Abstract
We investigated California black oak (Quercus kelloggii Newberry) acorn dispersal by rodents and birds in the months after a stand-replacing fire in a mixed conifer forest in the San Bernardino Mountains of southern California, USA. The objective of this study was to compare scatter-hoarding in a high-severity burn to that in an unburned forest. In the fall of 2007, we placed 600 magnet-bearing acorns under trees in the unburned area. Of the 600, we recovered 77 (13%). Dispersers moved acorns an average distance of 5 m and buried them to an average depth of 30 mm. By spring of 2008, 90% of the cached acorns were missing. In the high-severity burn, we recovered 59 (9.8%) of the 600 acorns placed under top-killed oaks; these had been scatter-hoarded an average of 5.27 m from the source plots and buried an average of 22 mm. By spring of 2008, 55% these acorns were missing, and many of those that we relocated had been re-cached in new locations. Our results suggest that scatter-hoarding of acorns may be a common phenomenon after fire, and likely plays an important role in seedling recruitment.
Highlights
Rodents and birds are indispensable to seedling recruitment of oaks (Quercus L.) worldwide, both as dispersers and planters (Steele and Smallwood 2002, Pons and Pausas 2007)
In the weeks after the fire, we initiated acorn dispersal experiments to assess the prevalence of post-fire scatter-hoarding
We wanted to know if vertebrates scatter-hoard acorns in either the unburned area or in the high-severity burn and, if so, we wanted to know how many acorns were hoarded and at what distances from the source trees
Summary
We investigated California black oak (Quercus kelloggii Newberry) acorn dispersal by rodents and birds in the months after a stand-replacing fire in a mixed conifer forest in the San Bernardino Mountains of southern California, USA. In the high-severity burn, we recovered 59 (9.8 %) of the 600 acorns placed under top-killed oaks; these had been scatter-hoarded an average of 5.27 m from the source plots and buried an average of 22 mm. In the high-severity portion of the burn, thousands of acorns covered the ground beneath black oaks and continued to fall in the weeks thereafter. Western gray squirrels (Sciurus griseus Ord) collected acorns from the burned canopies as well as from the ground, but unlike chipmunks and ground squirrels, they often foraged well away from the cover of outcrops All of these vertebrates consume acorns and, except for acorn woodpeckers, they scatter-hoard them as well (Best and Granai 1994, Carraway and Verts 1994). We expected that scatter-hoarding was taking place in unburned forests, we expected little or no scatter-hoarding in the high-severity burn mainly because foraging cover and caching microsites (coarse woody debris, shrub cover, and litter) had been all but eliminated there
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
