林业分工论的经济学基础

本文主要针对“林业分工论的理论依据问题”的争论作了较为详尽的阐述和看法。扼要回顾了“林业分工论”的要点,并对这一理论作了简明叙述,同时着重阐述了“林业分工论”的经济学基础。     

中国林产品对外贸易政策评价初探

首先回顾中国林产品对外贸易政策, 整体上概括当前中国林产品对外贸易政策; 构建对外贸易政策指标评价体系, 根据1998-2008年的林产品贸易数据, 对现有政策的效果进行实证分析评价; 得出结论:中国应将林业作为战略性产业进行扶持, 贸易政策应以国内市场为基础、以扩大出口和提高国际市场份额为目标、以国际市场为导向, 以进口保护促进出口政策, 改变外部经济的贸易政策。     

果树对低温的响应及抗寒评价体系研究进展

低温冷害是果树生产中常见的一种自然灾害,严重影响了果树生产的可持续发展。综述了果树抗寒性的评价、抗寒机制研究和抗寒基因工程研究,提出了该研究领域的前景展望,以期为果树抗寒性研究和抗寒育种提供科学依据。     

绵阳官司河流域水土流失综合报告

报告简述域地质地貌水文气象土壤，植被等地理因素的概况及其与土壤侵蚀的关系，指出本流域由于长防林的建立，发挥了保持水土作用，水土流失不严重，属轻度－中度侵蚀，最大侵蚀模数小于７４００［ｔ／（ｋｍ＾２．年］，全区平均侵蚀模数１７５４．４２［ｔ／ｋｍ＾２．年］；确定了水土流失类型，即片蚀，沟蚀，母质侵蚀三大类；分析了水土流失的原因：以泥岩和灰白砂岩，第四纪冰碛物堆积土侵蚀最高测定不同精植被类型的土壤质地     

银杏雌雄同株调查

一般学者均认为银杏是雌雄异株植物,虽然也有些文献记载“稀为同株”、但缺乏有力的语气年代有人曾对被认为是雌雄同株的银杏进行过调查和报道,但对是否自然形成的真正雌雄同株难于定论,１９９５年,作者在山东滕州市采集花粉时发现,在１株２０ａ生银杏的大枝上,雌雄花同步。     

巨尾桉人工林小径桉木常规干燥工艺优化

为提高桉树人工林小径桉木的干燥效率和质量,在对桉木干燥加工企业进行调研的基础上,对巨尾桉(Eucalyptus grandis×E.urophylla)锯材的堆积方式和干燥基准进行分析,制定优化干燥工艺.结果表明,采用优化后的干燥工艺,小径巨尾桉锯材从初含水率47.30％干燥至终含水率9.14％,共耗时178 h,平均干燥速率0.21％/h,比企业干燥工艺的干燥速率高出23.53％;干燥质量指标均满足GB/T 6491-2012对二级锯材的技术要求.该工艺可进行推广,有利于桉木锯材干燥生产的提质增效及节能减排.     

Ecology of termites from the genus <Emphasis Type="Italic">Nasutitermes</Emphasis> (Termitidae: Nasutitermitinae) and potential for science-based development of sustainable pest management programs

The genus Nasutitermes is among the most abundant wood-feeding Termitidae and an extremely diverse and heterogeneous group in terms of its biogeography and morphology. Despite the major role of several Nasutitermes species as structural pests, the phylogenetic status of this genus is still unclear, along with a confused taxonomy and species identification remaining difficult. The first aim of this review was thus to gather and discuss studies concerning the taxonomic status of the genus Nasutitermes in order to clarify this crucial point. Then, our goal was to gain new insights into the management of N. corniger, considered to be the most economically detrimental pest of this genus in South America and a Nasutitermes model species, while filtering available information concerning its biology through the prism of termite control, as well as critically examine the existing methods. We indeed strongly believe that increasing our knowledge of this species’ biological strategies is the key to progress in the challenging question of their sustainable management.     

Morphological plasticity and phosphorus uptake mechanisms of hybrid <Emphasis Type="Italic">Eucalyptus</Emphasis> roots under spatially heterogeneous phosphorus stress

In this study, we subjected the root systems of eight Eucalyptus hybrids currently cultivated in southern China to heterogeneous phosphorus stress to provide a scientific basis for the selection of a highly phosphorus-efficient Eucalyptus variety. When the ability of these hybrids to locate phosphorus under different experimental conditions (phosphorus supply in a homogeneous or heterogeneous manner vs. no phosphorus supply) was compared, the main growth characteristics of Eucalyptus, such as plant height, diameter, dry mass, and phosphorus content, significantly improved when the phosphorus supply was increased from no phosphorus or heterogeneous phosphorus (half of the phosphorus amount) to homogeneous phosphorus. Across these three conditions, the growth traits of different Eucalyptus hybrids differed significantly, indicating different adaptabilities of the hybrids to various phosphorus conditions. The growth traits of the aboveground tissues of Eucalyptus under different phosphorus conditions were largely influenced by the morphology of the underground root system. In addition, the root morphology of Eucalyptus under heterogeneous phosphorus treatment suggested that there were two mechanisms for locating nutrients. Eucalyptus hybrids such as Urophylla 3229, Grandis 9, Guanglin 3, 201-2, and Dunn produced more roots proximal to the phosphorus supply; the other hybrids, Urophylla 3216, Grandis 5, and Guanglin 9, relied mainly on the growth of roots opposite the phosphorus supply to obtain adequate nutrients for growth. With these two strategies, a wide range of nutrients was obtained, root distribution was greater, more soil volume was covered, the contact area of the roots with soil phosphorus was increased, and the uptake of phosphorus by the root system was increased. These results demonstrate that Eucalyptus relies on changes to morphological characteristics of the root system to increase accessibility to phosphorus resources.     

膨胀土地基工程设计的体会

膨胀土地基在建筑设计中非常重要。如地基发生变形,整栋楼房就要开裂、倒塌,膨胀土地基的胀缩变形是由于地基土的胀缩性及其含水量的变化引起的,因此,作者着重地论述了建筑物开裂主要原因是由:1.建筑场地土的胀缩性能及其分布的不均匀性;2.促使地基土含水量变化的外界条件;3.建筑物抵抗或适应地基不均匀变形的能力所造成的。     

纤维板生产线中连续辊压式热压机安装

内介绍了中密度纤维板设备安装过程中连续热压机的施工方法,对同类或近似的设备安装具有一定的参考价值。