There is an increasing need for accurate measurement of forest cover both in terms of its spatial and temporal variation for improvements in forest management. Forest cover can be estimated using Normalised Difference Vegetation Index (NDVI) from satellite data. The objective of this study was to assess leaf area of the forest cover from the spectral reflectance measured by satellite. This paper analyses the relationship between NDVI and different ages of managed pine plantation from 1994 - 1997 in the Kings Forest, East Anglia, UK. The Satellite data used were four - SPOT 2 HRV2 multi spectral images for June 1994, 1995, 1996 and 1997. Secondary data on forest management were derived from compartment records supplied by the Forestry Commission. Age is an important variable in forest growth. Therefore this study investigated changes of NDVI in different age groups <8, 8-18, 18-38, 38-58 and >58 years. The study found that during the period 1994- 1997 NDVI changed fairly little from 0.4-0.7. However in each age group slight changes can be easily recognised. There was a significant high positive correlation between NDVI and age in all four years with R2 values of 0.68, 0.66, 0.79 and 0.78 for 1994, 1995, 1996 and 1997 respectively. The results show that the NDVI changes provide important information on vegetation growth in a plantation forest. The results of comparing NDVI and age were also encouraging but further work is needed to determine the potential use of earth observation data in forest growth and management.