used to calculate a soil quality index (SQI) according to five dynamic soil properties: microbial biomass carbon, β-glucosidase, electrical conductivity, total organic carbon (TOC), and pH. Within the 18-month evaluation period, the effects of the biodegradable mulches on the SQI were minor, and dependent upon production system and time of incubation at all locations. In general, the SQI was higher in the high tunnel systems for some of the mulch treatments at Knoxville and Lubbock but the opposite was true at Mount Vernon. By the final sampling at 18 months, the SQI was lowest for WeedGuardPlus at Lubbock and Mount Vernon but at Knoxville, the WeedGuardPlus SQI was not significantly different from the no mulch control. Of the five SMAF indicators evaluated, soil microbial biomass and β-glucosidase activity were the most responsive to mulch and production systems, supporting the use of these variables as soil quality indicators for short-term changes due to this agricultural management practice.     

可持续生计分析框架下退耕户与非退耕户生计状况分析

基于西安市周至县退耕山区实地调查数据,运用国际惯用的分析生态工程影响的可持续生计分析框架,建立生计状况评价指标体系,对退耕户与非退耕户的生计状况进行对比分析.结果表明:与非退耕户相比,生计资本方面,退耕户的自然资本和物质资本更为丰富,人力资本和金融资本相对缺乏,社会资本无差异;生计策略方面,退耕户收入更低,支出略低;生计结果方面,退耕户贫困比率更高.并对结果予以解释和提出相应的政策建议.     

种养循环农作制度碳足迹评估——以鲜食玉米-奶牛-粪便还田循环模式为例

【目的】基于农业碳计量学方法对种养复杂系统全生命周期固碳减排效果的综合评估,是从全产业链视角开展我国低碳农作制度设计和优化的基础。本研究比较了5种系统情景及其对应的种养循环产业链碳足迹评估框架,以期为国内外低碳农作制度创建提供科学、合理、可用的方法学借鉴。【方法】研究基于ISO 14040发布的产品全生命周期碳足迹评价框架,结合IPCC提供的农田和养殖业温室气体核算体系,在不同的系统边界下,构建种养循环农作制度碳足迹评估框架,并以华南热作区鲜食玉米-奶牛-粪便还田循环模式为实证研究对象开展评估效果验证。【结果】评估框架明确了种养循环和分离模式全产业链都包含有农资投入、农田种植、动物养殖、粪便管理、运输和土壤碳汇变化等6个核算环节,并对各环节的碳计量学逻辑及其碳足迹核算方法进行了分析。案例结果表明,鲜食玉米-奶牛-粪便还田种养循环模式全生命周期碳足迹比分离模式降低了34.44%,表现出更好的固碳减排效果。评估框架对种养“耦合”或“脱耦”后对上游农资生产及运输环节的“间接排放”,以及下游产业链饲料替代和废弃物循环利用的“替代性减排”特征能够充分体现,实景系统田间实测数据和调研数据与背景系统...     

Influence of soil phosphorus status,texture, pH and metal content on the efficacy of amendments to pig slurry in reducing phosphorus losses

Cost‐effective strategies for using chemically amended organic fertilizers need to be developed to minimize nutrient losses in surface and groundwater. Coupling specific soil physical and chemical characteristics with amendment type could increase their effectiveness. This study investigated how water‐extractable phosphorus (P) was affected by chemical amendments added to pig slurry and how this effect varied with soil properties. A 3‐month incubation study was conducted on 18 different mineral soils, stored at 10 °C and 75% humidity and treated with unamended and amended slurry which was incorporated at a rate equivalent to 19 kg total P (TP )/ha. The amendments examined were commercial‐grade liquid alum, applied at a rate of 0.88:1 [Al:TP ], and commercial‐grade liquid poly‐aluminium chloride (PAC ), applied at a rate of 0.72:1 [Al:TP ]. These amendments were previously identified by the authors as being effective in reducing incidental losses of P. The efficacy of the amendments varied with the soil test P, the degree of P saturation (DPS ) and the Mehlich aluminium, iron and calcium, but not soil texture. Chemical amendments were most effective in soils with DPS over approximately 20%. Due to their high cost, the incorporation of amendments into existing management practices can only be justified as part of a holistic management plan where soils have high DPS .     

利用人工增雨为农田需水服务的信息系统框架

针对我国北方地区水资源严重短缺、农田水分供需矛盾日益尖锐的现状 ,提出了首选人工增雨为农田补水的思路 ,并初步设计了一个利用人工增雨为农田需水服务的农田需水信息系统框架。