PARENT SESSION
Poster Session # 16: Invasive Species.

Wednesday, August 6 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.

Invasive grass influence over paloverde performance in the arid Southwest.

Eilts, Alex¹, Huxman, Travis¹, ¹ University of Arizona, Tucson, Arizona

ABSTRACT- In the Sonoran Desert, buffelgrass (Pennistemum ciliare) has been systematically converting landscapes, primarily through mortality induced by alteration of the fire cycle. This study addresses the effects the bufflegrass on a suite of leaf level physiological traits and whole-plant survival in paloverde (Cercidium microphyllum) using a natural invasion gradient that has not experienced fire. Contrary to the expectation that buffelgrass would negatively affect the paloverde, pre-dawn water potential values were not significantly influenced by the presence of non-native species within the paloverde canopies as compared to plants without bufflegrass. Leaf-level photosynthetic gas exchange and chlorophyll fluorescence exhibited a similar pattern. In contrast the ecophysiological data, there was greater mortality for trees in bufflegrass patches. The difference in the data types is likely due to the habit in the paloverdes known as ′self pruning′; where by the root to shoot ratio is altered in the tree, maintaining water relations in the remainder of the tree. This study shows that in addition to the patterns of vegetation change associated with bufflegrass invasion and its influence on the fire cycle, native species can additionally be competitively displaced in the Sonoran Desert.

Key words: desert, Cercidium, invasive, Pennisetum