神农架林区森林资源可持续发展途径探讨

笔者以神农架林区为例,用全面规划、总体布局的观点分析林区资源特点与利用现状问题,并以天然林保护工程为重点,实现森林保护多种效益的永续利用为目标,以探讨我省国有林区森林资源可持续发展的有效途径,提出国有林区森林资源可持续发展的关键是对现有林科学合理地经营和管护,并指出在禁伐区、一般公益林区和商品林区应采取的不同策略。     

龙岩地区森林合理采伐量的探讨

本文根据龙岩地区森林资源现状,按龄级蓄积结构,采用"分期平衡法"测算1996-2010年内较为合理的采伐量。     

Comparison of depth- and mass-based approaches for estimating changes in forest soil carbon stocks: A case study in young plantations and secondary forests in West Java, Indonesia

Soil carbon (C) stocks in forest ecosystems have been widely estimated to a fixed soil depth (i.e., 0-30 cm) to clarify temporal changes in the C pool. However, surface elevations change as a result of compaction or expansion of the soil under forest management and land use. On the other hand, the calculation of soil C stocks based on “equivalent soil mass” is not affected by compaction or expansion of forest soil. To contribute to the development of a forest C accounting methodology, we compared changes in soil C stocks over 4 years between depth- and mass-based approaches using original soil data collected at 0-30 cm depths in young plantations and secondary forests in West Java, Indonesia. Our methodology expanded on the mass-based approach; rather than using one representative value for the mass-based calculation of soil C stocks, we adjusted individual values, maintaining the coefficient of variance in soil mass. We also considered the effect of an increase or decrease in soil organic matter on equivalent soil mass. Both increasing and decreasing trends in soil C stocks became clearer when the mass-based approach was used rather than the depth-based approach. The trends in soil C stocks based on equivalent soil mass were particularly evident in the surface soil layers (0-5 cm) and in plantation sites, compared with those for soil profiles including subsurface soil layers (0-30 cm) and in secondary forests. These trends in soil C stocks corresponded with temporal trends in litter stocks. We suggest that equivalent mass-basis soil C stock for the upper 30 cm of soil be calculated based on multiple soil layers to reduce estimation errors. Changes in soil organic matter mass had little effect on the estimation of soil C stock on an equivalent mass basis. For the development of a forest C accounting system, the mass-based approach should be used to characterize temporal trends in soil C stocks and to improve C cycle models, rather than simpler methods of calculating soil C stocks. These improvements will help to increase the tier level of country-specific forest C accounting systems.     

A reduced growth model based on stand basal area. A case for hybrid poplar plantations in northeast Spain

Whole-stand models normally require data on initial stand basal area and dominant height. Dominant height measurements are time-consuming and often imprecise, compromising subsequent predictions. Poplar plantations provide a special case where basal area correlates with site index; a whole-stand model could thus be based on stand basal area. We report a static model constructed by the generalized algebraic difference approach (GADA) for poplar plantations for three different hybrid poplars (Populus × euramericana (Dode) Guinier “I-214”, “MC”, and “Luisa Avanzo”) in northeast Spain. The transition function was based on current stand basal area and was fitted with data from 158 permanent plots ranging from 1- to 17-year-old plantations. Merchantable stand volume was estimated by a volume equation where height was predicted by a height–basal area relationship based on 458 temporary plots. The model differences between clones were compared using the nonlinear extra sum of squares method. Significant differences were detected, while Luisa Avanzo presented the highest merchantable volume at the end of the rotation. Errors in basal area predictions were below 20% within 6 years in the case of Luisa Avanzo and MC clones, and within 3 years in the case of I-214. Our research showed that satisfactory predictions can be obtained using GADA with a single transition function based on an easily measurable variable such as stand basal area.     

新疆早实核桃集约栽培模式的研究

本文基于新疆早实核桃集约栽培研究的 8年试验结果 :定植 (嫁接 )后第 8年平均株产核桃 9.67kg(最高株产达 2 0 .0 2kg) ,平均每 hm2产核桃 410 5 .3 5 kg(最高 hm2产核桃 5 5 2 2 .2 5 kg,660株 / hm2 ) ,间种产值 5 90 0 .5 5元 ,产值效益达 4695 4.0 5元 ;8年间平均每 hm2年产核桃 1115 .78kg,间种产值 9842 .85元 ,产值效益达 2 10 0 0 .6元。提出了适宜早实核桃集约栽培的品种、品种搭配、栽植密度 ,前期间作方式、间种作物 ,施肥浇水 ,幼树整形修剪及病虫害防治等一整套树体和田间管理技术措施 ,对新疆乃至全国早实核桃生产具有一定指导作用     

湖北省森林防火地理信息系统有关问题的探讨

本文就湖北省森林防火地理信息系统的建设目标、系统功能的设定等方面进行了专题论述 ,并就系统框架及运行和体系建设任务进行了探讨。     

坚持“三农”方向突出地域特点打造特色品牌——从朝阳实际谈地方公共图书馆如何为“三农”服务

坚持为“三农”服务的方向,从朝阳市情实际出发,改革地方中小型公共图书馆的旧模式,提高图书馆人对“三农”的认识,建设以“三农”内容为主题的特色馆藏,倾心开拓为“三农”特色服务途径,打造图书馆特色品牌,为推动农村经济发展贡献力量。     

国内文献传递发展不平衡性与改进途径研究

针对国内主要文献传递系统CALLS,CSDL,NSTL近几年的运行状况,结合已有的文献传递工作经验,分析文献传递发展过程中存在的制度管理、基础设施、服务方式等不平衡性因素.探讨各因素之间的因果关系与改进途径,为我国文献传递,资源共享的健康发展提供理论与技术支撑.     

表达伪狂犬病毒gC糖蛋白基因重组腺病毒的构建及其免疫效果

通过双酶切将伪狂犬病毒(Pseudorabies virus,PRV)Fa株gC囊膜糖蛋白基因片段亚克隆到5型腺病毒AdMax系统穿梭质粒pDC316中,得到pDC316-gC。用此质粒与腺病毒DNA辅助质粒pBHGloxΔ E1,3Cre共转染293细胞,包装出重组腺病毒Adv-gC。通过PCR鉴定和病毒空斑纯化,得到纯的高效价Adv-gC病毒液。间接免疫荧光实验证明此重组病毒能表达PRV gC蛋白。该病毒经肌注免疫Balb/c小鼠,能诱导小鼠产生特异的体液和细胞免疫反应。攻毒试验表明,此重组病毒能提供100%的免疫保护。     

低碳经济背景下的关中-天水经济区城市群定位及发展路径选择

城市群是国民经济的重要载体,衡量一个国家或地区社会经济发展水平的重要标志。城市群已成为我国城镇化发展的主体形态,城市群内各个城市间的相互作用能产生单个城市所没有的整体经济效益,从而达到1+1>2的共赢态势。在低碳经济背景下,我国城市群必然迎来新一轮的加速发展热潮。文中通过对我国中西部五大城市群进行比较研究,分析了关中-天水经济区城市群发展的主要特征和发展基础,最后提出城市群发展的路径。