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Forestry / Vegetation
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The Environmental Remote Sensing Monitoring and Research of JAINFENG Mountain Country Forest Park in HAINAN
Li Xuexian
The Bureau of Meteorology of Hainan Province
60 Haifu Road, Haikou, Hainan Province, China
P.C. 57023 Tel: (86)898-5350300
Abstract
Felling much tropical primeval forest exerts a tremendous influence to the ecological environment, and it can't make us optimistic, causes the danger of exhaustion to the tropical forest resources that aren't rich at first. In order to protect the precious heritage and organic gene pool, except that the administration strengthen execution of the law, the timely and precise monitoring of the tropical forest is a very important work, and the high effective work must be finished by remote sensing technology.
1. Introduction
Because of the special geographical environment, the Hainan Island still retains a small number of tropical primeval forest so far. Before 1938, the tropical primeval forest covered 46% of the Hainan Island. Because of being robbed by Japanese during the Second World 46% of the Hainan Islant. Because of being robbed by Japanese during the Second World war and the Chinese faults on the policy of the forestry and the agriculture after the liberation, the massive organic gene pool and headwaters conservation locality decreased by 99.96% in the past half a century and more. According to the interpretive results of the Landsat materials in Feb. 24,1994, there were 12 tropical primeval forests in the island now, about 64,307.64 hectares, covered 1.89% of the island. There were still 8,175.70 hectares' natural primeval forest (including the natural reserve) at the Jianfeng Mountain Country Forest Park renowned at home and abroad by the end of 1994, it had already been less than 18.45% of the whole forest region. It's still crucial to supply the information of monitoring for the government's departments promptly and precisely by the advanced modernized means, although the government have given order to stop any felling to the natural primeval forest geographical coordinates are 18°38'~18°50'N and 108°45'~109°03'E, the whole are is 447.33 km2. The regional landforms are mainly hills, low mountain, middle mountain, the summit of the mountain, the jainfeng Peak is 1412.5 meters above sea level. The river system converges to sea mainly in the shape of radiation, taking the Jainfeng Mountain as the center, the rivers are short, the riverbeds have large drops, the rivers suddenly rise or fall. There are usually 3~5 months of low water period in dry season, the rivers' upper reaches dry u further. There are water flow low only in the parts of the rivers in the primeval forest region throughout the year. Both the ground regulative functions and the bedrock's water-bearing properties are worse in the whole catchments region.
The Jainfeng Mountain belongs to the low latitudes area, tropical monsoon climate, warm or hot throughout the year, the average air temperature of 24.5 a year, the same of 19 in the coolest month, the absolutely lowest air temperature of 2.5 no forest and snow. A year is divided into the dry and wet season, the clear characteristics of rainforest climate, the 80~90% rainfall concentrates in the 5~10 months, specially in 8~10 months. The average rainfall is 1600~2600 mm per year, it's the region that have more rainfall in China.
2. The Technological Routes and the Informational Source
We selected the forest region's American Lansat~5 TM data that had nearly the same temporal in the three years of 1992~1994, conducted the image expansion, the precise geometric correction, the classification, the interpretation, the field verification and other operation. The concrete technological routes are as the figure 1.
Figure 1. The work's flow diagram of the wood Land's environmental remote sensing monitoring of JianFeng mountain country forest park
The work's informational types consisted of three parts, they were the Landsat TM data, the investigative and verified data about the forest region, the statistic, observational and visitant figures from the Bureau of Forestry of the Jainfeng Mountain and other departments. The TM data source was the informational kernel of the work. The work belonged to the item of environmental dynamic monitoring, the key of success or failure was the historical and up-to-data Landsat data which must have high quality and high resolution at the work. Because it's almost cloudy above hainan Island every day, the margin of selecting the data was so limited (The American Lansat-5 cover frequency is 23 times per year above hainan Island, there is hardly any selective margin if we want to get the data in different years which have the same temporal). We selected American Lansat-5 TM data as the main data source which had no cloud or less cloud on Nov. 1, 1992 (representing 1992), Feb. 24, 1993 (representing 1993) and Dec. 25, 1994 (representing 1994) at the work.
3. The Classificatory Principle by Computer on the Forest land the Analysis of the Spectral property of Object.
1) The Classification Principle and Method
The main purpose was environmental monitoring at the forest region, the main investigative and statistic object was the dynamic change of the every types of wood land and environmental destruction at this work. On these grounds, we divided the objects at the forest region into 15 categories according to the possibility of the remote sensing technology and the system software at present and the assignment and requirement, taking spectral combinative property of object as the main classificatory basis and principle. (As table 1, classification property of object as the main classificatory basis and principle. (As table 1, classification of wood land). In order to set up the nearly unified standard of brightness value.
Table 1
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