You are here

Harvard Forest >

Harvard Forest REU Symposium Abstract 2019

  • Title: Effects of Environmental Biotic Factors on Seedlings Survival
  • Author: Dayna De La Cruz (Wellesley College)
  • Abstract:

    The species identity of neighboring adult trees may affect seedling growth and survival by influencing the level of herbivory or pathogen load that seedlings experience. Our experiment tests the Janzen-Connell hypothesis which states that tree seedlings are more likely to survive under a heterospecific adult tree (HAT) rather than under a conspecific adult tree (CAT), due to the presence of species specific herbivores and pathogens near adults conspecifics. Our goal is to understand mechanisms that connect to patterns in biodiversity and quantify the impact that biotic factors have on seedling survival within the Prospect Hill of Harvard Forest. We tested the effects conspecificity and species evenness have on transplanted seedling survival in White Pine (Pinus strobus), Red Pine (Pinus resinosa), Northern Red Oak (Quercus rubra) and Norway Spruce (Picea abies) in 60 plots during the summer of 2019. Overall, 91% of the White Pine, 27% of the Red Pine, 94% of the Norway Spruce and 84% of the Red Oak survived. Seedlings (particularly Red Pine) survived at higher rates under HATs than under CATs. Red Oak seedlings under CATs typically exhibited greater leaf damage than Red Oak seedlings under HATs. Although the differences were not significant, all species had a higher survival under even plots than under uneven plots, suggesting that intraspecific seedling competition may matter for seedling survival over a longer period of time. This study provides useful information about the drivers of mortality in temperate forest seedlings, allowing for better predictions about the future demographics of temperate forests.

  • Research Category: Group Projects; Biodiversity Studies