Aspen Seedling Establishment and Growth after Wildfire in Central Arizona: An Instructive Case History
Reproduction of aspen (Populus tremuloides Michx) occurs primarily through asexual root suckering, and establishment by seed in western US landscapes has been considered extremely rare. Here, we describe a natural aspen seedling recruitment event after wildfire in Arizona, occurring during severe drought within low elevation, fenced ponderosa pine plantations. Aspen was not present in these prefire sites, and genetic analysis confirmed that 70 individuals in these exclosures were unique. Eleven years postfire, average seedling diameter was 4.2 cm and average height was 2.3 m. Seedlings established over a 6-year period, with 91% establishing in the first 3 years. Clonal development was both diverse and robust: 61% of seedlings produced 1‐39 suckers, and the total number of suckers (n = 246) now far exceeds the 70 seedlings. Aspen seedlings established during severe drought years had a greater association with large woody debris than those established later. The establishment of aspen seedlings during severe drought, along with the relative abundance of aspen seedlings in fenced exclosures (with only two seedlings observed outside exclosures) suggests that aspen seedling establishment in at least some locations may be more limited by herbivory than directly by warming climate.
Fairweather, M.L., E.A. Rokala, and K.E. Mock. 2014. Aspen seedling establishment and growth after wildfire in central Arizona: an instructive case history. Forest Science 60:703-712.