森林类型对大气中PM2.5值的影响

从2014年9月开始到2015年8月,在长沙市郊湖南省林业科学院杜家冲试验林场选择不同森林类型林分,对其大气中PM2.5持续监测1年。结果表明:该区大气中PM2.5值最高的为阔叶混交林,其次为2个空旷地,最低的为樟树林;大气中PM2.5值在不同林分间差异不显著,在不同时间段间差异显著。     

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。     

基于贡献度随机森林模型的公司债信用风险实证分析

运用贡献度随机森林方法（CRF）方法探讨公司债财务指标比率与其违约率的关系.运用连续属性离散化方法（OB）进行财务指标最优降维；运用WOE变换进行模型变量约简.研究表明，CRF模型的分类性能显著优于其他模型，测试集评估总体正确率达90.47%，AUC统计量、AR比率及K-S值分别提升了2.6%、7.6%、4.38%，变量贡献度量化了各财务指标对违约率影响，为诠释随机森林预测机制提供了依据.     

S‐locus diversity and cross‐compatibility of wild Prunus avium for timber breeding

Prunus avium is primarily cultivated for its fruit, sweet cherries. However, it is also used to produce high‐quality timber. In a P. avium seed orchard, gametophytic self‐incompatibility is a restriction for free pollen flow and should be considered when establishing basic forest materials. In this study, S‐locus diversity and cross‐incompatibility of wild cherry individuals in clonal banks established for breeding for timber production were investigated. Wild cherry trees (140) with outstanding forest growth habit, collected in northern Spain, grafted and planted in two clonal banks, were genotyped at the S‐locus. The self‐incompatibility S‐locus genes, S‐RNase and SFB, were analysed by PCR. Twenty‐two S‐haplotypes, resulting in 72 different S‐genotypes, were identified. The genotypes were grouped into 33 incompatibility groups and 39 unique genotypes. This initial S‐locus analysis revealed large genetic diversity of wild cherry trees from the Spanish northern deciduous forest, and provides useful information for seed orchard design. Wild P. avium displays significantly more genetic diversity than what is detected in local cultivars, revealing a narrowing of genetic diversity during local domestication.     

陕南秦巴山地退耕还林工程综合效益评价

为了解退耕还林工程带来的效益,基于2001—2014年陕南地区退耕还林工程的现状,参考国内外有关效益评价指标体系的原则和方法选取指标,建立陕南退耕还林评价指标体系,应用层次分析法确定各项指标权重,利用效益评价模型从生态、经济、社会3个方面对退耕还林的综合效益进行定量评价。结果表明,陕南三市退耕还林效益指数曲线均呈上升趋势,说明退耕还林效益正逐渐、稳定地显现,尤其从2004年开始,退耕还林的效益显现尤为明显,增速加快。汉中、安康、商洛的综合效益较接近且呈现出同步上升的趋势,截至2014年,汉中市退耕效益最高,综合效益指数为0.6630,安康市居中为0.4985,商洛市最低为0.4260。陕南地区退耕还林综合效益逐步显现且仍将保持平稳增长的态势。     

以投资为目的的森林资源资产评估问题探讨

随着以投资为目的的森林资源资产评估业务日益增多,许多相关的理论问题亟需解决。通过对该目的下的价值类型、评估方法、评估参数等问题研究发现:价值类型的选择主要取决于委托者的利益诉求,同时要考虑现实市场条件的限制,具体可选类型包括市场价值类型与投资价值类型;评估方法的选择要与评估目的、价值类型相适应。当选择市场价值类型时,市场比较法应该是评估首选。当选择投资价值类型时,如果委托方是财务投资者,收益现值法是评估首选,如果委托方是战略投资者,公式P=Va+S×K应是评估首选;评估参数的选择,要与评估方法相一致,市场法的关键参数是可比的参照对象,收益现值法应用的关键参数是投资收益率,公式P=Va+S×K应用的关键参数是收益分成率K。以投资为目的的森林资源资产评估中,还要考虑森林采伐限额及其他相关政策的影响。     

The routes to fruit: Governance of urban food trees in Canada

Interest in planting urban food trees (UFTs) in public spaces is growing in popularity as a form of urban greening and a potential food source. Currently there is minimal research on the governance and policy aspects of integrating food trees into cities. To fill this gap, we investigated the characteristics of UFT site governance and how it compares to current urban forest governance. Semi-structured interviews were conducted with relevant municipal officials in Calgary, Edmonton, Toronto and Victoria about their perspectives and involvement with UFT sites in their city. A scan of policy documents was completed to supplement the interviews. The interviews were analyzed using a deductive coding framework based on the Policy Arrangement Approach. We found that key actors at the UFT sites were local organizations and site champions, with minimal municipal engagement. Most site resources provided by municipalities were in-kind. There are also basic knowledge gaps about how to care for UFTs. Currently municipal by-laws prohibit the harvesting and removal of plant material, and are at odds with the purpose of UFT sites, with few municipalities fully integrating UFTs in policies. The primary discussion around UFTs centre concerns for public health and safety, management, and use of public space with limited discussions of benefits. This research demonstrates the value of co-governance models to support UFTs, while a shift in focus from risks to benefits could encourage additional resources and policy integration. Further, including UFTs into policy would also support foraging and food tree maintenance in public spaces, and more fully reflect the plurality of urban forest engagement.     

Random point sampling to detect gain and loss in tree canopy cover in response to urban densification

Urban tree canopy cover (UTC) is a simple, and common, measure of urban forest resource. Urban infill development is likely to lead to losses in UTC under private tenure, at a time when local governments are setting ambitious targets to increase UTC overall. Simple, statistically rigorous methods are required to benchmark and track change in UTC, whilst identifying which land-use types or tenures experience change.We estimated UTC in six Melbourne suburbs in 2010 and 2015 by randomly sampling 2000 points across public land, public streetscapes and private land. We were able to detect a net change in UTC of <2% over five years to a 95% level of confidence. A significant net decrease in UTC (−2.4%) was only detected in one of the six suburbs. Two suburbs had a net increase in UTC by +2.7% over five years. On private land, there was often areas of UTC loss, but this was generally offset by canopy gain in other areas of the private realm as well as in streetscapes and public land. Losses in UTC on private land were mainly due to tree removal, with or without subsequent construction works.This study describes a simple, but statistically rigorous, method to quantify UTC change and the drivers of change in different land-use types and tenure. Despite studying two suburbs will high rates of infill development, only one suburb showed evidence of net UTC decrease. The ‘dynamic equilibrium’ in UTC, whereby canopy losses area approximately offset by concurrent canopy gain, means that ambitious targets being set by local governments to increase UTC may be difficult to achieve without changes in tree protection and infill development policy and planning.     

丘陵岗地人工防护林退化成因分析

以桃江县人工防护林为研究对象,分析了导致林地退化的主要原因,包括管护措施不到位、造林技术缺陷、自然灾害侵害、生理老化、环境污染等。针对退化原因,提出了相应的改造措施。