基于决策树的漓江上游土地覆盖分类     

张熙  鹿琳琳  王萍  周春艳  冀婷婷 《测绘科学》2016,41(3):100-103,90

针对山区植被分类受地形复杂、植被类型多样、验证数据获取困难等因素限制基于多光谱数据的亚热带山区土地利用/覆盖分类存在困难,探究利用物候信息对亚热带山区植被实施分类的效果。综合运用归一化植被指数(NDVI)、比值植被指数(RVI)、归一化水指数(NDWI),同时考虑到海拔高度对植被类型的影响,建立决策树模型。该模型基于多时相Landsat TM影像,利用了不同地物类型的物候特征和光谱差异,将漓江上游地区分为8种土地覆盖类型。实验结果表明,分类结果总体精度达到86.40%,Kappa系数为0.83。  相似文献   

Review on Vegetation Phenology Observation and Phenological Index Extraction     

Cao Peiyu  Zhang Leiming  Li Shenggong  Zhang Junhui 《地球科学进展》2016,31(4):365-376

Vegetation phenology directly reflects the response of ecosystem physiological and ecological processes to environmental changes and has received increasing attention in climate change, which leads to the development of various phenology monitoring techniques and methods of extracting the phenological index. Based on relevant literatures, the monitoring techniques of vegetation phenology were reviewed. Second, the methods of extracting phenological index using different techniques were introduced systematically. Thirdly, the differences from multi-source data and from multi-methods were evaluated based on ground phenology record, flux observation and vegetation index. Although various methods have been adopted in current vegetation phenological studies, it should be aware of their appropriately spatiotemporal scales for different methods, and the mutual complementation will help to improve the system for phenology monitoring. Meanwhile, the comparison indicated the obvious differences in derived vegetation phenological index using various observation techniques and extraction methods, especially for the autumn vegetation phenological index. Such results highlight the importance to assess reasonably these differences from multi-source data and from multi-methods, and to establish a rational processing system for the mutual comparison and conversion from different methods.  相似文献   

气候变化对家燕物候期的影响分析     

王燕  戴晨  曹晨 《沙漠与绿洲气象(新疆气象)》2022,16(2):64-68

对镇江地区1984—2019年家燕物候资料(始见、绝见期)及同期气温、降水、日照等气象资料对比分析,结果表明:近36 a镇江地区家燕始见期在波动变化中呈提前的趋势,以4 d/10 a的速率提前.绝见期在波动变化中呈推后的趋势,以5 d/10 a的速率推后.间隔期在波动变化中呈延长的趋势,以9 d/10 a的速率延长;近...  相似文献   

基于数字相机图像的长白山森林物候模拟   总被引：1，自引：1，他引：0  

周磊  何洪林  孙晓敏  张黎  于贵瑞  任小丽  王佳音  张军辉 《资源与生态学报(英文版)》2013,(4):317-326

植被物候作为全球植被和陆面过程模型的重要参数,对其状态的准确描述在很大程度上决定着模型的模拟精度。温带森林作为北半球中高纬度地区主要植被类型及全球重要碳源,研究其物候期的变化将提高对区域碳通量的估算精度。本文以长白山阔叶红松林为研究对象,探讨了数字相机图像在物种尺度物候模拟及群落尺度物候模型改进方面的作用,结果如下：（1）物种尺度上,利用数字相机能获取两种植被（红松,蒙古栎）较为准确的物候期（与人工观测数据比较,绝对误差〈3d）;（2）群落尺度上,基于数字相机图像获取的冠层状态数据提高了基于气象数据的物候模型（GSI：growingseasonindex）的模拟精度（R2=0．9）,尤其是秋季物候模拟,为进一步分析群落物候的环境控制因子提供了有力手段。研究表明：数字相机不仅能够提供精确地基于物种尺度的物候数据,还可为遥感物候数据的校正提供参考,同时为生态模型中物候模块的改进及降低区域尺度碳通量模拟不确定性提供了新的思路。  相似文献   

梨树始花期预报   总被引：9，自引：0，他引：9  

张利华  任曙霞  张永强  仲维建  张仁祖  王静 《气象科技》2012,40(3):485-488

基于丰县1984—2009年气温、日照和降水量资料,分析越冬期不同时段的气象因子对梨树始花期的影响。结果表明:①后期因子影响大,前期相对较小;②温度、日照因子影响大,降水因子影响较小。越冬期温度水平高,光照充足,梨树始花期就偏早,反之始花期就偏晚;在上年12月至当年1月,除12月下旬外,最高气温偏高,影响梨树休眠期的需冷量积累,开花就越晚,最高气温偏低,需冷量的积累充足,有利于解除梨树休眠,开花就越早。采用逐步回归方法,利用SPSS软件,建立了梨树始花期预报模型,模型拟合效果较好,预报准确率满足业务要求,及时为政府和果农提供准确的始花期预报。  相似文献   

基于MODIS时序数据提取河南省水稻种植分布   总被引：1，自引：1，他引：0  

杨沈斌  景元书  王琳  王钊 《南京气象学院学报》2012,35(1):113-120

以河南省为研究区,利用2009年多时相8d合成MODIS地表反射率产品提取水稻种植分布。根据稻田含水量变化特征及水稻生长规律,构建水稻种植分布提取流程。为减少云等噪声的影响,对地表水含量指数（ILSW,land surface water content index）和增强型植被指数（IEV,enhanced vegetation index）的时序数据进行平滑重建。然后,依据豫北和豫南稻区水稻物候期差异,分别建立标准水稻IEV生长线,以计算像元尺度的水稻相似性指数作为影像分类的特征波段。同时,对重建的ILSW和IEV时序数据分别进行主成份分析,选择各自的前3个成份作为特征波段。在此基础上,采用支持向量机分类算法对组建的特征波段进行分类,提取影像中水稻的种植分布。结果显示,提取的河南省水稻种植分布与实际情况吻合较好,豫北稻区水稻分布呈现集中连片的特征,多分布在沿黄河两岸,而豫南稻区水稻种植广泛,多在大型水库灌区周边及沿淮和低洼易涝地区。与各地区水稻统计面积相比,MODIS提取的水稻面积平均相对误差为6.56%,根均方误差为5.63khm2。受到混合像元影响,以及个别地区水稻种植分散且面积相对较小,使该地区水稻面积相对误差超过±60%。  相似文献   

On the phenology of North Sea ichthyoplankton   总被引：2，自引：1，他引：2  

Greve  Wulf; Prinage  Sabine; Zidowitz  Heike; Nast  Jutta; Reiners  Frank 《ICES Journal of Marine Science》2005,62(7):1216-1223

  相似文献   

Identifying global synchronies in marine zooplankton populations: issues and opportunities   总被引：4，自引：1，他引：4  

Perry  R.Ian; Batchelder  Harold P; Mackas  David L; Chiba  Sanae; Durbin  Edward; Greve  Wulf; Verheye  Hans M 《ICES Journal of Marine Science》2004,61(4):445-456

  相似文献   

阿勒泰近20年物候(候鸟)观测资料统计分析   总被引：1，自引：0，他引：1  

梁效忠侯颜芹  白松竹 《沙漠与绿洲气象(新疆气象)》2004,27(3):19-20

根据阿勒泰20年的物候(候鸟)观测资料，分析候鸟的迁徙变化规律，并和阿勒泰近20年的气候变化做对比分析。  相似文献   

Phenology ofMedicago minimaandErodium cicutariumin semi-arid Argentina     

D.E. Fresnillo Fedorenko  O.A. Fernández  C.A. Busso  O.E. Elia 《Journal of Arid Environments》1996,33(4):409-416

The phenology ofMedicago minimavar.minimaandErodium cicutariumwas studied at two different field sites in the Calden District (approx. 10 million ha), a temperate semi-arid phytogeographical region in central Argentina. One site had been protected from wild and domestic herbivores for the 6 previous years. The other adjacent site had been exposed to continuous grazing by cattle for several decades. A phenological key was made for each species in 1988, and this key was improved during the 1989 growing season when phenological observations were made every 1–3 weeks.The growth cycle ofM. minimaandE. cicutariumwas similar at the two studied sites. Initiation of the cycle occurred in autumn and appeared to be associated with soil water availability. Phenological patterns were very dynamic at the reproductive stage in both species. This stage started earlier and was faster inE. cicutariumthan inM. minima. The end of the growing season occurred during late spring, concomitant with high maximum air temperatures. Our results suggest that these species hasten their development when air temperature increases and soil water availability decreases. This could be an important strategy in these species which allows them to persist as seeds, and produce a new generation under favourable environmental conditions.  相似文献