Can Buffelgrass Invasions Be Controlled in the American Southwest? Using Invasion Ecology Theory to Understand Buffelgrass Success and Develop Comprehensive Restoration and Management

Abstract

Since being introduced for rangeland improvements in the early to mid-20th century, several non-native grass species have spread beyond their initial planting sites in the American Southwest. Many of these species, especially those that have infiltrated desert ecosystems, can alter fire regimes, which in turn threatens native plant species. In Arizona desert ecosystems, buffelgrass (Pennisetum ciliare) increases fire frequency and intensity, which may create a positive feedback loop, resulting in a shift from native fire-sensitive plant communities to non-native grasslands. Although control efforts are currently underway, a more comprehensive ecosystem approach will be required to treat buffelgrass invasions in southeastern Arizona's deserts. Here, we evaluate the species and environmental factors that may contribute to plant invasion success. We highlight empirical buffelgrass literature as it pertains to invasion, integrate basic invasion ecology theory and restoration ecology to examine potential practical approaches for controlling buffelgrass invasions in southeastern Arizona, and use this information to provide the basis for comprehensive restoration and management. We also briefly discuss public policy related to buffelgrass control in the southwestern United States.

Climate change impacts on high elevation saguaro range expansion

“…Climate change may alter the success of native grasses in these grasslands through an alteration of the grassefire cycle and proliferation of invasive grass species (McPherson, 1995). Buffelgrass (P. ciliare) in particular is projected to thrive under a warming climate (Stevens and Falk, 2009). Olsson et al (2012) noted that wet summers and warm winters since the early 1980's have favored establishment of buffelgrass across a nearby Sky Island mountain range, but also noted that spread appeared to be high in subsequent average to dry years as well.…”

“…Both temperature and precipitation predictions suggest that potential and actual evapotranspiration will increase dramatically, which is expected to foster the spread of many invasive species and increase the occurrence, extent, and severity of wildfire. The non-native perennial buffelgrass (Pennisetum ciliare) has been shown to rapidly convert desert scrub ecosystems to grass-dominated landscapes (Olsson et al, 2012), limiting the distribution of saguaros at higher elevations (Stevens and Falk, 2009). Fire activity is also increasing at these elevations in the desert Southwest (Esque et al, 2004), and saguaros are highly susceptible to fire (McLaughlin and Bowers, 1982;Wilson et al, 1996).…”

Invasive buffelgrass detection using high‐resolution satellite and UAV imagery on Google Earth Engine

“…Buffelgrass threatens ecosystems in its introduced range because, compared to native vegetation, it increases the fuel load and intensity of fires (Jackson ; Esque et al. ; Stevens and Falk ; Martin et al. ).…”

A multi-objective optimization approach for invasive species control

“…This region represents the northern stretches of the Sonoran Desert, home of unique species such as the giant saguaro cactus (Carnegiea gigantean), which is a native cactus species and one of the defining plants of this desert (Niering and Lowe, 1984). Having sparse vegetation, the Sonoran Desert ecosystem is not fire adapted (Burquez-Montijo et al, 2002;Rogstad et al, 2008;Stevens and Falk, 2009). Buffelgrass forms dense stands crowding out native species and carrying wildfire (Bowers et al, 2006).…”

“…In particular, we apply a multi-objective optimization framework to the management of buffelgrass (Pennisetum ciliare), an invasive fire-prone African bunchgrass that spreads very rapidly across the Arizona desert. Buffelgrass is introduced to the United States for forage in the 1940s because of its drought hardiness, high establishment rates and grazing tolerance (Stevens and Falk, 2009). Since its introduction, buffelgrass has become invasive in southern Arizona.…”