Drivers of twoneedle pinyon (Pinus edulis) cone productivity: implication for wildlife

Description

Data pertaining to Chapter 2 "Drivers of twoneedle pinyon (Pinus edulis) cone productivity: implication for wildlife" of a New Mexico State University (Las Cruces) Master's thesis by Clare O'Connell titled: THE OSCURA MOUNTAINS COLORADO CHIPMUNK: EVALUATION OF MICROHABITAT SELECTION AND ECOLOGICAL DRIVERS IN PINYON-JUNIPER WOODLAND. Abstract: Seeds of twoneedle pinyon (Pinus edulis) serve as a nutritionally dense food resource for myriad of wildlife. Pinyons exhibit synchronist masting with high cone production occurring every 4-7 years. Per-tree cone production may be influenced by tree-level and site-level features. Our goal was to identify features that influence pinyon cone abundance and determine how cone production relates to microhabitat selection by the Oscura Mountains Colorado chipmunk (Neotamias quadrivittatus oscuraensis), an old growth pinyon-juniper specialist and seed-caching rodent. We hypothesized increased cone abundance would be exhibited by older trees and at sites with increased water availability. We hypothesized that the chipmunk would select stands exhibiting increased cone production. We used double observer abscission scar counts on five branches per tree averaged between observers to estimate tree cone abundance for the most recent eight years. We used linear modeling to determine tree- and site-level features influencing per tree cone abundance, incorporating site as a random-intercept for tree-level models. The most influential tree-level feature was diameter, with larger diameter trees having greatest cone abundance. Percent defoliation in the living tree canopy exhibited an inverse relationship with cone abundance. Water availability of a site was represented by reproductive tree density and heat load, both of which inversely influenced per-tree cone abundance. However, reproductive tree density exhibited a positive relationship with cone production across a stand. Estimated stand cone production did not influence microhabitat selection by the chipmunk. We encourage management of pinyon-juniper woodlands to consider drivers of pinyon cone productivity and influence of cone production on wildlife. We urge the protection of old growth stands to support wildlife, as older trees are the most influential determinant of cone abundance and concurrently provide structural complexity important for wildlife. Lastly, our study indicates thinning of pinyon-juniper woodlands as unwarranted for the goal of increasing cone production. Maximizing pinyon cone production would be best met by maintaining dense old growth stands.

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See O'Connell (2023) Master's thesis and associated published papers

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