In this study, we attempt to deepen our understanding of the mechanisms responsible for Quercus brandegeei’s observed lack of regeneration by identifying which animal species (wild and domesticated) most frequently were observed eating, passing by, or searching for seeds and seedlings. We established 10 paired plots (10 enclosed and 10 immediately outside enclosures) and positioned one motion-activated camera in each plot to observe animal visitations to Quercus brandegeei individuals over the course of several months (October 2019 – March 2020). No seeds and seedlings survived outside of enclosed areas at the end of the study based on their absence. Very few seedlings survived within enclosures. We did not make any comparisons between enclosure and unenclosed plots because the enclosures were being used by another study to test the effect of shade on seedling development. We present data on animals with the most frequent visits, greatest time spent in the plots, and who were observed eating and searching for seedlings. We found that pigs had the highest absolute number of visits (2058) and total time spent in the plots (>1436 hours). Their activity was split equally between type of activity observed (33.3% eating, 33.3% searching, 33.3% passing). Sheep had the next highest visitation (1489) and time spent in the plots (>173 hours). They spent 75% of time eating and 25% passing. Our results indicated that seed predation/destruction from livestock affected Q. brandegeei regeneration more than seed predation/destruction from wild animal species. However, even if seedling mortality is disproportionately caused by livestock, the total absence of live seeds outside of the fenced areas may suggest a compounding effect with climatic factors like drying or human collection of seeds.
Espinoza, Xavier O.
"Understanding the Effect of Ranching on Quercus Brandegeei Recruitment in the Sierra La Laguna Biosphere Reserve,"
DePaul Discoveries: Volume 12, Article 11.
Available at: https://via.library.depaul.edu/depaul-disc/vol12/iss1/11