Conservation-induced resettlement as a driver of land cover change in India: An object-based trend analysis     

《Applied geography (Sevenoaks, England)》2016

Located in the foothills of the Indian Himalaya, Rajaji National Park was established to protect and enhance the habitat of the Asian elephant (Elephas maximus) and tiger (Panthera tigris). In 2002 the Van Gujjars, indigenous forest pastoralists, were voluntarily resettled from the Chilla Range (an administrative unit of Rajaji National Park) to Gaindikhata, a nearby area where they were granted land for agriculture. In this study we used a variety of remote sensing approaches to identify changes in land cover associated with the resettlement. The methods comprise two main approaches. First, we used object-based image analysis (OBIA) to identify the pre-resettlement land cover classes of use areas (representing agricultural expansion and adjacent areas of grazing, and collection of fuelwood and fodder) and recovery areas (representing areas where settlements were removed, and the adjacent areas of resource use). Secondly, we used trend analysis to assess the gradual and abrupt changes in vegetation that took place in use and recovery areas. To conduct the trend analysis we used BFAST (Breaks For Additive Season and Trend), which separates seasonal variation from long-term trends, and identifies breaks that can be linked back to disturbances or land cover changes. We found that the OBIA classification yielded high average class accuracies, and we were able to make class distinctions that would have been difficult to make using a traditional pixel-based approach. Pre-resettlement, the recovery areas were classified as mixed forest and riparian vegetation. In contrast, the use areas were classified primarily as grass dominated, brush dominated, and plantation forest, and were located relatively far away from riparian areas. Following the resettlement, the trend analysis showed a sudden change in the seasonal variation of NDVI in areas converted to agriculture. Areas neighboring the new agricultural land experienced sudden decreases in NDVI, suggestive of disturbances, at a higher rate than the same land cover types elsewhere. At the same time, these neighboring areas experienced a gradual overall increase in NDVI which could be caused by an expansion of leafy invasive shrubs such as Lantana camara in areas heavily used for biomass collection. The recovery areas also experienced a gradual increase in NDVI as well as sudden breaks to this trend, but we lacked evidence to connect these changes to the resettlement. Our findings support the claim that the resettlement has shifted pressure from more ecologically valuable to less ecologically valuable land cover types, and suggest that to some degree resource use pressure has increased outside the park. The study employs a novel synthesis of OBIA and trend analysis that could be applied to land change studies more broadly.  相似文献   

观光旅游地客流时间分布特性的比较研究——以九寨沟、黄山及福建永安桃源洞鳞隐石林国家风景名胜区为例   总被引：22，自引：0，他引：22  

张捷  都金康  周寅康  张思彦  蒋兆刚 《地理科学》1999,(1)

旅游地与主要游客市场的空间结构（距离关系）在相当大程度上影响着游客年内分布、日变化等时间结构。旅游地旅游资源及旅游环境季节性特征也是游客年内分布的决定因子。  相似文献   

The 'Grasses' of the Big Scrub District of North-eastern New South Wales: A sedimentary record of late Holocene grasslands in a subtropical forest landscape     

W.E. Boyd  B.J. Stubbs  C. Averill 《The Australian geographer》1999,30(3):331-336

This paper records sedimentary data which indicate that at least part of the Wilsons River floodplain, on the margins of the subtropical rainforest known as the 'Big Scrub', has a long and certainly pre-European history of relative treelessness. Despite a general presumption that this lowland subtropical region was completely forested prior to European settlement, recent historical research has indicated that certain areas were naturally open. While the historical information is clear, the data reported here-a fossil pollen record and one radiocarbon date- reinforces that information for one type of locality, providing an initial indication of time depth.  相似文献   

30多年来呼伦贝尔草原沙漠化的演变特点及防治对策研究   总被引：14，自引：4，他引：10  

韩广  张桂芳 《中国沙漠》1998,18(3):221-225

采用遥感技术与野外调查相结合的方法,通过3个典型小区对呼伦贝尔草原30多年来的沙漠化演变特点进行了系统研究。结果表明:该区的樟子松林区发生着强烈的沙漠化逆转,许多地段已转变为非沙漠化土地;其它地区除部分地段由于人类的积极治理而发生沙漠化逆转外,仍处于不断发展的过程中。因此,对于樟子松天然分布区,可充分利用樟子松的优良防风固沙特性和较强的扩展能力来防治沙漠化,而对其它地区则应以封育为主,加强人工抚育和草原建设。  相似文献   

Nighttime convection in the interior of a dense Douglas fir forest     

Fred C. Bosveld  A.A. M. Holtslag  B.J. J.M. Van Den Hurk 《Boundary-Layer Meteorology》1999,93(2):171-195

Infrared radiative surface temperatures as observed over a dense Douglas fir forest during stable atmospheric conditions are analyzed. It is shown that the concept of a single surface temperature to describe both the thermal coupling and the radiative coupling between atmosphere and forest fails when longwave cooling is large and wind speeds are low. In such cases a decoupling of the radiative surface temperature from the air temperature aloft is observed. Conditions for decoupling are formulated in terms of an appropriate Richardson number. It is shown that a convective surface temperature comes into play that is coupled to the forest interior air temperature. Observed radiative surface temperature is then composed of this convective surface temperature and the aerodynamic surface temperature. Forest interior air temperature during nighttime is, in general, lower than air temperature above the canopy. A simple two-layer canopy model is used to explain this phenomenon in terms of the distribution of atmospheric sensible heat flux and storage heat flux over the two canopy layers.  相似文献   

Base flow separation for soil erosion simulation in a granitic forested headwater catchment using a process-based model,GeoWEPP     

Takuhei Yamasaki  Shoichiro Hamamoto  Taku Nishimura 《国际泥沙研究》2023,38(4):494-502

Distributed erosion models, which simulate the physical processes of water flow and soil erosion, are effective for predicting soil erosion in forested catchments. Although subsurface flow through multiple pathways is dominant for runoff generation in forested headwater catchments, the process-based erosion model, Geo-spatial interface for Water Erosion Prediction Project(Geo WEPP), does not have an adequate subsurface component for the simulation of hillslope water flow. In the current study, t...  相似文献   

Nutrient Fluxes in Rainfall,Throughfall, and Stemflow in Pinus densata Natural Forest of Tibetan Plateau     

《洁净——土壤、空气、水》2017,45(7)

  相似文献   

基于随机森林模型的农业电子商务浅析——洛川苹果网络销售问题与对策     

张晓涵  马敏飞  杨联安 《地下水》2020,(1):119-122

随着互联网产业的飞速发展,电子商务开始进入农业领域。以电子商务起步较早的"洛川苹果"作为研究对象进行调研。基于随机森林模型的决策树集成算法,对农业网络销售体系整体进行数据分析,模型构建,从问题表象出发挖掘其在不同部分的影响因子,最终基于影响因素解决问题,提出合理化建议:加强农村基础设施建设、健全农村公共服务体系以及完善农村电子商务培训制度等,因地制宜,推进农业电子商务的健康发展。  相似文献   

Slopewash,surface runoff and fine-litter transport in forest and landslide scars in humid-tropical steeplands,luquillo experimental forest,Puerto Rico     

Matthew C. Larsen  Angel J. Torres-Snchez  Iris M. Concepcin 《地球表面变化过程与地形》1999,24(6):481-502

Rainfall, slopewash (the erosion of soil particles), surface runoff and fine-litter transport steepland sites in the Luquillo Experimental Forest, Puerto Rico (18° 20’ N, 65° 45’ W) were measured from 1991 to 1995. Hillslopes underlain by (1) Cretaceous tuffaceous sandstone and silstone in subtropical rain (tanonuco) forest with vegetation recovering from Hurricane Hugo (1989), and (2) Tertiary quartz diorite in subtropical lower mantone wet (colorado and dwarf) forest with undisturbed forest canopy were compared to recent landslide scars. Monthly surface runoff on these very steep hillslopes (24° to 43°) was only 0·2 to 0·5 per cent of monthly rainfall. Slopewash was higher in sandy loam soils whose parent material is quartz diorite (averaging 46 g m⁻² a⁻¹) than in silty clay loam soils derived from tuffaceous sandstone and siltstone where the average was 9 g m⁻² a⁻¹. Annual slopewash of 100 to 349 g m⁻² on the surfaces of two recent, small landslide scars was measured initially but slopewash decreased to only 3 to 4 g m⁻² a⁻¹ by the end of the study. The mean annual mass of fine litter (mainly leaves and twigs) transported downslope at the forested sites ranged from 5 to 8 g m⁻² and was lower at the tabonuco forest site, where post-Hurricane Hugo recovery is still in progress. Mean annual fine-litter transport was 2·5 g m⁻² on the two landslide scars. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

1998-2012年青藏高原TRMM 3B43降水数据的校准   总被引：1，自引：0，他引：1  

石玉立  宋蕾 《干旱区地理》2015,38(5):900-911

运用1998-2012年青藏高原的TRMM 3B43降水数据以及气象台站实测降水数据,对比分析了青藏高原地区TRMM 3B43降水数据偏差分布规律。结果表明:(1) TRMM 3B43降水数据在青藏高原地区存在明显误差,特别是降水量大的地区和月份,偏差量较大。(2)青藏高原地区TRMM 3B43降水数据偏差分布与海拔、经纬度、降水量存在密切的关系。用偏差分布规律,加法修正法结合随机森林算法对青藏高原地区TRMM 3B43降水数据进行了校准。经过校准之后,数据精度得到显著提高,有效增加了数据的可用性,多年月平均数据决定系数R²最大可达到0.9(3、10月),最小也接近于0.5(12月),效率系数E均为正值,最大可达到90(3、10月);多年季平均和多年平均降水数据中除了第一季度结果稍差外(决定系数R²为0.58),其余数据校准效果均较好。  相似文献