Native upland pine savannas once dominated the southeastern U.S. Coastal Plain, but have mostly been converted to other land uses, including row-crop agriculture, pasture, pine plantation, and fire-excluded hardwood forest. There are concerns about the sustainability of the ecosystem services supporting these agroecosystems, including plant diversity, pollinator diversity and abundance, soil stability, soil carbon sequestration, and maintenance of natural water cycles. Restoration of abandoned fields to pine savanna has been predicted to improve many ecosystem services, but the rate of improvement is largely unknown. We present a chronosequence approach to infer long-term changes in ecosystem services over approximately one century following abandonment of agriculture and restoration of frequent fire and open-canopy pine communities. We measured plant, pollinator, and soil microbial species compositions, soil structure and chemistry, canopy cover and leaf area index, and timber age and biomass to predict when and if ecosystem services provided by restored pine savanna exceeds those of alternative land uses, specifically agriculture, pasture, pine plantation, fire-excluded forest, with native (never plowed) pine savannas as reference sites.
Results/Conclusions
Most ecosystem services provided by restored pine savanna exceeded those provided by other land uses, though time required varied among services. Ecosystem services including native plant species richness, perennial grass cover, total ecosystem carbon, and water recharge exceeded row-crop agriculture sites within 5-15 years and continued to increase over time. Restored pine savanna had higher water recharge rates than any other land use, including native pine savanna. However, pine plantations had greater amounts of merchantable timber, fire-excluded forests had greater total ecosystem carbon, and pastures had a greater percentage of perennial grass cover. Pollinator species richness of pine savannas did not exceed row-crop agriculture and pastures though the species composition of the bees suggest that they require nearby pine savanna soil and vegetation to complete their life cycles. These results highlight the positive influence that restored pine savanna has at the landscape scale and the importance of continued restoration and management efforts in the face of declining ecosystem services due to climate change stressors.