Quantifying woodland structure and habitat quality for birds using airborne laser scanning

Abstract

1. Vegetation height across a 157-ha deciduous woodland was estimated using an airborne remote-sensing technique, airborne laser scanning (ALS), and the data obtained were used to produce a three-dimensional map of the canopy surface of the entire wood. 2. Field-based estimates of a tree canopy density index were compared with mean vegetation height calculated from the ALS data for sample areas of 54 x 54 m2 centred on each of 36 nestboxes within the wood. Canopy density index increased with mean vegetation height, such that height explained 86% of the variation in the density index. Thus remote-sensed height could be used as a surrogate for the field-based estimates. 3. Mean chick masses (mass being used as a measure of habitat quality) for Great Tits (Parus major L.) and Blue Tits (P. caeruleus L.) using the boxes were also examined in relation to the ALS mean vegetation height for the same sample areas. 4. For Blue Tits, mean chick mass at 11 days of age increased with vegetation height around the nestbox, but for Great Tits, the relationship was negative. Possible reasons for this difference are discussed, but the results should be treated with caution because sample sizes were small. 5. The application of ALS in woodland ecology is discussed.