三峡库区腹地规模农地空间分布规律

山区农业转型对于我国山区耕地可持续利用效率、土地整治方向以及生态建设方向具有一定的指导意义,渝东北生态涵养发展区是重庆市农用地整治项目的主要分区,通过定义作为农业转型产物的"规模农地"相关概念及其判读标准,旨在提出一种新的研究路径对重庆市典型山区地貌的耕地利用现状给予指导和改善意见。首先选取三峡库区腹地5个区县为研究区,并结合研究区实际对"规模农地"进行等级划分,利用Arc GIS10.2等软件通过景观格局指数、核密度测算、空间自相关等方法从斑块特征、数量分布、空间格局三方面对研究区内规模农地的空间分布规律进行探讨。研究表明:(1)不同类型规模农地斑块特征呈现一定的规律性,小规模农地斑块密度最大为6.004,大规模农地平均最近指数MNN值最低为643.401,且农地规模越大,面积加权平均斑块分维数AWMPFD值和聚集度AI值越高;(2)中、大规模农地数量多集中在奉节县,微、小规模则多集中在巫山县,且规模农地自身及其相互之间存在固定的邻接性规律,即同类斑块之间的邻接性与其斑块大小成反比,不同类型斑块之间则与之相反;(3)研究区规模农地整体空间分布主要集中在奉节县中部以及巫溪县东部,沿江流域的平坝地区分布相对密集,且不同类型规模农地在空间上存在明显的自相关性。     

The multifunctionality of urban farming: perceived benefits for neighbourhood improvement

Urban farming – a type of urban agriculture focused on entrepreneurial food production – serves multiple functions in neighbourhoods; yet these are not well delineated. Expectations for urban farming often centre on traditional measures of economic development, potentially overlooking other benefits. Through a qualitative case study conducted in Baltimore, Maryland, we sought to understand community perceptions regarding the ways in which urban farms can benefit cities. Interviews with residents, neighbourhood leaders, and urban farmers in three residential neighbourhoods with urban farms revealed the pathways by which community members view farms as improving neighbourhoods. Benefits stemmed from four primary changes urban farms made to study neighbourhoods: creation of public projects welcoming involvement, physical improvement of degraded space, production of local food, and creation of new businesses. These changes led to multiple perceived benefits including increased social connectedness, a transformed physical landscape, improved neighbourhood reputation, increased access to fresh produce, and educational, youth development, and employment opportunities. Our findings demonstrate the importance of a multifunctional paradigm that accounts for social and educational functions in assessing the value of urban farming and bring empirical evidence to the concept of multifunctional agriculture. Urban farms with strong social aims may appear to contribute little to economic development if measured using traditional indicators of success such as job creation or fiscal impacts, but provide numerous other benefits for community development.     

Drought,water access,and urban agriculture: a case study from Silicon Valley

In California, the growing popularity of urban agriculture (UA) has unfolded against a backdrop of historic drought. While UA is often celebrated as an urban sustainability strategy, it must be able to persist during drought if it is to perform these functions. Using Santa Clara County – the geographic core of Silicon Valley – as a case study, we use interviews and surveys to explore the implications of drought for UA. We show how developing an understanding of water access for UA during a drought requires examining the social and institutional context of water management and use. In metropolitan California, the highly decentralised water supply system combined with the diverse institutional arrangements that support UA create an uneven landscape of water access. Consequently, the pressure to change water-consuming practices – that is, the stress that institutional drought responses place on different water users – is geographically and socially differentiated. Among UA water users, responses to drought have also varied, in part because the possibilities for change are constrained by the sociotechnical arrangements of UA sites and the different purposes of UA.     

Decline of traditional rice farming constrains the recovery of the endangered Asian crested ibis (Nipponia nippon)

Traditional agriculture benefits a rich diversity of plants and animals. The winter-flooded rice fields in the Qinling Mountains, China, are the last refuge for the endangered Asian crested ibis (Nipponia nippon), and intensive efforts have been made to protect this anthropogenic habitat. Analyses of multi-temporal satellite data indicate that winter-flooded rice fields have been continuously reduced across the current range of crested ibis during the past two decades. The rate of loss of these fields in the core-protected areas has unexpectedly increased to a higher level than that in non-protected areas in the past decade. The best fit (R² = 0.87) numerical response model of the crested ibis population shows that a reduction of winter-flooded rice fields decreases population growth and predicts that the population growth will be constrained by the decline of traditional winter-flooded rice fields in the coming decades. Our findings suggest that the decline of traditional rice farming is likely to continue to pose a threat to the long-term survival and recovery of the crested ibis population in China.

Electronic supplementary material

The online version of this article (doi:10.1007/s13280-015-0649-5) contains supplementary material, which is available to authorized users.     

农业源水污染物削减技术探讨

农业面源污染是水体中COD、氮、磷等指标的主要来源。它包括农药化肥施用、畜禽养殖和农村生活污水排放。对农业源水污染物进行削减是实现污染物总量控制的重要手段。通过详细总结国内外现有农业源水污染物削减技术方法,分析对比其优缺点和实用性,筛选出适用于不同农业污染来源的污水处理技术。结果表明,畜禽养殖废水的适宜处理技术有厌氧/缺氧/好氧(A/A/O)、序批式活性污泥法(SBR)、膜生物反应器(MBR)、升流式厌氧污泥床(UASB)、厌氧沼气池;农地施肥污水的适宜处理技术有SBR、MBR、UASB;农村生活污水的适宜处理技术有厌氧沼气池、生物滴滤池、人工湿地、稳定塘。     

Climate Change and Population Growth in Timor Leste: Implications for Food Security

The climate in Timor Leste (East Timor) is predicted to become about 1.5 °C warmer and about 10 % wetter on average by 2050. By the same year, the population is expected to triple from 1 to 2.5–3 million. This article maps the predicted changes in temperature and rainfall and reviews the implications of climate change and population growth on agricultural systems. Improved cultivars of maize, rice, cassava, sweet potato and peanuts with high yield performance have been introduced, but these will need to be augmented in the future with better adapted cultivars and new crops, such as food and fodder legumes and new management practices. The requirements for fertilizers to boost yields and terracing and/or contour hedgerows to prevent soil erosion of steeply sloping terrain are discussed. Contour hedges can also be used for fodder for improved animal production to provide protein to reduce malnutrition.     

四川生态旅游农业模式及其可持续发展之浅见

本文论述了生态旅游农业的特点和四川发展生态旅游农业的优势和意义,归纳了四川生态旅游农业的几种模式,并对四川生态旅游农业可持续发展提出了几点浅见。     

循环农业是发展循环经济的基础

论述了发展循环农业是发展循环经济的基础,以及发展循环农业应采取的方针政策及具体措施。指出发展农业循环经济是我国实现农业经济可持续发展的必然选择。     

汶川地震次生山地灾害链成灾特点与防治对策

地震次生山地灾害链是山地灾害链的一种特殊形式。由于地震作用后,灾害单体之间的连锁作用强烈,成灾机理更加复杂,防治难度大增,因此只针对灾害单体的减灾思想,很难对灾害链整体进行遏制,而必须从灾害链的各个关联环节着手,建立新的减灾框架。从汶川地震次生山地灾害链的成灾特点和防治思路两个方面进行了探讨,针对成灾规律特征,提出了5种山地灾害链的断链防治思路。     

北京现代都市低碳农业的前景与策略

现代都市发展低碳农业是降低温室气体排放,实现国家宏观战略目标的重要组成部分.本文对低碳农业的定义、特征进行了初步阐述,认为低碳农业是通过技术改进和制度创新建立起来的一种低投、高产、低(负)碳、生态的现代农业,具有系统开放性、技术集成性、生命周期性、过程安全性四个特征.利用碳汇/源平衡方法分析北京农业现状,结果表明:目前北京农业领域的碳源与汇分别为10-20 TgCO2eq·a-1和10.23-14.16 TgCO2eq·a-1,碳源基本稳定,碳汇还有较大的发展潜力.根据北京市生态特点和未来农业的定位,发展低碳农业,在技术层面上,可以加强与种植相关的土壤碳汇建设,与养殖相关的减排和其他减排技术;在制度层面上,建立农业布局调整机制,大力发展清洁生产机制、生态补偿机制、农业准入机制和综合调节机制.预测北京低碳农业的前景,初步估算未来北京农业的碳汇潜力可以达到20-30 TgCO2eq·a-1,直接的碳源可以减少到4-5 TgCO2eq·a-1.通过发展低碳农业,不仅可以抵消农业碳源,还能抵消6%-10%总温室气体,真正起到净碳汇功能.