Effects of cattle management on oak regeneration in northern Californian Mediterranean oak woodlands

PLoS One. 2014 Aug 15;9(8):e105472. doi: 10.1371/journal.pone.0105472. eCollection 2014.

Abstract

Oak woodlands of Mediterranean ecosystems, a major component of biodiversity hotspots in Europe and North America, have undergone significant land-use change in recent centuries, including an increase in grazing intensity due to the widespread presence of cattle. Simultaneously, a decrease in oak regeneration has been observed, suggesting a link between cattle grazing intensity and limited oak regeneration. In this study we examined the effect of cattle grazing on coast live oak (Quercus agrifolia Née) regeneration in San Francisco Bay Area, California. We studied seedling, sapling and adult density of coast live oak as well as vertebrate herbivory at 8 independent sites under two grazing conditions: with cattle and wildlife presence (n = 4) and only with wildlife (n = 4). The specific questions we addressed are: i) to what extent cattle management practices affect oak density, and ii) what is the effect of rangeland management on herbivory and size of young oak plants. In areas with cattle present, we found a 50% reduction in young oak density, and plant size was smaller, suggesting that survival and growth young plants in those areas are significantly limited. In addition, the presence of cattle raised the probability and intensity of herbivory (a 1.5 and 1.8-fold difference, respectively). These results strongly suggest that the presence of cattle significantly reduced the success of young Q. agrifolia through elevated herbivory. Given the potential impact of reduced recruitment on adult populations, modifying rangeland management practices to reduce cattle grazing pressure seems to be an important intervention to maintain Mediterranean oak woodlands.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animal Distribution
  • Animal Husbandry
  • Animals
  • California
  • Cattle
  • Conservation of Natural Resources
  • Forests*
  • Grassland
  • Herbivory
  • Plant Dispersal
  • Quercus / growth & development*

Associated data

  • figshare/10.6084/M9.FIGSHARE.1116231

Grants and funding

This study has been developed thanks to a study abroad fellowship (Formación del Profesorado Universitario) of Spain Ministry of Education, Culture and Sport to ALS. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.