The ‘other’ Hardwood: Growth, Physiology, and Dynamics of Hickories in the Central Hardwood Region, USA

Hickories (Carya spp.) are common species in eastern US forests. Despite being a noted component of the most prevalent forest type in the eastern US, remarkably little is known about the ecology and silvics of the genera, especially compared to oaks (Quercus spp.). To improve our understanding about the dynamics of hickories in stand development and forest succession, we used a variety of datasets from oak-hickory forests of the Central Hardwood Region to assess growth, physiology, and demography. Our findings suggest that hickories may have a conservative root-centered growth strategy that exceeds that of oaks, with highly plastic physiology. This allows for long-term persistence of hickories in the mid and understory while being responsive to favorable increases in available light. The reproduction dynamics of hickories suggest a gradual and consistent recruitment to the mid and overstory in contrast to the single, unimodal age distribution of oaks following historic disturbance. This is achieved by periods of higher growth rates and lower mortality rates, especially in subordinate canopy positions when compared to oaks. These findings suggest that contemporary removal of historic disturbance regimes may continue to support hickory recruitment to the overstory, but active forest management is necessary to maintain the oak-hickory forest type in the Central Hardwood Region.