John C. Gilbert

Structure and Diversity of Longleaf Pine (Pinus palustris Mill.) Forest Communities in the Mountain Longleaf National Wildlife Refuge, Northeastern Alabama

ABSTRACT: The Mountain Longleaf National Wildlife Refuge (MLNWR), located in northeastern Alabama, is unique in that it holds significant acreages of young and old-growth montane longleaf pine forest (Pinus palustris Mill.). We conducted a study to aid in the management and restoration of longleaf pine communities on the MLNWR. Our objectives were to: (1) establish permanent forest monitoring plots; (2) document herbaceous and woody vegetation; and (3) measure forest diversity, structure, and fuel loads in montane longleaf pine communities with varying fire and management histories. We established 48 plots, 0.04 ha in area, in winter 2008 and measured all plots in summer 2008. The MLNWR has recently incorporated prescribed burning in their management plans and each plot was categorized by the year it was burned (2008, 2006, 2004, no-burn) and whether hardwood control treatments were applied. We identified 18, 19, and 22 different woody plant species in the overstory, mid-story, and understory, respectively, across plots. Longleaf pine basal area ranged from 5 to 10 m2 ha-1 and represented as much as 80% of basal area across plots. Mid-story basal area and woody plant species diversity were lower in plots receiving fire or hardwood control. Longleaf pine regeneration was found in only 17 plots and was highest in burned plots or plots receiving hardwood control. Burning also increased grass and herbaceous ground cover. Fuel loads were high with an average humus layer accumulation of 35 Mg ha-1. Regular fire intervals are needed to reduce fuels and mid-story density and aid in the regeneration of longleaf pine.

Overhead shading and growth of young longleaf pine

A study to determine the effects of environmental conditions on the growth of longleaf pine (Pinus palustris Mill.) was initiated in 1969 on the Escambia Experimental Forest near Brewton, Alabama, USA. This study sample consisted of forty young naturally regenerated, even aged longleaf pine seedlings evenly divided between two soil types. At the beginning of the study, the seedlings were 14 years from seed and ranged in height from 0.8 to 1.5 m. From 1969 to 1970, height and diameter measurements were recorded once to four times weekly during the growing seasons and once a month during the dormant seasons. To test the effects of shading on growth, cheesecloth was suspended over 10 randomly selected seedlings from each soil type only during the first growing season, from March 28 to September 24, 1969. This study provides data from the only known in-field shading experiment with longleaf pine seedlings of this size. The effects of the shading treatment and soil type were evaluated for height and diameter growth. The shading treatment did not have a significant effect on either height or diameter growth, but soil type had a significant effect on diameter growth.