Dynamics of biomass evaluated with remote sensing in Pinus pinaster in Portugal

Abstract

Above ground biomass was estimated with an allometric functions with crown projection area on a per area basis, for Pinus pinaster stands in Portugal. The allometric function is a linear function with crown projection area as explanatory variable derived from the vegetation mask of high spatial resolution satellite images. It was attained with contrast split segmentation over normalized different vegetation index. The above ground biomass was calculated on a per square grid of 500 m2, for high spatial resolution satellite images of 2004, 2007 and 2011 and its dynamics evaluated. During the period under analysis two types of disturbance occurred forest fires and salvage cuttings (to control the pinewood nematode). The results indicated a trend towards the decrease of above ground biomass from 2004 to 2007, due mainly to forest fires and salvage cuts and an increase in circa half of the area from 2007 to 2011. The increase in above ground biomass was due to growth as well as natural regeneration mainly in the burned areas. Overall, the advantages of monitoring biomass with remote sensing data are the monitoring of the entire area (without conversion or extrapolation methods), it is a simple method, especially indicated for stands and/or forests where disturbances and natural regeneration occur, and its implementation in a geographical information system is straightforward being a useful tool to forest management and planning. Moreover, the monitoring of above ground biomass can be done at several temporal and/or spatial scales enabling increasing the flexibility in monitoring above ground biomass and carbon.