基于TM影像的重庆市北碚区地表植被覆盖变化

在3S技术支持下,利用重庆市北碚区1988年与2007年的Landsat TM影像数据,编制归一化植被指数(NDVI)图,进而计算生成植被覆盖度图像.通过掩膜技术和变化检测等方法提取了研究区1988-2007年的植被覆盖变化信息.研究结果表明:北碚区20年间植被覆盖面积增加了14.30 km2,变化率为1.94%.研究区的植被覆盖变化主要表现为低植被覆盖度类型面积增加,高植被覆盖度类型面积减少,具体表现为植被覆盖度小于40%的覆盖类型面积变化率为108%;而80%～90%和90%～100%的覆盖类型面积变化率分别为-67.70%和-19.07%.空间分布特征方面,其植被覆盖度高的区域主要分布在缙云山脉和中梁山脉,且其变化不大;而低植被覆盖度的区域主要分布在嘉陵江沿线、北碚旧城及新城建设区,且表现出较大变化.

Abstract：

Normalized difference vegetation index (NDVI) maps were plotted from the TM image data source of Beibei in the years of 1988-2007 based on the 3S technique, and vegetation fraction maps were computed and drawn from them. The vegetation fraction change in Beibei from 1988 to 2007 was derived using mask technique and change detection within the ERDAS software. The results showed that the total area of vegetation fraction in Beibei district increased by 14.30 km2 or 1.94% while the coverage pattern changed. In the past 20 years, low vegetation fraction increased while high vegetation fraction decreased.Considered from the perspective of its spatial distribution patterns, vegetation fraction was high and changed little in Jinyun Mountain and Zhongliang Mountain areas and was low and changed greatly in the center of district and along the Jialing River.     

Detecting Agro-Droughts in Southwest of China Using MODIS Satellite Data

The normalized difference vegetation index (NDVI) has proven to be typically employed to assess terrestrial vegetation conditions. However, one limitation of NDVI for drought monitoring is the apparent time lag between rainfall deficit and NDVI response. To better understand this relationship, time series NDVI (2000-2010) during the growing season in Sichuan Province and Chongqing City were analyzed. The vegetation condition index (VCI) was used to construct a new drought index, time-integrated vegetation condition index (TIVCI), and was then compared with meteorological drought indices-standardized precipitation index (SPI), a multiple-time scale meteorological-drought index based on precipitation, to examine the sensitivity on droughts. Our research findings indicate the followings: (1) farmland NDVI sensitivity to precipitation in study area has a time lag of 16-24 d, and it maximally responds to the temperature with a lag of about 16 d. (2) We applied the approach to Sichuan Province and Chongqing City for extreme drought monitoring in 2006 and 2003, and the results show that the monitoring results from TIVCI are closer to the published China agricultural statistical data than VCI. Compared to VCI, the best results from TIVCI3 were found with the relative errors of -4.5 and 6.36% in 2006 for drought affected area and drought disaster area respectively, and 5.11 and -5.95% in 2003. (3) Compared to VCI, TIVCI has better correlation with the SPI, which indicates the lag and cumulative effects of precipitation on vegetation. Our finding proved that TIVCI is an effective indicator of drought detection when the time lag effects between NDVI and climate factors are taken into consideration.     

Response of Vegetation Cover to Climate Change and Influence of Dusty Weather in the Desert- loess Transitional Zone of China

[Objective] This study aimed to analyze the relationships of the normalized difference vegetation index （NDVI） （1981-2006） in the desert-loess transitional zone of China with precipitation and temperature. [Method] The average method and the correlation function were applied in this study. [Result] The results indicated that dur- ing the growing season NDVI was positively correlated with precipitation in the cur- rent month, last month and the month before last, especially the last month. NDVI mostly negatively correlated with temperature, especially the temperature in the last month, which shows that the higher temperature, the more adverse the conditions for vegetation growth. [Conclusion] NDVI from August to October clearly is one of the significant factors influencing dust storm weather in spring of the next year.     

A Fractal Method of Estimating Soil Structure Changes Under Different Vegetations on Ziwuling Mountains of the Loess Plateau, China

Fractal method is a new method to estimate soil structure. It has been shown to be a useful tool in studies related to physical properties of soil as well as erosion and other hydrological processes. Fractal dimension was used to study the soil structure in soil at different stages of vegetative succession on the Ziwuling Mountains. The land use and vegetation types included cultivated land, abandoned land, grassland, two types of shrub land, and three types of forests. The grassland, shrub land, and forested areas represented a continuum in vegetative succession that had occurred naturally, as the land was abandoned in 1862. Disturbed and undisturbed soil samples were collected from ten vegetation types from depths of 0-10, 10-20, and 20-30 cm on the Ziwuling Mountains, at a site with an elevation of about 1 500 m. Particle size distribution was determined by the pipette method and aggregate size distribution was determined by wet sieving. The results were used to calculate the particle and aggregate fractal dimension. The results showed that particle and aggregate fractal dimensions varied between vegetation types. There was a positive correlation between the particle fractal dimension and the weight of particles with diameter 〈 0.001 mm, but no relationship between particle fractal dimension and the other particle size classes. Particle fractal dimension was lower in vegetated soils compared to cropland and there was no consistent relationship between fractal dimension and vegetation type. Aggregate fractal dimension was positively correlated with the weight of 〉 0.25 mm aggregates. Aggregate fractal dimension was lower in vegetated soils compared with cropland. In contrast to particle fractal dimension, aggregate fractal dimension described changes in soil structure associated with vegetative succession. The results of this study indicate that aggregate fractal dimension is more effective in describing soil structure and function compared with particle fractal dimension.     

Plant Diversity and Vegetation Structure in Encroached and Non-encroached Areas of Borana Rangelands： The Case of Hallona and Medhacho Pastoralist Associations

The Borana rangelands are important areas of cattle production in Ethiopia. However, these rangelands are threatened by the increasing changes in the natural vegetation from grass and forbs dominated into unpalatable bushy woody vegetation resulting in the loss of some of the highly desirable grass species. This study was conducted to assess the impacts of bush encroachment on the biodiversity, structure and cover of the native vegetation in bush encroached and non-encroached sites. Vegetation data were collected from both sites by laying quadrate plots along transects using a systematic sampling method. According to the results, higher number of species was recorded in the non-encroached sites than that in the encroached sites. The diversity indices for the non-encroached and the encroached sites were 3.16 and 2.67, respectively. The abundance and cover analysis indicated that there was high density and cover of herbaceous species in the non-encroached site. There was a significantly higher density of woody species cover in the encroached site. Generally, the bush encroachment in the Borana rangelands has hampered the diversity of the native vegetation, particularly the grasses and forbs and reduced the ground cover, exposing large parts of the rangelands for soil erosion and other degradation process.     

THE FIRST EPIDEMIC OF DENGUE HEMORRHAGC FEVER IN THE PEOPLE’S RE-PUBLIC OF CHINA FU XI QIU,QIU QIAN CHEN,QI YA HO,WEN—ZHOU CHEN,ZHI GUO ZHAO,AND BI WEI ZHAO

The first epidemic of dengue in China associated with significant severe and fatal hemorrhagic disease which met the World Health Organization case defintion occurred on Hainan Island in1985—1986.The epi-demic began in Zhan County in September1985,spread throughout the coastal areas,and ultimately involved 13 counties and cities of the island in1986.The mosquito vector was Aedes aegypti.the morbidity associated with dengue infection on Hainan Island was1,913 per100,000 residents,with a case fatality raie of0.25%.     

Simple method for extracting the seasonal signals of photochemical reflectance index and normalized difference vegetation index measured using a spectral reflectance sensor

A spectral reflectance sensor(SRS) fixed on the near-surface ground was developed to support the continuous monitoring of vegetation indices such as the normalized difference vegetation index(NDVI) and photochemical reflectance index(PRI). NDVI is useful for indicating crop growth/phenology, whereas PRI was developed for observing physiological conditions. Thus, the seasonal change patterns of NDVI and PRI are two valuable pieces of information in a crop-monitoring system. However, capturing the seasonal patterns is considered challenging because the vegetation index values estimated by the reflection from vegetation are often governed by meteorological conditions, such as solar irradiance and precipitation. Further, unlike growth/phenology, the physiological condition has diurnal changes as well as seasonal characteristics. This study proposed a novel filtering method for extracting the seasonal signals of SRS-based NDVI and PRI in paddy rice, barley, and garlic. First, the measurement accuracy of SRSs was compared with handheld spectrometers, and the R~2 values between the two devices were 0.96 and 0.81 for NDVI and PRI, respectively. Second, the experimental study of threshold criteria with respect to meteorological variables(i.e., insolation, cloudiness, sunshine duration, and precipitation) was conducted, and sunshine duration was the most useful one for excluding distorted values of the vegetation indices. After data processing based on sunshine duration, the R2 values between the measured vegetation indices and the extracted seasonal signals of vegetation indices increased by approximately 0.002–0.004(NDVI) and 0.065–0.298(PRI) on the three crops, and the seasonal signals of vegetation indices became noticeably improved. This method will contribute to an agricultural monitoring system by identifying the seasonal changes in crop growth and physiological conditions.     

Geographical Design of Riparian Buffers with Long-term Vegetation Cover Reconstructed in Agricultural Landscapes

Reconstructing long-term vegetation cover along streams has become a popular practice for ecological restoration in fragmented agricultural landscapes. To maximize ecological restoration benefits with the least cost, this paper developed a GIS- based model framework for the geographical design of the location and width of riparian buffers to be reconstructed with long-term vegetation cover. The framework integrated three models： the 0-1 mathematical programming model, an economical model and an ecological model. It was tested in an agricultural landscape with a drainage system consisting of 92 stream segments with cropland banks. Each segment had five restoration options in terms of buffer width： 0, 5, 10, 15 and 20 m, thus making a total of 460 decision units in the landscape. For each unit, the economical model estimated the annual rental payment to the farmer who owned the targeted cropland margin along a stream to be converted into a vegetation buffer, whereas the ecological model predicted its corresponding habitat benefits at the landscape level. The 0-1 programming model minimized the total payments, subject to the designed habitat improvement and proposed acreages of riparian cropland set-aside annually. The model identified a cost-effective combination of riparian buffers from 460 units. The results showed that achieving the habitat improvement goal at the least cost required a spatial configuration of vegetation buffers with variable width. This finding suggests that the size and location of buffers directly affect restoration costs and environmental benefits. Thus, the best management practices of agricultural landscape restoration can only be achieved by a specific geographical design with the model framework.     

Effects of Vegetation Succession on Soil Fertility Within Farming-Plantation Ecotone in Ziwuling Mountains of the Loess Plateau in China

To further understand the relationship between vegetation succession and soil fertility within farming-plantation ecotone in Ziwuling Mountains of the Loess Plateau, nine kinds of widely distributed communities at different succession stages were selected, and the effects of vegetation succession on soil fertility were studied through the methods of comparing two hierarchical clustering （similarity index： B） and other multivariate analysis. The results showed that： （i） the similarity in clustering pattern of nine communities which classified by plant species and soil nutrients respectively showed a trend of B ^-overall plant-soil0-10cn〉B^-overall plant-soil 10-20 cm 〉B^- overall plant-soil 20-40 cm, and for the top soil, it showed a trend of B^- grass-soil 0-10 cm 〉 B^-shrub-soil 0-10 cm 〉 Btree-soil0-10 cm; （ii） soil fertility increased during the succession process from abandoned land to forest community, and the soil fertility of forest community showed an increased order of coniferous forest →mixed forest →broadleaf forest; （iii） during the process of vegetation succession, the variation of topsoil fertility was higher than that of the subsurface soil （coefficient of variation： CV0-10 cm 〉CV 10-20 cm 〉 CV20-40 cm）, and when the succession developed into the stages of shrub and forest communities, the top soil fertility had been improved significantly; and （iv） for the subsurface soil of the communities at the advanced succession stages, the soil fertility also increased to some extent. Our results suggested that the method of comparing two hierarchical clustering reflected the similarity level of different cluster patterns, therefore, it was helpful to study the relationship between vegetation succession and soil fertility. There was a corresponding relationship between the change process of soil fertility from the top soil to subsurface soil and the process of vegetation succession from the early stages to the advanced stage. The differentiations of soil fertility in vertical space and horizontal space were both caused by vegetation succession, which was significant for both the shrub and forest communities. The improved level of forest soil fertility was related to forest vegetation types and the improved fertility level of broad-leaved forest-soil community was higher than that of the coniferous forest soil. In the practice on soil fertility ecological restoration of the loess plateau, it is important to carry out reasonably artificial forestation so as to enhance the restoration and improvement of soil fertility.     

海南岛药用蕨类植物资源调查(英文)

There are almost 400 species(containing 8 varieties)of pteridophytes on Hainan Island,belonging to 43 families and 114 genera,one third of which are officinal.To understand the distribution of pteridophytes resources of Hainan Island,we conducted this survey mainly by photographing the habitat,plant morphology,sorus and specific traits of some pteridophytes.The results showed that nearly 32 families and 94 species were recorded.These pteridophyte herb resources play important roles in medical treatment of native Li nationality people.     

植物微生态学、植物微生态制剂与微生物肥料

论述了微生态学引起微生物学的观念革命及生态制剂的崛起,植物微生态学概念及发展历程;介绍了植物微生态制剂的筛选、作用机理、性能特点及应用效果;展望了植物微生态制剂的发展前景。     

煤矿开采对植被和土壤的影响及植被恢复策略

论述了煤炭开采导致的矿区植被破坏现状、土壤污染现状,以及植物修复技术在矿区生态恢复和建设中的作用,为矿区生态恢复提供理论基础。     

城市植被分类研究进展

城市植被作为城市生态系统的重要组成部分,发挥着巨大的生态效益,因此合理地对城市植被进行分类有利于城市建设和规划。概述了当前城市植被分类的研究进展,分析了现有植被分类体系存在的问题,并对城市植被研究的发展方向进行了展望。     

基于AutoCAD的数字化植被图制作方法

以1／10000的车八岭地形图底图为基础，基于AutoCAD制作了车八岭国家级自然保护区的植被景观生态旅游图．在此基础上归纳出基于AutoCAD制作数字化植被图的一般方法，并探讨了关键的技术问题.     

植被介质分布的相关性

本文提出了用相关分布的概念来概括一切植被介质的非Poisson分布;用相关性表示实际分布对Poisson分布的偏离;用相关函数定量描述相关性.导出了在相关分布介质中辐射的透过函数与散射率公式;找到了真实植被相关性的3个来源,即不均匀性相关、遮挡性相关和有限尺度相关.还提出了真实植被的相关层次结构的概念.从而为建立相关分布介质植被辐射理论和实际计算准备了最重要的概念基础.     

基于植被分布因子主成分分析的福建省植被区划

采用经纬度、海拔高度、年降水量、年活动积温、温暖指数(WI)、寒冷指数(CI)、干燥度指数(K)和湿度指数(HI)等对福建省植被地带性分布规律进行定量解释,并首次引入极端最低气温等进行综合研究。通过主成分分析得出限制福建省地带性植被生长的主导环境因子是水热状况因子、地理位置因子、降水因子和极端温度因子等4个指标;以主成分得分作为划分的指标,经过系统聚类,结合《福建省植被图》,将福建省植被带划分为9个区,并对各分区的气候、植被特点进行描述。     

吉林西部地表植被归一化植被指数的时空分布特征

基于GIMMS归一化植被指数(ND,V,I)数据集(1998—2008年)通过极值处理得到每15d的最大值,采用空间自相关分析和趋势分析方法,研究吉林西部地表植被分布的空间特征,结果表明:1998—2008年,吉林西部生长季的地表植被表现出明显的上升趋势;空间分析可知,研究区地表植被的空间分布表现出明显的正相关,但是局部地表植被分布有破碎倾向,空间分布的整体性一般。     

黄土高原地区土地植被承载力与植被生态恢复建设

土地植被承载力是黄土高原地区土壤水分与植物生长关系调控、合理利用水土资源和生态植被建设的核心问题之一.分析了土地植被承载力对植被结构的影响,认为在大气降雨量为唯一土壤水分输入量的黄土高原,土地植被承载力决定了植物群落密度,直接影响植被结构.从植被地带和群落适应性原理、缓解土壤干旱、控制植被生产力三个方面探讨了生态恢复与土地植被承载力的相互关系,并提出了黄土高原生态恢复建设必须优先考虑土地植被承载力,根据土地植被承载力进行植被生态恢复建设是黄土高原生态环境得以改善和持续发展的必由之路.