Book

Description

Fennel pondweed (Potamogeton pectinatus) growing in shallow (<70 cm) water of lake Lauwersmeer (The Netherlands) was studied in relation to Bewick's swans (Cygnus columbianus bewickii). This research was carried out using an IKONOS-2 image of 18th August 2005 and field data collected during September and October 2005. These two datasets provided both qualitative and quantitative results on; (i) distribution of fennel pondweed, (ii) relationship between measured above ground biomass and below ground (tuber) biomass, (iii) relationship between measured tuber biomass and remote sensing estimated biomass, (iv) distribution of foraging Bewick's swans in relation to tuber density (biomass) and water depth in nine creeks of lake Lauwersmeer. The distribution of Potamogeton pectinatus was mapped using Maximum likelihood classifier and a reclassification was done based on field observations and knowledge from literature. Biomass estimation was carried out using six combinations of multispectral band ratios and NDVI. The spectral indices were extracted and predictive equations for biomass generated using simple linear and quadratic regression models. Total foraging Bewick's swans per creek were calculated from the daily foraging counts and a spatial representation of the foraging flocks was created using estimated position of each flock recorded during field work. The water depth map was created from point measurements using Moving Average interpolation technique.