沼气发酵在复合农业生态系统中的作用

沼气发酵系统是复合农业生态系统中物质循环和能量转化的枢纽。它以农业有机废弃物为原料，经厌氧消化，生产出高效、洁净、多用途的燃料、饲料和肥料。本文论说了开展沼气发酵对保护农村生态环境。促进生态农业发展所具有的重要意义，提出了目前我国沼气发展过程中存在的一些问题和今后应采取的措施。     

A holistic approach to the development of sustainable agriculture: application of the ecosystem health model

Serious resource depletion has made sustainable agriculture an important and pressing issue for scientists, policy makers, and stakeholders worldwide, particularly in developing countries. Researchers have focused on methods to assess agriculture correctly, and to introduce sound solutions for sustainability, but have reached no agreement. In this paper, we introduce the theoretical framework of the agro-ecosystem health model, a new holistic approach, and apply it at a regional scale using four aspects (4S): sound structure, stable function, safe service, and sustainable development. We examine how 12 indicators of an agro-ecosystem health assessment (AHA) were selected using three dimensions based on this theoretical framework. In an AHA, we used an amoeba approach to examine a high-yield agro-ecosystem in Huantai County, Shandong Province, China. The results indicate that this model of ecosystem health can reflect the complex ecological, economic, and human conditions of an agro-ecosystem and evaluate these conditions using perspectives pertinent to system structure, function, and responses (services).     

Exposure of tadpoles of Fejervarya limnocharis (Anura: Ranidae) to combinations of carbaryl and cypermethrin

Cypermethrin and carbaryl are both used to control pests of rice paddy crops but the two insecticides have different modes of action. In some areas or climates, the breeding of frogs living in rice paddy fields and the application of the insecticides coincide. The effects of the acetylcholinesterase (AChE) inhibitor carbaryl and the sodium channel blocker cypermethrin, both individually and in combination, were investigated on the survival and emergence of froglets of Fejervarya limnocharis using a 3?×?3 concentration factorial design (0, 25, and 50?μg L^?1). Compared to controls, carbaryl showed no effect on survival and froglet emergence. Exposure to cypermethrin reduced the survival and froglet emergence in a concentration-dependent manner. When tadpoles were exposed to combinations of carbaryl and cypermethrin, the influence of carbaryl on survival and froglet emergence is less significant than that of cypermethrin.     

农业生态系统碳循环研究

为了搞清我国农业生态系统碳循环状况,以１９９０年和２０００年为例,对系统周年内碳的吸收、排放、固定和转移量进行了计算分析,绘制出全国农业生态系统碳循环框图。结果表明,１９９０年和２０００年碳的排放、固定、转移量占当年吸收量分别为８９．７％和９１．０％、９．１２％和７．８３％及１．１８％和１．１６％。说明无论是现阶段还是气候变化后,我国农业生态系统对碳的吸收量均大于排放量,对大气ＣＯ２浓度而言,不是源而是汇。