Bur Oak (Quercus macrocarpa) Enrichment Plantings Enhance Successional Restoration of an Old Field

ABSTRACT Abandoned crop fields in central Kansas, USA, are soon colonized by several non-native and native woody species. This study compared subsequent vegetation change in control (unmanipulated) old field successional plots and plots planted with Quercus macrocarpa (bur oak) seedlings following cessation of row crop agriculture. The site, a former corn field, was subject to invasion primarily by Ulmus pumila (Siberian elm), Lonicera tartarica (Amur honeysuckle), and Juniperus virginiana (eastern redcedar). I established eight 20 m × 32 m plots in April 2007, four as controls and four each containing 40 bur oak seedlings planted 4 m apart. I monitored permanent 4 m × 4 m quadrats (12 quadrats per plot) for 16 years for the presence of naturally establishing herbaceous and woody species. I sampled a total of 94 herbaceous and 27 woody species, with L. maackii, U. pumila, and J. virginiana occurring in 95 to 100% of quadrats by 2022. Total species richness, total woody species richness, native woody species richness, and richness of animal-dispersed woody species were higher in the oak plots than in the controls. Dissimilarity between the treatments steadily increased with time. The results suggest that an enrichment planting of bur oak seedlings at the outset can influence the early successional trajectory of old fields, and indicate that such plantings can drive restorations away from invasive non-native species and toward more desirable native species in later years.