农业生态系统的氮素循环研究进展

在自然和人为作用的双重驱动下,地球表面氮素的生物地球化学过程及其环境效应成为当前全球变化中区域研究的重要内容。探讨了氮素循环各个过程及其数量特征,对氮素循环模型进行了介绍,并对当前生态系统中氮素循环的研究热点进行了简要的论述。     

农牧交错带农业生态服务功能的作用及其保护途径

目前全球农业生产覆盖全球25％～30％的土地面积，约50％的可利用土地已经被农业占据。如果农业生态系统．特别是生态脆弱区的系统服务功能得不到恢复与保护．那将会拖全球环境保护的“后腿”。由于中国的国情决定了在生态脆弱区环境保护中必须坚持环境保护与发展农业生产“两手抓“。因此．农业生态系统服务功能的恢复、维持应该成为该地区生态环境保护与建设的重要组成部分。农业生产不仅要提高生态系统服务的产品功能，更要恢复和维持其各种维持生命的间接服务功能。本文在分析农业生态系统服务功能退化表现与影响因素的基础上．提出了针对各项服务功能的恢复与维持对策。     

Application of processed organic municipal solid waste on agricultural land – a scenario analysis

Source separation, composting and anaerobic digestion, with associated land application, are increasingly being considered as alternative waste management strategies to landfilling and incineration of municipal solid waste (MSW). Environmental life cycle assessments are a useful tool in political decision-making about waste management strategies. However, due to the diversity of processed organic MSW and the situations in which it can be applied, the environmental impacts of land application are very hard to determine by experimental means. In the current study, we used the agroecosystem model Daisy to simulate a range of different scenarios representing different geographical areas, farm and soil types under Danish conditions and legislation. Generally, the application of processed organic MSW resulted in increased emissions compared with the corresponding standard scenarios, but with large differences between scenarios. Emission coefficients for nitrogen leaching to the groundwater ranged from 0.03 to 0.87, while those for nitrogen lost to surface waters through tile drains ranged from 0 to 0.30. Emission coefficients for N₂O formation ranged from 0.013 to 0.022 and for ammonia volatilization from 0.016 to 0.11. These estimates are within reasonable range of observed values under similar conditions. Furthermore, a sensitivity analysis showed that the estimates were not very sensitive to the mineralization dynamics of the processed organic MSW. The results show that agroecosystem models can be powerful tools to estimate the environmental impacts of land application of processed MSW under different conditions. Despite this, agroecosystem models have only been used to a very limited degree for this purpose.     

Management of an Agroecosystem

Agroecosystems (AESs) are autotrophic ecosystems managed by man. The goal of the management is to obtain the maximum possible amount of high-quality agricultural products while preserving agricultural resources, primarily the soils and biodiversity. The main components of the management of AES structures and functions, including primary and secondary biological production, the ratio between the energy flows in the plant–man and plant–livestock–man food chains, the efficiency of energy transfer in the plant–livestock link, and conservation of agricultural resources, are considered.     

农田生态系统四川短尾鼩种群能量动态的研究

用标志重捕法对四川短尾鼩种群数量及能量动态研究.结果表明：种群数量在每年6月和10月有两个高峰;四川短尾鼩的只采食量为4．212±0．86g／d,排泄量为2．18±0．12g／d身体器官热值为15．50kJ／g．食物热值为16．51kJ／g．生物量为214．38±59．96g／hm2,静止代谢率r（RMR）为22．909kJ／d,通过种群的能量为50．74kJ／d,次级生产量为169．25kJ／ha·d,生长效率（P／A）为0．097,本文用Odum的能路语言（energycircuitlanguape）,对四川短尾在生态系统中的能量地位进行了定位.     

土地利用系统规划和设计方法探讨

应用系统思想和生态学原理，提出了以土地─食物─人这一耦合运行发展过程研究为中心、以建立合理的土地利用系统为目标的农区土地利用规划和设计方法模型框架，其中包括：目标设计；土地评价；农业生态系统分析；土地利用系统定量化研究模拟模型；土地利用系统结构优化；土地利用系统生态设计；多层次人工控制系统设计。     

Species diversity of spiders (Arachnida, Aranei) in agroecosystems of Moscow oblast and Krasnodar krai

A census of spiders has been taken in Moscow oblast and Krasnodar krai (the Kuban Plain) in fields under corn, vetch-oat mixture, and winter wheat (in the central and peripheral zones separately), as well as on their margins and in adjoinint areas of other biotopes. Spiders were collected using entomological sweeping and pitfall traps. On the whole, 286 species of 20 families and 146 genera have been found (205 species in Moscow oblast and 139 species in Krasnodar krai). The level of species diversity does not change significantly; a noticeable decrease in this parameter is observed only in the central zones of fields. In Moscow oblast, species diversity reaches a peak at field margins; in Krasnodar krai, no regular differences in this parameter between the forest strip, field margin, and the peripheral zone of a crop field has been revealed. Species diversity usually decreases toward the field center. However, changes in species diversity at a distance of more than 100 m from the margins are insignificant.     

Biodiversity Loss in Latin American Coffee Landscapes: Review of the Evidence on Ants,Birds, and Trees

Abstract: Studies have documented biodiversity losses due to intensification of coffee management (reduction in canopy richness and complexity). Nevertheless, questions remain regarding relative sensitivity of different taxa, habitat specialists, and functional groups, and whether implications for biodiversity conservation vary across regions. We quantitatively reviewed data from ant, bird, and tree biodiversity studies in coffee agroecosystems to address the following questions: Does species richness decline with intensification or with individual vegetation characteristics? Are there significant losses of species richness in coffee‐management systems compared with forests? Is species loss greater for forest species or for particular functional groups? and Are ants or birds more strongly affected by intensification? Across studies, ant and bird richness declined with management intensification and with changes in vegetation. Species richness of all ants and birds and of forest ant and bird species was lower in most coffee agroecosystems than in forests, but rustic coffee (grown under native forest canopies) had equal or greater ant and bird richness than nearby forests. Sun coffee (grown without canopy trees) sustained the highest species losses, and species loss of forest ant, bird, and tree species increased with management intensity. Losses of ant and bird species were similar, although losses of forest ants were more drastic in rustic coffee. Richness of migratory birds and of birds that forage across vegetation strata was less affected by intensification than richness of resident, canopy, and understory bird species. Rustic farms protected more species than other coffee systems, and loss of species depended greatly on habitat specialization and functional traits. We recommend that forest be protected, rustic coffee be promoted, and intensive coffee farms be restored by augmenting native tree density and richness and allowing growth of epiphytes. We also recommend that future research focus on potential trade‐offs between biodiversity conservation and farmer livelihoods stemming from coffee production.     

人工林与其紧邻农田中野生植物与土壤线虫群落特征对比

我国北方农耕区休耕地种植杨树现象较为普遍,但是人工林对农业生态系统中生物多样性的保护作用却鲜有关注.在山东省宁津县选取3块样地,均为休耕地种植杨树林且紧邻小麦玉米轮作田,对比人工林下、田埂及农田内的草本植物群落特征、土壤线虫群落特征及土壤化学性质,以探究人工林对农业生态系统中生物多样性的作用.结果表明:①植物样方总物种数和样方平均物种数均呈现农田<距田埂30 m人工林下<距田埂10 m人工林下<田埂<距田埂20 m人工林下<距田埂5 m人工林下的变化规律,其中,距田埂5 m人工林下植物样方总物种数为21种,农田内11种.人工林下草本植物群落多样性指数、丰富度指数均显著高于农田内杂草植物群落相应指数(P<0. 05).②农田、田埂及距田埂5 m的人工林下的土壤线虫组成存在差异,农田和人工林下土壤线虫优势属为头叶属(Cephalobus),而田埂中为真头叶属(Eucephalobus).土壤线虫群落多样性指数、成熟指数、植物寄生线虫成熟指数及线虫通路比在人工林下、田埂和农田之间差异均不显著(P≥0. 05),土壤线虫均为耐环境压力类群.③人工林下与农田土...     

Soil-erosion and runoff prevention by plant covers in a mountainous area (se spain): Implications for sustainable agriculture

In the Mediterranean region the intensities and amounts of soil loss and runoff on sloping land are governed by rainfall pattern and vegetation cover. Over a two-year period (1998–1999), six wild species of aromatic and mellipherous plants (Thymus serpylloides subsp. Gadorensis, Thymus baeticus Boiss, Salvia lavandulifolia Vahl., Santolina rosmarinifolia L., Lavandula stoechas L. and Genista umbellata Poiret) were selected for erosion plots to determine their effectiveness in reducing water erosion on hillslopes of the Sierra Nevada Mountain (SE Spain). The erosion plots (including a bare-soil plot as control), located at 1,345 m in altitude, were 2 m² (2 m × 1 m) in area and had 13% incline. The lowest runoff and soil erosion rates, ranging from 9 to 26 mm yr⁻¹ and from 0.01 to 0.31 Mg ha⁻¹ yr⁻¹, respectively, over the entire study period, were measured under the Thymus serpylloides. Lavandula stoechas L. registered the highest rates among the plant covers tested, runoff ranging from 77 to 127 mm yr⁻¹ and erosion from 1.67 to 3.50 Mg ha⁻¹ yr⁻¹. In the bare-soil plot, runoff ranged from 154 to 210 mm yr⁻¹ and erosion from 4.45 to 7.82 Mg ha⁻¹ yr⁻¹. According to the results, the lowest-growing plant covers (Thymus serpylloides and Salvia lavandulifolia Vahl.) discouraged the soil erosion and runoff more effectively than did the taller and open medium-sized shrubs (Santolina rosmarinifolia L., Genista umbellata Poiret, Thymus baeticus Boiss and Lavandula stoechas L.). Monitoring allowed more direct linkage to be made between plant covers and the prevention of erosion, with implications for sustainable mountain agriculture and environmental protection.