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
Qaidam cattle(Bos taurus) is an important endemic breed in Northwest China, which is mainly distributed in the northwest of Qinghai-Tibet Plateau. It has strong adaptive ability to plateau and swamp conditions, such a...Qaidam cattle(Bos taurus) is an important endemic breed in Northwest China, which is mainly distributed in the northwest of Qinghai-Tibet Plateau. It has strong adaptive ability to plateau and swamp conditions, such as cold tolerance and insect resistance. In this study, the first complete mitochondrial genome of Qaidam cattle was reported. The circular double-stranded genome is 16 340 bp in size, and contains 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes, and a D-loop region. The overall nucleotide composition is 33.4% A, 27.2% T, 26.0% C and 13.4% G, with a total A +T content of60.6%. The gene order and composition are similar to those of other B. taurus breeds. Molecular phylogenetic analysis indicated that Qaidam cattle was split as an independent clade and nested within Asian cattle breeds.展开更多
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。
基金Supported by China Agriculture Research System(CARS-37)Science and Technology Support Projects in Gansu Province(1504NKCA052)+1 种基金Innovation Project of Chinese Academy of Agricultural Sciences(CAAS-ASTIP-2014-LIHPS-01)Central Publicinterest Scientific Institution Basal Research Fund(1610322016006)
文摘Qaidam cattle(Bos taurus) is an important endemic breed in Northwest China, which is mainly distributed in the northwest of Qinghai-Tibet Plateau. It has strong adaptive ability to plateau and swamp conditions, such as cold tolerance and insect resistance. In this study, the first complete mitochondrial genome of Qaidam cattle was reported. The circular double-stranded genome is 16 340 bp in size, and contains 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes, and a D-loop region. The overall nucleotide composition is 33.4% A, 27.2% T, 26.0% C and 13.4% G, with a total A +T content of60.6%. The gene order and composition are similar to those of other B. taurus breeds. Molecular phylogenetic analysis indicated that Qaidam cattle was split as an independent clade and nested within Asian cattle breeds.
