条（白蜡条）农间作生态经济效益与配置

根据二十多年来的调查研究,着重论述条农间作在改变生态环境、提高作物产量、增强物质能量循环以及生物效应和经济效益等方面的作用,为条农间作的合理配置、类型划分提出理论依据.     

基于能值改进模型的红米与烤烟作物系统可持续性评价——以贵州省盘州市为例

为准确测度农作物生产的可持续发展水平,进一步提高可持续发展能力。将碳排放与碳固定视为农田系统环境产出,纳入能值分析框架,建立能值改进指标,评价区域红米和烤烟2种不同作物生产模式的可持续性并进行灵敏性测试。研究发现,红米和烤烟系统的能值投入分别是1.26E+17sej/hm²和1.24E+17sej/hm²,产品能值产出分别是2.61E+16sej/hm²和6.55E+15sej/hm²,红米生产模式的产品产出效率较好。在环境能值产出方面,红米系统表现为净温室气体排放“源”,碳排放（5.97E+16sej/hm²）远大于碳固定（1.30E+15sej/hm²）,减排潜力较大;而烤烟系统则表现为碳固定盈余,碳排放（1.95E+14sej/hm²）小于碳固定（3.42E+14sej/hm²）。温室气体排放量变化对作物系统环境负载率和可持续发展水平的影响最大。结论表明,在传统能值分析体系中增设碳排放与碳固定指标可为农业系统可持续性评价提供更加全面的测算思路和方法借鉴。     

农田土壤磷素流失研究进展

本文对近些年来有关农田土壤磷素流失及其对水环境的影响进行综述。主要从农田土壤磷素的流失现状阐述磷素流失对水体的影响,讨论了磷肥的施用、土壤性质以及磷素的运输途径对土壤磷素流失的影响及其相关机理,同时阐述了土壤磷素流失的环境风险,最后该研究领域存在的若干问题。     

北京郊区民俗旅游产品创新体系探析

北京郊区民俗旅游是北京未来旅游产业发展的重点,现今民俗旅游产品的娱乐方式、起居习俗等体现文化内涵的活动比较匮乏。为对京郊民俗旅游产品存在的问题进行深入剖析,构建民俗旅游产品创新体系,采用实地调查走访的方法,对京郊民俗旅游产品的经营现状进行研究分析,了解游客对目前京郊民俗旅游产品的看法。希望通过对京郊的民俗旅游资源进行分类研究,分析民俗旅游资源与旅游产品的关系,试图重新建立京郊民俗旅游产品的创新体系,满足当今旅游市场的需求变化。     

Nitrogen transfer from a legume tree to the associated grass estimated by the isotopic signature of tree root exudates: A comparison of the N leaf feeding and natural N abundance methods

Nitrogen (N) transfer from legume trees to associated crops is a key factor for the N economy of low-input agroforestry systems. In this work, we presented a new approach to estimate N transfer based on the ¹⁵N content of root exudates and N released by root turnover of the donor plant (Gliricidia sepium) and the temporal change of the ¹⁵N content of the receiver plant (Dichanthium aristatum). The study was carried out in greenhouse using two isotopic methods: ¹⁵N leaf feeding (LF) and the natural ¹⁵N abundance (NA). Measurements of exudate ¹⁵N were made at several dates before and after tree pruning. A time-dependent box model was devised to quantify N transfer in time and to make comparisons between the isotopic methods. In NA, although tree roots and exudates presented a similar ¹⁵N signature before tree pruning, exudates were strongly depleted in ¹⁵N after pruning. In LF, exudates were always depleted in ¹⁵N in relation to tree roots. Hence, the current assumption used in N transfer studies concerning the equal ¹⁵N/¹⁴N distribution in tissues of the donor plant and in its excreted N was not confirmed in our study. Before pruning, N transfer functioned as a two-N-source system (soil N and exudates N) and both isotopic methods provided similar estimates: 11–12% for LF and 10–15% for NA. Calculations performed with the model indicated that N transfer occurred with small or nil fractionation of ¹⁵N in exudates. After pruning, there was a third N source associated with N released from tree root turnover. During this period, the isotopic signature of the receiver plant showed a transient state due to the progressive decrease of ¹⁵N content of that N source. The amount of N derived from the tree represented 65% of the total N content of the grass at the end of the experiments.     

耕地资源安全评价指标体系研究

耕地是土地资源的精华,耕地资源安全居于国家资源安全的核心地位。从耕地资源的主要功能出发,分析耕地资源安全的内涵,探讨建立区域耕地资源安全评价指标体系的原则和思路,提出区域耕地资源安全评价指标体系,为开展区域耕地资源安全状态评价奠定技术基础,并提出了应用该指标体系时需注意的一些问题     

基于Internet的多年生和无性繁殖作物种质资源数据管理系统的设计与实现

果树、茶树、桑树、薯类、无性繁殖蔬菜、苎麻、甘蔗、橡胶等多年生和无性繁殖作物是我国农业生产的重要组成部分。为加快我国多年生和无性繁殖作物种质资源的收集、整理、鉴定评价和创新利用,加强种质资源规范化管理,促进资源信息交流,提高资源数据库管理水平,笔者采用动态web数据库的策略,执行浏览器／服务器（B/S）体系结构,建立了基于Internet的多年生和无性繁殖作物种质资源源数据管理系统,对多单位、多作物进行统一、规范的管理, 实现种质资源数据库的共建、信息共享。     

北京郊区自然资源与社会经济信息管理平台建设的研究

为提高北京农村和农业的决策分析能力,进一步整合与开发郊区信息资源,建设了北京郊区自然资源与社会经济信息管理平台。首先,从结构体系、数据组织、功能模块、监测范围和监测内容方面详细阐述了系统平台结构与内容;其次,开展了数据标准化处理、多源异构数据融合、空间一体化存储与管理、数据快速采集与更新等平台技术体系研究;最后,指出了平台运行与日常维护工作并讨论了平台建设存在的问题。结果表明：系统平台经过5年建设与运行实现了郊区信息资源的定性分析、定量计算和直观展示相结合的空间一体化管理模式,对北京社会主义新农村建设和基层三农发展具有重要的现实意义。     

Effects of shade,altitude and management on multiple ecosystem services in coffee agroecosystems

Agroforestry systems provide diverse ecosystem services that contribute to farmer livelihoods and the conservation of natural resources. Despite these known benefits, there is still limited understanding on how shade trees affect the provision of multiple ecosystem services at the same time and the potential trade-offs or synergies among them. To fill this knowledge gap, we quantified four major ecosystem services (regulation of pests and diseases; provisioning of agroforestry products; maintenance of soil fertility; and carbon sequestration) in 69 coffee agroecosystems belonging to smallholder farmers under a range of altitudes (as representative of environmental conditions) and management conditions, in the region of Turrialba, Costa Rica. We first analyzed the individual effects of altitude, types of shade and management intensity and their interactions on the provision of ecosystem services. In order to identify potential trade-offs and synergies, we then analyzed bivariate relationships between different ecosystem services, and between individual ecosystem services and plant biodiversity. We also explored which types of shade provided better levels of ecosystem services. The effectiveness of different types of shade in providing ecosystem services depended on their interactions with altitude and coffee management, with different ecosystem services responding differently to these factors. No trade-offs were found among the different ecosystem services studied or between ecosystem services and biodiversity, suggesting that it is possible to increase the provision of multiple ecosystem services at the same time. Overall, both low and highly diversified coffee agroforestry systems had better ability to provide ecosystem services than coffee monocultures in full sun. Based on our findings, we suggest that coffee agroforestry systems should be designed with diversified, productive shade canopies and managed with a medium intensity of cropping practices, with the aim of ensuring the continued provision of multiple ecosystem services.     

原生动物在环境毒理学研究中的应用

环境毒理学一直是环境科学的重要分支,其研究成果对于确定污染物生物效应、作用机理以及制定环境监测指标都有重要意义。原生动物在环境毒理学研究中具有特殊的地位和作用。本文概述了原生动物在水体监测,污水净化及土壤环境评价等方面的应用,以及作为环境毒理学研究模式生物的独特优势,对原生动物在毒理学研究中的发展前景进行了展望。     

Impacts of long-term jujube tree/winter wheat–summer maize intercropping on soil fertility and economic efficiency—A case study in the lower North China Plain

Agroforesry is a common traditional practice in China, especially in the saline-alkaline regions, like the lower North China Plain (LNCP) characterized by lower yields of food crops. Adding trees to the agricultural land creates additional fruitsets or woody biomass besides food crops, enabling farmers to diversify the provision of farm commodities. However, the productivity of many agroforestry systems has been lower than expected in recent years, highlighting the need for a mechanistic understanding of below- or above-ground interactions. The study combined investigation and experimental data together to evaluate the effects of long-term intercropping agroforestry system [jujube tree (Zizyphus jujuba Mill. var. inermis (Bunge) Rehd.)/winter wheat–summer maize] on soil fertility balance, crop production and system economic efficiency over the past 22 years in LNCP, with a view to developing an effective fertilization management for the moderately alkaline soils. Except remain higher pH, the soils are basically free of sodic and soil salinity is not the major restriction factor for intercrops, even through there are some fluctuation with season and distance from jujube tree. The intercropping system significantly reduced soil nutrient contents, like soil organic C (SOC), total N (TN), available P (avail. P) and K (avail. K) in most parts of the ecotone of the system, but increased those nutrients in the belt of underneath the edge of tree canopy, The growth of intercrops at the belt of 3.5 m from tree was severely negative stressed by jujube tree in term of lower soil moisture, nitrate, avail. P and K although receiving more photosynthetically active radiation (PAR), whereas the winter wheat growing at the 2.5 m row had more water and nutrients supplied and thus produced more grain yield. Uneven fertilization to the ecotone (about 1–2.5 m of the intercrop field boundary) could partly offset the consumption and competition for nutrients between the tree and the intercrops, and improved the grain yields by 12.1% and 14.5% in the ecotone regions (distance from jujube trees) of 1.5 m for winter wheat and 2.5 m for summer maize by increasing respective yield components. Although the mean grain yield of intercropped winter wheat and summer maize was reduced by 35.6 and 35.2%, respectively, compared to sole cropping system, the intercropping system proved to be a profitable land use type based on net income and economic returns, in addition to the wood and ecological benefits of the jujube tree in the moderate desalinate- alkaline regions.     

西北干旱区域水资源可持续利用评价指标体系的构建

水资源是人类赖以生存和发展的一个极其重要的因素。水资源的可持续利用是实现人类社会经济、资源、环境协调发展的基本前提。笔者针对西北干旱区独有的气候水文特征,从区域水资源与区域经济社会的相互关系出发,从区域水资源承载力的本质概念进行分析,拓展认识和界定区域水资源储备量和区域水资源承载能力的内涵意义。基于区域水资源的储备、消耗、再生的3大功能过程,考虑区域社会调节活动对区域水资源功能过程的影响,构建了1个以指标层变量、分类层指标和目标层指数3个等级层次体系,并适用性较强的西北干旱区域水资源可持续利用评价指标体系。     

中国传统稻鱼共生系统的历史分析

中国是历史上最早进行稻田养鱼的国家,这种传统的生态农业方式既充分、合理地利用水土资源,又能增产粮食和水产品,具有显著的经济、社会和生态效益,因而被传承下来,并在稻作区广泛传播,成为极富生命力的农业文化遗产,对当今农业生产中生物多样性的利用富有启发意义。这一历史传统的形成和发展,与自然资源、经济发展状况、生态环境条件和文化传统密不可分。今天传统稻鱼生产方式正面临诸多亟待解决的问题。     

陇南山区国土资源承载力评价研究 ——以两当县为例

为把握两当县国土资源承载力的空间分异特征,从而立足本地资源,拓宽发展思路,加快山区发展,笔者分别对两当县水资源、土地资源、矿产资源承载力进行评价:(1)利用综合指标法对水资源和土地资源的承载力进行评价,水资源承载力结果为:高承载力主要分布在泰山、云屏、张家和兴化4个乡镇,中等承载力的乡镇有站儿巷、左家、西坡、鱼池、杨店、显龙和金洞;城关为低承载区。土地资源承载力结果为:高承载力主要分布在鱼池、云屏、泰山、金洞、站儿巷、显龙、杨店、兴化和左家这9个乡镇,中等承载力的有城关和西坡;张家为低承载区;(2)利用模糊综合评价法对矿产资源承载力进行评价,得出两当县矿产资源高承载力主要分布在云屏、站儿巷、鱼池、显龙、西坡、金洞、泰山、兴化这8个乡镇,张家、城关和杨店为中等承载力,左家为低承载区;(3)利用综合评价方法进行了两当县国土资源承载力评价。高承载力的乡镇为:泰山、云屏、张家和兴化,中等承载力的乡镇有鱼池、左家、杨店、显龙、站儿巷、西坡和金洞,城关属于低承载力区。     

重碳酸盐型盐碱虾池浮游植物与理化因子的相关关系

选择重碳酸盐型盐碱南美白对虾塘作为研究对象,研究浮游植物与水体理化因子的相关关系。结果表明,与虾池浮游植物生物量显著相关的理化因子有水温、透明度、总碱度、化学耗氧量、氨氮和总磷,其中,水温、总碱度、化学耗氧量和氨氮呈显著正相关,透明度和总磷呈显著负相关,水温、透明度、总碱度、化学耗氧量、氨氮和总磷是影响虾池浮游植物高密度发生的重要理化因子。     

Germplasm conservation of oca (Oxalis tuberosa Mol.) through botanical seed. Seed formation under a system of polymorphic incompatibility

Seven clonal accessions representing all three stylar morphs of tristylous oca were intercrossed and selfed in a complete diallelic crossing design. The four traits total capsule production, total number of seeds/capsule, total number of seeds containing an embryo/capsule, and percent seeds containing an embryo of all seeds per capsule were recorded. Both capsule and seed production were highest in the legitimate pollinations (in which styles are pollinated with pollen of the corresponding anther level), but also in illegitimate pollinations of mid-styled seed parents with long-level anther pollen of short-styled accessions. All 18 types of pollination, consisting of 6 legitimate, 6 illegitimate intermorph, and 6 illegitimate intramorph pollinations, expressed gradually different levels of capsule and seed production. Intramorph pollinations and selfs of mid-styled seed parents were less incompatible than intramorph pollinations and selfs of the long- and short-styled morphs. All accessions studied expressed an intact system of heteromorphic stylar incompatibility despite their exclusive clonal propagation for millennia. A maximum of 16,3 seeds/capsule containing an embryo was obtained in an individual legitimate cross of two accessions, although an average of 25 ovules are present in a flower of O. tuberosa. The results are discussed in relation to the establishment of a genebank based on botanical seed of this clonally propagated, valuable Andean tuber crop. This revised version was published online in July 2006 with corrections to the Cover Date.     

THE LSP METHOD FOR INTERFACING AUTOCAD WITH HIGH-LEVEL LANGUAGE

On the basis of comparing with usual methods,a method for interfacing AUTOCAD with high-level language by LSP file is proposed in thispaper.It solves the problem that a large number of graphics are drawn continuallywhile DXF and SCR file are not in a condition to use.This method is simple andconvenient to make good use of AUTOCAD graphic functions.