Print PageWe tested the effects of Rhamnus cathartica (common buckthorn) invasion and restoration of previously invaded areas on woodland carbon (C) dynamics. Common buckthorn is a Eurasian shrub to small tree that has become widely invasive throughout the upper Midwest. Documented correlates of buckthorn invasion suggest it may impair C storage, these include: depauperate understory vegetation, rapid decomposition, loss of the litter layer, and a positive association with mineralization-promoting invasive earthworms. Our study site was the Chicago Botanic Garden’s Mary Mix McDonald Woods (Glencoe, IL). Much of McDonald Woods was heavily invaded by dense thickets of buckthorn. The site has been restored to dry-mesic oak woodland in phases over the past 20+ years. In summer 2010, we compared unrestored, buckthorn-dominated patches to a chronosequence of stands where restoration had begun in 1996, 2003, and winter 2010. We expected restoration to alter plant-community structure, with recovery of robust understory vegetation and litter. We predicted that these structural changes would lead to increased sequestration of C in pools of recalcitrant soil organic matter (SOM) and reduced losses of C via soil erosion and soil CO2 efflux.
Results/Conclusions
Understory plant diversity and cover increased with time since restoration. Leaf-litter biomass was up to 43-times higher in older restored areas than unrestored and newly restored patches (P = 0.0002). C storage in slow-turnover pools of mineral-associated SOM increased 12% with restoration (P = 0.007). Soil-erosion assays were inconclusive due to equipment failure. CO2 flux was highly variable in time and space and did not consistently differ by restoration treatment (P = 0.11). We conclude that buckthorn invasion might impair and restoration enhance the ability of woodlands to perform C-storage ecosystem services. This builds upon an already-strong rationale for restoring buckthorn-invaded woodlands on biodiversity grounds.
