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 Jil...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.展开更多
Spatial distribution is fundamental for understanding species coexistence mechanisms in forest communities.Here we comprehensively explored fine-scale spatial patterns of tree species in a secondary warm-temperate dec...Spatial distribution is fundamental for understanding species coexistence mechanisms in forest communities.Here we comprehensively explored fine-scale spatial patterns of tree species in a secondary warm-temperate deciduous broad-leaved forest community in north China.Aggregated distribution patterns were predominant.Species functional traits had no significant effects on their spatial patterns.The aggregation intensity decreased with increasing DBH and abundance.The multivariate linear stepwise regression showed that abundance and maximum DBH were correlated with the aggregation intensity.Our results partially confirm that species attributes(abundance,DBH)and habitat heterogeneity may primarily contribute to spatial patterns and species coexistence in this secondary forest.展开更多
Accessibility is an important tool</span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;&qu...Accessibility is an important tool</span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">to evaluate the maturity of a regional traffic network structure</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> which </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">describes the traffic convenience in the traffic</span><span style="font-family:Verdana;"> network. </span><span style="font-family:Verdana;">The paper defines a new accessibility index by using the resident pop</span><span style="font-family:Verdana;">ulation weighted average value of the sum of inverse of the traveling time </span><span style="font-family:Verdana;">distance and time threshold coming from ordinary traffic network, and then uses this accessibility index to analyze the spatial-temporal characteristics of Henan highway network, as well as its evolution patterns from 2005 to 2020. The results show that with the expansion and improvement of Henan highway network, city accessibility level has been significantly improved, spatial convergence is obvious, the cities in the north central are always High-High aggregation area, the cities in the south are always Low-Low aggregation area, gradually forming the characteristics of Northwest high and Southeast low, relative balance between East and West. There is some non-conforming phenomenon in highway mileage growth and improvement of the city accessibility levels, but this situation is being weakened, the highway network layout is gradually rationalized, the spatial distribution of city accessibility and that of population are beginning to converge.展开更多
为准确掌握广东省森林干扰与森林恢复的动态特征,文章基于谷歌地球引擎(Google Earth Engine,GEE)云平台构建Landsat长时序年度无云地表反射率影像集,采用LandTrendr(Landsat-based detection of Trends in Distur-bance and Recovery)...为准确掌握广东省森林干扰与森林恢复的动态特征,文章基于谷歌地球引擎(Google Earth Engine,GEE)云平台构建Landsat长时序年度无云地表反射率影像集,采用LandTrendr(Landsat-based detection of Trends in Distur-bance and Recovery)算法提取广东省1990—2020年森林干扰与森林恢复的时空分布特征,并分析其演变的驱动因素,比较不同森林类型的干扰与恢复特征。结果表明:(1)1990—2020年,广东省的森林干扰总面积约为1.35×10^(4)km^(2),集中分布在广东省西部、东部和中部小范围地区,干扰面积最大的3个城市分别为韶关、梅州、清远市;森林恢复总面积约为1.91×10^(4)km^(2),集中分布在广东省北部和西部地区,恢复面积最大的3个城市分别为韶关、清远、肇庆市。(2)广东省森林干扰与森林恢复均集中发生在海拔小于等于600 m的地区,高海拔地区的森林面积较为稳定;广东省森林干扰集中发生在坡度小于等于25°的地区,森林恢复集中发生在坡度小于等于35°的地区。(3)广东省森林干扰在1996年后发生较为频繁,其中2011年的森林干扰面积最大;森林恢复主要集中在2001—2016年,其中2012年的森林恢复面积最大。(4)广东省的森林干扰与森林恢复主要受雨雪冰冻灾害、台风、病虫害等自然因素以及森林火灾、城市化、采伐、林业政策等人为因素的综合影响,其中雨雪冰冻灾害对广东省北部地区的常绿针叶林的影响较大,但该类型的森林恢复也较快。展开更多
基于Global Fire Atlas遥感数据,借助ArcGIS 10.2和Origin等软件,分析了2003—2016年内蒙古地区野火特点,结合时间、空间的因素,探讨野火的时空动态规律。结果表明:2003—2016年内蒙古野火发生不是完全随机分布的,而是呈现一定的时空分...基于Global Fire Atlas遥感数据,借助ArcGIS 10.2和Origin等软件,分析了2003—2016年内蒙古地区野火特点,结合时间、空间的因素,探讨野火的时空动态规律。结果表明:2003—2016年内蒙古野火发生不是完全随机分布的,而是呈现一定的时空分布规律。该特征规律有助于强化区域火管理,增强重点防火区域的防火建设与宣传,科学安排防火工作,降低林火发生率,实现森林可持续发展。并对存在的不足与问题提出相关建议。展开更多
基金financially supported by the National Key Research and Development Plan(2017YFD0600106)the National Natural Science Foundation of China under Grant31470497+1 种基金Project 2013-007,Jilin Provincial Forestry Departmentsupported by the Program for New Century Excellent Talents in University(NCET-12-0726)
文摘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.
基金This study was supported by the National Key R&D Program of China(2017YFC0505601)the National Natural Science Foundation of China(31570630)State Key Laboratory of Forest and Soil Ecology(LFSE2015-13).
文摘Spatial distribution is fundamental for understanding species coexistence mechanisms in forest communities.Here we comprehensively explored fine-scale spatial patterns of tree species in a secondary warm-temperate deciduous broad-leaved forest community in north China.Aggregated distribution patterns were predominant.Species functional traits had no significant effects on their spatial patterns.The aggregation intensity decreased with increasing DBH and abundance.The multivariate linear stepwise regression showed that abundance and maximum DBH were correlated with the aggregation intensity.Our results partially confirm that species attributes(abundance,DBH)and habitat heterogeneity may primarily contribute to spatial patterns and species coexistence in this secondary forest.
文摘Accessibility is an important tool</span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">to evaluate the maturity of a regional traffic network structure</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> which </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">describes the traffic convenience in the traffic</span><span style="font-family:Verdana;"> network. </span><span style="font-family:Verdana;">The paper defines a new accessibility index by using the resident pop</span><span style="font-family:Verdana;">ulation weighted average value of the sum of inverse of the traveling time </span><span style="font-family:Verdana;">distance and time threshold coming from ordinary traffic network, and then uses this accessibility index to analyze the spatial-temporal characteristics of Henan highway network, as well as its evolution patterns from 2005 to 2020. The results show that with the expansion and improvement of Henan highway network, city accessibility level has been significantly improved, spatial convergence is obvious, the cities in the north central are always High-High aggregation area, the cities in the south are always Low-Low aggregation area, gradually forming the characteristics of Northwest high and Southeast low, relative balance between East and West. There is some non-conforming phenomenon in highway mileage growth and improvement of the city accessibility levels, but this situation is being weakened, the highway network layout is gradually rationalized, the spatial distribution of city accessibility and that of population are beginning to converge.
文摘为准确掌握广东省森林干扰与森林恢复的动态特征,文章基于谷歌地球引擎(Google Earth Engine,GEE)云平台构建Landsat长时序年度无云地表反射率影像集,采用LandTrendr(Landsat-based detection of Trends in Distur-bance and Recovery)算法提取广东省1990—2020年森林干扰与森林恢复的时空分布特征,并分析其演变的驱动因素,比较不同森林类型的干扰与恢复特征。结果表明:(1)1990—2020年,广东省的森林干扰总面积约为1.35×10^(4)km^(2),集中分布在广东省西部、东部和中部小范围地区,干扰面积最大的3个城市分别为韶关、梅州、清远市;森林恢复总面积约为1.91×10^(4)km^(2),集中分布在广东省北部和西部地区,恢复面积最大的3个城市分别为韶关、清远、肇庆市。(2)广东省森林干扰与森林恢复均集中发生在海拔小于等于600 m的地区,高海拔地区的森林面积较为稳定;广东省森林干扰集中发生在坡度小于等于25°的地区,森林恢复集中发生在坡度小于等于35°的地区。(3)广东省森林干扰在1996年后发生较为频繁,其中2011年的森林干扰面积最大;森林恢复主要集中在2001—2016年,其中2012年的森林恢复面积最大。(4)广东省的森林干扰与森林恢复主要受雨雪冰冻灾害、台风、病虫害等自然因素以及森林火灾、城市化、采伐、林业政策等人为因素的综合影响,其中雨雪冰冻灾害对广东省北部地区的常绿针叶林的影响较大,但该类型的森林恢复也较快。
文摘基于Global Fire Atlas遥感数据,借助ArcGIS 10.2和Origin等软件,分析了2003—2016年内蒙古地区野火特点,结合时间、空间的因素,探讨野火的时空动态规律。结果表明:2003—2016年内蒙古野火发生不是完全随机分布的,而是呈现一定的时空分布规律。该特征规律有助于强化区域火管理,增强重点防火区域的防火建设与宣传,科学安排防火工作,降低林火发生率,实现森林可持续发展。并对存在的不足与问题提出相关建议。
