| dc.description.abstract | Open ecosystems (i.e., prairies, savannas, and open woodlands) are often considered global biodiversity hotspots and terrestrial carbon (C) sinks. In the southeastern U.S., these fire-maintained landscapes have declined significantly since European settlement, largely due to conversion to agriculture and pasture, fire exclusion, and woody encroachment, with only a few remnant areas remaining. While open ecosystem restoration is increasing in the region to enhance biodiversity and associated ecosystem services, C storage potential remains under-researched, particularly regarding belowground pools. This thesis explores these dynamics across ecosystem pools (trees and snags, groundlayer vegetation, leaf litter, soil organic layer, mineral soil (0–30 cm depth), and fine and coarse roots) through two complementary studies. The first study quantified C stocks across an 80-year fire-managed mosaic in the Black Belt Prairie, Southeastern Plains, comparing remnant prairies, savannas, and woodlands to recently restored areas as well as closed, degraded woodlands. Remnant prairies contained the greatest total ecosystem C (287.76 Mg C ha⁻¹), significantly outperforming closed woodlands (220.83 Mg C ha⁻¹) and savannas (132.48 Mg C ha⁻¹). Notably, prairies stored the majority of C within mineral soil (279.39 Mg C ha⁻¹), highlighting that while closed systems sequester C primarily in tree biomass, some prairies store considerable belowground C. The second study evaluated restoration trajectories in the Interior Plateau across a time-since-restoration gradient ranging from active cropland and grazing fields to nine years since prairie restoration, using remnants as benchmarks. Total ecosystem C increased from 50.80 Mg C ha⁻¹ (early stages) to 71.74 Mg C ha⁻¹ at five years, with advanced stages (9 years: 59.66 Mg C ha⁻¹) approaching remnant values (62.81 Mg C ha⁻¹). Aboveground C was dynamic. Groundlayer vegetation C increased from 0.82 to 3.26 Mg C ha⁻¹ by 9 years. Conversely, mineral soil C remained stable, suggesting more time or additional factors impact this pool. Collectively, this research highlights that open ecosystems in the southeastern U.S. can support substantial C stocks, thus providing ecosystem service co-benefits related to biodiversity conservation and C storage. | en_US |
