| Summary: | 碩士 === 國立嘉義大學 === 林業研究所 === 91 === ABSTRACT
This research has used the Global Positioning System (GPS) to measure the coordinates position of the control point, next, to go with the guide line measurement to measure up to the preset sample area position, then used the Geographic Information System (GIS) technique to survey the difference between the preset ground sample area and the photo image took from the air on right shot so as to see the feasibility of using GPS as the sampling control point. Besides, in order to understand whether the accuracy of the GPS instrument — Trimble GeoExplorer II has achieved the operation requirement, we have surveyed at the triangle points set by the Ministry of the Interior in advance, and then further made comparison on the surveying results. Upon the surveying results achieving the required accurate range, next, at the open field around the present sample area to set up the control point to go with the guideline and to measure the preset sample area, then, used the multi-functional laser measurement instrument to investigate the tree height, tree width and sample wood distribution for the consequent analysis of the forest wood operation information.
The study result indicated that used GPS receiver to proceed with the satellite signal receiving nearby the third grade triangle points of the sample area set by the Ministry of Interior, after differential positioning, the difference between the coordinates position and the third grade triangle points coordinates set by the Ministry of Interior was only 3.88 meters, which has achieved the accurate range of the instrument (2-5 meters). After using GPS to measure the sample area control point and the sample area applied GIS technique to overlapped on basic diagrams of the forest area photos through the guideline measurement, the sample area positions have all fallen onto the preset Cryptomeria janonica forest ground, which indicated that the control points used GPS to set may assist the positioning of the sample area coordinates. At the same time, this research has used the GPS control points set by Taiwan Highway Bureau, Ministry of Communications as the known point a little far from the sample area to measure up to the fifth sample area position through guideline so as to simulate the traditional guide point measurement, which totally 78 surveying points. In addition, we have also set up GPS control point beside the preset fifth sample area and measured up to the sample area position for total 8 points through guideline, then used the GIS to overlap the two measurement results onto the photo basic diagrams, as a result, the long guideline end point measured was 2.6070 meters away from the sample area, while the short guideline end point measured was only 0.4791 meters away from the sample area. This proved that the long distance measurement was the major cause of the allowance generated from the forest area guideline measurement. Also, due to GPS has the absolute coordinates positioning function; it is capable of analyzing and surveying the area and attribution information of every tree within the sample area. The analysis indicated that the closure percentage obtained with ArcGis software calculation and the degree of crown closure of the number of tree crown degree at the sample area observed from the picture took from air under the vertical scope according to on-site survey of the number tree crown at the sample area to do the analysis after obtained the degree of closure percentage of the number tree crown at the sample area upon compared the density meter, the difference between the two results was only between 0.49 to 8.67%, which meant the two analyses were quite close.
If based on the survey of the tree height, tree width and tree crown digital of the cryptomeria at the sample area to build up the growth mode of the cryptomeria cubic area with regression analysis, it has more than 86% of explanation capability. Besides, according to the accumulation diagram and production ability diagram drawn for cryptomeria forest ground at Chiayi forest area, this research result is good enough for future decision making on the most appropriate forest wood production and the best wood cutting time, as well as the plan and application of the forest wood operation.
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