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381.
382.
根据NOAA/AVHRR (National Oceanic and Atmospheric Administration/Advanced Very High Resolution Radiometer)卫星归一化植被指数(NDVI)数据和CASA(Carnegie-Ames-Stanford Approach)模型的计算结果,过去30 年间(1982-2011 年),青藏高原生长季植被覆盖度和植被净初级生产力(NPP)呈总体上升态势,
植被总体变好。青藏高原生态系统碳汇功能增强,占全国增加碳汇的10%左右。气候条件的变化是青藏高原植被总体变好的最为重要的驱动因子,退牧还草等大型生态工程的生态效应也比较显著。青藏高原植被总体变好的同时,存在着区域不平衡。植被变差的区域主要集中在海拔较高的、生态更为脆弱的藏北高原、西藏“一江两河”和三江源的部分地区,尤其是藏北高原西部的高寒草原和高寒荒漠出现了较为严重的草地退化,其原因是气候变暖变干叠加人类活动(如超载放牧等)的影响。为了应对气候变化和人类活动对青藏高原植被的影响,应该加强青藏高原生态系统变化长期监测系统与平台建设,加大生态补偿和大型生态工程的实施力度。 相似文献
383.
Use of a multi-temporal grid method to analyze changes in glacier coverage in the Tibetan Plateau 总被引:3,自引:0,他引:3
This paper describes a multi-temporal grid method for quantifying changes in glacier coverage. A multi-temporal grid synthesizes spatial, attribute and process components of glacier information by sequentially combining spatial data from satellite images or maps. It enables us to identify glacier retreat and advance areas in individual grid cells for three or more periods of data sets. Discrepancies among the sequential data sets were detected graphically and numerically, including noise from geo-location error, misclassification, or different interpretation results in various pixel resolutions. Noise was detected and corrected to a large extent by visualization of the synthetic grid. The paper compares the results with that from a common method based on individual data sets, focusing on the Mt. Naimona'Nyi and Mt. Qomolangma regions at the northern slopes of the Himalayas. Results show that the identified noise (e.g. by 2.5 km2 in the Mt. Naimona'Nyi region) is much larger than measurement uncertainty calculated by sensor resolution and co-registration error (e.g. by 0.015 km2 in the Mt. Naimona'Nyi region). After noise removal, we notice that glacier recession clearly accelerates. The multi-temporal grid method results in a better quantification of glacier variation. It shows that glaciers in the Himalayas have both retreated and advanced during the last several decades, with retreat dominating and accelerating. Glaciers on the northern slope of Mt. Qomolangma in the middle Himalayas retreat more extensively and faster than those in the Mt. Naimona'Nyi region in the western Himalayas. 相似文献
384.
基于GIS与USLE的榆中县土壤侵蚀 总被引:5,自引:0,他引:5
在GIS与RS技术支持下应用USLE模型对位于黄土高原西部的榆中县进行土壤侵蚀强度的定量估算,探讨区域土壤侵蚀的空间变异性以及与坡度梯度和土地利用方式之间的关系.得出榆中县的年均侵蚀总量为813137t,年均侵蚀模数为247t/km~2,并且土壤侵蚀的空间变异性明显,年均侵蚀模数与年均侵蚀总量随坡度梯度的增加都呈指数增加.在分析不同土地利用方式下的土壤侵蚀状况后发现,低覆盖度草地才是区域最主要的侵蚀地带. 相似文献
385.
林清江 《江西科技师范学院学报》2009,(2):17-20
改革开放后,闽南地区民营企业发展迅猛,为闽南地区经济的发展,人民生活水平的提高做出巨大贡献,在福建省经济发展中具有举足轻重的地位。但是。普遍存在的人力资源管理理念落后、管理方式陈旧、管理水平偏低等现象.严重地制约了企业的发展。本文就该地区民营企业人力资源管理中存在的问题进行深入的分析,在此基础上提出相应的具有实用性的对策建议.并对如何加强闽南地区民营企业人力资源管理作出进一步思考。 相似文献
386.
Peng ShiQiu Xu XiangDe Shi XiaoHui Wang DongXiao Zhu YuXiang Pu JingJiao 《科学通报(英文版)》2009,54(4):706-710
To improve the numerical simulation of the severe snow storms occurred in the south of China and the middle/lower reaches
of Changjiang River during January of 2008, the observations from the automatic weather stations (AWS) over the Qinghai-Xizang
Plateau (QXP) and its surrounding areas were assimilated into the Weather Research and Forecasts (WRF) model using multi-cycle
3-dimensional variational data assimilation (3DVAR). Due to the large-scale special topography of the QXP and its surrounding
areas which may reach up to the mid-troposphere, the AWS located at different height on the deep slope of the plateau are
different to those located on plains and take a role analogous in some extent to that of radio soundings in obtaining the
vertical “profile” information of the atmosphere, and have the advantages in the aspects of sampling frequency, location/height
fixing, and synchronization. The information captured by these AWS may carry the early-warning “strong signals” in the upstream
sensitive area for the downstream weather systems to the east of the plateau and thus the assimilation of these AWS data is
expected to lead to significant improvements on the simulation of the severe weather system occurred in its downstream areas
through adjusting the 3-dimensional structures of the atmospheric thermal-dynamics for the initial conditions of the model.
This study indicates that the assimilated information of moisture, temperature and pressure carried in the observations of
AWS over the Qinghai-Xizang Plateau and its surrounding areas is very important and useful in the forecasting of precipitation
in its downstream areas.
Supported Jointly by National Natural Science Foundation of China (Grant Nos. 90502003 and 40625017), LaSW Project (Grant
No. 2008LASWZI04), the Key Project of AMS (Grant No. 2008Z006), the JICA Program and the International Sci-Tech Cooperative
Project (Grant No. 2007DFB20210) 相似文献
387.
There are many controversial issues in loess studies such as natural vegetation types on the Chinese Loess Plateau during the historical periods and the spatial and temporal evolution of C3/C4 plants. Elemental carbon isotopic composition (δ^13Cec) in the loess section may offer new evidence for these problems. Elemental carbon (EC) is produced by incomplete combustion of vegetation, and its carbon isotopic composition has a very small difference from that of the formal vegetation, then δ^13Cec can be used as a record to recover the changes of vegetation. Elemental carbon was extracted by applying the oxidation method from the Ioess-paleosol sequence in the central Chinese Loess Plateau, and its car- bon isotope composition was analyzed by the isotope mass spectrometer. The results showed that the vegetation in this region was a mixed type of C3 and C4 plants, dominated with C3 plants in most of the time. Since late Quaternary, C3/C4 plants may not follow a simple glacial-interglacial cycle mode on the Chinese Loess Plateau, but showing fluctuations. C3 plants increased gradually in L4 period, and more C3 plants occurred during $3 period, and C4 plants increased again during L3-- L2 periods, after that, Cs plants dominated again during S1 --S0 periods. During periods of paleosol development, C3 plants were abundant in S3 and S1, and there were more Ca plants in S2 and SO. During periods of loess sedimen- tation, there were more C3 plants in L4 and L1, and there were more C4 plants in L3 and L2. On the orbital timescale, the vegetation variations revealed by δ^13Cec record are consistent with the results of pollen data and also similar to the results obtained by organic carbon isotopic composition since the last glacial period. 相似文献
388.
青海省藏族大学生闲暇体育现状的调查分析 总被引:1,自引:0,他引:1
杨根旺 《青海师范大学学报(自然科学版)》2009,(1)
采用问卷调查法,调查研究了青海省高校藏族大学生闲暇体育的现状及分析了存在的问题,提出了青海高校藏族大学生闲暇体育的看法.对今后开展针对性、实用性强的闲暇体育,培养藏族大学生体育意识,树立终身体育意识,养成经常参加体育锻炼的习惯,具有十分重要的意义. 相似文献
389.
基于皮尔斯的符号三角理论和实证分析,提出在近代闽南侨乡文化的特殊场合下,"五脚基"能成为"洋楼"的表征符号的观点."五脚基"作为一种符号媒介,能够与"洋楼"客体对象建立表征关系,这种表征关系体现为存在关联、标识关联、类构关联3个方面,而"五脚基"符号媒介在与"洋楼"客体对象建立表征关系后,它也就能上升为一种更"发达"的符号."五脚基"除了作为闽南人用来指代"外廊文化体"的符号外,当其处在近代闽南侨乡特定的文化场合内的时候,却还有表征"洋楼"的功能. 相似文献
390.
灰色关联度分析在高原粳稻新品种评价上的应用 总被引:3,自引:0,他引:3
通过运用灰色关联度对四川省2008年凉山州水稻新品种中粳组区域试验5个试点的试验结果进行分析,结果表明,西粳1号的综合性状表现最好,其次是西粳2号,天香1号和西粳3号综合性状表现较好,2006-427综合性状最差。对灰色关联度分析和方差分析的结果进行比较,表明方差分析不能反应出与产量性状和生产需求相关的其他性状的信息,易造成对品种评价的片面性,而灰色系统理论对参试品种的综合性状进行分析,能克服只靠产量排序带来的弊端,弥补方差分析的不足。 相似文献