The analysis of the 3 stages＇ （1988,1996,2000） variation of land-cover is performed according to Thematic Mapper （TM） and Enhancement Thematic Mapper（ETM） satellite image by combining ground GIS database with G...The analysis of the 3 stages＇ （1988,1996,2000） variation of land-cover is performed according to Thematic Mapper （TM） and Enhancement Thematic Mapper（ETM） satellite image by combining ground GIS database with GPS field collected data in the area of Xiaowan-Dachaoshan Reservoirs of Lancangjiang River cascaded Hydropower Area. Consequently, the land-cover is divided into five subclasses, namely water, paddy field and wetland, bare dryland and sparse shrub, secondary forest and density forest. The result showed that the areas of bare land, upland and secondary forest decreased in 1988-1996, whereas from 1996 to 2000, water body and density forest keep invariability while the areas of paddy field and wetland, bare dryland and sparse scrub increasing and the area of secondary forest decrease; Features of reciprocal transformation between density forest and other type of land-cover had two points, i.e. secondary forest, bare dryland and sparse shrub converted to density forest; and density forest converted to secondary forest and paddy field and wetland. It reflects the dynamic variation of density forest; the area which slope less than 8° and greater than 15° shows bigger variation, however, less change in 8°-15°.展开更多
Background： Ecosystem representation is one key component in assessing the biodiversity impacts of land-use changes that will irrevocably alter natural ecosystems. We show how detailed vegetation plot data can be use...Background： Ecosystem representation is one key component in assessing the biodiversity impacts of land-use changes that will irrevocably alter natural ecosystems. We show how detailed vegetation plot data can be used to assess the potential impact of inundation by a proposed hydroelectricity dam in the Mokihinui gorge, New Zealand, on representation of natural forests. Specifically we ask： 1） How well are the types of forest represented Locally, regionally, and nationally; and 2） How does the number of distinct communities （i.e. beta diversity） in the target catchment compare with other catchments nationally？ Methods： For local and regional comparisons plant species composition was recorded on 45 objectively located 400 m2 vegetation plots established in each of three gorges, with one being the proposed inundation area of the Mokihinui lower gorge. The fuzzy classification framework of noise clustering was used to assign these plots to a specific alliance and association of a pre-existing national-scale classification. NationaLly, we examined the relationship between the number of alliances and associations in a catchment and either catchment size or the number of plots per catchment by fitting Generalised Additive Models. Results： The four alliances and five associations that were observed in the Mokihinui lower gorge arepresent in the region but limited locally. One association was narrowly distributed nationally, but is the mostfrequent association in the Mokihinui lower gorge; inundation may have consequences of national importance to its long-term persistence. That the Mokihinui lower gorge area had nearly twice as many plots that could not be assigned to pre- existing alliances and associations than either the Mokihinui upper or the Karamea lower gorges and proportionally more than the national dataset emphasises the compositional distinctiveness of this gorge. These outlier plots in the Mokihinui lower gorge may be unsorted assemblages of species or reflect sampling bias or that native- dominated woody riparian vegetation is rare on the landscape. At a national scale, the Mokihinui catchment has a higher diversity of forest alliances and associations （i.e. beta-diversity） than predicted based on catchment size and sampling intensity. Conclusions： Our analytical approach demonstrates one transparent solution to a common conservation planning problem： assessing how well ecosystems that will be destroyed by a proposed land-use change are represented using a multi-scale spatial and compositional framework. We provide a useful tool for assessing potential consequences of land-use change that can help guide decision making.展开更多
Trang Bang is the largest agricultural production district of TayNinh province, Vietnam that has a great influence on the socio-economic development of the whole province. This study assessed land use - land cover cha...Trang Bang is the largest agricultural production district of TayNinh province, Vietnam that has a great influence on the socio-economic development of the whole province. This study assessed land use - land cover change in Trang Bang district from 1995 to 2017, the results provide scientific evidence for the safe and effective identification of causes and safeguards for mulch. The study was conducted by an expert classification system and the land use/land cover (LULC) was classified into 6 classes: food-crops, fruit-tree, water, built-up, industry and shrub. The result showed that the LULC there decreased between 1995 and 2017. All the two land cover types (food-crops, fruit-tree) decreased 141.2 km2 (41.4%) in 2017 compared with 1995, while the area of industrial and urban land (industry, built-up) increased 70.0 km2 (20.6%). The overall classification accuracies in 1995, 2007, and 2017 were 94.2%, 98.0%, and 96.3% respectively. The overall kappa coefficients for the image classification were 0.90, 0.97, and 0.94 in 1995, 2007, and 2017 respectively. In general, the average classification was above 90%, and this proved that the classification was reliable and acceptable. The result show that the LULC in the study area decreased during 1997-2017 and tended to decrease in recent years.展开更多
文摘The analysis of the 3 stages＇ （1988,1996,2000） variation of land-cover is performed according to Thematic Mapper （TM） and Enhancement Thematic Mapper（ETM） satellite image by combining ground GIS database with GPS field collected data in the area of Xiaowan-Dachaoshan Reservoirs of Lancangjiang River cascaded Hydropower Area. Consequently, the land-cover is divided into five subclasses, namely water, paddy field and wetland, bare dryland and sparse shrub, secondary forest and density forest. The result showed that the areas of bare land, upland and secondary forest decreased in 1988-1996, whereas from 1996 to 2000, water body and density forest keep invariability while the areas of paddy field and wetland, bare dryland and sparse scrub increasing and the area of secondary forest decrease; Features of reciprocal transformation between density forest and other type of land-cover had two points, i.e. secondary forest, bare dryland and sparse shrub converted to density forest; and density forest converted to secondary forest and paddy field and wetland. It reflects the dynamic variation of density forest; the area which slope less than 8° and greater than 15° shows bigger variation, however, less change in 8°-15°.
基金funded by Meridian Energy Limited,New Zealandby Core funding for Crown Research Institutes from the New Zealand Ministry of Business,Innovation and Employment’s Science and Innovation Group
文摘Background： Ecosystem representation is one key component in assessing the biodiversity impacts of land-use changes that will irrevocably alter natural ecosystems. We show how detailed vegetation plot data can be used to assess the potential impact of inundation by a proposed hydroelectricity dam in the Mokihinui gorge, New Zealand, on representation of natural forests. Specifically we ask： 1） How well are the types of forest represented Locally, regionally, and nationally; and 2） How does the number of distinct communities （i.e. beta diversity） in the target catchment compare with other catchments nationally？ Methods： For local and regional comparisons plant species composition was recorded on 45 objectively located 400 m2 vegetation plots established in each of three gorges, with one being the proposed inundation area of the Mokihinui lower gorge. The fuzzy classification framework of noise clustering was used to assign these plots to a specific alliance and association of a pre-existing national-scale classification. NationaLly, we examined the relationship between the number of alliances and associations in a catchment and either catchment size or the number of plots per catchment by fitting Generalised Additive Models. Results： The four alliances and five associations that were observed in the Mokihinui lower gorge arepresent in the region but limited locally. One association was narrowly distributed nationally, but is the mostfrequent association in the Mokihinui lower gorge; inundation may have consequences of national importance to its long-term persistence. That the Mokihinui lower gorge area had nearly twice as many plots that could not be assigned to pre- existing alliances and associations than either the Mokihinui upper or the Karamea lower gorges and proportionally more than the national dataset emphasises the compositional distinctiveness of this gorge. These outlier plots in the Mokihinui lower gorge may be unsorted assemblages of species or reflect sampling bias or that native- dominated woody riparian vegetation is rare on the landscape. At a national scale, the Mokihinui catchment has a higher diversity of forest alliances and associations （i.e. beta-diversity） than predicted based on catchment size and sampling intensity. Conclusions： Our analytical approach demonstrates one transparent solution to a common conservation planning problem： assessing how well ecosystems that will be destroyed by a proposed land-use change are represented using a multi-scale spatial and compositional framework. We provide a useful tool for assessing potential consequences of land-use change that can help guide decision making.
文摘Trang Bang is the largest agricultural production district of TayNinh province, Vietnam that has a great influence on the socio-economic development of the whole province. This study assessed land use - land cover change in Trang Bang district from 1995 to 2017, the results provide scientific evidence for the safe and effective identification of causes and safeguards for mulch. The study was conducted by an expert classification system and the land use/land cover (LULC) was classified into 6 classes: food-crops, fruit-tree, water, built-up, industry and shrub. The result showed that the LULC there decreased between 1995 and 2017. All the two land cover types (food-crops, fruit-tree) decreased 141.2 km2 (41.4%) in 2017 compared with 1995, while the area of industrial and urban land (industry, built-up) increased 70.0 km2 (20.6%). The overall classification accuracies in 1995, 2007, and 2017 were 94.2%, 98.0%, and 96.3% respectively. The overall kappa coefficients for the image classification were 0.90, 0.97, and 0.94 in 1995, 2007, and 2017 respectively. In general, the average classification was above 90%, and this proved that the classification was reliable and acceptable. The result show that the LULC in the study area decreased during 1997-2017 and tended to decrease in recent years.
