树皮结构特征与树木耐火性的关系研究

调查了云南油杉、旱冬瓜、云南松、直杆蓝桉、华山松5个滇中地区主要造林树种的树皮结构特征,分析了树皮结构与树木耐火性的关系,结果表明：云南油杉、旱冬瓜和直杆蓝桉树木的树皮耐火性较强,华山松树皮的耐火性最差．在此基础上提出了相应的森林防火对策．     

昆明西山森林公园主要林型地表可燃物的潜在燃烧性

通过外业调查和实验室测定,以单位面积热量为关键指标,研究了昆明西山国家森林公园的华山松、云南油杉、地盘松、麻栎和旱冬瓜5个主要林型地表可燃物的潜在燃烧性。结果表明,地表可燃物潜在燃烧性最强的是华山松,其次为地盘松,最弱的是旱冬瓜,云南油杉和麻栎的潜在燃烧性很接近。5种林型地表可燃物的潜在燃烧性从强到弱依次为华山松、地盘松、云南油杉、麻栎和旱冬瓜。     

3种针叶树种树皮抗火性研究

通过测定和分析云南油杉、云南松、华山松3种针叶树种树皮的厚度、导热系数、外界热辐射作用下的失重过程和树皮内表面温度4个因子，结合3个树种在火烧迹地上的死亡率数据，得出如下结论：树皮的结构、导热系数是决定这3种树种耐火性差异的主要因素，3种针叶树种树皮的抗火性由强到弱的顺序为云南油杉〉云南松〉华山松，与这3个树种的死亡率由小到大的顺序相同。     

滇中火灾高发区15种木本植物燃烧性研究

以15种木本植物的化学性质和生物学生态学特性为评判标准,采用层次分析法对滇中火灾高发区15种木本植物的燃烧性进行研究。结果表明,燃烧性由大及小的顺序为:云南松、地盘松、蓝桉、华山松、滇油杉、黑荆、藏柏、旱冬瓜、南烛、厚皮香、矮杨梅、云南含笑、光叶石栎、炮仗花杜鹃、碎米花杜鹃。文章对采用的和摒弃的一些因子做了说明。     

云南切梢小蠹对云南松及20个非寄主树种叶的趋向行为研究

本项研究选取云南切梢小蠹寄主植物云南松的针叶和藏柏、樟树、滇青冈等20种非寄主树种的叶与云南松针叶混合物(质量比为1∶4),利用Y型嗅觉仪测定其趋向行为,测试云南切梢小蠹对纯云南松针叶、混合样及空气间的趋向行为选择的差异性.结果表明,以云南松针叶作参照,云南切梢小蠹对云南松+藏柏、云南松+缅桂、云南松+滇朴、云南松+旱冬瓜的趋向率较低,分别为32.3％、33.4％、32.3％、31.5％;以空气作参照,混合样趋向率由小到大依次为云南松+藏柏、云南松+缅桂、云南松+滇朴、云南松+旱冬瓜,分别为38％、39％、40％、42％,均小于50％;藏柏、缅桂、滇朴、旱冬瓜4个树种对云南切梢小蠹表现较强的趋避作用,可作为营建抗云南切梢小蠹虫危害的混交树种.     

旱冬瓜叶片提取物对云南切梢小蠹的行为影响分析

为研究云南切梢小蠹对寄主植物和非寄主植物的行为反应,在实验室内利用Y型嗅觉仪测试了云南切梢小蠹对云南松和旱冬瓜乙醇提取物的行为反应;录制了云南切梢小蠹在云南松和旱冬瓜乙醇提取物气味影响下的运动视频,并利用Ethovision XT动物行为分析软件对视频进行了分析,得到了云南切梢小蠹的运动轨迹和运动数据。Y型嗅觉仪测试结果表明:云南松提取物气味能够引诱云南切梢小蠹,而旱冬瓜提取物气味则对试虫有明显的趋避作用。由运动视频分析所得的运动轨迹和运动数据可知,云南切梢小蠹在寄主植物云南松区域的平均停留时间为1133.7±59.7s,在旱冬瓜区域的平均停留时间为652.0±58.0s,且两者具有显著性差异(T=5.7883,P0.01)。     

干旱背景下昆明西山国家森林公园的可燃物特征

通过连续2年的外业调查和实验室分析,研究了持续干旱背景下西山国家森林公园的华山松、云南油杉、地盘松、麻栎和旱冬瓜等5个主要林型的可燃物特征,结果表明：与2012年的载量相比较,华山松林的载量增加了2．68kg · m^ -2,增加59．16％,地盘松林的载量增加了4．06kg · m^ -2,增加1．28倍,增长很明显;云南油杉的载量增加了0．01kg · m^ -2,麻栎林的载量增加了0．05kg · m^ -2,增加不明显;而旱冬瓜林的载量减少了0．12kg· m -2,减少了5．77％。     

昆明市松华坝水源区森林植被类型及水源涵养量估算

通过设置固定样地和临时样地调查,对昆明市松花坝水源区的森林植被类型及水源涵养量进行了研究,认为：松花坝水源区的植被类型以滇石栎为主的常绿阔叶林、以栓皮栎、旱冬瓜为主的落叶阔叶林、云南松和华山松为主的针叶林以及灌木林以及人工华山松林、云南松林、旱冬瓜以及圣诞树林等。松华坝水源区的森林涵养水源功能显著,通过估算松花坝水源区每年的水源涵养量为37.96×107m^3。     

大理市桉树低值林分改造初探

据 2 0 0 2年森林资源二类调查 ,大理市有桉树 (主要是蓝桉 )林分面积 2 2 13hm2 ,其中低值、劣质林分占85 8% ,因此必须进行改造 ,其措施包括 :①用云南松、冲天柏、麻栎、栓皮栎、旱冬瓜、车桑子等更换蓝桉 ;②进行带状和块状整地、清林、造林 ,营造混交林。     

昆明市城市森林常见树种对大气氟化物的净化作用动态研究

为研究昆明市城市森林常见树种对大气氟化物的吸收净化作用的年内季节性动态变化,应用直接采样和统计分析方法,对选定的树种蓝桉Eucalyptus globulus、云南松Pinus yunnanensis、华山松Pinus armandii、圆柏Sabina chinensis在4个季节中对大气氟化物的吸收作用进行了对比分析。结果表明:(1)植物叶片中的氟化物主要来自于大气中,并且与大气氟化物含量有明显的相关性,相关系数在0.970~0.999(P0.05)之间。大气中氟化物含量的季节性变化由高到低依次是:冬季(58μg·dm-2d-1)春季(47μg·dm-2d-1)秋季(31μg·dm-2d-1)夏季(26μg·dm-2d-1),出现的最高浓度值是最低浓度值的2.23倍。(2)春季、夏季、冬季植物叶片中氟化物含量由高到低依次均为:蓝桉圆柏华山松云南松;而秋季植物叶片中氟化物含量由高到低依次为:蓝桉云南松华山松圆柏。春季到夏季、秋季到冬季过程中,叶片中氟化物积累量由高到低依次均为:蓝桉圆柏华山松云南松;夏季到秋季过程中则为:云南松华山松蓝桉圆柏。(3)大气氟化物浓度与叶片中的氟化物含量具有一元线性关系。随着季节变化,华山松对氟化物最为敏感,春季和秋季,华山松叶片的氟含量与大气氟化物含量的相关性最高;夏季为圆柏和华山松;冬季为蓝桉。在土壤生境相同的条件下,两者的相关性越高,就能更准确的指示大气氟化物浓度变化的高低,准确地评价大气环境质量。     

Studies on Selection of Fire Resistant Tree Species for Subtropical Area of China

Fire disaster is the primary one of the facts of deforestation. Although in recent years the level of forest management and technique for fire suppression have been improving and fire fighting force has been strengthened, the area of fire has not been decreased obviously. Using biological fire resistant technique can effectively prevent the campaign fire. In this paper, fire resistant ability and component about 12 tree species, in mountain area of Daguishan, Guangxi Zhuang Autonomous Region, have been analyzed in laboratory. The results from this study indicated as the followings: (1) For all the tree species, fire resistant ability of leaf is more susceptible than that of branches and bark, and the broadleaf tree species are stronger than coniferous tree species in fire-resistance. (2) Calorific vdlue, water content, combustion temperature and ash content are main indexes affectingfire resistance. Heat value relates to lignin content and benzene-ethanol extractive content linearly. (3) By means of the     

Tree mortality after low-intensity prescribed fires in managed Pinus sylvestris stands in southern Finland

Abstract

Tree mortality, its causes, and the input of dead charred wood were studied in 11 managed 30–45-year-old Scots pine (Pinus sylvestris L.) stands 1 year after experimental low-intensity prescribed burnings in southern Finland. First, the relationship between fire-induced tree damage and several external variables, e.g. stand density, within-stand wind speed, open-air wind speed, the Finnish Forest Fire Index (FFI) and flame height, was studied. Secondly, the study examined which damage and morphological characteristics best predicted tree mortality. Tree mortality was very variable in the experimental plots, ranging from 0% to 48% on the basis of stem number and from 0% to 41% in terms of wood volume. The input of dead and charred wood decreased with stand age, being 19.4 m³ ha^?1 in 30–35-year-old stands, but only 1.7 m³ ha^?1 in 45-year-old stands. The input of dead wood was on average 10 m³ ha^?1, representing less than 5% of the mean volume before the prescribed fire. The external variables that best explained fire-induced damage were within-stand wind speed, flame height and FFI. Tree mortality was best predicted by charred stem ratio with bark thickness, and by charred stem ratio with tree diameter. The results indicate that prescribed burning that is conducted downwind increases tree mortality and changes subsequent stand structure with increasing within-stand wind speed.     

广西大桂山区防火树种的选择研究

森林火灾是危害森林的一大主要自然灾害,采用生物防火可以有效地控制特大森林火灾的发生。本文对广西大桂山区的木荷、火力楠、杨梅等１０种常绿阔叶树种和杉木、马尾松两种针叶树种的叶、小枝和皮的燃烧性能及其组成成分进行了测定,结果表明：（１）各树种均以叶的抗火性能最差,阔叶树种比针叶树种的抗火性能强;（２）热值、含水量、燃点和灰分含量是影响叶的抗火能力的主要指标。木质素含量和苯乙醇抽取物与总发热量有线性相关关系;（３）由多目标决策方法对１２种树的抗火性能综合排序得知,木荷、红椎、杨梅的抗火性强,润楠、米老排、火力楠、大桂山荷和木莲的抗火性中等,稠木、观光木的抗火能力较弱,杉木、马尾松的抗火能力强。     

云南橡胶树小蠹虫研究

云南植胶区橡胶树小蠹虫为4个科17个种的小蠹虫群体,是主要蛀食橡胶树死亡组织的次期性害虫,长期生存在橡胶林中。1990年后,橡胶树小蠹虫为害逐渐明显,表现大量发生,虫害树快速死亡,造成严重的经济损失。经2000～2007年的研究表明:橡胶树小蠹虫种群结构已发生重要变化,活蛀性的角面长小蠹(Platypussecrelus Sampson)、小杯长小蠹(P.calicutus Chapuis)已发展成为优势种,致使橡胶树小蠹虫种群从次要害虫逐渐变为主要害虫,成为橡胶树衰退重要的促进因素(Contributing factors);橡胶树衰退,特别是过度的乙烯利刺激割胶导致的橡胶树衰退,是促变小蠹虫群体结构并逐渐发展成为主要害虫的主要诱因。因此,提高管理水平,调控生产技术,使胶林生态系统达到新的平衡,才是有效地控制橡胶树衰退趋势和控制小蠹虫为害于经济阈值之下的正确途径。     

Response of Ocotea bullata,Curtisia dentata and Rapanea melanophloeos to medicinal bark stripping in the southern Cape,South Africa: implications for sustainable use

Tree bark is commonly used for traditional medicine in southern Africa and further afield. Increasing demand and commercialisation have resulted in the overexploitation of many species, posing a major challenge to forest managers to develop mechanisms for sustainable resource use. An experimental bark harvesting research project was initiated in the southern Cape, South Africa, to inform best practices for bark harvesting based on tree response to bark stripping. The species selected for the study, Ocotea bullata, Curtisia dentata and Rapanea melanophloeos, are much sought after and well represented in southern Cape forests. The treatment entailed removing vertical strips of bark, 1 m in length and of different strip widths, covering the full range of tree size classes ≥10 cm DBH. The treatments were applied during two seasons, winter and summer. Evaluations were done every six months to assess tree response to bark stripping in terms of bark regrowth through phellogen edge and sheet development, and susceptibility to insect and fungal damage. The results show a differential response of tree species in terms of phellogen edge and sheet growth, as well as susceptibility to fungal and insect attack. Rapanea melanophloeos was the most vulnerable to fungal and insect damage and displayed little bark regrowth following wounding. Curtisia dentata showed best bark regrowth through sheet development. Only O. bullata, though, showed adequate bark regrowth (through edge development) to allow for sustainable strip harvesting. Bark regrowth is influenced by season of stripping, although this is difficult to define considering the wide range of environmental and other factors affecting tree response to bark removal. Smaller trees are more vulnerable to bark stripping, especially with a wide strip, with poorer bark regrowth than bigger trees.     

Prescribed fire effects on bark beetle activity and tree mortality in southwestern ponderosa pine forests

Prescribed fire is an important tool in the management of ponderosa pine (Pinus ponderosa Dougl. ex Laws.) forests, yet effects on bark beetle (Coleoptera: Curculionidae, Scolytinae) activity and tree mortality are poorly understood in the southwestern U.S. We compared bark beetle attacks and tree mortality between paired prescribed-burned and unburned stands at each of four sites in Arizona and New Mexico for three growing seasons after burning (2004–2006). Prescribed burns increased bark beetle attacks on ponderosa pine over the first three post-fire years from 1.5 to 13% of all trees, increased successful, lethal attacks on ponderosa pine from 0.4 to 7.6%, increased mortality of ponderosa pine from all causes from 0.6 to 8.4%, and increased mortality of all tree species with diameter at breast height >13 cm from 0.6 to 9.6%. On a per year basis, prescribed burns increased ponderosa pine mortality from 0.2% per year in unburned stands to 2.8% per year in burned stands. Mortality of ponderosa pine 3 years after burning was best described by a logistic regression model with total crown damage (crown scorch + crown consumption) and bark beetle attack rating (no, partial, or mass attack by bark beetles) as independent variables. Attacks by Dendroctonus spp. did not differ significantly over bole heights, whereas attacks by Ips spp. were greater on the upper bole compared with the lower bole. Three previously published logistic regression models of tree mortality, developed from fires in 1995–1996 in northern Arizona, were moderately successful in predicting broad patterns of tree mortality in our data. The influence of bark beetle attack rating on tree mortality was stronger for our data than for data from the 1995–1996 fires. Our results highlight canopy damage from fire as a strong and consistent predictor of post-fire mortality of ponderosa pine, and bark beetle attacks and bole char rating as less consistent predictors because of temporal variability in their relationship to mortality. The small increase in tree mortality and bark beetle attacks caused by prescribed burning should be acceptable to many forest managers and the public given the resulting reduction in surface fuel and risk of severe wildfire.     

Deep BarkID: a portable tree bark identification system by knowledge distillation

Species identification is one of the key steps in the management and conservation planning of many forest ecosystems. We introduce Deep BarkID, a portable tree identification system that detects tree species from bark images. Existing bark identification systems rely heavily on massive computing power access, which may be scarce in many locations. Our approach is deployed as a smartphone application that does not require any connection to a database. Its intended use is in a forest, where internet connection is often unavailable. The tree bark identification is expressed as a bark image classification task, and it is implemented as a convolutional neural network (CNN). This research focuses on developing light-weight CNN models through knowledge distillation. Overall, we achieved 96.12% accuracy for tree species classification tasks for ten common tree species in Indiana, USA. We also captured and prepared thousands of bark images—a dataset that we call Indiana Bark Dataset—and we make it available at https://github.com/wufanyou/DBID.

     

Insect Herbivore Responses to Management Practices in Conifer Forests in North America

ABSTRACT

Pine-dominated forests in southeastern North America and at low-to-mid elevations in western North America historically were characterized by frequent, low-intensity fire that maintained wide spacing of site-adapted tree species, conditions that optimized biochemical defenses of trees and dispersal distances of herbivorous insects. Mixed conifer forests at higher elevations were wetter, denser, and characterized by infrequent stand-replacing fire and relatively isolated insect outbreaks. Increased density and altered tree species composition in managed forests have increased forest vulnerability to extensive outbreaks of bark beetles and defoliators. Herbivore-generated tree mortality and litter accumulation increase the likelihood of catastrophic fire. Management practices that produce an appropriate mixture of site-adapted tree species and wide host spacing are recommended to minimize the negative effects of herbivorous insects and fire. However, the creation of stumps, as a result of mechanical thinning, can favor lower-bole and root-colonizing insects that also may vector root diseases.     

Estimating bark volumes for 16 native tree species on the Sierra Madre Occidental,Mexico

Abstract

The Sierra Madre Occidental ecoregion accommodates some of the richest biodiversity anywhere in North America and contains about two-thirds of the standing timber biomass in Mexico. Worldwide forest trees provide an industrial output of about 363 million cubic meters, with the volume of bark accounting for an estimated 10% of total tree volume, so that bark is a very important nonwoody product. In this study, the proportion of bark volume (PBV) and its correlation with selected tree characteristics as well as the relationship between total tree volume and wood volume (WV) and total volume and bark volume (BV) were calculated for the first time for the 16 common and commercially most important tree species in the temperate pine-oak forest region of El Salto (Durango) on the Sierra Madre Occidental, Mexico. Measurements were made on 2,027 felled trees. The PBV in the species investigated ranges from 0.129 to 0.260 depending on the species and genus, with a mean value of 0.175. BV and WV can be accurately estimated. The approach used in this study is simple and effective, and very user-friendly. The method is recommended for researchers wishing to develop bark models for other tree species.