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根据云南松分布区的立地,按土壤——地形为主导因子,将云南松立地划分为45个立地类型,通过质量评定和等级划分,确定云南松的最佳生境是:在云南松适生区内的阴坡紫色砂岩、紫色砂页岩上发育的中厚层紫色土、火山灰岩上发育的中厚层火山灰土,以及阴坡地段由石灰岩、花岗岩、砂岩、砂页岩、片麻岩等发育的红壤,并由这些因素构成的各种立地类型。 相似文献
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云南松森林计划烧除试验研究（之一） 总被引：5，自引：0，他引：5
云南松是我国西南林区的主要组成树种,分布于四川西南和云南大部,面积3 267万亩,蓄积2.78亿立方米。云南松分布区地处我国横断山系,自然地理环境特殊,冬春季受到西风环流南支急流的控制,气候干暖、少雨,加之此时正是云南松及其林下灌丛、草本的休眠期,林下枯枝落叶最容易着火,酿成森林火灾。因此,云南松林区是我国森林火灾最严重地区之一。据对四川的多年统计,云南松林区森林火灾受害面积占全省的80%,相应地云南省占70%以上,该省在 相似文献
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金沙江流域不同海拔处云南松生态弹性及生长衰退过程 总被引：1，自引：0，他引：1
【目的】研究影响金沙江流域云南松生长的关键气候因子及不同海拔处云南松的生态弹性和生长衰退历史,为预测未来极端干扰事件对云南松生长动态的影响提供依据,为该区森林保护提供理论支撑。【方法】用生长锥钻取金沙江流域永仁县不同海拔处云南松树轮样芯,建立不同海拔树轮年表。利用树木径向生长变化百分率研究云南松生长衰退历史,用抵抗力和恢复力指标判断云南松的生态弹性,用响应分析和冗余分析方法研究不同海拔云南松生长与气候因子的关系。【结果】限制云南松径向生长的主要气候因子在低海拔区(1 845 m)和中海拔区(2 340 m)为生长季初期3—5月的月平均气温、降水量、干旱强度以及生长旺季的降水量及干旱强度,在高海拔区(2 740 m)为生长季初期的干旱强度及生长旺季7月的平均气温;过去近150年中,研究区域云南松在1884—1886、1897—1900、1903—1906、1947—1949和2009—2011年间发生了生长衰退;相同时段的径向生长衰退现象在低海拔区域最明显,高海拔区次之,中海拔区较弱;不同海拔的云南松对相同年份极端干旱事件的生态弹性不同,抵抗力表现为中海拔高海拔低海拔,恢复力表现为低海拔高海拔中海拔;随年份后延,低海拔区云南松应对极端干旱事件的抵抗力在增强,恢复力在下降,中海拔区云南松的抵抗力稳定,恢复力在2012年极端干旱事件时增强,高海拔区云南松的抵抗力和恢复力在研究期内稳定。【结论】接近云南松林分布气候界限环境的树木更易发生径向生长衰退,位于水热条件适宜环境下的云南松抵抗极端事件干扰的能力更强,接近云南松林生长极限环境的树木受极端事件干扰后的恢复能力更强。 相似文献
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采用全样本调查方法,对近年云南松种质资源保存库内云南松的松梢斑螟虫害发生情况进行调查,对云南松受害率、株受害枝梢、受害指数进行统计分析.结果表明,云南松种质资源保存库内云南松上松梢斑螟平均受害株率为5.08％,平均每株受害梢数量为0.28个;云南松种质资源的21个分布区来源地中受害最严重的前5位依次为腾冲、天峨(广西)... 相似文献
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从云南松自然分布区的不同生态区,不同经纬度,不同海拔高度和不同江河流域共收到各地的代表种源149个。选择了水热条件有明显分异的11个裁培点,同步进行裁培对比试验。3年的试验材料证实,不同种源苗期生长差异是极显著的。表现好的种源高生长超过对照20.5～200.6％,径生长超过12.9～103％,优劣种源间差异更为显著。通过分析,初步掌握了云南松的一些地理变异规律;得出种源内各性状间彼此存在一定的相关关系。为云南松种源选择和早期鉴定提供了技术依据。 相似文献
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综合采用线路调查法和红外触发相机调查法,对长青保护区内的林麝及其活动痕迹进行分析总结,结果表明:陕西长青国家级自然保护区林麝(Moschus berezovskii)喜欢在针阔混交林、中等海拔、坡度较陡、西南或南向的区域活动,其主要分布区为大坪和柏杨坪片区,次要分布区为杨家沟、石塔河、东坪和九池等地;林麝种群稳步发展,柄息地持续恢复,但仍显岛屿状、零星化分布特点.严格控制保护区内的人为活动,是林麝及其栖息地保护和恢复的基本对策. 相似文献
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Forest fires caused by natural forces or human activities are one of the major natural risks in Northeast China. The incidence and spatial distribution of these fires vary over time and across the forested areas in Jilin Province, Northeast China. In this study, the incidence and distribution of 6519 forest fires from 1969 to 2013 in the province were investigated. The results indicated that the spatiotemporal distribution of the burnt forest area and the fire frequency varied significantly by month, year, and region. Fire occurrence displayed notable temporal patterns in the years after forest fire prevention measures were strictly implemented by the provincial government. Generally, forest fires in Jilin occurred in months when stubble and straw were burned and human activities were intense during traditional Chinese festivals. Baishan city, Jilin city, and Yanbian were defined as fire-prone regions for their high fire frequency. Yanbian had the highest frequency, and the fires tended to be large with the highest burned area per fire. Yanbian should thus be listed as the key target area by the fire management agency in Jilin Province for better fire prevention. 相似文献
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Aqil Tariq Hong Shu Saima Siddiqui Iqra Munir Alireza Sharifi Qingting Li Linlin Lu 《林业研究》2022,33(1):183-194
Most forest fires in the Margalla Hills are related to human activities and socioeconomic factors are essential to assess their likelihood of occurrence.This study consid-ers both environmental (altitude,precipitation,forest type,terrain and humidity index) and socioeconomic (popula-tion density,distance from roads and urban areas) factors to analyze how human behavior affects the risk of forest fires.Maximum entropy (Maxent) modelling and random forest (RF) machine learning methods were used to predict the probability and spatial diffusion patterns of forest fires in the Margalla Hills.The receiver operating characteristic(ROC) curve and the area under the ROC curve (AUC) were used to compare the models.We studied the fire history from 1990 to 2019 to establish the relationship between the prob-ability of forest fire and environmental and socioeconomic changes.Using Maxent,the AUC fire probability values for the 1999s,2009s,and 2019s were 0.532,0.569,and 0.518,respectively;using RF,they were 0.782,0.825,and 0.789,respectively.Fires were mainly distributed in urban areas and their probability of occurrence was related to acces-sibility and human behaviour/activity.AUC principles for validation were greater in the random forest models than in the Maxent models.Our results can be used to establish preventive measures to reduce risks of forest fires by consid-ering socio-economic and environmental conditions. 相似文献
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长沙县森林火灾发生规律研究 总被引：1，自引：0，他引：1
根据长沙县"十一五"期间森林火灾发生的统计数据,从地域、时间、火因和肇事者等分析森林火灾发生的规律.结果表明:森林火灾发生存在明显的地域差异,据此可分为重灾区、较重灾区、较轻灾区、轻灾区和无灾区;森林火灾主要发生在防火期内,其中春防期明显多于冬防期,2月或3月为高发期,一天中的起火高峰在10:00—18:00;森林火灾发生主要由人为因素引起,森林火灾的肇事者老人最多,占30.6%。通过对森林火灾发生规律的调查分析,为长沙县"十二五"期间的森林火灾防控对策提出了建议。 相似文献
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Recent fire statistics and preliminary fire history data suggest that fire has been historically responsible for maintaining
the vegetative communities up to present in Daxinganling region. Forest types, and even tree species, arc dependent on the
degree of fire intensity, fire size, depth of burn and fire frequency. Selected samples of larch, pine, birch and spruce forest
were studied in terms of species composition as determined by fire frequency which mainly depends on topography and site conditions.
Intervals between fires range between 6 and 170 years. 相似文献
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根据玛可河林区近7年森林火灾资料分析,选择着火时间、地点、原因、地类和面积等因素进行相关分析,得出如下结论:森林火灾主要集中在冬、春两季;冬季降水量少,气候干燥,易发生森林火灾,春季正是春耕生产季节,生产性火源和人为火源并重,易发生森林火灾;从火灾空间分布分析,班前地区森林火灾次数最多,其次是王柔和友谊桥地区;从地类分析,牧草地发生火灾面积最大,其次是灌木林地和阔叶林地,有林地较少。 相似文献
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James K.Agee 《林业研究》1993,4(2):1-10
Forest fire history can be reconstructed over past centuries across a widevariety of forest types.Fire scars on living tress,and age classes of forest stands,are thetwo sources of information for these reconstructions.Point and area frequencies are usedto reconstruct fire history.Point frequencies are useful in forest types that burn withfrequent,low intensity fire so that many fire-scarred residual trees exist.A true point isa single tree,but more often point estimates are made by combining fire scar records fromseveral adjacent trees.Area frequences are applied where fires are infrequent but ofmoderate to high intensity,so that stand ages are used across wide areas to estimate firereturn interals.Proper selection and application of fire history methods are essential toderiving useful ecological implications from fire history studies.This review evaluates the common methods of determining fire history:what thetechniques are,where they are best applied,and how to interpret them in an ecologicalcontext.E 相似文献
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Thomas Zumbrunnen Gianni B. PezzattiPatricia Menéndez Harald BugmannMatthias Bürgi Marco Conedera 《Forest Ecology and Management》2011,261(12):2188-2199
Understanding the factors driving past fire regimes is crucial in the context of global change as a basis for predicting future changes. In this study, we aimed to identify the impact of climate and human activities on fire occurrence in the most fire-prone regions of Switzerland. We considered forest fires, land use and meteorological data over the period 1904-2008 in the neighboring mountain cantons (states) of Valais and Ticino, which are characterized by distinct climatic regimes.The presence/absence of fire ignitions was analyzed using the Nesterov ignition index (as a proxy for fire weather), road density (for ignition sources), livestock density (for biomass removal), and change in forest area (for fire-prone abandoned agricultural areas).We found that fire weather played a key role in fire occurrence in both regions. Road and livestock densities had similar influences in the two cantons. However, while the increase in forest area was well correlated with fire occurrence in Ticino, no such correlation was evident in Valais, probably because land abandonment and forest cover change have been less extensive there. Our findings emphasize the non-linear nature of the relationships between fire occurrence and anthropogenic drivers, as we found thresholds above which road density was no longer correlated with fire occurrence. This implies that the projected future increase and spatial concentration of the human population may not result in a further increase in fire risk in intermediately to densely populated areas in both cantons.The driving factors behind fire activity differ slightly in the two cantons, in particular with increasing forest area enhancing fire occurrence in Ticino but not in Valais. These differences should be taken into account when assessing future fire risk, especially in Valais where the potential for an increase in the fire-prone area is still high. Fires are likely to become more frequent in a warmer climate, but future fire activity may develop differently in the two cantons. This should be taken into account when planning optimized fire prevention measures. This case study should help to better understand fire activity in highly populated regions where fire activity is still moderate but might markedly increase under a projected more fire-prone climate. 相似文献
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Forest wildfires pose significant and growing threats to human safety, wildlife habitat, regional economies and global climate change. It is crucial that forest fires be subject to timely and accurate monitoring by forest fire managers and other stake-holders. Measurement by spaceborne equipment has become a practical and appealing method to monitor the occurrence and development of forest wildfires. Here we present an overview of the principles and case studies of forest fire monitoring (FFM) with satellite- and drone-mounted infrared remote sensing (IRRS). This review includes four types of FFM-relevant IRRS algorithms: bi-spectral methods, fixed threshold methods, spatial contextual methods, and multi-temporal methods. The spatial contextual methods are presented in detail since they can be applied easily with commonly available satellite IRRS data, including MODIS, VIIRS, and Landsat 8 OLI. This review also evaluates typical cases of FFM using NOAA-AVHRR, EOS-MODIS, S-NPP VIIRS, Landsat 8 OLI, MSG-SEVIRI, and drone infrared data. To better implement IRRS applications in FFM, it is important to develop accurate forest masks, carry out systematic comparative studies of various forest fire detection systems (known as forest fire products), and improve methods for assessing the accuracy of forest fire detection. Medium-resolution IRRS data are effective for landscape-scale FFM, and the VIIRS 375 m contextual algorithm and RST-FIRES algorithm are helpful for closely tracking forest fires (including small and short-lived fires) and forest-fire early warning. 相似文献
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《Forest Policy and Economics》2002,4(1):43-54
All of the Mediterranean countries face a serious forest fire problem. The main factors that affect the problem of forest fires in Greece are vegetation, climate conditions and most of all, arson (Proceedings of Forest Fires in Greece, Thessaloniki, 1990, p. 97). In Greece, after 1974, the number of forest fires and the total burned areas have risen dramatically. The design of an effective fight and prevention policy is a very important matter, as it can minimize the destruction. This paper describes an expert system that classifies the prefectures of Greece into forest fire risk zones, using a completely new methodology. The concept of fuzzy expected intervals (F.E.I.) was defined by Kandel and Byatt (Proc. IEEE, 66, 1978, 1619) and offered a very good approach towards forest fire risk classification. Fuzzy expected intervals are narrow intervals of values that best describe the forest fire problem in the country or a part of the country for a certain time period. Fuzzy logic was applied to produce a F.E.I. for each prefecture of the country. A successful classification of the prefectures of Greece (in forest fire risk zones) was performed by the expert system by comparing the produced fuzzy expected intervals to each other and by using a supervised machine learning algorithm that assigns a certain weight of forest fire risk to each prefecture (Machine Learning, John Wiley and Sons, 1995). 相似文献
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Fire is quite a common natural phenomenon closely related to forest hydrology in forest ecosystem. The influence of fire on water is indirectly manifested in that the post fire changes of vegetation, ground cover, soil and environment affect water cycle, water quality and aquatic lives. The effect varies depending upon fire severity and frequency. Light wildland fires or prescribed burnings do not affect hydrology regime significantly but frequent burnings or intense fires can cause changes in hydrology regime similar to that caused clear cutting. 相似文献