Response of Natural Stands of Shortleaf Pine to Thinning and Fertilization With Nitrogen and Phosphorus

Abstract

This paper reports the results of fertilizer experiments conducted with thinned and unthinned natural stands of shortleaf pine. Nitrogen and phosphorus were applied singly and in combination on both thinned and unthinned plots. The plots were located on three soil series found in close association in the Great Valley Region of eastern Tennessee.Four-year response in basal area growth per tree was increased as much as 300% over the unthinned check by thinning and application of nitrogen. An increase of up to 40% over the thinned check was achieved with nitrogen alone. These responses were still evident 4 years after fertilization. Basal area growth response to phosphorus was erratic throughout the study period.The results indicate that stand density must be low enough at the time of nitrogen application to allow growth to proceed unhindered.

Ecological Relationships of Bristlecone Pine

“…However, most pines respond to increased ? with improved growth (Curlin, 1963;Heilman and Gessel, 1963;Wagle and Beasley, 1968), and bristlecone pine is probably no exception. Unfortunately, our studies do not permit us to sort out the relative contribution of moisture vs. nutrients of the soils studied to the growth pattern of bristlecone pine.…”