INVESTIGATING THE LOW TEMPERATURE EFFECT ON VEGETATION COVER DURING EARLY SPRING AT LIEN-HUA-CHI EXPERIMENT FOREST IN TAIWAN

摘要

Temperature is an important environmental factor affecting plant growth and geographical distribution. Early spring is the most crucial period for plants to burst. It is also the period that plants are very sensitive to the temperature changes. In low temperature events which exceed the tolerance range, the growth pattern of the plants can be disturbed. In order to investigate the temperature effect on plant growth, this study selects the area of Lien-Hua-Chi experimental forest as the case and uses the daily data of temperatures in March from 2000 to 2010. The normalized difference vegetation index (NDVI) is calculated based on the SPOT images before and after the low temperature events. The low temperature effects on the vegetation cover can be quantified by analyzing the changes of NDVI, which provide valuable information on cold resistance of different topographic sites by comparing the results between different elevations and aspects in this area. The results show that the natural forest is more sensitive to the low temperature during early spring, and the change of NDVI change ratio is related to the topographic positions. The NDVI is lower while the decrease of NDVI is larger at the higher elevations and the windward aspects.