Statistical analysis of spatial pattern: A comparison of grid and hierarchical sampling approaches

Previous studies have combined random-site hierarchical sampling designs wi th analysis of variance techniques, and grid sampling with spatial autocorr elation analysis. We illustrate that analysis techniques and sampling desig ns are interchangeable using densities of an infaunal bivalve from a study in Poverty Bay, New Zealand. Hierarchical designs allow the estimation of v ariances associated with each level, but high-level factors are imprecisely estimated, and they are inefficient for describing spatial pattern. Grid d esigns are efficient for describing spatial pattern, and are amenable to co nventional analysis. Our example deals with a continuous spatial habitat, b ut our conclusions also apply in disjunct or patchy habitats. The influence of errors in positioning is also assessed. The advantages of systematic sa mpling are reviewed, and more efficient hierarchical approaches are identif ied. The distinction between biological and statistical significance in all analyses is emphasised.