综合地理数据与MODIS物候特征的区域土地覆盖制图(英文)     

蔡红艳  张树文  卜坤  杨久春  常丽萍 《地理学报(英文版)》2011,21(4):705-718

The study developed a feasible method for large-area land cover mapping with combination of geographical data and phenological characteristics, taking Northeast China (NEC) as the study area. First, with the monthly average of precipitation and temperature datasets, the spatial clustering method was used to divide the NEC into four ecoclimate regions. For each ecoclimate region, geographical variables (annual mean precipitation and temperature, elevation, slope and aspect) were combined with phenological variables derived from the moderate resolution imaging spectroradiometer (MODIS) data (enhanced vegetation index (EVI) and land surface water index (LSWI)), which were taken as input variables of land cover classification. Decision Tree (DT) classifiers were then performed to produce land cover maps for each region. Finally, four resultant land cover maps were mosaicked for the entire NEC (NEC_MODIS), and the land use and land cover data of NEC (NEC_LULC) interpreted from Landsat-TM images was used to evaluate the NEC_MODIS and MODIS land cover product (MODIS_IGBP) in terms of areal and spatial agreement. The results showed that the phenological information derived from EVI and LSWI time series well discriminated land cover classes in NEC, and the overall accuracy was significantly improved by 5.29% with addition of geographical variables. Compared with NEC_LULC for seven aggregation classes, the area errors of NEC_MODIS were much smaller and more stable than that of MODIS_IGBP for most of classes, and the wall-to-wall spatial comparisons at pixel level indicated that NEC_MODIS agreed with NEC_LULC for 71.26% of the NEC, whereas only 62.16% for MODIS_IGBP. The good performance of NEC_MODIS demonstrates that the methodology developed in the study has great potential for timely and detailed land cover mapping in temperate and boreal regions.  相似文献   

高寒山区退耕地不同植被恢复方式下群落稳定性     

赵成章  董小刚  石福习  达光文  杨文斌 《山地学报》2011,29(1)

稳定的群落结构是退耕地生态系统恢复的主要标志之一.以祁连山东段旱泉沟流域退耕区为例,采用野外调查和室内分析相结合的方法,研究了建植6 a的人工草地群落稳定性,结果表明:人工草地在短期内形成了不同于撂荒地的植被格局,草地群落盖度、高度和地上生物量特性明显优于撂荒地和天然草地,部分人工草地物种丰富度和多样性高于撂荒地,功能群结构仍以多年生禾草占优势,无芒雀麦+紫花苜蓿混播草地多样性指数低,处于高产和稳定阶段;各草地根系主要分布在0～10 cm土层,不同草地类型0～20 cm土壤含水量变化最大,4种人工草地对土壤水分的影响表现为提高30～50 cm土层的水分含量,在水分涵蓄方面优于撂荒地.但与天然草地相比未形成密丛型禾草,群落稳定性差,草地群落的演替方向具有不确定性.  相似文献   

贵州喀斯特石山植被的自然恢复———以公路裸岩陡边坡为例     

朱克亮 《山地学报》2011,29(6)

选取贵州喀斯特山区公路建设同一山体不同时段开挖的裸岩陡边坡上的植被自然恢复情况调查;选取贵州喀斯特山区不同地质背景,同一时段开挖的裸岩陡边坡上的植被自然恢复情况调查,对喀斯特地区基础建设形成的裸岩陡边坡植被自然恢复及其速率进行讨论.为石漠化地区工程建设开挖的裸岩陡边坡生态恢复治理提供思路,并对喀斯特石漠化治理具借鉴意义.  相似文献   

喀斯特城市植被覆盖度时空变化对地表温度的影响   总被引：3，自引：0，他引：3  

王修信  朱启疆  梁宗经  罗涟玲  农京辉  汤谷云 《地理与地理信息科学》2011,27(4):107-110

随着桂林喀斯特城市的快速扩展、地表植被覆盖度的变化,城市热岛现象越来越明显。以桂林1989-2006年5景TM/ETM遥感图像为数据源,利用遥感归一化植被指数反演植被覆盖度Pv,利用Qin单窗算法反演地表温度ts,分析Pv空间和时间变化对ts的影响。结果表明,在空间上ts随Pv的提高而降低,呈明显负相关关系。在时间上Pv<0.2面积比例逐年增加,1989年7.8%、1991年15.2%、2000年20.7%、2005年21.1%、2006年22.7%;而Pv≥0.7面积比例逐年减少,1989年49.2%、1991年27.4%、2000年27%、2005年16.5%、2006年11.1%。其导致地表温度高于茂密林地表面温度的比率z>20%的高温像元比例逐年上升;而z≤10%的低温像元比例逐年下降,1989年28.9%、1991年25.4%、2000年23.7%、2005年22.2%、2006年20.4%。植被覆盖的喀斯特山峰呈现显著的凉岛现象,从而调节喀斯特城市气候环境。  相似文献   

基于小波的浙江省NDVI与自然—人文因子多尺度空间关联分析   总被引：1，自引：0，他引：1  

徐芝英  胡云锋  甄霖  庄大方 《地理研究》2015,34(3)

对地表植被的空间分布格局及其与自然、人文因子间的关系开展综合的、多尺度的定量分析,这是全球气候变化背景下土地利用与覆被研究中的一项重要内容。以地处亚热带湿润季风区的浙江省为研究区,设置了东西向(样线A)和北南向(样线B)两条样线,并应用小波分析方法对研究区NDVI、高程、坡度和土地利用强度等因子的尺度特征以及这些因子间的多尺度相关关系进行了分析。结果表明:1研究区内,NDVI、高程、坡度及土地利用强度的空间分布格局存在四个尺度域;2上述因子在样线A及样线B上的空间分布分别存在两个主要特征尺度,其中东西向(样线A)上的特征尺度为40 km和80 km,北南向(样线B)上主要的特征尺度为30 km和50 km;3在较大尺度域(8 km以上),土地利用强度是影响NDVI空间分布的最主要因素,而在小尺度域(0~8 km),坡度和高程因子成为影响NDVI分布的主要因子。研究还认为,小波分析方法为识别地理要素空间分布的特征尺度、量测要素间任意尺度、任意位置上的相干关系,提供了方便的工具。  相似文献   

新疆塔里木河下游柽柳、芦苇对生态输水的响应   总被引：9，自引：2，他引：7  

陈亚宁  李卫红  陈亚鹏  王强 《冰川冻土》2004,26(5):595-601

通过对塔里木河下游生态输水过程中地下水埋深变化的动态监测和天然植物生理指标的测试分析, 探讨了塔里木河下游柽柳、芦苇对生态输水的响应. 研究表明, 塔里木河下游河道输水对抬升其附近的地下水位起到了明显效果, 地下水埋深呈逐级抬升过程. 输水河道附近的地下水埋深由输水前的5～8 m抬升到了2～4 m; 植物各项生理指标对地下水位变化反应敏感, 表现出明显的梯度变化. 不同植物生长由于对地下水位要求深度不一样, 随地下水位变化而表现出不同的响应, 芦苇的反应敏感区约在150～200 m之间, 而柽柳则多在200～250 m之间. 结合野外样地的实际调查分析推测, 芦苇和柽柳的胁迫地下水位分别为3.5 m和4.0 m.  相似文献   

Changes in streamflow regime following vegetation changes from paired catchments     

Fangfang Zhao  Zongxue Xu  Lu Zhang 《水文研究》2012,26(10):1561-1573

Vegetation changes can significantly affect catchment water balance. It is important to evaluate the effects of vegetation cover change on streamflow as changes in streamflow relate to water security. This study focuses on the use of statistical methods to determine responses in streamflow at seven paired catchments in Australia, New Zealand, and South Africa to vegetation change. The non‐parametric Mann–Kendall test and Pettitt's test were used to identify trends and change points in the annual streamflow records. Statistically significant trends in annual streamflow were detected for most of the treated catchments. It took between 3 and 10 years for a change in vegetation cover to result in significant change in annual streamflow. Presence of the change points in streamflow was associated with changes in the mean, variance, and distribution of annual streamflow. The streamflow in the deforestation catchments increased after the change points, whereas reduction in streamflow was observed in the afforestation catchments. The streamflow response is mainly affected by the climate and underlying vegetation change. Daily flow duration curves (FDCs) for the whole period and pre‐change and post‐change point periods also were analysed to investigate the changes in flow regime. Three types of vegetation change effects on the flow regime have been identified. The relative reductions in most percentile flows are constant in the afforestation catchments. The comparison of trend, change point, and FDC in the annual streamflow from the paired experiments reflects the important role of the vegetation change. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Characteristics of canopy interception loss in Moso bamboo forests of Japan     

Yoshinori Shinohara  Kohei Kuramoto  Kyoichi Otsuki 《水文研究》2013,27(14):2041-2047

In recent years, Moso bamboo (Phyllostachys pubescens) forests have rapidly expanded in Japan by replacing surrounding coniferous and/or broadleaved forests. To evaluate the change in water yield from forested areas because of this replacement, it is necessary to examine evapotranspiration for Moso bamboo forests. However, canopy interception loss, one of the major components of evapotranspiration in forested areas, has been observed in only two Moso bamboo forests in Japan with relatively high stem density (~7000 stems/ha). There are, in fact, many Moso bamboo forests with much lower stem density. Thus, we made precipitation (Pr), throughfall (Tf) and stemflow (Sf) observations for 1 year in a Moso bamboo forest with stem density of 3611 stems/ha and quantified canopy interception loss (Ic). Pr and Ic for the experimental period were 1636 and 166 mm, respectively, and Ic/Pr was 10%. The value was approximately the same as values for the other two Moso bamboo forests and lower than values for coniferous and broadleaved forests. On the other hand, Tf/Pr and Sf/Pr for our forest (86% and 4%, respectively) were approximately 10% of Pr larger and smaller than values for the other two Moso bamboo forests. These results suggest that the difference in stem density greatly affects precipitation partitioning (i.e. Tf/Pr and Sf/Pr) but does not greatly change Ic/Pr. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Modeling the effects of riparian planting strategies on stream temperature: Increasing suitable habitat for endangered Formosan Landlocked Salmon in Shei‐Pa National Park,Taiwan     

T. Y. Lee  J. C. Huang  L. Y. Liao  C. S. Tzeng  C. H. Yang  P. K. Kalita  C. P. Tung 《水文研究》2012,26(24):3635-3644

Reducing or stabilizing the stream temperature of ChiChiaWan Creek is a crucial work for Formosan Landlocked Salmon because ChiChiaWan Creek is the only one habitat for this endangered species. Planting trees in the riparian zone would be one of the alternatives. The purpose of this study was to evaluate the effects of several planting strategies on daily maximum stream temperature along the river. The results showed the effective vegetative shading angles should be more than 50° along ChiChiaWan Creek to reduce the direct solar radiation heating effectively. Upstream planting with 70° vegetative shading angle could be the most effective way among all the scenarios. However, this planting strategy could not improve the worst situations in summer because of the large solar elevation angles. The upstream planting in ChiChiaWan Creek was strongly recommended because the canopies could be easier to extend to totally cover the narrow width of river producing the most effective shades. Practicing the upstream planting with 90° vegetative shading angle can increase more than 1 km long suitable habitats for the endangered Salmon in summer. Alternatively, the west‐side planting scenario was the second effective way for temperature reduction. Our result provided a useful suggestion for the authorities in charge of saving the Formosan Landlocked Salmon, particularly under the stress of global warming. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

城市建设用地遥感信息提取方法研究   总被引：4，自引：0，他引：4  

车风  林辉 《测绘科学》2010,35(4):97-99

本文利用CBERS-02B影像,通过分析各个地类的光谱特征,发现了长沙市城市建设用地和其他背景地物的区别,并在此基础上选取了土壤调节植被指数(SAVI)、归一化水体指数(NDWI)和比值居民地指数(RRI)作为三个指数波段,重新进行波段组合,从而减少了波段数据的冗余,最后采用最大似然法分类,提取出城市建设用地信息,其正确率达到85.6%。  相似文献