四川盆地丘陵区坡地农林复合系统内部结构和系统综合效能的研究

针对四川盆地丘陵区农林生产特点和坡地农林复合系统特征,对其内部结构进行综合研究。分析了林带对农作物的正,负效应,依据林带间散射辐射分布规律、农地水土流失特征和农作物产量分布格局等方面与林带间距离的相互关系,提出了坡地林带间距离应不小于３倍林带平均高,才能保证农作物不至于减产;同时,对建成的坡地农林复合系统模式进行综合效能分析,表明,与农地系统对比,坡地农林复合系统提高了土地生产力、能量转化率、营养     

农林复合系统林分生长发育时期及其经营措施的研究

本文根据农林复合系统中林分（以林带为主体）的特殊性，结合树木生长发育和林带结构变化规律，将农林复合系统中林分生长发育划分为幼龄期、中龄期（速生期）和防护成熟期。并采用林分径级离散度、防护成熟龄、更新龄等量化指标将３个生长发育时期定量化；对于东北地区农田林网中杂交杨、乡土杨的幼龄期为０～５、０～８，速生期６～１５、９～２４，实际防护成熟期１６～３３、２５～３６，防护成熟期１６～自然成熟龄、２５～自然成熟龄。同时给出各生长发育时期相应的经营措施。为农林复合系统中林木经营提供可靠的依据。     

农林复合模式蒸散耗水的研究

应用土壤分层水量平衡模型，对林带与冬小麦的根系吸水量、林带和农田的蒸散耗水量、林带影响农田土壤水分范围与程度进行了研究，结果表明：（１）冬小麦拔节至乳熟期间，林带根系吸水以消耗农田土壤水分为主，主要表现在０．０～１．５Ｈ（Ｈ为树高）范围内。（２）林带可降低１２．３％的农田蒸散量。（３）由于林带的影响，在农田中，０．０～０．５Ｈ为土壤水分降低区，０．５～５．０Ｈ为土壤水分提高区。总体平均，０～２００ｃｍ农田土壤贮水量可提高１１．２％。     

民勤绿洲防护林带作用下作物生长分析分析

本试验对比研究了小麦和玉米在枣树和杨树2种农田防护林带作用下的生长状况和产量.结果表明:枣树林带下的作物生长状况明显优于杨树林带.枣树林带下小麦的干物质积累速度高于杨树林带51.4%,致使生物产量相对杨树林带高38.4%.不同种植方式小麦、玉米的粮食产量增加4.2%～13.0%.增产的原因之一是枣树林带下作物不同生育期农田土壤含水率均高于杨树林带.可见枣树林带的胁地作用弱于杨树林带.推广枣树防护林,实现枣粮间作,是提高民勤绿洲农业产量的重要措施.     

民勤绿洲防护林带作用下作物生长分析

本试验对比研究了小麦和玉米在枣树和杨树 2种农田防护林带作用下的生长状况和产量。结果表明 :枣树林带下的作物生长状况明显优于杨树林带。枣树林带下小麦的干物质积累速度高于杨树林带 51 4% ,致使生物产量相对杨树林带高 38 4%。不同种植方式小麦、玉米的粮食产量增加 4 2 %～ 13 0 %。增产的原因之一是枣树林带下作物不同生育期农田土壤含水率均高于杨树林带。可见枣树林带的胁地作用弱于杨树林带。推广枣树防护林 ,实现枣粮间作 ,是提高民勤绿洲农业产量的重要措施     

农林复合系统水热资源利用率的研究

系统地研究了农林复合系统对自然资源利用率的影响,结果表明：农林复合系统具有提高资源利用率的功能,但系统内不同模式之间光能利用率差异较大,梨粮复合模式光能利用率比周边种植模式高１０．３％,系统内光能利用率则比旷野平均提高了２５．０％。农林复合系统水分利用率一般可比旷野农田高１０．３％～１５．２％。农林复合模式热量利用效率比一般旷野农田高１１％～１３％。农林复合系统不仅能改善农田生境与提高资源利用效率,还能增加农民的经济收入,可在我国北方平原农区大力推广。     

海涂农田林网防护效益研究

对上虞市海涂实验农场农田林网防护效益的测定,结果表明通风结构审林带防风效能达到３１．０％左右;在八九月份高温干旱季节,林网内增加相对湿度约１．８％。林带背风而树高２～３倍地区为林带增产作用的显著范围,棉花产量比对照区增产１３．０％～３８．１％,除林缘等胁地外,受林带有利影响测试区棉花产量平均增产８．４％。     

海涂农田林网防护效益研究

对上虞市海涂实验农场农田林网防护效益的测定，结果表明通风结构窄林带防风效能达到３１．０％左右；在八九月份高温干旱季节，林网内增加相对湿度约１．８％。林带背风而树高２～３倍地区为林带增产作用的显著范围，棉花产量比对照区增产１３．０％～３８．１％，除林缘等胁地外，受林带有利影响测试区棉花产量平均增产８．４％。     

三峡库区农林复合生态系统植物物种多样性指数

三峡库区农林复合生态系统物种多样性simpson指数为1．02～11．2,shannonwiener指数为0．10～3．87,物种丰富度S为6～23,海拔及坡向对物种多样性有一定的影响;坡度变化对物种多样性影响不大;农林复合经营结构对生物多样性有着较大的影响,柑桔种植类型通过复合经营物种丰富度S提高1～2．2倍,simpson指数提高72．5％～150％,shannon－wiener指数提高1．3～2．3倍;生物地埂、生物带对物种多样性影响显著,生物多样性的提高,增强了防止土壤侵蚀的效能,提高了土地生产力。     

农林复合生态系统防尘效应初探

通过对农林复合生态系统的防尘效应初步研究表明：在沙质土壤类型区，农林复合生态系统具有较高的防尘效应，它能够有效地减少尘埃的输送量，能够减少降尘量１７．２％～６４．０％；动力速度，防风效能，风速、土壤湿度是决定降尘量大小的主要因子；农林复合生态系统的建立，使沙尘基本上得到控制，为农作物提供了良好的生长发育条件。     

农田防风林的胁地现象及补救措施

调查分析了挖断根沟前后距林带近和和远处农作物的产量。结果表明：在山西省北部半干旱风沙区，存在着林带胁地的现象，挖断根沟是一项较好的克服胁地影响的措施，能够大幅度地减少因胁地而带来的减产。     

木麻黄优良无性系营建农田防护林试验

利用速生、抗性强的木麻黄P10-33优良无性系,采其小枝经水培出根后培育容器苗,结合配套的造林技术,在平潭县营建农田防护林试验,取得较好的效果。重点介绍营建木麻黄优良无性系农田防护林的技术和初步成效,旨在为将营建农田防护林的单位提供一些借鉴。     

A preliminary investigation into agroforestry practices in the savanna belt of western Nigeria

This paper evaluates agroforestry practices in a part of the Guinea savanna belt of south-western Nigeria. The attitude of local farmers to tree planting in crop fields was evaluated. Tree adoption on the farm was assessed by identifying the tree species on the field and their frequencies. The results show that there is little indication that the trees are deliberately utilized to enhance farm operations in the area. It is concluded that greater attention needs to be given to the promotion of agroforestry techniques in the savanna belt. This is especially important as the increasing demand for food would put pressure on the soil resources.     

杉木人工林生长过程表编制的研究*

利用近些年来在南方１４省（区）有关单位搜集的杉木人工林（实生）标地４４６５块材料，以杉木带、区及地位指数表为分类基础，编制了５组杉木人工林生长过程表（南带，北带及中带东区、中区、西区各编一组）。各表标准差大部分在±５％以下，最大不超过±７．８％。并根据各带、区生长过程表，提出经营意见及间伐、主伐年龄。     

Effect of windbreak on the yield of cotton crop in semiarid regions of Haryana

The beneficial effects of shelterbelts and windbreaks have been convincingly demonstrated in the temperate regions of the world. Investigations conducted on the biological effects of windbreaks are relatively few in arid and semiarid zones. In the semiarid regions of Haryana under Social Forestry programmes large scale plantations along roads, canals, fields, etc. were undertaken. In this region, an area having a windbreak of Dalbergia sissoo (18 years old) was selected and cotton was raised in the agricultural fields. The tree belt is able to reduce the windspeed by 15 to 45% depending upon season and wind speed. Observations on morphological characters and crop yield revealed that the belt height had a significant effect on plant growth. In general growth and cotton productivity increased upto distance of four times the tree height to the leeward of belt. Depending upon the orientation of tree belt, an increase in cotton yield was found to be 4 to 10%. Plant growth (in terms of leaf area, leaf number, plant height) and yield (seed cotton production) were observed to be high in sheltered area as compared to open fields. The results indicate that windbreak establishment should be adopted and integrated to a whole farming system, in semiarid regions.     

Agroforestry potential of Dacryodes edulis in the oil palm-cassava belt of southeastern Nigeria

Between June 1993 and June 1994, 112 farmers in the oil palm (Elaeis guineensis)-cassava (Manihot esclentus) belt of southeastern Nigeria were interviewed to determine the status and agroforestry potential of Dacryodes edulis. Between 50% and 100% of respondents in different states within the belt owned D. edulis trees. On average, a farmer owned 9.3 trees, the largest number being 16, by farmers in Imo State. Twenty percent of farmers in the system rated D. edulis their best farm tree. It was present in all the farm niches: homegardens (51.4%), tree crop plots (20.7%) food crop plots (11.4%), secondary forest/fallow (14.2%) and virgin forest (2.5%). The tree is planted primarily for home consumption and sale to generate cash. At the current densities, on-farm D. edulis trees generally did not decrease yield of companion crops or trees. Except for ring weeding around the stem, D. edulis trees received little or no management attention. More than 50% of the trees produced 33 to 50 kg of fruit tree⁻¹ annually. This is valued at US $0.4 to 0.8 kg⁻¹. Farmers were willing to plant more D. edulis trees provided trees with traits such as less height for easy harvesting of fruits, larger fruit, more fruits, sweeter fruits and year round production of fruits were available. Possible agroforestry technologies into which D. edulis may fit include live fences, scattered trees in food crop fields, shade trees in tree crop plots and contour bund or hedgerow planting. Research is required to determine best tree accessions, canopy management strategies, optimum tree population and improved methods on post- harvest handling of fruits. This revised version was published online in June 2006 with corrections to the Cover Date.     

防护林保护下农作物产量的田间分布模型

本文以国内外农田防护林的大量观测资料为基础,划分了农作物在防护林保护下产量田间分布的主要类型,并借助计算机进行定量分析,提出且验证了相应的数学模型(FNC-I～FNC-Ⅳ),经F检验,有85.7％的实例超过了O.05的显著水平。最后从作物总产计算、对照点模拟、带距优化三方面简介了模型的应用。     

沿海防护林体系的结构与功能及发展趋向

本文应用综合分析的方法,在回顾沿海防护林体系历史的基础上,着重论述了沿海防护林体系的“网片带点”结构和降低区域性风速、调节区域性气候、减弱飞盐危害、加固海堤安全、提高土壤肥力、保护农作物丰产稳收、增加生物多样性等功能;提出了沿海防护林体系背负的使命和发展中的问题及对策。     

枣粮间作优化模式初步探讨

就枣粮间作水平结构和垂直结构与间作地光照条件、作物产量、枣树群体产量等关系进行了调查研究，提出了适合太原市自然条件的枣粮间作优化模式，即枣带走向以南北为宜，带距10～15m，株距3m。这种模式可改善生态条件，总产值比一般模式的总产值增加46.89%。     

木麻黄防护林带对改善农田小气候效应的研究

通过对木麻黄防护林带庇护下的农田小气候进行定位观测,分析了木麻黄林带的防护功能,结果表明:木麻黄农田防护林带具有降低风速的作用,背风面20~100 m,风速比对照点降低27%~67%,且随着风速的增大,降低风速的效果越明显;林带对气温和地温具有调节作用,背风面各点白天增温,夜间降温;林带能够减小蒸发量,林带背风面20~100 m范围内日均蒸发量比对照点降低16.2%~24.2%。