大理州森林火险天气预报方法

选用2001～2010年大理州的森林火灾次数与对应的气象数据进行统计分析,分析结果表明日最高气温、平均相对湿度、最大风速和前15日累计降水量对大理州森林火灾有较好的指示性,其中日平均相对湿度对大理州森林火险天气等级指示性最强。根据实际应用需要选用日最高气温、平均相对湿度、最大风速和前9日的降水数据建立模型计算森林火险天气等级。利用2011年大理州森林火灾数据对模型的模拟效果进行检验,检验效果很好,说明运用此模型进行大理州森林火险天气预报是可行的。     

中国森林火灾发生特征及其与主要气候因子的关系研究

基于火灾年鉴数据及CRU格点气象资料,借助时间序列、皮尔逊相关分析及线性回归分析等方法,分析了我国1950—2017年期间森林火灾发生的特征及其气候驱动因子,并建立了火灾导致伤亡人数的预测模型。结果表明:1)森林火灾发生次数、森林受灾面积、受伤人数、死亡人数及伤亡人数等5个参数随时间均具有相似的变化趋势,且相互间均存在显著正相关(P0.01)。2)1950年以来,全国森林火灾次数、受灾森林面积及伤亡人数均呈显著的下降趋势。3)1950—1987年期间,全国森林火灾发生次数与生长季降水呈正相关,与非生长季降水则呈负相关;1988年以后,除5月和9月外,森林火灾的发生与降水基本呈负相关关系。4)1950—1987年间,全国森林火灾发生次数与生长季末温度呈正相关;1988年以后,森林火灾发生次数与前1年及当年生长季或生长季前的均温、最高温及最低温呈负相关。5)1950—1987年间全国森林火灾发生次数与前1年的PDSI呈正相关,并在6月、9月、11月和12月达到显著水平;1988年以后,森林火灾发生次数与逐月PDSI呈负相关关系。可燃物数量及其含水率是决定林火发生的关键因子,特别是在气候变暖背景下,高温触发的"暖干旱"现象可能会改变传统认为的火灾-气候关系,因此未来需要进一步深入研究气候变暖背景下森林火灾发生规律及其影响因素,才能科学合理地做好林火预防与管理工作。     

内蒙古大兴安岭林火与气象因子关系研究

基于内蒙古大兴安岭1990—2019年森林火灾历史档案和同期气象因子的数据,对该地区林火与气象因子间的相关性进行了研究。结果表明,林火发生与气象因子间的关系密切。林火发生次数随着温度的升高和降水的减少呈上升趋势;研究区日均相对湿度范围在58%~62%,火灾发生次数最多;林火发生次数与日照时数、日均温、日最高温间均呈显著正相关;过火面积与日均相对湿度间呈显著负相关,与日照时数间呈显著正相关。     

林火与气象及林分组成的关系

一、林火与气象的关系森林火灾与防火期月平均气象因子的关系,我们选取崇安、平和、龙岩三县、代表福建省闽北、闽南和闽西类型,统计各县月气象要素范围内出现的森林火灾次数、面积。应用数理统计方法,探讨森林火灾与月平均气象因子之间的相关关系(见表1) 它们的规律是①森林火灾次数和面积,随着月平均较差温度(△T)增加而递增,呈正相关关系,特别是较差温度在6—12℃之间,森林火灾次数、面积明显剧增。②森林火灾次数,面积,随着月平均相对湿度、     

建阳区森林火灾与气象因子相关性研究

对建阳区历年来3次最大典型森林火灾与气象因子的相关性研究表明:气温较高、相对湿度较小、风速偏大时,火灾发生概率较大,且空气温度为最主要气象因子。根据3次森林火灾气象要素的日变化规律看,下午14时左右是森林火灾发生的重要时段。且火灾与其发生的前3 d气象要素相关,即前3 d气温越高、空气相对湿度越小、风速越大,火灾越容易发生,各F值均大于F0.01(F0.01=7.5910),达到极显著。风速不仅影响森林火灾的发生,还直接影响其蔓延。     

合作市大气中PM_(10)浓度变化特征与气象要素的相关性分析

利用合作市2015、2016年供暖期大气颗粒物浓度的监测资料,结合同期气象要素(风速、气温、气压、相对湿度、降水量)进行了相关性分析。结果显示:合作市大气颗粒物浓度与风速、气温、相对湿度、降水量都呈负相关,与气压呈正相关,都具有较高的相关性,故合作市冬季气象因素与当地供暖期大气颗粒物的聚积和扩散在一定范围内具有显著相关性,但是合作市冬季综合气象条件不利于大气颗粒物稀释扩散,若要进一步改善合作市环境空气质量,必须对污染源采取控制措施。     

黔南州森林春季防火期主要气象因子与林火时空动态

运用克里格空间数据制图和传统统计分析相结合的方法对2001—2008年黔南州森林春季防火期主要气象因子与林火情况进行研究,结果表明:黔南州森林春季防火期内降雨量、蒸发量和最大风速相对空间分布不均匀,而最高气温、最小空气相对湿度则相反;空间分布上存在一定的水平地带性和垂直地带性,时间动态明显;森林火灾次数及火场面积呈逐渐增加趋势;空间分布上以都匀、平塘和罗甸3地为分界线,东南部6个县市森林火灾次数及火场面积大于西北部6县市。     

大兴安岭东部森林火灾发生的气候条件辨识

就大兴安岭东部森林火灾发生的气候条件进行了风险辨识,结论是:空气湿度是火险天气中的关键因素,相关系数为-0.81,表明湿度愈大火灾发生次数愈少,空气湿度小于60%时,就有发生森林火灾的可能,当相对湿度在35%￣50%之间时火灾发生次数较多。气温与森林火灾相关系数仅为0.36,当最高温度在-10￣10℃时是火灾发生的高峰期。风是森林火灾发生蔓延的重要因素,相关系数高达0.92。发生火灾时,当风速大于2.5m/s时,火灾蔓延开始加大。雷击火发生和蔓延的气候指标是平均气温为14￣20℃,降水量小于7mm,14时相对湿度15%￣38%,雷暴日数多于4天,平均风速2.5￣5.5m/s,14时风速大于3m/s。本着适用及着眼于近期与长远计划相结合的原则,选用了春季小于10mm降水日数、春季平均气温、地理因子、受灾面积、雷击火次数等7个因子进行了聚类分型,将火灾划分为3个区。     

西藏色季拉山西藏红杉径向生长对气温和降水波动的响应

[目的]基于色季拉山地区特有树种西藏红杉年轮样芯,研究西藏红杉径向生长对气温和降水量的波动响应。[方法]利用树木年代学的方法,结合TASP-Win及ARSTAN程序建立标准年表,采用Pearson及bootstrap的计算方式将年轮宽度指数与1961—2020年气温及降水分别进行相关分析。[结果]径向生长在气温波动前后存在较大的差异。在气温波动前西藏红杉与前一年8月,当年1月及6月平均气温呈正相关（P<0.05）,与前一年9—10月及12月平均降水呈正相关,与前一年8月降水呈负相关,与1月至12月的相对湿度呈显著正相关（P<0.01）。在气温发生波动后,与当年3—12月平均气温呈负相关,与前一年8月及当年6月降水为显著正相关。[结论]藏东南地区的气候条件极为特殊,气候的波动导致水热条件发生变化是限制西藏红杉径向生长的主要原因,在非生长季,气温短暂的变化对树木径向生长同样有着显著的影响。     

我国大兴安岭地区夏季林火的火环境研究

利用Arcgis和SPSS软件对大兴安岭地区1967-2008年夏季火险期森林火灾发生当天的气象因子和火点位置的植被和地形因子进行了定性和定量分析,探讨了夏季火的火环境特征,以期为防火部门进行森林管理及政策制定提供依据。结果表明:近42年来,夏季火发生时的日平均气温和最高气温范围分别为15~25℃、24~34℃,而且平均气温和最高气温不同导致夏季火发生次数具有极显著差异性,P﹤0.01;夏季火发生时,降水量主要为0~1 mm,而且具有极显著差异,P﹤0.01;平均风速范围0.5~3 m/s,不同风速发生火灾次数具有显著性差异,P﹤0.05;平均气压集中在945~975 h Pa,P﹤0.05;平均空气相对湿度55%~70%,P﹤0.01。通过对地形和植被的相关因子进行分析可知,夏季火主要发生在中高等海拔的平坡或缓坡区域,植被类型以落叶针叶林为主,其次是草甸。     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。     

Natural Regeneration in Clear-cuts: Effects of Scarification,Slash Removal and Clear-cut Age

The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided.     

Risk Perception Among Non-industrial Private Forest Owners

Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken.     

Interactions in decomposition and N mineralization between tropical legume residue components

In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts (stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea (Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea, largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols. Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its components are mixed.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization, (2) milk sewage sludge at 40 kg N ha⁻¹ target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha⁻¹. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹); (2) Lolium perenne L. var. Tove (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea (Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m², with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.