The Effect of Growth Rate, Age, and Chestnut Blight on American Chestnut Mortality

摘要

The factors affecting tree mortality have a significant impact on forest dynamics. Trees experience numerous biotic and abiotic stresses, and allocation of available resources can determine tree survival in different conditions. Recent studies support an intraspecific relationship between radial growth rate and longevity. This study investigates the existence of such a relationship in the American chestnut [Castanea dentata (Marsh.) Borkh.] across a landscape in southwestern Virginia. Growth rate and age at death were measured on basal cross sections of recently dead American chestnuts. The relationships between growth rate and age at death and between growth rate and chestnut blight presence were analyzed. Average growth rate during the first 10 years of growth and age at death were correlated; chestnuts with fast early growth died younger than chestnuts with slow early growth. Additionally, we found that the average growth rate during the last 10 years of growth was a significant predictor of blight infection at death. Our results provide further support for a link between radial growth rates and longevity within species. Our results also support previous findings that relate radial growth rates to blight susceptibility, possibly due to tradeoffs in resource allocation to growth versus defense. This study emphasizes the impact of life history on mortality in a tree hosting a pathogen and could inform forest management practices for chestnut conservation in the face of potential mortality from blight infection.