Essential variables to consider for an efficient control strategy for invasive plants include dispersion pattern (i.e., satellite or invasion front) and patch expansion rate. These variables were demonstrated for buffelgrass [Pennisetum ciliare(L.) Link], a C4perennial grass introduced from Africa, which has invaded broadly around the world. The study site was along a roadway in southern Arizona (USA). TheP. ciliareplant distributions show the pattern of clumping associated with the satellite (nascent foci) colonization pattern (average nearest neighbor test,z-score −47.2, P<0.01). The distance between patches ranged from 0.743 to 12.8 km, with an average distance between patches of 5.6 km. Median patch expansion rate was 271% over the 3-yr monitoring period versus 136% found in other studies of establishedP. ciliarepatches. TargetingP. ciliaresatellite patches as a control strategy may exponentially reduce the areal doubling time, while targeting the largest patches may have less effect on the invasion speed.

Determining the efficacy of artificial water developments for desert bighorn sheep (Ovis canadensis mexicana) populations is an important conservation concern as projected climatic changes pose potentially severe effects to the species in the southwestern United States. We monitored daily visitation frequencies and temporal activity patterns of bighorn sheep at 20 water developments on the Barry M. Goldwater Range-East in Arizona, USA, from January 2015 to December 2018. We evaluated the effects of weather, landscape, and interspecific presence on these data using zero-inflated modeling and temporal activity analysis. Approximately 95% of visits by sheep occurred during summer primarily in response to relatively high temperatures and low precipitation. Conversely, sheep were nearly absent from developments during nonsummer when vegetative moisture was relatively high, especially if temperature was low and precipitation high. The frequency of visits by bighorn sheep increased when interspecifics were present owing to high use of water developments by all species during summer. Bighorn sheep altered their temporal activity to avoid the high activity periods of predators and competitors in all seasons. Water developments with terrain offering antipredator protection also had greater frequencies of visits, but these features did not affect the probability of absence. Overall, our study indicates that water developments provide hydration and thermoregulatory relief to bighorn sheep during the hot and water-limited conditions