Defining competition vectors in a temperate alley cropping system in the midwestern USA: 2. Competition for water

A study was carried out in an alley cropping system in the Eastern Maize Belt of the United States with the objective of quantifying the competition for water between trees (black walnut (Juglans nigra L.) and red oak (Quercus rubra L.) and maize (Zea mays L.). Spatial and temporal variation in soil moisture, tree and maize rooting patterns, tree and maize water uptake, and maize leaf area expansion were determined in three treatments; barrier (polyethylene root barriers separating maize and tree roots), trench (trenching without a polyethylene barrier), and no barrier (control). Significant temporal variation in soil moisture was observed in both black walnut and red oak alley cropping systems. The barrier and trench treatments resulted in higher soil moisture in the maize alley and lower soil moisture in the tree row than the no barrier treatment. Uptake of water by maize was higher in the barrier than the no barrier treatment. However, tree water uptake was higher in the no barrier treatment than in the barrier treatment because tree roots utilized water from the maize alley. Maize leaf area was negatively impacted by water stress in the no barrier treatment. Quantification of rooting patterns revealed that maize and tree roots were concentrated in the top 30 cm soil layer where water fluctuations were greatest. The barrier and trench treatments successfully eliminated the belowground root competition between trees and maize and resulted in greater leaf area and higher grain yields than the no barrier treatment. Thus, competition for water rather than competition for light seems to be critical in defining the productivity and sustainability of this alley cropping system.This revised version was published online in November 2005 with corrections to the Cover Date.     

香椿栽培技术

作者根据多年的实践经验，总结了香椿的栽培技术，包括采种、播种、育苗、种植、管理、病虫害防治及菜用林培育等技术。     

章古台沙区采伐迹地更新造林技术研究

通过多年的生产实践和科学研究，总结出从树种选择、整地、造林、抚育、施肥到病虫害防治等一整套可行的采伐迹地更新造林技术，并提出9种可行的造林设计模式。对于干旱沙区采伐迹地更新造林技术有一定参考意义。     

太行山区浆水镇土地资源优化配置研究

山区土地资源优化配置的主体核心是确定各种农作物、林果、牧草资源的占地比例及规模。装水镇土地资源优化配置利用方向,在于建设发展以板栗、苹果为主的林果生产基地,畜牧养殖业在于发展以消耗饲草为主的大牲畜(主要是牛)和山羊,另外,种植在5级地上的粮食作物,应以旱作为主。     

贵州亚热带地区的野生香花类观赏植物资源

贵州亚热带地区有野生香花类观赏植物23科39属（1亚属）70种（含新分布种和变种）。分布垂直带谱为海拔160－1000m。花色分为白色、黄色、紫色、黄绿色和红色5类。生境类型分为森林湿地型、疏林灌丛型、山坡草地型和附生型，以森林湿地型和疏林灌丛型的种类居多。银钟花、大叶木莲、尖叶木、云川醉鱼草、紫萼、香槐、两粤黄檀、单性木兰、苍白秤钩风和扭肚藤处于濒危状态。     

境之谷生态小区绿化规划设计

结合周边自然环境,本着"以人为本,因地制宜"的原则,北京"境之谷"生态小区的设计充分考虑当地的实际情况,规划合理的功能分区,考虑业主受教育水平普遍很高的特点,设计以回归田园生活为理念,为业主创造一个舒适惬意的居住环境。     

山区核桃高效栽培技术效益分析

为提高山区综合开发的经济效益,研究了山区采用隔坡沟状梯田整地、高标准种植早实薄皮核桃的效果及投入产出情况.结果表明,山区采用高规格隔坡沟状梯田整地后极大促进了核桃幼树的生长,栽植后第2年即开始结果,平均单株结果1.3个,树高达221.7 cm,地径5.7 cm;栽植后第3年全树主枝7.7个,单株结果33.3个;第4年地径11.9 cm,全树主枝10个,叶面积指数为5.14,单株结果191.5个,单株核桃坚果产量2.5 kg.采用这种山区治理方式,整地建园一次性投入108 900元/hm2,前5 a总投入180 900元/hm2,前5 a总产值195 624元/hm2,5 a后可收回全部投资且有盈余,经济效益显著.     

雷州尾叶桉树冠指标与抚育间伐关系的探讨

通过对雷州尾叶桉树冠有效受光面积、树冠比率、树冠投影面积进行调查研究,分别用树冠有效受光面积、树冠比率、投影面积与胸径建立一元幂函数回归方程进行研究与分析,结果表明树冠有效受光面积公式对指导培育中径材较好;树冠比率与树冠投影面积公式的回归效果基本一致,对指导培育小径材较为理想,并利用上述回归公式编制单株营养面积、公顷立木株数和公顷基面积表为尾叶桉人工林的抚育间伐设计与施工提供理论依据。     

国有林业产业对地区经济发展贡献度的动态演绎分析

基于1998~2018年黑龙江省国有林业产业数据,从发展规模、产业结构、投入产出效益、专业化水平等4个方面对黑龙江省国有林业产业发展现状进行总体概述和分析。借助产业贡献度指标测算国有林业产业对黑龙江省经济发展的贡献水平,并基于三次产业构成进一步对国有林业产业贡献度进行了结构性动态评价。研究得出:黑龙江省国有林业产业对地区经济发展贡献呈现稳步上升的特征,第一产业表现突出,第二、三产业呈小幅下降、小幅上升的反向变动特征。基于结果分析,从产业自身发展和持续推进多种经营产业转型两个方面提出方向性建议。     

Small-scale forestry development in Leyte,Philippines: The central role of nurseries

This paper presents results of survey research into the role of the forestry nursery sector in the development of smallholder forestry in Leyte, Philippines. Seedling production in the province is basically carried out by three categories of nurseries: individual, communal and the government. Seedlings in the government nurseries are primarily raised for free distribution to landholders but the extension scheme fails to reach the majority of the smallholder farmers. Seedling demand of landholders is mostly catered for by the more numerous and accessible individual and communal nurseries. However, problems of capital outlay, sources and supply of germplasm, technical knowledge in nursery management for both timber and fruit trees and low sales are among the major impediments in the sustainability of small-scale nurseries. Most of the communal nurseries fail to sustain the operation after the withdrawal of supporting agencies. Knowledge on site-species matching is needed not only by small-scale nursery operators but also by the managers of government nurseries. It is concluded that the seedling industry in the province is not well established and there is a need to organise better the overall nursery system so as to improve the availability of seedlings and promote appropriate site and species combinations.