Modelling gap microclimates in broadleaved deciduous forests using remotely sensed data (contribution of GPS to geometric correction and product validation)

Abstract

When treefalls occur or tree crowns are damaged due to windthrow, tree death, disease or anthropogenic disturbance, the gaps that are created in the forest canopy initiate dramatic changes in abiotic conditions, particularly microclimate. It is generally acknowledged that the magnitude of the changes in microclimate is related to the size, shape and 3-D geometry of the gap and characteristics of the remaining surrounding canopy. However, there is currently a paucity of models that are able to describe these relationships, particularly in temperate forests. Furthermore, we currently have very limited ability to characterise the consequences of the variations in the spatial distribution of gaps on the microclimatic conditions across entire forest stands. The present project aims to address these issues by using a unique combination of field observations, numerical modelling and remote sensing techniques. In situ observations at the field site are helping to provide the empirical evidence with which to construct a dynamic spatio-temporal model of gap microclimates, while experiments over the growing season will develop robust and extendible remote sensing techniques for characterising relevant gap and canopy properties. The use of the NERC GEF GPS equipment, deployed during an extensive ground campaign coinciding with the NERC ARSF overflights, has enabled a comprehensive validation of our outputs.