Ecologists require spatially explicit data to relate structure to function. To date, heavy
reliance has been placed on obtaining such data from remote‐sensing instruments mounted
on spacecraft or manned aircraft, although the spatial and temporal resolutions of the data
are often not suited to local‐scale ecological investigations. Recent technological
innovations have led to an upsurge in the availability of unmanned aerial vehicles (UAVs)–
aircraft remotely operated from the ground–and there are now many lightweight UAVs on …

A flexible method is needed for constrained ordination on the basis of any distance or
dissimilarity measure, which will display a cloud of multivariate points by reference to a
specific a priori hypothesis. We suggest the use of principal coordinate analysis (PCO,
metric MDS), followed by either a canonical discriminant analysis (CDA, when the
hypothesis concerns groups) or a canonical correlation analysis (CCorA, when the
hypothesis concerns relationships with environmental or other variables), to provide a …