Native upland pine-grassland communities on Ultisols of the southeastern U.S. Coastal Plain are known for their distinctive flora, high native plant diversity, and dependence on frequent (1-3 year interval) fire. Similar to other “old-growth grasslands” throughout the world, plants in these communities are mostly perennial, depend heavily on root reserves for resprouting following fire, are thus sensitive to soil disturbance, and have limited dispersal capability. Abandonment of agricultural fields in the early 20th century and subsequent management with frequent prescribed fire has resulted in development of unique anthropogenic plant communities through unmanaged recolonization by native plants. This study compares species composition and soil characteristics between natural reference and post-agriculture communities to infer limitations on seed dispersal and implications for wildlife habitat and management using fire. We measured plant species composition and soil texture and chemistry within multiple (18-36) 100 m2 plots within each of three pine-grassland community types: native Pinus palustris-Aristida stricta, native P. echinata-Schizachyrium scoparium, and post-agriculture P. taeda/P. echinata-Andropogon. We also compared species composition among undisturbed, recently disked, and repeatedly disked areas within the Pinus palustris-Aristida stricta community at two sites 3-4 years following the last disturbance to gain further insights into dispersal capabilities and limitations.
Results/Conclusions
Multivariate analyses showed the three community types to be compositionally distinct. The two native communities had 114 indicator species together and the post-agriculture community had 29 out of 307 total. Soil in the post-agriculture community had shallower A horizons and higher clay content, indicating past soil erosion. The comparison of undisturbed, single-disked, and repeatedly-disked areas showed 18% of species were significantly reduced by the single disking, and 31% (inclusive of the previous group) failed to colonize the repeatedly disked soil, despite the close proximity of parent plants. These species are the most common and flammable in native, undisturbed communities, such that the range of conditions for effective burning is reduced in disturbed areas. The remaining 69% of species were resilient to or responded positively to the single disturbance and were capable of colonizing the repeatedly disked soil. Results of the study reveal a range of species life history characteristics from "climax" to "ruderal" with regard to soil disturbance within the context of frequent fire. While soil disturbance remains a conservation concern, the anthropogenic community resulting from eventual recolonization by most native species provides habitat for many declining animal species and ecosystem services associated with natural, frequently-burned pine-grassland communities.