Visual counts of acorns of california black oak (Quercus kelloggii) as an indicator of mast production

Abstract

In 1995, acorn production of California black oak(Quercus kelloggii) was measured on 20 mature trees located in two stands in Placer County, California. Acorn production of each tree was measured using three 0.8 m2 cone traps and a single 30 sec visual count. Visual counts were compared with trap data to develop statistical relationships between the two methods because visual counts have some advantages over traps, and we desired an efficient measure of the amount of acorns available as food for wildlife. Visual counts were positively correlated (P < 0.020) with several trap measures including wet acorn weight, weight of sound acorns, dry acorn weight, and total number of sound acorns. Linear regression of square-root transformed data found that visual counts could be used to predict total weight of sound acorns and total weight of dry acorns (P < 0.003). These results indicate that visual counts are adequate surrogates for more detailed measures of acorn production.