黄河源地区草地退化空间特征

There are about 400 million hm2 of grassland in China, which account for 13% of the grassland in the world and 41% of the total land area of China. It is the biggest terrestrial ecosystem in China (Liu et al., 2003). Due to impacts of global change and ec…     

Spatial and temporal variability in the net primary production of alpine grassland on the Tibetan Plateau since 1982简

Based on the GIMMS AVHRR NDVI data （8 km spatial resolution） for 1982-2000, the SPOT VEGETATION NDVI data （1 km spatial resolution） for 1998-2009, and observa- tional plant biomass data, the CASA model was used to model changes in alpine grassland net primary production （NPP） on the Tibetan Plateau （TP）. This study will help to evaluate the health conditions of the alpine grassland ecosystem, and is of great importance to the pro- motion of sustainable development of plateau pasture and to the understanding of the func- tion of the national ecological security shelter on the TP. The spatio-temporal characteristics of NPP change were investigated using spatial statistical analysis, separately on the basis of physico-geographical factors （natural zone, altitude, latitude and longitude）, river basin, and county-level administrative area. Data processing was carried out using an ENVI 4.8 platform, while an ArcGIS 9.3 and ANUSPLIN platform was used to conduct the spatial analysis and mapping. The primary results are as follows： （1） The NPP of alpine grassland on the TP gradually decreases from the southeast to the northwest, which corresponds to gradients in precipitation and temperature. From 1982 to 2009, the average annual total NPP in the TP alpine grassland was 177.2x1012 gC yrl（yr represents year）, while the average annual NPP was 120.8 gC m^-2 yr^-1. （2） The annual NPP in alpine grassland on the TP fluctuates from year to year but shows an overall positive trend ranging from 114.7 gC m^-2 yr^-1 in 1982 to 129.9 gC m^-2 yr^-1 in 2009, with an overall increase of 13.3%; 32.56% of the total alpine grassland on the TP showed a significant increase in NPP, while only 5.55% showed a significant decrease over this 28-year period. （3） Spatio-temporal characteristics are an important control on an- nual NPP in alpine grassland： a） NPP increased in most of the natural zones on the TP, only showing a slight decrease in the Ngari montane desert-steppe and desert zone. The positive trend in NPP in the high-cold shrub-meadow zone, high-cold meadow steppe zone and high-cold steppe zone is more significant than that of the high-cold desert zone; b） with in- creasing altitude, the percentage area with a positive trend in annual NPP follows a trend of ＂increasing-stable-decreasing＂, while the percentage area with a negative trend in annual NPP follows a trend of ＂decreasing-stable-increasing＂, with increasing altitude; c） the varia- tion in annual NPP with latitude and longitude co-varies with the vegetation distribution; d） the variation in annual NPP within the major river basins has a generally positive trend, of which the growth in NPP in the Yellow River Basin is most significant. Results show that, based on changes in NPP trends, vegetation coverage and phonological phenomenon with time, NPP has been declining in certain places successively, while the overall health of the alpine grassland on the TP is improving.     

利用Matlab和Visual C++实现卡尔曼滤波的新方法

阐述了Matlab与Visual C++的优缺点,提出了一种利用Matlab和Visual C++实现卡尔曼滤波的新方法.利用Matlab的Add-in插件可快速将M文件集成到C++中,创建独立的C/C++程序.通过实例介绍在Visual C++ 6.0环境下如何实现Matlab与Visual C++的混合编程.     

北京周围建设用地空间分布格局及解释

城市对其周围土地利用格局的影响历来是地理学研究的重点领域, 大城市周围建设用地比例高, 分析和解释大城市周围的建设用地格局可进一步拓展我们对此领域的认识。本文 以2005 年北京中心区周围50 km 范围内的建设用地数字化图件为基础, 由内而外, 建立5 个宽度为10 km 的缓冲带, 分析了北京2005 年建设用地空间格局的变化, 并从自然、历史和经济学的角度对此格局作出诠释。主要结论如下: 北京市周围建设用地格局呈现出四条非常清晰的放射带, 这几条放射带和2200 多年前的秦朝驰道吻合; 北京市周围建设用地图斑的空间分布的连续性并没有受到行政区域划分的影响; 缓冲带30-40 km 可能是北京城市中心区在平面上的影响界线; 在缓冲带10-20 km 和缓冲带30-40 km 内, 城市用地比例呈现出两个峰值。     

大渡河上游不同地带居民对环境退化的响应

Environmental degeneration in the Tibetan Plateau attracts worldwide attention, whereas case studies on how the residents understand and respond to environmental degeneration are scarce. Using a Participatory Rural Appraisal method, this paper investigates how the people in different regions in the upper Dadu River understand and respond to environmental degeneration, based on comparative field surveys in three villages, in which Danzamu village is chosen from villages in the valley region, Kerma village from mountainside region, Rico village from the mountain and plateau region. The results show that: (1) although awakened to environmental degeneration, the residents in different regions have different responses. As agricultural labors have been transferred to the secondary and tertiary industries, population pressure in Danzamu and Kerma villages is mitigated. Residents in Danzamu village actively respond to natural disasters and forest degradation, as their livelihoods never rely on forests and rangelands again. Whereas the residents in Kema village negatively respond to natural disasters, forest and meadow degradation and the ruin of wildlife resources, as their livelihoods still rely on stockbreeding. Labors in Rico village are hard to transfer to the secondary and tertiary industries, so they have to raise more livestock to make a living. Active measures are just taken to avoid livestock loss, not to avoid forest and meadow degradation and the ruin of wildlife resources. So the most fragile region is the mountain and plateau region and mountainside region, not the valley region. (2) Livelihood strategy is the key factor affecting the residents to respond to population pressure and environmental degeneration. So the framework of sustainable livelihood strategy should be used to explain and intervene in issues of population pressure and environmental degradation in ecotones. (3) Transferring agricultural labors to the secondary and tertiary industries were favorable to improving people’s livelihood. It is necessary to reduce the education fees to speed up the pace of labors transferring in the mountainside region. In the mountain and plateau region, preferable ways also include the development of towns, highways, education equipment and other establishments. Foundation: National Natural Science Foundation of China, No.40471009; No.30270256; National Basic Research Program of China, No.2002CB412500; No.2005CB422006; Knowledge Innovation Project of CAS, No.KZCX3-SW-339 Author: Yan Jianzhong, Ph.D., specialized in LUCC, global change and regional responses.     

青藏高原植被覆盖对水热条件年内变化的响应及其空间特征

利用1982-2000年NOAA/AVHRR卫星的NDVI数据(时间分辨率旬,空间分辨率8 km×8 km),结合同时期的气温和降水资料,基于时滞互相关方法和GIS工具,分析了青藏高原植被覆盖对水、热条件年内变化的时滞响应及其空间特征。结果如下:①除高寒荒漠、森林外,青藏高原植被NDVI与同期旬均温和旬降水相关性均呈高度正相关。其中,中等覆盖度的植被受水、热影响表现更为强烈。②青藏高原植被NDVI对气温和降水有滞后效应,且滞后水平存在空间差异,高原北部(柴达木盆地、昆仑山北冀)和高原南部植被对降水、和温度的响应比较迟缓,而高原中、东部地区植被对温度和降水的响应比较敏感。③不同植被类型对水热条件的响应程度也存在差异,由高到低依次是草甸、草原、灌丛、高寒垫状植被、荒漠,最后是森林。     

The dynamic response of lakes in the Tuohepingco Basin of the Tibetan Plateau to climate change

The Tibetan Plateau (TP) is particularly sensitive to the influences of climate change. As indicators of climate change, lakes on the TP play a key role in the Earth’s climatic system. Lake Yazi (LY), Lake Tuohepingco (LT) and Lake Changtiao (LC) in the Tuohepingco Basin are three inland lakes on the plateau. The extents of LY, LT and LC were obtained using object-based image analysis for remote sensing and 22 images from Landsat satellites (from September to December between 1972 and 2015). Inter-annual changes in the extent of LY, LT and LC were then analyzed. The results show that the total area of the three lakes underwent a change from shrinkage to expansion between 1972 and 2015. In general, there was a trend toward shrinkage during 1972–1999, distinct expansion during 2000–2007 and slight expansion during 2008–2015. Moreover, we found that 14 other lakes have also expanded dramatically since 2000. Lakes at 30°N and 35°N (LY, LT and LC are also located in this region) exhibited the same dramatic period of expansion between 2000 and 2005. In other words, 2000 appears to be a critical transition point for changes in lake size on the TP. Lakes at the same latitudes in the Tibetan Plateau interior may have a similar period of dramatic expansion after 2000. The warming-triggered deglaciation or permafrost degradation, increased precipitation and decreased evapotranspiration may be the influencing factors of lake expansion in the Tuohepingco Basin. Temperature showed relatively higher correlation with lake extent, while precipitation and evaporation were slightly correlated with lake area. Given the importance of wetlands to human society, these are no trivial issues, and we now need accelerated research based on long-term and continuous remote sensing.     

Glacier Changes on the Qiangtang Plateau between 1976 and 2015: A Case Study in the Xainza Xiegang Mountains

Xainza County on the Qiangtang Plateau (QP) spans a transitionally climatic and eco-environmental zone and is therefore a very sensitive region. Glaciers in this area are one of the most important kinds of land cover as well as key water resources, yet our understanding of their current status and spatio-temporal change remains limited. Using Landsat images, this study investigated the current distribution of glaciers (2015) in the Xainza Xiegang Mountains as well as the spatio-temporal changes that took place over six time periods between 1976 and 2015. Results show that, in 2015, 131 glaciers covered a total area of 74.59 ± 5.25 km², mainly located between 5,600 and 6,000 m above sea level (a.s.l). Between 1976 and 2015, the total number of glaciers increased by 12, while their areas decreased by 24.98% (24.83 km²). Glacial retreat has induced a loss of water resources of 11.77 × 10⁸ m³ over the last 39 years, while spatial heterogeneities in glacial changes across various sub-basins, aspects, and altitudinal zones are also clearly observed. Climate warming is the key factor driving this continuous glacial retreat; the high-quality dataset presented in this paper for the Xainza Xiegang study area is crucial for the ongoing assessment of climatic and eco-environmental changes.     

基于随机森林模型的干旱绿洲区张掖盆地地下水水质评价

为合理准确评价地下水水质,建立了基于随机森林（RF）模型的地下水水质评价模型,并根据张掖盆地81个地下水采样点的pH值、Cl^-、SO₄^2-、NO₃^-、Na⁺、NH₄⁺含量及总硬度的监测数据,对研究区的地下水水质进行了综合评价。结果表明：盆地地下水水质主要为Ⅱ、Ⅲ、Ⅳ类水,其中甘州区地下水埋藏较深,水体不容易受到来自地面的污染,水质较好,大多数地方为Ⅱ类水;临泽县和高台县地下水埋藏较浅,水质较差,大多数地方为Ⅲ类水,尤其高台县的水位最浅,再加上地处河段下游,污染更为严重,部分地区达到Ⅳ类。根据指标的重要性度量发现影响研究区域地下水水质的主要因子是NO₃^-含量;其次是NH₄⁺、SO₄^2-、Na⁺、Cl^-含量及总硬度、pH值。为验证模型的有效性,将地下水水质评价结果与基于支持向量机（SVM）和人工神经网络（ANN）的地下水水质综合评价模型模拟结果进行对比,3个模型均能很好地评价研究区地下水水质,但RF模型的评价结果更为准确。     

近30年珠穆朗玛峰国家自然保护区冰川变化的遥感监测

利用1976、1988和2006年的3期陆地卫星遥感数据,采用面向对象的解译方法并结合专家知识分类规则自动提取珠穆朗玛峰国家自然保护区(以下简称珠峰保护区)3个时期的冰川信息,并利用遥感、地理信息系统和图谱的方法对冰川时空分布特征和变化及其原因与不确定性进行了分析。结果如下:(1)2006年珠峰保护区内冰川面积为2710.17±0.011km²,为研究区总面积的7.41%,主要分布在研究区南部海拔4700～6800m的高山区;(2)1976-2006年,珠峰保护区冰川持续退缩明显,总面积减少501.91±0.035km²,冰湖扩张迅速(净增加36.88±0.035km²);研究区南坡子流域冰川退缩率(16.79%)高于北坡子流域(14.40%);珠峰保护区冰川以退缩为主,退缩冰川主要分布于海拔4700～6400m,退缩区上限海拔为6600～6700m;(3)1976年以来,气温显著上升和降水减少是冰川退缩的关键因素。