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One of North Carolina’s richest sources of plant diversity, the longleaf pine ecosystem, is also one of the most threatened.

This ecosystem needs frequent prescribed fire for plants to receive the light, space and nutrients they need to thrive. Doctoral student Kyle Palmquist studied the effectiveness of current fire management practices by re-sampling 59 permanent vegetation plots almost 20 years after they were established. “Prior to this work, there had been no long-term assessment of the stability of biodiversity in longleaf pine communities in North Carolina,” she said.

Her study was conducted on Marine Corps Base Camp Lejeune (in collaboration with Duke University), the Green Swamp Wilderness Preserve, a major natural heritage site for the Atlantic coastal plain, and other areas. Findings indicate that frequently burned sites gained the most species over time. Plots resampled on Camp Lejeune and Croatan National Forest had dramatic increases in diversity, whether measured in large or small areas; Palmquist attributed these ecosystem gains to increased burning efforts during the past 20 years, relative to fire frequency in the early and mid-20th century.

In contrast, the Green Swamp Wilderness Preserve’s richness was constant at large areas but had strongly declined in smaller areas. The Green Swamp had a history of prescribed fire every year or so until a decade ago, when fire managers decreased burning to every two-to-five years. UNC-Chapel Hill researchers had documented, in the 1970s and 1980s, that the Green Swamp had the highest small-scale richness in plant species ever documented in North America; however, increased drought frequency and reduced fire frequency caused a dramatic drop in plant richness.

Estimates place North Carolina’s natural longleaf pine acreage at about 200,000, with little high-quality, frequently burned habitat left. Palmquist’s research has implications for fire management decisions regarding the state’s longleaf ecosystem—and for the biodiversity this ecosystem contains.