The Relationship between NDVI, Stand Age and Terrain Factors of Pinus elliottii Forest

Normalized difference vegetation index (NDVI) derived from remotely sensed image was a commonly used input parameter in many models concerned on forest ecosystem. But it was often interfered by many biological or physical factors such as the background under the tree crown, the nature of different kinds of tree, and so on. The relationship between NDVI, stand age and terrain factors of the planted Pinus elliottii forest in Minhou Baisha forest farm of Fujian province, P. R. china, was explored using the dataset include topographic maps, QuickBird satellite image and tabular materials of forest management survey and cutting area survey. Normalized and integrated grade of terrain factors was calculated according to the weighted effect of stand condition factors on the development of Pinus elliottii include altitude, slope and aspect. NDVI was derived from QuickBird image. Then correlation analysis between the terrain grade and NDVI of Pinus elliottii was performed. And it was found that NDVI was increased with the terrain grade when the forest age is less than 19 years old, whereas it is decreased when the forest age is 19 years old or more. The growth recession in lifespan of Pinus elliottii and the corresponding stand rebuilding measures were regarded as the reasons caused this abnormal phenomenon.