太原市森林公园林带对空气PM2.5的净化效率

开展城市绿地滞尘效应研究对指导城市绿地建设具有重要科学意义。为了研究城市交通主干道周边绿地的滞尘效应，以太原市森林公园西侧紧邻滨河东路南北长600 m，东西宽100 m的针叶混交林带为研究对象，在林带最西侧与道路交界处设对照点（0 m），由西向东垂直于路面在林带内分别设置20、40、60、80 m 4个监测点，用中流量大气PM2.5采样器（100 L/min）在各点对PM_2.5进行日间采样，分析林带内PM_2.5浓度的变化特征并计算林带对PM_2.5的净化效率。结果表明:1）林带宽度影响其对大气PM_2.5的净化效率，从20~60 m的净化效率逐渐提高，80 m处略低于60 m；2）林带对局部空气PM_2.5净化效率与区域空气质量呈负相关，当空气质量为优良时，林带可以有效地降低局部PM_2.5，当空气质量为中重度污染时，林带20~40 m宽处会聚集较高浓度的PM_2.5；3）林带内分时段净化效率显示，9:30-11:00的净化效率最低，12:30-17:00净化效率较高，且15:30-17:00林内PM_2.5质量浓度最低，提示该时段适宜市民在公园内活动。     

广西县级林地变更调查试点技术方法

为探索广西县级林地年度变更调查技术方法,以鹿寨县为例,运用遥感自动检测技术、森林资源管理信息平台等,对地类及管理属性变化图斑进行变更,形成本期林地数据库和林地变化数据库。文章分析了林地变更调查的关键技术方法,指出了存在的问题,并提出相应的建议。     

Nutrient cycling and biomass flows in a low-quality forest stand improvement system in the Lesser Khingan Range of China

The material flow and bulk internal flow analyses were used to establish a material accumulation and cycling model for a low-quality forest stand improvement system and a series of processes were considered. The model was applied in a one-hectare low-quality forest plot in the Lesser Khingan Range of China. Results showed that during 1997–2007, the stands absorbed 270.19 kg of N, 74.28 kg of P, and 124.39 kg of K from soils, 51.82 kg of N and 2.38 kg of P were directly absorbed by foliage, and 16.25 kg of K was released to soils by eluviation. Until 2007, the accumulated nutrients in the stands included 236.91 kg of N, 65.28 kg of P, and 108.55 kg of K. When horizontal strip clearcutting was applied in 2007, 50% accumulated nutrients in the stands were shifted due to harvesting operations, and 212.74 kg of N, 26.97 kg of P, and 98.88 kg of K were accumulated in soils, declining by 9.47% for N, 3.68% for P, and 17.60% for K, respectively, compared with year 1997. 94.61 t per hectare of biomass was generated, of which the biomass in stands accounted for 87.36%. The felled tree biomass was 36.89 t per hectare, of which 84.90% and 10.03% of biomass were utilized in terms of logs and other means, and the rest was left on site.     

农村社会服务人才的研究述评和基本厘定

“三农”问题的根本解决、农村社会的繁荣稳定,都需要大量的农村社会服务人才参与其中.目前只“就农村改革”谈农村实用人才、只“为农业建设”说农业管理者和指导者、只“据农民发展”论农民带头人和专合组织负责人,都不是真正而完全的农村社会服务人才.农村社会服务人才应是具有一定专业知识或专门技能,面向或立足于农村这一微型社会,为其经济、科技、教育、卫生、文化、体育、生态等的科学发展提供创造性、价值性服务的各类劳动者,它具有自身的特点和地位.     

Enhancing pedotransfer functions with environmental data for estimating bulk density and effective cation exchange capacity in a data‐sparse situation

Soil bulk density (BD) and effective cation exchange capacity (ECEC) are among the most important soil properties required for crop growth and environmental management. This study aimed to explore the combination of soil and environmental data in developing pedotransfer functions (PTFs) for BD and ECEC. Multiple linear regression (MLR) and random forest model (RFM) were employed in developing PTFs using three different data sets: soil data (PTF‐1), environmental data (PTF‐2) and the combination of soil and environmental data (PTF‐3). In developing the PTFs, three depth increments were also considered: all depth, topsoil (<0.40 m) and subsoil (>0.40 m). Results showed that PTF‐3 (R²; 0.29–0.69) outperformed both PTF‐1 (R²; 0.11–0.18) and PTF‐2 (R²; 0.22–0.59) in BD estimation. However, for ECEC estimation, PTF‐3 (R²; 0.61–0.86) performed comparably as PTF‐1 (R²; 0.58–0.76) with both PTFs out‐performing PTF‐2 (R²; 0.30–0.71). Also, grouping of data into different soil depth increments improves the estimation of BD with PTFs (especially PTF‐2 and PTF‐3) performing better at subsoils than topsoils. Generally, the most important predictors of BD are sand, silt, elevation, rainfall, temperature for estimation at topsoil while EVI, elevation, temperature and clay are the most important BD predictors in the subsoil. Also, clay, sand, pH, rainfall and SOC are the most important predictors of ECEC in the topsoil while pH, sand, clay, temperature and rainfall are the most important predictors of ECEC in the subsoil. Findings are important for overcoming the challenges of building national soil databases for large‐scale modelling in most data‐sparse countries, especially in the sub‐Saharan Africa (SSA).     

吉林省公益林管理地理信息系统研究

本文对公益林管理系统进行需求和可行性分析,应用Microsoft Visual C#、Java等编程语言,在个人电脑终端客户、服务器和手机上开发了公益林管理地理信息系统,该系统适用于公益林管理,工作效率高,达到了实时监管公益林森林资源的目的。     

三岔子林区黄檗野生种群资源状况的调查与分析

以吉林省三岔子林业局不同林龄的林分为对象,调查与分析黄檗野生种群的资源状况,结果表明:单位面积活立木平均株数在幼龄林林分中占12.3%,在中龄林中占3.8%,在成过熟林中占2.6%,3个龄组林分的平均株数比例为6.2%;单位面积活立木平均蓄积在幼龄林林分中占7.3%,在中龄林中占2.4%,在成过熟林中占1.3%,3个龄组林分的平均蓄积比例为3.7%。     

满归林业局森林资源现状与分析

文章对满归林业局的森林资源现状进行了阐述,并对其龄组的结构状况进行了必要的分析,同时,提出了建议与措施。     

低效林的近自然经营技术

探讨了低效林的概念与类型,分析了低效林的成因及其改造方法,并针对我国长江上游大面积低效林的现状,试图通过引进近自然经营技术理念,为大面积地改造低效林,实现森林的可持续经营提供指导.     

林业经济发展与气候因素的因果关系

森林资源是林业经济发展的基础能源,又与气候存在着因果关系.气候因素中的气温、湿度、降水、光照等对森林生长产生起决定性影响,林业生产总值深受气候影响,同时林业经济的发展可能对气候产生正反两方面作用.因此,人们在发展林业经济过程中要考虑到气候变化因素,积极发展木本油料能源产业.