Pin Oak Acorn Production on Green Tree Reservoirs in Southeastern Missouri

Abstract

Pin oak (Quercus palustris) acorn production on green tree reservoirs and adjacent nonflooded areas in southeastern Missouri was measured from 1956 to 1969. Production of sound, fully developed acorns varied greatly from year to year (from 8,200 hain 1967 to 445,000 ha-' in 1957), but averaged around 155,900 acorns (142 kg) ha-' per year. The production of sound acorns did not vary significantly between the flooded and nonflooded areas. On the green tree reservoirs, acorn production increased with increased stocking and tree size. The percentages of acorns that were infested with insects decreased with increasing crop size, and were greater on the nonflooded than on the flooded areas. Average overall insect infestation rate was around 25 percent. J. WILDL. MANAGE. 41(2):218-225 This paper analyzes 14 years of acorn production data from a study initiated in 1956 to determine the effects of flooding, stocking, and tree size on acorn production, tree growth, and oak reproduction. Green tree reservoirs are forested riverbottom lands that are artificially flooded during the winter to attract migrating ducks. Thousands of acres along the major rivers of the Mississippi Flyway have been converted into these reservoirs, and each winter they provide resting and feeding areas for hundreds of thousands of ducks. Flooding provides favorable habitat for the ducks and, because it is done only in the dormant season, the trees are not killed. The forests on most green tree reservoirs in the lower Mississippi Flyway are composed primarily of bottomland oaks-pin oak, willow oak (Q. phellos), overcup oak (Q. lyrata), water oak (Q. nigra), cherrybark oak (Q. falcata var. pagodaefolia), and others, and the acorns from these trees are an important component in the fall and winter diet of mallards (Anas platyrhynchos) and wood ducks (Aix sponsa). These acorns are also occasionally taken by ring-necked ducks (Aythya collaris), black ducks (Anas rubripes), pintails (Anas acuta), and others (Rudolph and Hunter 1964, Brakhage 1967, Martin et al. 1951, Korschgen 1955). In 1955, the Missouri Department of Conservation developed 2 green tree reservoirs totaling 526 hectares for public duck hunting in southeastern Missouri. Because the effect of various pin oak management practices was not known, research was begun to study the effects of flooding, stocking, and tree size on acorn production and tree growth. The purpose of this paper is to cover the acorn production phase of that study. Preliminary analysis of the growth data indicated that the flooding may ieduce tree growth somewhat (Minckler 1967).