Carbon stock of oil palm plantations and tropical forests in Malaysia: A review

In Malaysia, the main land change process is the establishment of oil palm plantations on logged‐over forests and areas used for shifting cultivation, which is the traditional farming system. While standing carbon stocks of old‐growth forest have been the focus of many studies, this is less the case for Malaysian fallow systems and oil palm plantations. Here, we collate and analyse Malaysian datasets on total carbon stocks for both above‐ and below‐ground biomass. We review the current knowledge on standing carbon stocks of 1) different forest ecosystems, 2) areas subject to shifting cultivation (fallow forests) and 3) oil palm plantations. The forest ecosystems are classified by successional stage and edaphic conditions and represent samples along a forest succession continuum spanning pioneer species in shifting cultivation fallows to climax vegetation in old‐growth forests. Total carbon stocks in tropical forests range from 4 to 384 Mg C/ha, significantly wider than the range of total carbon stocks of oil palm plantations, 2 to 60 Mg C/ha. Conversion of old‐growth forest areas to oil palm plantations leads to substantial reduction in carbon storage, while conversion of forest fallows to oil palm plantations may sustain or even increase the standing carbon stock.     

Assessing the utility WorldView-2 imagery for tree species mapping in South African subtropical humid forest and the conservation implications: Dukuduku forest patch as case study

Indigenous forest biome in South Africa is highly fragmented into patches of various sizes (most patches < 1 km²). The utilization of timber and non-timber resources by poor rural communities living around protected forest patches produce subtle changes in the forest canopy which can be hardly detected on a timely manner using traditional field surveys. The aims of this study were to assess: (i) the utility of very high resolution (VHR) remote sensing imagery (WorldView-2, 0.5–2 m spatial resolution) for mapping tree species and canopy gaps in one of the protected subtropical coastal forests in South Africa (the Dukuduku forest patch (ca.3200 ha) located in the province of KwaZulu-Natal) and (ii) the implications of the map products to forest conservation. Three dominant canopy tree species namely, Albizia adianthifolia, Strychnos spp. and Acacia spp., and canopy gap types including bushes (grass/shrubby), bare soil and burnt patches were accurately mapped (overall accuracy = 89.3 ± 2.1%) using WorldView-2 image and support vector machine classifier. The maps revealed subtle forest disturbances such as bush encroachment and edge effects resulting from forest fragmentation by roads and a power-line. In two stakeholders’ workshops organised to assess the implications of the map products to conservation, participants generally agreed amongst others implications that the VHR maps provide valuable information that could be used for implementing and monitoring the effects of rehabilitation measures. The use of VHR imagery is recommended for timely inventorying and monitoring of the small and fragile patches of subtropical forests in Southern Africa.     

随机森林机器算法在江苏省小麦赤霉病病穗率预测中的应用

基于2002—2018年江苏省13个市的小麦赤霉病病穗率资料与生育期观测资料、相应时段内的逐日气象数据,应用随机森林机器学习算法,分生育期、分区域定量评估影响病穗率的主要气象因子特征变量和贡献率,按不同起报时间建立预测模型并进行验证。结果表明,各生育期重要特征变量贡献率的排序为:抽穗扬花期＞拔节期＞越冬期。抽穗扬花期湿度、连续≥3 d的雨日和日照对赤霉病起主导作用,拔节期日照、降雨量、湿度和雨日与越冬期气温和降雪对赤霉病均具有前期影响,甄别出的重要特征变量排序结果符合赤霉病菌发育、释放、侵染和流行规律;基于随机森林算法建立的病穗率预测模型的精度与重要特征变量个数、赤霉病发生区域、M_try参数设定、生育期有关;最早可在3月初进行预测,预测时效近3个月,起报时间越接近乳熟期,输入的重要特征变量越多,则病穗率预测准确率越高,病穗率模拟值与实测值的波动趋势完全一致,对赤霉病“中等”和“偏重”等级模拟效果好,表明随机森林算法在赤霉病预测中有较高的可靠性和业务应用潜力。      

合成孔径雷达森林资源监测技术研究综述

合成孔径雷达（Synthetic Aperture Radar,SAR）技术凭借其全天时、全天候的成像能力以及对森林垂直结构信息敏感的特点,在森林资源监测中具有独特的优势,已成为当前森林资源遥感调查技术的研究热点.本文首先介绍了SAR森林资源监测技术的发展背景、发展轨迹和相关知识;然后,重点阐述了极化SAR、干涉SAR、极化干涉SAR和层析SAR在林地覆盖类型分类、变化检测以及森林参数定量化估测应用中的技术方法;最后,就SAR在森林资源监测研究和应用中存在的问题与发展趋势进行了总结与展望.     

基于机器学习的降雨量雷达回波数据建模与预测

以浙江省2016年1-10月的雷达回波强度数据为基础,分别应用随机森林模型、BP神经网络模型、卷积神经网络模型来预测降雨量并进行对比.建模分析结果表明,随机森林模型预测效果精确度较低,容易低估较大的降雨强度,而BP神经网络和卷积神经网络预测的效果都比随机森林好,特别是卷积神经网络,其预测值与真实值更加接近,且对较大的降雨强度拟合较好.     

基于随机森林的暴雨灾害人口损失预估模型及应用

基于2009—2017年的广西县级暴雨灾情记录,综合考虑致灾因子、孕灾环境和承灾体因素选取7个解释变量,运用随机森林算法,构建暴雨灾害人口损失预估模型;并以精细化网格降水实况分析和预报产品驱动模型,预估是否发生人口损失。研究结果表明:模型训练样本及测试样本的分类准确率均在90%以上,致灾因子(降水情况)是最主要的解释变量,重要性从大到小依次是前10 d降水距平百分率、过程最大日雨量、最大小时雨量和短时强降水频次。应用智能网格降水产品对广西地区近两年的暴雨灾害过程进行回报试验,准确率超过70%。     

榆林飞播林区土壤地球化学特征

以榆林飞播林区的土壤微生物、土壤养分和土壤可溶性盐为研究对象,对林区土壤可溶性盐的变化规律及其与土壤养分、微生物的相关性进行研究,为水土资源可持续利用以及飞播造林功效的提高提供理论依据.研究表明,研究区土壤属硫酸盐型,土壤层分异特征不显著,土壤仍处于初级发育阶段.土壤总盐与养分的相关性不明显,适当增加K⁺利于真菌的存活和生物量的积累,在1 kg土壤中,每增加1 g K⁺,真菌数量就会增加14个左右.在土层表层,适量减少Cl^-能促进土壤细菌的生长,在40 cm土层的盐分上行过程中出现表聚现象,在土壤中层,出现板结现象,在土壤底层,HCO₃^-和Na⁺质量分数的增加,有利于土壤全氮质量分数的增加,且HCO₃^-的影响力最强.     

Forest certification eligibility as a screen for CDM sinks projects

Abstract

Parties negotiating the Kyoto Protocol recently agreed that Clean Development Mechanism (CDM) investments can include carbon sequestration projects in developing countries. However, guidelines for achieving the socio-economic and environmental objectives of the CDM, and other concerns with sinks projects, have yet to be elaborated. Independently of the Kyoto process, international efforts have advanced to define and certify sustainably managed forests through processes, such as that of the Forest Stewardship Council (FSC). In this paper, the FSC-US principles and criteria for sustainable forest management are evaluated in light of current concerns for guiding afforestation and reforestation projects in the CDM. It is found that the FSC criteria would help to meet some of the objectives of the Kyoto Protocol, including provisions to reduce the risk of premature carbon loss, and features that could somewhat lessen leakage of emissions outside the project area. Existing FSC monitoring and verification procedures provide some, but insufficient, overlap with expected requirements for measuring carbon stock changes. FSC principles and criteria articulate stringent guidelines for meeting environmental and social goals that reflect years of negotiations between environmental, timber, human rights and labor interests.     

Investigations on the runoff generation at the profile and plot scales,Swiss Emmental

This article describes an investigation on runoff generation at different scales in the forested catchment of the Sperbelgraben in the Emmental region (Swiss Prealps) where studies in the field of forest hydrology have a history of 100 years. It focuses on the analysis of soil profiles and the subsequent sprinkling experiments above them (1 m²), as well as on surface runoff measurements on larger plots (50 to 110 m²). In the Sperbelgraben investigation area, two very distinct runoff reactions could be observed. On the one hand, very high production of saturation overland flow was registered on wet areas of gleyic soils, with runoff coefficients between 0·39 and 0·94 for profile irrigation. On the other hand, almost no surface runoff was measured on Cambisols, with the exception at some sites of a hydrophobic reaction detected at the beginning of storms after dry periods (coefficients for profile irrigation: 0·01–0·16). This pattern was observed during 1 m² soil plot irrigation and on surface runoff plots. Apart from a less distinctive signal of the water‐repellent litter layer on the larger surface runoff plots, the dominant hydrological processes at the two scales are the same. The determined runoff reaction at the two scales corresponds well with information from a forest site type map describing soil and vegetation characteristics and used as a substitute for a soil map in this study. Theoretical considerations describing forest influence on flood discharge are discussed and evaluated to be in good agreement with observations. These findings are a sound foundation for application in hydrological catchment modelling. Copyright © 2006 John Wiley & Sons, Ltd.     

Logs and Snags in a Shola Forest of Kerala, India

Introduction Dead wood is an important structural and functional component of a forest ecosystem(Fridman and Welheim 2000). Recent studies also indicate that dead wood is important for maintaining both plant and animal diversity in different forest ecosystems (Grove 2001) as it serve as an energy source (Bray and Gorham 1964) and habitat for an array of organisms. Dead wood can also help reduce erosion, increase soil organic matters (McFee and Stone 1966), and suitable conditions for seedli…