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Lila Nath Sharma Ole Reidar Vetaas Ram Prasad Chaudhary Inger Elisabeth Måren 《山地科学学报》2014,11(4):838-849
The ecotone, the spatial transition zone between two vegetation communities, is claimed to have more species than the adjoining communities. However, empirical studies do not always confirm higher richness at the ecotone. The ecotone position and structure are dynamic over time and space and it is driven by the changes in climate, land use or their interaction. In this context, we assessed the forest- grassland ecotone of temperate mountains in central Nepal by i） comparing species composition and richness across the ecotone, ii） analyzing if the forestgrassland ecotone is shifting towards the grassland center by colonizing them with trees, and iii） discussing the consequence of changed disturbance regime in the dynamics of this ecotone and the surrounding grasslands. We analyzed vegetation data sampled from belt transects laid across the forest- grassland ecotone in semi-natural grassland patches. Vegetation data consisting of species richness and composition, and size structure and regeneration of the two most dominant tree species, namely Rhododendron arboreum and Abies spectabilis, from the transects, were used to analyze the trend of the forest-grassland ecotone. Forest and grasslands were different in terms of floristic composition and diversity. Vascular plant speciesrichness linearly increased while moving from forest interior to grassland center. Spatial pattern of tree size structure and regeneration infers that forest boundary is advancing towards the grasslands at the expense of the grassland area, and tree establishment in the grasslands is part of a suceessional process. Temporally, tree establishment in grasslands started following the gradual decline in disturbance. We argue that local processes in terms of changed land use may best explain the phenomenon of ecotone shift and consequent forest expansion in these grasslands. We underpin the need for further research on the mechanism, rate and spatial extent of ecotone shift by using advaneed tools to understand the process indepth. 相似文献
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高分辨率卫星遥感数据在土地利用动态监测中的应用研究 总被引：37，自引：8，他引：29
选择土地利用变化类型较多的北京市大兴区为试验区,通过分析印度IRS、韩国KOMPSAT-1、美国IKONOS等高分辨率卫星数据的获取途径、覆盖周期、卫星运行状况、监测成本估算、技术条件和设备要求,对其在土地利用动态监测中的可行性进行了研究;测算了高分辨率卫星数据的主要技术参数;分析原始图像上各主要土地类型的灰度分布范围及其直方图特征,总结不同土地利用覆盖类型与融合图像变化信息的光谱特征。通过精度测算,确定了最大成图比例尺。比较利用高分辩率卫星IRS、KOMPSAT-1和SPOT与陆地卫星TM多光谱数据组合的土地利用动态监测结果(识别率、判对率、图斑边界吻合精度、可监测的最小图斑面积等),确定了不同高分辨率卫星数据与TM多光谱卫星数据组合后对土地利用类型的识别能力,建立了土地利用动态监测解译标志。在解决了若干关键技术问题的基础上,形成了一套可推广的、实用的技术方法和工作流程. 相似文献
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城市规划和土地利用规划的矛盾与协调─—以三亚市为例 总被引：1，自引：0，他引：1
本文通过对现今城市规划与土地利用规划矛盾的分析，提出了协调两者关系的思路，认为两者间的矛盾和问题是客观存在的，两者的协调不能强求数量指标上的一致，而应在地区发展战略的界定下，达到两者间城镇空间布局形态和环境容量规模的相互一致，并据此对三亚市城市规划与土地利用规划的协调进行了分析。 相似文献
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为研究区域尺度干沉积过程，发展了一新的干沉积速度型（ＮＤＤＶＰ）。ＮＤＤＶＰ与１０２２次于沉积速度（Ｖｄ）实测资料之间平均比值为１．０６±０．８２，表明ＮＤＤＶＰ与实测资料有好的一致性。用分别具有ＮＤＤＶＰ和原Ｖｄ型的高分进区域酸沉积模式（ＥＭ３）作实例预测，发现仅由Ｖｄ型的不同所引起的ＳＯ＝４中心浓度之间最大比值可达２．４，用ＮＤＤＶＰ预测的物质浓度和干沉积量比用原Ｖｄ型有明显的改善。 相似文献
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The devastating effect of soil erosion is one of the major sources of land degradation that affects human lives in many ways which occur mainly due to deforestation, poor agricultural practices, overgrazing,wildfire and urbanization. Soil erosion often leads to soil truncation, loss of fertility, slope instability, etc.which causes irreversible effects on the poorly renewable soil resource. In view of this, a study was conducted in Kelantan River basin to predict soil loss as influenced by long-term land use/land-cover(LULC) changes in the area. The study was conducted with the aim of predicting and assessing soil erosion as it is influenced by long-term LULC changes. The 13,100 km~2 watershed was delineated into four sub-catchments Galas, Pergau, Lebir and Nenggiri for precise result estimation and ease of execution. GIS-based Universal Soil Loss Equation(USLE) model was used to predict soil loss in this study. The model inputs used for the temporal and spatial calculation of soil erosion include rainfall erosivity factor,topographic factor, land cover and management factor as well as erodibility factor. The results showed that 67.54% of soil loss is located under low erosion potential(reversible soil loss) or 0-1 t ha~(-1) yr~(-1) soil loss in Galas, 59.17% in Pergau, 53.32% in Lebir and 56.76% in Nenggiri all under the 2013 LULC condition.Results from the correlation of soil erosion rates with LULC changes indicated that cleared land in all the four catchments and under all LULC conditions(1984-2013) appears to be the dominant with the highest erosion losses. Similarly, grassland and forest were also observed to regulate erosion rates in the area. This is because the vegetation cover provided by these LULC types protects the soil from direct impact of rain drops which invariably reduce soil loss to the barest minimum. Overall, it was concluded that the results have shown the significance of LULC in the control of erosion. Maps generated from the study may be useful to planners and land use managers to take appropriate decisions for soil conservation. 相似文献
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和田绿洲土地利用动态监测系统研究 总被引：2，自引：3，他引：2
以和田绿洲为研究对象，详细地介绍了和田绿洲土地利用动态监测系统的总体目标、总体设计方案、数据库和数据流程、软硬件环境和系统功能。在系统支持下有效地实现了和田绿洲土地利用动态监测。由于本系统具有使用灵活、高效准确、可操作性和适应性强等特点，可为从事绿洲研究的科研工作者提供数据存储、处理、分析和应用的强有力的技术支撑。 相似文献
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为了满足城市发展对用地资料的需要，采用彩红外航空遥感和地理信息系统相结合的方法，对杭州西湖风景区的用地情况进行调查，文中介绍这次工作的技术路线、航空遥感资料判读与用地图编制、资料建库与应用等方面的情况。 相似文献
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南方丘陵山区耕地现状,潜力与开发对策：以德庆县为例 总被引：1，自引：0，他引：1
德庆县属南方丘陵山区,耕地详查面积较统计面积大４０％大部分耕地因洪,涝,旱,土质瘠薄而低产,高产优质田仅占３０％,中低产达７０％,远较传统认识的多,这在南方丘陵山区有普遍性。 相似文献