林火生态因子的时空动态

本文从林分的时空角度入手 ,着重分析了不同林分、林龄、郁闭度随时间的推移导致森林火灾危险性的变化 ,其一般规律是 :中郁闭度林分 ,年龄增加、郁闭度增加 ,林木枝下高增加快 ,从而地表火发生率降低 ,树冠火危险性增大 ;长期未郁闭的疏林 ,地表火危险长期存在 ,林分生产力低 ;灌木、草坡是地表火发生率最高 ,生产力最低的类型。所以 ,根据不同分区林分特点 ,提出了合理的营林防火措施     

林下郁闭度对竹荪产量影响分析与效益评价

对不同林分生态环境中郁闭度对林下栽植竹荪产量影响分析,结果表明:不同林分生态环境对林下栽植的竹荪产量影响具有共性,郁闭度为0.6的环境中竹荪产量最高,郁闭度为0.8的竹荪产量其次,竹荪产量最低的为郁闭度为0.4林分生态环境。应用Tukey分析方法对不同林分生态环境中郁闭度因子对竹荪产量影响进行方差分析,郁闭度为0.6的生态环境与郁闭度为0.8、郁闭度为0.4的生态环境间均存在1%的极显著差异,郁闭度为0.8的林分环境与郁闭度为0.4的林分环境之间对栽植的竹荪产量也存在1%的极显著差异。相同郁闭度生态环境中不同林分条件下竹荪产量大小为:阔叶树>竹林>针叶树。林下栽植竹荪具有较好的经济效益,竹荪产量可达480.00kg/hm^2,纯收入可达30750元/hm^2。     

承德县人工针叶林地表枯死可燃物参数估测及潜在地表火行为评价

森林地表枯死可燃物是森林燃烧的基础物质之一,直接影响着地表火行为发生的强度.承德县境内分布着大面积的人工针叶林,林下积蓄的枯枝落叶较多,发生地表火的危险性极高,因此,对影响潜在地表火行为的因子,即地表枯死可燃物的各类载量及含水率进行调查研究(Shan et al.,2002),从而实时掌握不同林分的潜在地表火行为状况,显得尤为重要.     

杉木-闽楠混交林林分结构与生产力功能耦合关系研究

为了研究林分结构与生产力功能之间的关系,探讨确定杉木-闽楠混交林的合理林分结构,为维持群落结构稳定和提高林木生产力提供依据。以湖南省永州市金洞林场杉木-闽楠混交林为研究对象,利用获取的调查数据,运用主成分分析方法,分析平均胸径、平均高、郁闭度、混交度等林分结构因子与生产力功能间的耦合作用。建立林分结构与功能的耦合关系模型,对林分结构和生产力功能进行分析,结果表明,林分结构因子与生产力功能密切相关。生产力综合评价指数较高的林分具有的特征为:中等密度(1 500株/hm~2)、郁闭度为0.7左右、林层结构为复层林。这种结构特征有利于保持较好的生产力功能,是金洞林场杉木-闽楠混交林的最佳林分结构。     

不同林分郁闭度对半夏生长的影响

研究了不同林分郁闭度对半夏地上部生长性状、块茎形态性状、叶片形态性状和生物量及其分配等方面的影响。结果表明:林分郁闭度对半夏株高、茎基径的生长的影响均达到了极显著水平,且半夏株高随着林分郁闭度的增大而增大;当林分郁闭度为0.5时,半夏块茎长、块茎宽、块茎高,以及单株总鲜重、单株叶鲜重、单株茎鲜重、单株块茎鲜重、单株总干重、单株叶干重、单株茎干重和单株块茎干重均达到最大值;在不同的林分郁闭度下,半夏生物量向叶、茎和块茎传输的分配趋势并不一致。     

5种药材在不同郁闭度油桐林下生长研究

在不同郁闭度油桐林分套种玉竹、黄精、石蒜、桔梗和麦冬,测定不同药材在不同郁闭度油桐林分地上部分鲜重增量和地下部分鲜重生长情况。结果表明:油桐林分郁闭度在0.7以上的可套种玉竹、黄精等耐阴性药材,郁闭度在0.5~0.7可套种石蒜和麦冬等偏中性药材,在郁闭度小于0.3~0.5的可套种桔梗等喜光性药材。     

杜仲林下复合种植钩藤效果初探

为促进宜昌市夷陵区林下经济产业规模发展,提高经济效益,通过对钩藤在杜仲林下不同林分郁闭度的复合种植与不同抚育措施经营效果对比试验,结果表明:林分郁闭度在0.4~0.6之间,钩藤种植的成活率、保存率高,且产量最高;在钩藤不同生长时期,实施定干、短截、打顶等抚育措施,将极大促进钩藤分侧枝抽发,增加商品枝数量,大幅度提高产量。     

天然兴安落叶松白桦中幼林疏密度和郁闭度数量化关系的研究

林分郁闭度是一个较难精确获得的调查因子,但可利用其与疏密度的数量关系计算求出。文中介绍了这种方法后又明确指出:不同树种组成的林分,或同一林分在抚育前后,郁闭度与疏密度有不同的数量关系。     

地表火对桉树人工林生长的影响

对2005年12月发生在广州地区桉树人工林火烧林分的调在表明:不同类型地被物产生的地表火的强度不同,对桉树造成的烧伤程度亦不同;各种地被物的组成中,形成的地表火强度由强到弱顺序为五节芒+芒萁＞五节芒+芒其+锡叶藤+假鹰爪＞芒萁+白茅＞芒萁+桃金娘+车轮梅;低度的地表火对桉树的高生长有促进作用,而中度、高度和强度地表火对桉树高生长不利.     

城镇周边马尾松林分套种任豆技术研究

为进行马尾松林套种任豆研究,提高林分质量,对上杭县才溪镇周边不同郁闭度马尾松林分进行了套种试验。结果表明:任豆任豆的保存率、胸径生长、树高生长、冠幅生长差异极显著,其中林分郁闭度0.3～0.4套种生长效果最好,林分郁闭度0.4～0.5套种生长效果次之。在上杭县城镇周边郁闭度0.5以下的马尾松林分可大力推广种植任豆,提升林分质量。     

落叶栎林对森林火灾的影响分析

根据落叶栎林的特点,着重分析了落叶栎林与森林火灾的关系,结果表明,落叶栎林不仅存在着较强的潜在地表火,而且存在着潜在树冠火危险,是栎林火灾的最大隐患之一。同时还简要分析了栎类由于长期的自然适应而对森林火灾产生的抗火机制。     

海南岛尖峰岭热带林林分生产力的探讨

本文探讨了不同森林带林分的生产力及影响产量的因素。研究结果表明,不同森林带林分生产力差异显著,热带山地雨林产量最高,常绿季雨林稍次,山顶苔藓矮林最低;同带间不同森林类型差异不显著。由于尖峰岭的天然林已达成熟阶段,干形变化不大,因此,影响林分总产量的主要因素是林分的平均直径、树高和密度。次生林目前尚处于中幼龄阶段,产量较低,如能加强管理,可获高产。大面积的次生林是一不可忽视的后备资源,应加强管育,促使早日成材。     

龙胜县森林火险等级区

以广西龙胜县为研究区,调查分析该县森林火险状况及影响要素,结合森林资源载量及森林防火实际,选取树种（组）燃烧类型、人口密度、气象因子、火灾次数等11项主要林火影响因子,综合运用层次分析法(AHP)、聚类分析法及ArcGIS空间分析法,区划森林火险等级。结果表明,各村（分场）可区划为Ⅰ（高火险区）、Ⅱ（中火险区）、Ⅲ（低火险区）3个火险等级;Ⅰ、Ⅱ、Ⅲ级火险区面积分别占研究区总面积的35.47%、38.33%、26.20%。高火险区主要分布在东部和南部,中火险区集中于西部和北部,低火险区分散在高、中火险区之间。区划结果有利于总结、突出研究区森林火情特点和重点。     

Fuel types and crown fire potential in <Emphasis Type="Italic">Pinus halepensis</Emphasis> forests

There is a lack of knowledge to identify and classify forest structures according to the risk of crown fires, especially in Mediterranean regions. In this study, for the first time, we use real information, obtained after a wildfire that burnt under extreme meteorological conditions, to classify forest structures of Pinus halepensis into fuel types as a function of crown fire potential. We identified fourteen forest structures which characterize many forest types in Western Mediterranean areas depending on canopy closure, number of tree layers, percent of each tree layer and overall tree density. By using the pattern of fire types that burnt the most numerous forest structures, we have identified four fire hazard groups of forest structures which are considered different fuel types. The first two had the lowest risk of active crown fires and they differed in the proportion of surface fires and passive crown fires. The third fuel type was the threshold between structures with low and high extreme fire behavior; while the fourth had a high risk of active crown fires. Firefighters and forest managers who are demanding this kind of schema, will test and upgrade this classification of fuel types in function of crown fire potential during future wildfires.     

Factorial analysis on forest canopy density restoration in the burned area of northern Great Xing＇an Mountains, China

The restoration of forest landscape has drawn much attention since the catastrophic fire took place on the northern slope of Great Xing‘an Mountains in 1987. Forest canopy density, which has close relation to forest productivity, was selected as a key factor to find how much the forest quality was changed 13 years after fire, and how fire severity, regeneration way and terrain factors influenced the restoration of forest canopy density, based on forest inventory data in China, and using Kendall Bivariate Correlation Analysis, and Distances Correlation Analysis. The results showed that fire severity which was inversely correlated with forest canopy density grade was an initial factor among all that selected. Regeneration way which did not remarkably affect forest canopy density restoration in short period, may shorten the cycle of forest succession and promote the forest productivity of conophorium in the future, Among the three terrain factors, the effect of slope was the strongest, the position on slope was the second and the aspect was the last.     

天然林区小班森林资源数据的更新模型

以吉林省汪清林业局为例,根据１９９７年森林经理调查的８４８块固定样地数据,与全林整体模型方法相结合,建立了适合于天然林区林业局（场）无人为干预小班森林资源数据更新的林分级生长模型组。该组模型包括林分密度指数,平均高,断面积,形高,郁闭度等林分测算因子的生长或变化模型。     

木荷生物防火工程的应用效果研究

进行了木荷防火林带的模拟火烧试验，并对木荷针叶树混交林燃烧性作了定量分析，结果表明，木荷防火林带能够有效地阻隔地表火和树冠火蔓延；通过合理规划与布局，可从宏观上控制林火蔓延，防止大面积森林火灾发生；木荷在混交林中可成为间歇式的限制性林火蔓延带，降低林分燃烧性，形成微观密集型的防火网络体系，控制森林火灾发生。     

Mastication and prescribed fire impacts on fuels in a 25-year old ponderosa pine plantation, southern Sierra Nevada

Due to increases in tree density and hazardous fuel loading in Sierra Nevadan forests, land management is focusing on fuel reduction treatments to moderate the risk of catastrophic fires. Fuel treatments involving mechanical and prescribed fire methods can reduce surface as well as canopy fuel loads. Mastication is a mechanical method which shreds smaller trees and brush onto the surface fuel layer. Little data exist quantifying masticated fuel beds. Despite the paucity of data on masticated fuels, land managers desire fuel loading, potential fire behavior and fire effects such as tree mortality information for masticated areas. In this study we measured fuel characteristics before and after mastication and mastication plus prescribed burn treatments in a 25-year old ponderosa pine (Pinus ponderosa C. Lawson) plantation. In addition to surface fuel characteristics and tree data collection, bulk density samples were gathered for masticated material. Regressions were created predicting masticated fuel loading from masticated fuel bed depth. Total masticated fuel load prior to fire treatment ranged from 25.9 to 42.9 Mg ha⁻¹, and the bulk density of masticated fuel was 125 kg m⁻³. Mastication treatment alone showed increases in most surface fuel loadings and decreases in canopy fuel loads. Masticated treatment in conjunction with prescribed burning reduced both surface and canopy fuel loads. Detailed information on fuel structure in masticated areas will allow for better predictions of fire behavior and fire effects for fire in masticated fuel types. Understanding potential fire behavior and fire effects associated with masticated fuels will allow managers to make decisions on the possibility of mastication to create fuel breaks or enhance forest health.     

塞罕坝林场森林可持续经营对策

通过对塞罕坝林场森林经营现状的分析，根据分类经营的思想，提出了调整林种结构和现实林龄结构，加强更新树种选优工作和护林防火以及提高员工素质，解决林牧矛盾等森林可持续经营的发展策略。