经济林良种推广现状及政策建议

经济林良种是经济林产业的“芯片”,是经济林生产优质、高产、高效的物质基础。完善经济林良种推广政策,是实现经济林产业高质量发展的根本保障。通过数据收集和整理,系统梳理全国经济林良种推广现状,指出经济林良种推广中还存在着良种使用率不高,经济林低产低效;部分经济林良种存在超范围推广;良种审定过多,结构性过剩和种植品种过多,对接生产加工不畅等突出问题。进而提出从以种植为目标的良种推广转变为以生产加工等市场需求为导向的良种推广思路。从优化良种供给、加强良种推广的宏观指导、强化科技支撑和宣传培训、实施经济林提质增效工程和充分发挥产业协会、创新联盟的作用等方面给出优化经济林良种推广的政策建议。     

何刚德《抚郡农产考略》农业经济思想初探

《抚郡农产考略》是清末江西有代表性的农学著作,不仅保存有抚州地区大量农产种类、栽培与加工技术等资料,还包含了大量的商品经济信息。作者何刚德已经认识到自给自足的自然经济会对生产有束缚作用,他在记载各类农产品时,提出“价值”的概念且用货币价格对其衡量,并深入揭示了农产品上市时间、供求、地理、交通条件等因素对价格的影响,进而寻求增值之道。何氏提倡多种经营,大力种植棉花、烟叶等经济作物,发挥柑橘、甘蔗等名优特产优势,促进农业的商品化生产。他还建议通过深加工的方式获取更高利润,并对未能引进西方的先进加工技术而感到惋惜。《抚郡农产考略》体现了中国近代官僚知识分子对农业经济转型的探索,具有重要的历史价值与现实意义。     

凤阳山不同林分土壤腐殖质特征及影响因素

以浙江省凤阳山海拔1 300~1 400 m处不同林分类型(阔叶混交林、针阔混交林、杉木林、竹林)为对象,测定不同土层土壤基本理化性质、酶活性及腐殖质质量分数,分析土壤腐殖质特征及影响因素,为凤阳山自然保护区的土壤肥力和可持续经营发展提供理论依据。结果表明:土壤腐殖质质量分数针阔混交林最高,阔叶混交林、竹林、杉木林次之;胡敏酸质量分数针阔混交林最高,杉木林最低;富里酸质量分数针阔混交林最高,竹林最低。除磷酸酶活性随土层加深无统一规律外,4种林分脲酶活性、过氧化氢酶活性及蔗糖酶活性土壤随土层加深皆呈现降低趋势。土壤pH值、土壤密度与土壤腐殖质质量分数、胡敏酸质量分数和富里酸质量分数均呈现显著的负相关;除磷酸酶活性相关性不显著外,土壤脲酶活性、蔗糖酶活性、过氧化氢酶活性、总孔隙度、毛管孔隙、非毛管孔隙与土壤腐殖质质量分数、胡敏酸质量分数和富里酸质量分数均呈现显著的正相关。凤阳山不同林分类型对土壤腐殖质特征的影响较土层深度更显著,土壤理化性质及酶活性与土壤腐殖质质量分数有着密切关系。     

Nutrients in litterfall,forest floor and mineral soils in two adjacent forest ecosystems in Greece

The fluxes of masses and the nutrients Ca,Mg,K,N,P and S were determined in the litterfall of two adjacent forest ecosystems of Hungarian oak(Quercus frainetto L.)and European beech(Fagus sylvatica L.)in a mountainous area of northeastern Greece in 2010–2015.The foliar litterfall for both species reached about 70%of the total litterfall,and was significantly higher from the other two fractions(woody and rest litterfall).The fluxes of masses and nutrients were compared between ecosystems for each fraction separately.Only one significant statistical difference was found,that of K in the woody litterfall.In addition,the stocks of masses and nutrients were calculated in the forest floors and mineral soils of the two ecosystems.Likewise,the stocks of nutrients in the forest floors and mineral soils were compared between ecosystems.In the L horizon of the forest floors,statistical differences,as a result of species effect,were found for the stocks of Ca and N.In the FH horizons,the masses and all the nutrient stocks differed significantly,as the beech plot had much higher quantities of organic matter and nutrients.These higher quantities were probably due to low soil temperatures(microclimate)and high acidity in the beech plot(species effect)that slowed down decomposition.In the mineral soils,the propagation of random error derived from random errors of the individual soil layers was an important factor in the statistical comparisons.Because of the soil acidity in the beech plot,the stocks of exchangeable base cations were significantly higher in the oak plot,whereas the other nutrient stocks did not differ.     

农业大数据的发展现状与发展趋势

介绍了农业大数据的概念和发展现状,阐述了农业大数据理论在农业中的主要应用,分析了农业大数据发展过程中存在的问题,并预测了农业大数据的发展趋势。     

豚草粗提物对杨树水泡型溃疡病的抑菌作用研究

为解决豚草提取物在林业病虫害防治中的推广与应用问题,以豚草叶片为试验材料,采用温浸-超声波联合提取法提取抑菌活性物质,并开展其对杨树水泡型溃疡病病原菌的室内外抑菌试验。室内抑菌试验表明,粗提物浓度为16 mg/mL时,抑菌率达到73.62%;林间防治试验表明,最小抑菌浓度为 40 mg/mL,抑菌率达到95.14%。通过以上抑菌试验确定豚草粗提物对杨树水泡型溃疡病有较好的抑制效果。     

周晓平(宁化县县属国有林场,福建,宁化365400)

近些年来宁化县非常注重高质量、高品位绿色发展要求,保护好绿水青山才能成就金山银山的经营理念不断向纵深推进,人们对乡土树种越来越倍加珍惜,因此急需加快乡土树种栽培与保护。本文从乡土树种林业内涵展开分析,阐述了乡土树种在宁化县生态恢复过程中的作用,主要从乡土树种具有生长快_^[1]、适应性强、病虫害少、用途多、改良土壤性强、森林植物群落多样性丰富、林分生产力强、再生繁衍能力强等方面深入探索,从而证明了乡土树种在树种优选方面的重要作用。     

The economic benefits and costs of trees in urban forest stewardship: A systematic review

Understanding the benefits provided by urban trees is important to justify investment and improve stewardship. Many studies have attempted to quantify the benefits of trees in monetary terms, though fewer have quantified the associated costs of planting and maintaining them. This systematic review examines the methods used to jointly analyse the costs and benefits of trees in the urban landscape, assesses the relative balance of benefits and costs, and attempts to understand the wide variation in economic values assigned in different studies. The benefits most frequently studied are those related to environmental regulation and property values, and the available data show that these usually outweigh the costs. Aesthetic, amenity, and shading benefits have also been shown to provide significant economic benefits, while benefits in terms of water regulation, carbon reduction and air quality are usually more modest. Variation in benefits and costs among studies is attributed largely to differences in the species composition and age structure of urban tree populations, though methodological differences also play a role. Comparison between studies is made difficult owing to differences in spatiotemporal scope, and in the way urban forest composition and demographic structure were reported. The overwhelming majority of studies concern deciduous trees in Northern America, and much less is known about urban forests in other regions, especially in the tropics. Future work should thus seek to fill these knowledge gaps, and standardise research protocols across cities. In light of ambitious goals in many cities to increase tree cover, ongoing advances in valuation methods need to provide a more comprehensive accounting of benefits and costs, and to better integrate economic assessment into the decision-making process.     

运用植被指数时序特征对落叶松人工林分类

为探究植被指数时序特征是否有利于落叶松人工林提取,以孟家岗林场为研究试验区域,根据落叶松人工林季相和物候特征,利用Landsat8OLI影像数据提取研究区内5种植被的归一化植被指数(I NDV)、差值植被指数(I DV)、比值植被指数(I RV)、增强型植被指数(I EV),构建相应的植被指数时序特征。采用最大似然和随机森林两种方法对单一时相影像和加入植被指数时序特征的影像进行对比试验。结果表明:影像中加入植被指数时序特征后,最大似然算法的分类总体精度为89.53%,Kappa系数为0.87,比单一时序特征的影像分类精度提高了13.35%;随机森林算法的森林类型分类总体精度为93.22%,Kappa系数为0.92,比单一时序特征的影像分类精度提高了19.8%。因此,加入植被指数时序特征后能得到更高的落叶松人工林提取精度。     

Exploring tree diversity and stand structure of savanna woodlands in southeastern Sudan

Savanna woodlands in Sudan host great biodiversity, provide a plethora of ecosystem goods and services to local communities, and sustain numerous ecological functions. Although the importance of the Acacia trees in these areas is well known, up-to-date information about these woodlands' diversity is limited and changes in their woody vegetation composition, density, diversity and relative frequency are not monitored over time. This study explored tree diversity and stand stage structure in Nuara Reserved Forest, a typical savanna woodland ecosystem in southeastern Sudan. A total of 638 circular sample plots (1000 m² for each) were established using a systematic sampling grid method. The distance between plots was 200 m. In each plot, all living trees with diameter at breast height (DBH) ≥5.00 cm were identified and counted, and their DBH values were recorded. From these data, tree composition, diversity, density and stage structure were assessed. There were 12,259 individual trees representing four species (Acacia seyal, Balanites aegyptiaca, Acacia Senegal and Acacia mellifera) that belong to two families. The dominant species was Acacia seyal. Average tree density was 191 trees/hm² and the Shannon-Weiner index for trees diversity was 0.204. Overall, young trees comprised 86.30% of the forest. The state of tree richness and density in the study area was low compared to other similar environments in the region and around the world. We recommended adoption of a proper management system that includes monitoring of woody vegetation diversity in this forest, and management actions to enhance tree diversity and sustain ecosystem services to local communities. In addition to care for the dominant Acacia seyal stands, more attention and conservation should be devoted to reestablishing Acacia senegal and Acacia mellifera trees because of their high ecological and economic values for local communities.