SPATIAL PATTERN-ANALYSIS FOR UNDERGROUND PROPAGULES OF POTAMOGETON-GRAMINEUS L IN 2 NORTHERN CALIFORNIA IRRIGATION CANALS

We sampled areas of two canals (Solano Irrigation District, California ) that were dominated by Potamogeton gramineus L. The ratios of varian ce to mean for winter bud abundance in the Byrnes Canal indicated that winter buds were not randomly distributed. Clumping was detected at a patch size of 7.2 cm diameter in both 1985 and 1989. Applying two qua drat variance methods to data from the Weyend Canal also indicated tha t winter buds were clumped. The radius of the patch size was 1.65 m. P atch edges were not sharply defined, and the spaces between patches we re not empty. Geostatistical analysis yielded an experimental semivari ogram for winter bud abundance, using the spherical equation, with a s ill of 49776, a nugget of 32378, and a range of influence of 57 m.