森林地景變遷之監測研究

Monitoring of Forest Landscape Change

鄭祈全(Chi-Chuan Cheng)

《台灣林業科學》 14卷4期 (1999/12) Pp. 493-507

https://doi.org/10.7075/TJFS.199912.0493

摘要

地景生態理論與地理資訊系統之整合，為研究森林地景變遷之必要條件。本研究以林試所六龜生態經營區為試區，應用地理資訊系統及地景結構指數，探討砍伐與林道開闢對地景結構之影響，並監測地景變遷。研究方法係應用數位航測製作試區1988年與1996年二期之林型圖，建檔於地理資訊系統，並在含基質與不含基質二種情況下，計算地景組成與地景排列等地景結構指數，以分析砍伐與林道開闢對地景之影響。研究結果如下：（一）砍伐與林道開闢會增加地景內之區塊數和區塊類型數，以致改變區塊類型之變異和豐富度，及區塊分佈特性，進而影響地景多樣性、地景均勻度以及地景分散列等指數。地景多樣性指數較能區分出地景結構之差異，且所得結果較一致，故較適於分析地景變遷，其中又以Shannon指數最為適合。（二）分析砍伐及林道開闢對地景之影響時，不含基質之地景結構指數差異幅度均較含基質之情況下為大，但含基質情況所得的結果較具一致性。（三）無論是否含基質，Shannon多樣性指數t檢定結果顯示砍伐及林道開闢等人為干擾，不論個別或綜合，均未對試區森林地景造成顯著影響。上述結果顯示應用地理資訊系統及地景結構指數分析經營作業對森林地景之影響，確實可行有效，惟建議宜以Shannon地景多樣性指數代表地景組成。在量化地景結構時，則應將屬於基質之天然闊葉混合林併入計算為宜。

關鍵字

地景變遷 ； 地理資訊系統 ； 監測

並列摘要

The integration of landscape ecology and geographic information system (GIS) is a prerequisite for the study of forest landscape change. In this study, the demonstration forest of ecosystem management at the Liukuei Branch Station, Taiwan Forestry Research Institute was selected as the study area. The objective was to apply GIS and quantitative indices of landscape structure to investigate the effects of cutting and forest roads on the landscape. Forest type maps of the area in 1988 and 1996 were derived using digital photogrammetry and GIS. To analyze the effects of cutting and forest roads on the landscape, indices of landscape structures referring to landscape composition and landscape configuration were calculated either including or excluding the matrix. The results are as follows: (1) Cutting and forest roads increased the number of patches and patch types within the landscape, and therefore altered the variety, abundance, and configuration of the patches, which in turn affected the index values of landscape diversity, evenness, and interspersion and juxtaposition. Diversity indices, especially the Shannon diversity index, were more suitable for analyzing landscape changes because they could differentiate landscape structures more easily and give reasonably consistent results. (2) When analyzing the effects of cutting and forest roads on the landscape, the differences between index values appeared to be greater in indices excluding the matrix than in indices including the matrix. However, including the matrix in indices could obtain more consistent results. (3) Regardless of whether the matrix was included in or excluded from the analysis, the effects of cutting and forest roads on the landscape, whether individually or collectively, were not significant based on the t-test result of the Shannon diversity index. The results indicate that integrating GIS and quantitative indices of landscape structure is a feasible and efficient way of analyzing effects of management practices on landscapes. We recommend the use of the Shannon diversity index for representing landscape composition. In addition, the matrix, which is commonly made of natural broadleaf forests, should be included when quantifying landscape structures.

並列關鍵字

landscape change ； geographic information system ； monitoring