Development a cartographic index of the vigour of forest stands from Ikonos imagery data

This study develops a cartographic index of forest stands vigour from Ikonos imagery data. The study area located at GOUNAMITZ (New-Brunswick, Canada) consists mainly of fir, tolerant and intolerant hardwoods at mature and overmature stages. Forest inventory plots were set up in the stands; dendrometric measures (height, DBH, annual increment, etc.) were collected and used to estimate reference values of stands vigour using Lebel’s equation. Reflectance values of the differents tree species inventoried were later extracted from the Ikonos image following the processes of fusion, segmentation and classification. Vegetation indices (NDVI, MSAVI, and TSAVI) were also extracted from the same image. The different data obtained from the image were then linked by multiple regression models to earlier estimated reference values ofstands vigour. Obtained results showed that the linear regression model yielded the best estimates of forest stands vigour. Determination coefficients (r 2) were 0.771, 0.783 and 0.776 respectively for fir, intolerant hardwoods and tolerant hardwoods species. Further, the regression model used was validated by comparing for 36 reference plots, the values of vigour computed from forest inventory data to values estimated by the model. The overall regression on the studied fir, tolerant and intolerant hardwood stands generated RMSE, of 0.17, 0.29 and 0.10, respectively. In a second step, the results of this study were generalized to map the vigour of forest stands throughout the whole area of the study.