Analysing land-cover changes in relation to environmental variables in Hesse,Germany

Land-use and land-cover changes affect ecological landscape functions and processes. Hence, landscape ecologists have a central interest in a comprehensive understanding of such changes. Our study focuses on the relationships between environmental conditions and agricultural land-cover changes. We present a method to (i) characterise the major spatial-temporal processes of land-cover changes, (ii) identify the correlations between environmental attributes and land-cover changes and (iii) derive potential environmental drivers of land-cover changes in a German marginal rural landscape. The method was applied to study land-cover dynamics from 1945 to 1998 in the districts of Erda, Steinbrücken and Eibelshausen, situated in the marginal rural landscape of the Lahn-Dill Highlands, Germany. We employed land-cover data gained by the interpretation of multi-temporal aerial photographs. Various environmental variables were introduced into the analyses. We identified physical landscape attributes (elevation, slope, aspect, available water capacity and soil texture) and structural landscape dimensions (patch size, patch shape and distance between patch and nearest settlement). With the aid of GIS, K-means partitioning and canonical correspondence analysis, we investigated land-cover trajectory types, land-cover transitions at individual time intervals and their relationships to these environmental variables. Our results show that, between 1945 and 1998, land-cover changes correlated with the physical attributes of the underlying landscape. On the other hand, the structural landscape dimensions correlated with land cover only in periods of minor land-cover changes (1972–98). Greater diversity of physical landscape attributes is correlated with greater land-cover dynamics. Besides the important influence of socio-economic factors, land-cover changes in the study areas took place within the relatively stable physical constraints of the underlying landscape.This revised version was published online in May 2005 with corrections to the Cover Date.     

IKONOS数据在植被景观制图和景观空间格局分析中的应用——以丘陵沟壑区准格尔五分地沟小流域为例

本文利用高分辨率 IKONOS数据 ,绘制了内蒙古准格尔旗五分地沟小流域植被景观图 ,并分析不同尺度的景观格局。结果表明 :IKONOS遥感数据在大比例尺植被景观制图方面具有较大的应用潜力。格局分析还表明 ,研究区植被景观为典型的人工生态、天然草原和耕地植被的高度镶嵌体 ,人工乔木林是各景观类型中面积最大的一类。整个研究区景观破碎度较大。     

Contribution of Biological Control to Integrated Pest Management of Tephritid Fruit Flies in the Tropics and Subtropics

The biological control of pest tephritid flies using parasitoids has been successful in relatively few subtropical and tropical regions. The best documented successes were in Hawaii and Florida, USA, Fiji and southern Europe. There were relatively limited successes in Australia, Costa Rica and Mexico. With the accidental establishment of new pest tephritids, such as Bactrocera latifrons (Hendel) in Hawaii or Bactrocera papayae Drew and Hancock in Australia, foreign exploration for new parasitoids is essential. A renewal of interest in classical biological control has recently occurred, although not at the same level as in the 1940s and 1950s. New parasitoid species are currently being obtained for several tephritids, such as Ceratitis capitata (Weidemann), B. latifrons and Anastrepha suspensa (Loew). The advances in mass rearing and quality control technology for parasitoids has enabled researchers to perform large-scale field testing of these parasitoids to determine the potential of augmentative releases. Numerous studies on the augmentative release of parasitoids have been done. Historically, the larval—pupal parasitoid Diachasmimorpha longicaudata (Ashmead) has been the most frequently studied parasitoid, due to the ease of rearing this species. However, recent successes in rearing other species with different biologies, e.g. the egg—pupal parasitoid Biosteres arisanus (Sonan), the gregarious eulophid, Tetrastichus giffardianus (Silvestri) and the pupal parasitoid, Coptera sp., will enable researchers to broaden the repertoire of parasitoid species for the future. Both successes and failures in augmentative releases have occurred. Without knowledge of the behavioural ecology of parasitoids, the reasons for success or failure can only be surmised. Recent research on the dispersal and host habitat finding of tephritid parasitoids will provide insights into improving augmentation and conservation strategies. The integrated pest management (IPM) of tephritid flies in the tropics has been less well-developed than research and programmes for tephritids in temperate zones. Significant emphasis is now being placed on the development of quarantine treatment methods that are environmentally sound; thus IPM will take a larger role. Several existing pest management strategies are reviewed which show the potential for compatibility with the activities of tephritid parasitoids. These include trap cropping, insecticides with selective toxicity to the target pests, mass trapping with parapheromones, the sterile insect technique and field sanitation.     

利用NOAA／AVHRR资料监测干旱环境变化的研究

本文介绍了利用ＮＯＡＡ卫星提取宏观范围干旱环境信息的方法。通过对植被、降水、地表、温度等诸多环境因子的遥感信息提取、分折，得出了一套利用气象卫星资料监测干旱环境的方法，并对绿洲植被，防护林生态效益，草地旱情等干旱区生境现象进行了监测评估，取得了较好效果。     

西方盲走螨保护越冬的研究

引自加利福尼亚的西方盲走螨释放于兰州地区苹果园,由于不能抵御当地1月份低温,未能自然越冬。针对该螨越冬场所:对苹果大树用旧棉絮、麦颖等材料,外围以塑料薄膜包扎枝干;对幼树,采取树冠下地表盖草压土等保护措施,使该螨存活越冬,翌年继续发挥控制李始叶螨的作用。     

棉田间种红花招引草蛉防治棉蚜

棉田中间种红花带,利用红花上的桃蚜,招引、繁殖大量草蛉,以控制棉田蚜虫,取得很好效果。红花田内草蛉成虫最多年份每亩达4万多头。不间种红花的对照田,从5月开始,用药7次。在棉蚜高峰期,蚜害株和卷叶率均比间种红花田严重。间种红花的棉田,经济效益有所增加。     

An evaluation of four crop : weed competition models using a common data set

Summary To date, several crop : weed competition models have been developed. Developers of the various models were invited to compare model performance using a common data set. The data set consisted of wheat and Lolium rigidum grown in monoculture and mixtures under dryland and irrigated conditions. Results from four crop : weed competition models are presented: almanac , apsim , cropsim and intercom . For all models, deviations between observed and predicted values for monoculture wheat were only slightly lower than for wheat grown in competition with L. rigidum , even though the workshop participants had access to monoculture data while parameterizing models. Much of the error in simulating competition outcome was associated with difficulties in accurately simulating growth of individual species. Relatively simple competition algorithms were capable of accounting for the majority of the competition response. Increasing model complexity did not appear to dramatically improve model accuracy. Comparison of specific competition processes, such as radiation interception, was very difficult since the effects of these processes within each model could not be isolated. Algorithms for competition processes need to be modularised in such a way that exchange, evaluation and comparison across models is facilitated.     

数据挖掘在现代农业物流体系创新与优化中的作用

农业物流逐渐体现出信息化、网络化和智能化的发展方向，作为现代农业物流的重要特征，对数据挖掘技术的应用提出了要求。主要分析了数据挖掘技术应用于现代农业物流体系创新与优化的重要意义，并对数据挖掘技术在现代农业物流体系创新与优化中的优势及实现关键技术进行了分析，指出了数据挖掘技术将为现代农业物流体系创新与优化提供越来越强大的支持功能。     

基于LOC度量在软件项目中的应用与估算

软件项目通常采用LOC（Line Of Code软件规模代码行）衡量项目规模。软件开发工作量和工期估算历来比较复杂，因为软件本身的复杂性、历史经验和估算工具的缺乏，以及一些人为错误，导致软件项目的规模估算和实际情况相差甚远。本文通过具体实例探索出一套适合衡量软件项目规模的计算方法，在详细分析数据的基础上，提出了一种可行的LOC软件估算方法，从而提高软件项目管理的水平。     

Novell网络环境下数据库软件的开发与研制

在局域Ｎｏｖｅｌ网络环境下开发数据库软件，首先应该解决存放在网络服务器中的数据库能够被多个工作站上的用户并行使用，必须正确处理数据库打开失败及数据库记录加锁失败等在网络上经常遇到的难题，同时必须建立良好的系统配置，以提高网络的工作效率。