Document: NAN-3-48-8

Selective herbivory by the desert woodrat (Neotoma lepida) on joshua trees (Yucca brevifolia) .

SANFORD, M.P.* and N.HUNTLY

Idaho State University, Pocatello, ID 83209-8007, USA ¹

Abstract:
We studied whether the desert woodrat (Neotoma lepida) selectively feeds on joshua trees (Yucca brevifolia) based on leaf nitrogen. Joshua trees allocate higher tissue nitrogen to south-facing leaves. We measured azimuth of all leaf rosettes of 22 Yucca trees containing Neotoma herbivory at our Mojave Desert study site and determined numbers and proportions of rosettes with eaten leaves or leaf parts. Nitrogen content was measured for leaves on north and south-facing rosettes, immature and mature leaves, leaf bases and tips, and for uneaten and partially eaten leaves. Neotoma herbivory was concentrated on leaf tips, mature leaves, leaves of south-facing rosettes, and trees with higher mean nitrogen. Leaf tips and leaves of south-facing rosettes contained more nitrogen than leaf bases and leaves of north-facing rosettes. Mature leaves had higher water content than immature leaves. Neotoma fed from more rosettes of trees that had higher nitrogen content. Thus, N. lepida fed selectively within leaves, among and within rosettes, and among trees of Y. brevifolia based on nitrogen and on water content.

Keywords: herbivory, nitrogen

This abstract is being presented at: 8:15 AM in session:
Oral Session #21: Small Mammal Population Ecology.