南仁山自然保護區地處於台灣南部恆春半島東側，屬於亞熱帶低地雨林，因爲受到地形效應和東北季風影響，生態環境異質性極高，植物組成和林分結構極具複雜。本研究的目的是利用1999年5月、7月、9月、11月及2000年1月、3月，六個不同生長季節的SPOT衛星影像，利用長期生態研究站所設置的500個10m×10m次生林樣區，探討南仁山次生林永久樣區於不同植群型之常態化差異植生指標(Normalized Difference Vegetation Index, NDVI)的季節性變化和東北季風的影響。研究結果得知，NDVI以秋季（9月）最高，平均爲0.689，夏季（7月）次之，平均爲0.659，冬季（1月）最低，平均爲0.449。其中冬季和夏季有較明顯的差異，顯示出冬季時因受東北季風影響，而使常態化差異植生指標有顯著的下降。
The Nanjenshan ecological nature reserve was located on eastern Hengchun peninsula in southern Taiwan, belong to the subtropical lowland rainforest, it has been subjected to unusual topography and the northeast monsoon, so that its ecological environment heterogeneity extremely high, vegetation composition and forest stand structures have become extremely complicated. The purpose of this research was to study the effect of northeast monsoon and various vegetation types on the secondary forest permanent plot of Nanjenshan. In this study we applied normalized difference vegetation index (NDVI) to detect seasonal variation with six dates of SPOT images, which were gathered at different times of the year-May, July, September and November 1999, and January and March 2000, respectively. The results shows that NDVI had the highest degree (0.689) in autumn (September), secondly (0.659) was in summer (July), the lowest (0.449) in winter (January). The NDVI of winter was significantly different from those of other seasons, therefore, it was quite clear that northeast monsoon will effect the vegetation growth and decrease NDVI.
