Forest fragmentation and its impact on species diversity: an analysis using remote sensing and GIS

The process of forest fragmentation, a common phenomenon occurring in tropical forests, not only results into continuously forest getting fragmented but also brings about several physical and biological changes in the environment of forests. Consequently, there is a loss of biodiversity due to change in habitat conditions. These remnant fragments provide the last hope for biodiversity conservation. The present study deals with the impact of decreasing patch size of a fragmented forest on the diversity of the tropical dry deciduous forests in Vindhyan highlands, India. There is considerable change in the vegetation cover of this region owing to rapid industrialization and urbanization, which has also contributed to forest fragmentation. In the present study, remotely sensed data has been used to describe the changes brought about in vegetated areas over a period of 10 years as a result of fragmentation and its impact on biodiversity was assessed. Further, in order to assess the loss of species with respect to the reduction in patch size, species area curves for various change areas were analysed. It was observed that the rate of decrease in the number of species is faster in the case of negative change areas as compared to the positive change areas of the region. Various diversity indices also support this observation. Such an analysis would help in formulating appropriate conservation measures for the region.     

遥感和GIS支持下的城市植被生态效益评价

在综合国内外的城市植被生态效益研究的基础上,指出运用遥感和GIS技术将能更有效地进行植被生态效益的评价。文中介绍了美国AMERICAN FORESTS协会在进行城市和区域的植被生态效益研究中所采用的城市生态系统分析法（UEA）,以及在ARC/VIEW地理信息系统软件基础上开发的City-green模块的基本特点及其应用,以期促进遥感和GIS技术在我国城市植被生态效益定量评价中的应用,以及区域的可持续发展和生态建设。     

Simulating the East African wildebeest migration patterns using GIS and remote sensing

The Serengeti–Mara ecosystem in East Africa is a spectacular natural heritage endowed with diverse fauna and flora. The presence of the seasonally migrating wildebeest (Connochaetes taurinus) is a major boost for tourism. This migration however has enormous impacts to the ecosystem. Consequently efforts at monitoring the herd's migration trends and patterns remain a challenge to wildlife managers and ecologists in the region. In this paper, the relative influence of vegetation (normalized difference vegetation index), landscape and relief on herds migration routes are investigated and the migration routes simulated using GIS and remote sensing techniques. The results are compared with the annual mean route taken by the herds, as determined by radio tracking over the 1995–1997 period. Green vegetation availability is shown to be the major criterion in route choice. It is also shown that during the dry season phases of the migration (western trek, western corridor), the herd endures complex relief (complexity quantified based on slope and inter‐visibility) in the search for greener grass. During the season of abundance (southern trek), relief becomes critical in making route choices, with herds avoiding difficult terrain, notwithstanding their relatively more abundant vegetation. The method proposed in this paper is viable for rapid prediction of approximate routes for the migrating wildebeest in different climatic conditions.     

Antibiotic resistance in the bacteria of a remote upland river catchment

The incidence of antibiotic resistance was determined in a total of 183 heterotrophic bacteria of non-faecal origin isolated from the catchment of a remote upland stream. Some 40% were sensitive to each of the eight antibiotics tested while more than 35% were resistant to at least two compounds. Three isolates each carried seven resistance determinants. Unsuccessful attempts were made, using two curing techniques, to demonstrate that resistance was plasmid-borne. The high incidence of antibiotic resistance, particularly amongst pseudomonads, in an environment virtually free from anthropogenic influence is surprising, and has implications for the assessment of the spread of antibiotic resistance amongst populations of environmental bacteria.     

基于 RS与 GIS的区域景观镶嵌结构研究

以兰州市西固区为区域背景,以RS和GIS为技术手段,按照地貌特征将研究区划分为四个分区,运用多样指数、优势度、破碎度、分离度等指标研究区域景观镶嵌结构的数量特征;运用分形理论建立各种景观类型形态的分形结构模型,以分维数为依据分析各种景观形态的复杂性;探讨控制和影响区域景观格局的主要因素。     

Differentiating aquatic plant communities in a eutrophic river using hyperspectral and multispectral remote sensing

1. This study evaluates the efficacy of remote sensing technology to monitor species composition, areal extent and density of aquatic plants (macrophytes and filamentous algae) in impoundments where their presence may violate water‐quality standards. 2. Multispectral satellite (IKONOS) images and more than 500 in situ hyperspectral samples were acquired to map aquatic plant distributions. By analyzing field measurements, we created a library of hyperspectral signatures for a variety of aquatic plant species, associations and densities. We also used three vegetation indices. Normalized Difference Vegetation Index (NDVI), near‐infrared (NIR)‐Green Angle Index (NGAI) and normalized water absorption depth (D_H)_, at wavelengths 554, 680, 820 and 977 nm to differentiate among aquatic plant species composition, areal density and thickness in cases where hyperspectral analysis yielded potentially ambiguous interpretations. 3. We compared the NDVI derived from IKONOS imagery with the in situ, hyperspectral‐derived NDVI. The IKONOS‐based images were also compared to data obtained through routine visual observations. Our results confirmed that aquatic species composition alters spectral signatures and affects the accuracy of remote sensing of aquatic plant density. The results also demonstrated that the NGAI has apparent advantages in estimating density over the NDVI and the D_H. 4. In the feature space of the three indices, 3D scatter plot analysis revealed that hyperspectral data can differentiate several aquatic plant associations. High‐resolution multispectral imagery provided useful information to distinguish among biophysical aquatic plant characteristics. Classification analysis indicated that using satellite imagery to assess Lemna coverage yielded an overall agreement of 79% with visual observations and >90% agreement for the densest aquatic plant coverages. 5. Interpretation of biophysical parameters derived from high‐resolution satellite or airborne imagery should prove to be a valuable approach for assessing the effectiveness of management practices for controlling aquatic plant growth in inland waters, as well as for routine monitoring of aquatic plants in lakes and suitable lentic environments.     

Contribution of space remote sensing to river studies

• 1 A review is presented of types of satellite remote-sensing data currently available, and their recent uses in studies of river systems.
• 2 Broad-scale assessments of relative water quality may be carried out, although precise indication of water quality requires samples to be taken in situ.
• 3 In the event of flooding, the extent of inundation may be determined and damage assessed quickly. Some radar data allow measurements of flood water even when obscured by vegetation.
• 4 Riparian vegetation may be mapped over large areas, although the recognition of specific tree species remains difficult.
• 5 One of the most basic and widely used applications of remote-sensing data for rivers is that of mapping, both as a single event and over time to follow changes, e.g. channels in a delta. Entire catchments may be mapped, although the efficiency of detection of low-order streams is dependent upon the characteristics of the system used.
• 6 Remote-sensing data has been widely used in all of the above types of study, but is rarely employed on a long-term basis. Several factors can explain this situation, including, for example, the absence of reliable absolute relationships between spectral data and ecological parameters.
• 7 A clear definition of observational needs (e.g. spectral bands, ground resolution, acquisition frequency) of stream ecologists, together with the identification of ecological parameters that may be collected relatively easily from space, will improve remote sensing as an ecological tool in many restoration and management situations.

     

玛纳斯河流域盐渍化灌区生态环境遥感监测研究

土壤盐渍化已成为全球性问题,给生态环境及农业生产带来严重的威胁。为了快速、准确评价土壤盐渍化给区域生态坏境带来的影响,该文提出了新的完全基于遥感数据的遥感生态指数(SSEI,Soil Salinization Ecology Index)来监测玛纳斯河流域盐渍化灌区生态环境变化。该指数利用主成分分析的方法耦合与土壤盐渍化相关的土壤盐度、地表反照率、植被覆盖度和土壤湿度四大地表参数,指数构建是数据本身性质所决定,不同于以往遥感与非遥感指数加权叠加易受人为影响。研究结果表明:耦合与盐渍化信息相关的各遥感指数得到的生态指数,能够对土壤盐渍化影响区域的生态环境进行快速、定量、客观的监测。将该指数应用到新疆玛纳斯河流域灌区,结果表明在近26年优和良等级生态环境面积增加了12.89%,这说明灌区生态环境有所改善。该研究对土壤盐渍化监测与评价具有一定参考意义。     

基于GIS的浙江省水稻遥感估产最佳时相选择

水稻遥感估产最佳时相选择应包括水稻种植面积估算最佳时相和水稻产量预报最佳时相两部分。在水稻遥感估产最佳时相选择中,由于首次引入GIS技术提取水稻可能种植区域,缩小了研究范围,植被种类也较简单一,因此仅用农作物物候历即可确定水稻种植面积估算最佳时相,而不需要考虑所有的植被类型。利用盆栽试验和小区试验研究水稻产量与不同时期的农学参数、农学参数与植被指数及水稻产量与植被指数的关系,结果表明,水稻产量与农业参数、农学参数与光谱变量的关系均以孕穗以抽穗期最好,水稻产量与光谱变量的关系则从分蘖盛期到抽穗期的极显著。因此,以孕穗期到抽穗期作为建立水稻遥感估产模型的最佳时期。再利用1998年各地的水稻发育期观测资料,确定各区水稻产量遥感最佳时相。     

Ecosystem measures of river health and their response to riparian and catchment degradation

1. Measurements of ecological patterns are often used as primary biological indicators of river health. However, these patterns provide little information about important stream ecosystem processes (e.g. the sources and fate of energy and nutrients). The direct measurement of these processes is considered fundamental to the determination of the health of stream and river ecosystems. 2. In this paper we used two basic approaches to assess stream ecosystem response to catchment disturbance and, particularly, to the loss of riparian vegetation in different forested biomes across Australia. Benthic gross primary production (GPP) and respiration (R₂₄) provided measures of the amounts of organic carbon produced and consumed within the system, respectively. Stable isotope analysis was used to trace the fate of terrestrial and instream sources of organic matter in the aquatic food web. In a focal catchment in SE Queensland, additional measurements were taken of riparian attributes, catchment features and water quality. 3. Baseline measurements of GPP and R₂₄ from undisturbed forest streams provided reference values for healthy streams for comparison with sites where the catchment or riparian vegetation had been disturbed. These values of metabolism were low by world standards in all biomes examined. Preliminary data from the Mary River catchment in SE Queensland indicated that these parameters were sensitive to variations in riparian canopy cover and, to a lesser extent, catchment clearing, and predictive models were developed. The ratio P : R (GPP : R₂₄) was used to determine whether sites were net consumers (P < R) or producers (P > R) of carbon but this was not considered a reliable indicator of stream health on its own. 4. Although forest streams were typically net consumers of carbon (P < < R), stable isotope analysis of metazoan food webs indicated a high dependence on inconspicuous epilithic algae in some biomes. 5. A dramatic decline in the health of forest streams was observed when GPP substantially exceeded R₂₄, especially when instream primary producers shifted from palatable unicellular algae to prolific filamentous green algae and macrophytes. These sources of instream production do not appear to enter aquatic food webs, either directly through grazing or indirectly through a detrital loop. Accumulation of these plants has led to changes in channel morphology, loss of aquatic habitat and often a major decline in water quality in some of the streams studied.     

基于遥感和Penman-Monteith模型的内陆河流域不同生态系统蒸散发估算

遥感数据具有很好的时空连续性,它是区域蒸散发通量估算的有效方法。引入了一个简单的具有生物物理基础的Penman-Monteith(P-M)模型,分别利用黑河流域高寒草地阿柔站和干旱区农田盈科站2008—2009年的气象数据和MODIS(Moderate Resolution Imaging Spectroradiometer)叶面积指数(LAI),实现了2008—2009年日蒸散发的估算,并同时实现了对植被蒸腾和土壤蒸发的分别估算。结果表明,利用P-M公式模拟的蒸散发与实测的蒸散发具有较好的一致性,日蒸散发模拟的决定系数(R2)超过0.8。估算的高寒草甸和干旱区农田玉米全年平均的蒸腾分别为0.78 mm/d和1.20 mm/d,分别占总蒸散发的60%和61%,土壤蒸发分别为0.53和0.77 mm/d,占总蒸发的40%和39%。可见两种生态系统的作物蒸腾均强于土壤蒸发,同时农田玉米蒸腾强于高寒草甸蒸腾。研究结果证明了基于遥感的P-M公式可以很好地实现对高寒草地和干旱区农田生态系统蒸散发的估算。通过考虑土壤水分变化对气孔导度的影响,可以提高模型对农田蒸散发的模拟精度。     

毛乌素沙地中间锦鸡儿根瘤菌的多样性及其抗逆性

从内蒙古毛乌素沙地优势物种中间锦鸡儿收集根瘤,分离根瘤菌15株,对其进行同工酶电泳,聚类分析证明中间锦鸡儿的遗传多样性.对其耐盐性、耐酸碱性、生长温度范围、产酸产碱性、过氧化氢酶活性以及唯一碳源利用能力进行比较研究,结果表明,所有中间锦鸡儿根瘤菌均分泌H⁺,都具有过氧化氢酶活性,73.3%的菌株可以在含3%NaCl的YMA培养基上生长,80%的菌株可以抵抗50℃高温,除对乳糖和淀粉利用表现出差异外,中间锦鸡儿根瘤菌对其余碳源没有选择性,证明中间锦鸡儿根瘤菌具有较强的抗逆性,但仍存在菌株间差异,是对毛乌素沙地多种景观生态类型的适应.作为一种新的种质资源,中间锦鸡儿根瘤菌可用于恶劣生境固氮.     

森林生态系统生物多样性的遥感评估

目前的评估由于方法的原因,常常会遗留下一些含糊不清的地方。遥感则可以作一种观察生态系统多样性和单个生态系统中各种结构侧面的重要工具。它提供了一种能够跨越几个不同空间尺度实施评估的手段,并且对于评估生态系统格局随时间的变化也是必不可少。现在许多不同的遥感技术已经被应用在生态学研究中。大多数工作所用的数据主要是来自机载和星载平台提供的摄影和数字光学图像,目前则越来越强调激光扫描和合成孔径雷达数据的应用。这些技术手段为从景观到林分规模的不同现象的评估提供了机会。遥感提供了可用于确定森林生态系统中生物多样性景观尺度的元素最有效的工具。例如基质和斑块的相对百分比以及它们的配置。在中间尺度,遥感为评价廊道的存在和边界的特性提供了理想的工具。在林分尺度,遥感技术可用来获取关于森林分结构属性的信息,例如冠层表面的特性,是否存在冠内分层等等。随着的发展,遥感将更广泛地应用于生态学研究。     

基于GIS的渭河下游河流沿线区域生态风险评价

以渭河下游河流沿线区域为研究区,基于风险度量的基本原理和区域生态风险评价的流程框图,构建了综合生态风险值的计算模型,即综合生态风险值是综合风险概率、综合生态损失度和综合社会经济易损度的叠加.在研究区历史资料考证和2002年ETM+遥感影像景观分类的基础上,通过选取干旱、洪水、污染和水土流失,利用地理信息系统和现代地理学中的大量数学方法,按照评价步骤和计算模型,将研究区4种生态风险源综合评价结果划分为低风险区,较低风险区,中等风险区,较高风险区和高风险区5个级别.研究结果为环境管理和生态风险决策提供数量化的理论依据和数据支持.     

An integrated comparative approach to mangrove vegetation mapping using advanced remote sensing and GIS technologies: preliminary results

This study aims to develop an integrated methodology applying Remote Sensing and Geographic Information Systems (GIS) techniques for the assessment of the ecological status of mangrove forests. The study area is located at Phangnga Bay, Thailand. Various commonly available remote sensing data are evaluated for mangrove vegetation mapping. The satellite sensors used are covering the visible and infra-red (VIR) spectrum up to the microwave region of the electromagnetic spectrum. This study provides recommendations regarding the selection of a single sensor approach or sensor combination that fulfills a minimum requirement for practical mangrove mapping and inventory purposes (e.g. mangrove and non-mangrove areas, varying stocking density, dominant species composition and impact of human activities). Both their technical capabilities and their potentials are presented in correlation with the existing ground conditions.Asian Institute of Technology Bangkok, Thailand; National Research Council of Thailand Bangkok, Thailand; Royal Forestry Department Bangkok, Thailand     

遥感与GIS支持下的盘锦湿地水禽栖息地适宜性评价

盘锦湿地位于辽河三角洲的核心地带,是重要的水禽栖息地。受自然和人类活动的影响,该地区水禽栖息的生境面积不断缩小,致使湿地生态系统受到严重破坏,生物种群数量急剧下降。在此背景下,以GIS/RS为技术手段,根据盘锦湿地环境特点,采用层次分析法,从干扰条件、水源状况、遮蔽物以及食物丰富度4个方面对盘锦湿地水禽栖息地适宜性进行空间分析,再按照不同指标因子的等级划分,得到适宜性最好、适宜性良好、适宜性一般以及适宜性最差4个等级的盘锦湿地水禽栖息地适宜性评价图。结果表明:(1)盘锦湿地水禽栖息地适宜性最好、适宜性良好、适宜性一般、适宜性差的面积分别为803.79,913.47,905.29,1023.65hm2,分别占总面积的22.04%,25.05%,24.83%,28.07%;(2)前三类总面积为2622.55 hm2,占71.93%,说明盘锦地区水禽栖息的适宜地区较多,主要分布于流域、河漫滩等人为干扰较少的芦苇湿地以及食物和水源比较充足的大面积耕地中;(3)基于遥感分析和GIS空间分析技术,能有效、简便地对湿地生态环境处于快速动态变化中的水禽栖息地适宜性进行快速、客观准确的评价分析,其结果能为盘锦湿地水禽种群及其生存环境的规划、保护、管理和决策提供数据支持和科学依据。     

Integrating GIS and remote sensing for vegetation analysis and modeling: methodological issues

Abstract. GIS and remote sensing have emerged as distinct spatial data handling technologies with their own methods of data representation and analysis. Combining them as tools to support vegetation analysis and modeling thus presents a number of challenges. The paper begins by describing the major data sources, applications, and software characteristics of each technology, and then compares them within a consistent terminological framework that emphasizes the digital representation of continuously varying spatial data. Because the spatial continuum can be discretized in many different ways, and because each can only approximate the truth, both GIS and remote sensing are subject to error and uncertainty. Integration, and subsequent analysis and modeling, require that explicit attention be directed to uncertainty. The paper reviews the models of error that have been developed in recent years for spatial data and examines their use in the interface between GIS and remote sensing. The paper looks at the functional requirements of modeling, and includes discussion of error propagation.