Improving estimates of acceptable growing stock in young upland oak forests in the Missouri Ozarks

Estimates of regeneration or growing stock in young oak forests may be too high unless criteria are established that define explicitly acceptable growing stock. In young hardwood stands, crown class can be used to identify acceptable growing stock because it is related to the future growth and survival of reproduction. A method is presented for assigning crown class categories to hardwood stems based on their diameters (dbh). Young upland oak forests originating from clearcuts in the Missouri Ozarks were sampled to determine the relationship between dbh and crown class. Stands were 19 to 25 yr old. Threshold diameters (TD) separating one crown class category from another were determined using regression analyses. TD was not significantly affected by species group, and in some cases by aspect and slope position. Quadratic mean stand diameter (QMSD) was significantly related to TD. As QMSD increased so did TD. When QMSD equals 3 in., trees with dbh greater than or equal to 3.9 in. are allocated to the codominant and dominant crown class category, and those greater than or equal to 2.5 in. to the dominant, codominant, and intermediate category. TD can be used to assign a crown class category to individual trees, thereby improving estimations of acceptable growing stock. By this method, crown class can be used to define acceptable growing stock and evaluate stocking, yet it does not have to be measured in stand inventories.