Modeling the relationships between land use and land cover on private lands in the Upper Midwest, USA

This paper presents an approach to modeling land-cover change as a function of land-use change. We argue that, in order to model the link between socio-economic change and changes in forest cover in a region that is experiencing residential and recreational development and agricultural abandonment, land-use and land-cover change need to be represented as separate processes. Forest-cover change is represented here using two transition probabilities that were calculated from Landsat imagery and that, taken together, describe a Markov transition matrix between forest and non-forest over a 10-year period. Using a three-date land-use data set, compiled and interpreted from digitized parcel boundaries, and scanned aerial photography for 136 sites (c. 2500 ha) sampled from the Upper Midwest, USA, we test functional relationships between forest-cover transition probabilities, standardized to represent changes over a decade, and land-use conditions and changes within sample sites. Regression models indicated that about 60% of the variation in the average forest-cover transition probabilities (i.e. from forest to non-forest and vice versa) can be predicted using three variables: amount of agricultural land use in a site; amount of developed land use; and the amount of area increasing in development. In further analysis, time lags were evaluated, showing that agricultural abandonment had a relatively strong time-lag effect but development did not. We demonstrate an approach to using forest-cover transition probabilities to develop spatially-constrained simulations of forest-cover change. Because the simulations are based on transition probabilities that are indexed to a particular time and place, the simulations are improved over previous applications of Markov transition models. This modeling approach can be used to predict forest-cover changes as a result of socio-economic change, by linking to models that predict land-use change on the basis of exogenous human-induced drivers.     

陕西大暴雨时空分布特征及减灾对策

通过对陕西１９５７～１９９８年共４２年９７个测站的逐日降水量中大暴雨资料进行时间和空间尺度分析，总结归纳出陕西灾害性大暴雨的天气气候基本特征和规律性，并提出相应的减灾对策。     

成都市农业环境的主要问题及对策

本文指出成都市农业环境受工农业生产发展所造成的污染和对生态环境的破坏都较严重。为此,提出保护农业环境的关键在于:建立健全农业环境管理机构,健全法制,加强农业环境意识及促进农业生态系统的良性循环,加速生态农业建设,尽量减小农业自身污染。     

垃圾场渗出污水厌氧处理的可行性研究

采用血清瓶静态试验法研究了垃圾渗出污水的厌氧处理的可行性。试验表明:垃圾渗出污水对厌氧发酵微生物无抑制作用,有良好的厌氧降解性,产气率为0.321/g·COD,污水中的大部份有机物都能被厌氧消化,COD_cr去除率为78.2%,发酵过程中还能获得能源——沼气。具有良好的应用前景。     

印铁涂装烘房有机废气的直接燃烧法处理实践

本文通过采用催化法和直燃法两种工艺处理印铁涂装生产的有机废气的工业实践,对设计和运行中的一些要点进行分析和探讨。     

论代表性的涵义及工业废水重点源采样方案的设计原则

数据代表性是指监测结果在表征被监测对象特性时所能达到的真实程度;样品代表性是指局部体现整体时所能达到的真实程度。加密监测是重点原调查的质量基础,不能简化行事。监督性监测中,通过测定流量比例混合样来获取总量控制所必需的漉量加权平均值浓度数据,并以此来减小工作量。为满足浓度控制需要,时间—浓度确定型废水的峰浓度样应单独测定。     

岷江生态环境问题及其对策研究

本文主要探讨岷江流域的生态环境问题及其对策。全文分为两个部分。(1)研究岷江生态环境问题;(2)解决岷江生态环境问题的主要对策。     

瓦勃氏呼吸仪测定乐果合成废水的可生化性

本文概述了瓦勃氏呼吸仪测定有机污染物的可生化性的基本原理和方法。通过测定用乐果合成废水驯化后的微生物的生化呼吸线和相对耗氧速度曲线,结果表明:乐果合成废水是有毒的,但是完全可以被特异驯化后的微生物所降解;其降解速度与时间和废水所含污染物的浓度有关。     

绵阳城区环境质量现状及对策

本文叙述了绵阳城区的环境质量现状。根据绵阳历史及发展，到２０１０年要建成为１００万人口的大城市，提出未来的绵阳城区既是一个开放型、式功能、综合性的现代化中心城市，又应是一个环境优美、整齐清洁、繁荣兴旺、高度文明的现代化城市。必须高度重视环境保护工作，建议采取包括环境规划、抓好环境建设及环境管理等措施。     

大巴山区化学药剂防治与农业生态环境保护对策

本文对大巴山区农业生产中用化学药剂防治状况及存在的主要问题进行了分析研究。在此基础上，提出开展农药区划和区域性宏观调控，建立农药污染监测管理机制，进一步提高综合防治技术水平和专业化防治程度，加强防止污染微观技术的研究与推广控制策略和措施，以实现对化学药剂防治与农业生态环境保护。把农业环境保护工作纳入农业发展和国家农业环境保护的总体规划。