Relationships of Native Desert Plants with Red Brome (Bromus rubens): Toward Identifying Invasion-Reducing Species

Abstract

The interactions between native and exotic species occur on a continuum from facilitative to competitive. A growing thrust in invasive species science is differentiating where particular native species occur along this continuum, with practical implications for identifying species that might reduce the invasibility of ecosystems. We used a greenhouse experiment to develop a competitive hierarchy of 27 native species with red brome, an invasive annual grass in the arid lands of the southwestern United States, and a field study to assess in situ responses of brome to native perennial species in the Mojave Desert. Native species most competitive with brome in the competition experiment included the annuals Esteve's pincushion and western fiddleneck and the perennials eastern Mojave buckwheat, sweetbush, and brittlebush, which reduced brome biomass to 49 to 70% of its grown-alone amount. There was no clear difference in competitive abilities with brome between annual and perennial natives, and competiveness was not strongly correlated (r = 0.15) with the biomass of the native species. In the field, sweetbush and brittlebush supported among the least cover of brome, suggesting congruence of the strong early competitive abilities of these species with in situ patterns of brome distribution. At the other extreme, brome attained its highest average cover (19%) below littleleaf ratany, significantly greater than all but 3 of the 16 species evaluated. Cover by brome was only weakly related (r = 0.19) to the area of the perennial canopy, suggesting that factors other than the sizes of perennial plants were linked to differences in brome cover among species. Results suggest that (1) interactions with brome differ substantially among native species, (2) these interactions are not as closely linked to biomass production as in more temperate regions, and (3) there is potential for identifying native species that can reduce invasion of desert ecosystems.

The effect of consumer pressure and abiotic stress on positive plant interactions are mediated by extreme climatic events

“…Positive interactions in arid environments can also have indirect effects that are nontrophic on the annual plant community (Lortie et al ., ). Invasion by non‐natives is increasingly becoming a critical issue even in relatively high‐stress ecosystems (Rodríguez‐Buriticá & Miriti, ; Abella et al ., ). Moreover, there is an increasing need to consider multiple factors when modeling interactions of native and exotic species with climate variation (Preston et al .…”

Alternative pathways to landscape transformation: invasive grasses, burn severity and fire frequency in arid ecosystems

“…; Abella ; Abella et al . ). It has generally been thought resistance to invasion and resilience from fire (Brooks & Chambers ) were lowest in mid‐elevation areas in the Mojave Desert because biophysical conditions were the most favourable for invasive grasses (Brooks & Matchett , Brooks, Minnich & Matchett in press).…”

“…Munro), non-native forbs or native forbs (Brooks 1999). Many studies in the Mojave Desert have shown abundance of both native and non-native vegetation changes after fire and also vary with time since fire, sometimes resulting in communities once dominated by native woody shrubs being converted to ones where herbaceous species, and especially invasive grass, either dominate or are a much greater part of the community than prior to burning (Callison, Brotherson & Bowns 1985;Minnich 1995;Lei 1999;Brooks & Matchett 2003, 2006Webb et al 2003;Abella 2009;Abella et al 2011). It has generally been thought resistance to invasion and resilience from fire (Brooks & Chambers 2011) were lowest in mid-elevation areas in the Mojave Desert because biophysical conditions were the most favourable for invasive grasses (Brooks & Matchett 2006, Brooks, Minnich & Matchett in press).…”

Root Inputs Influence Soil Water Holding Capacity and Differentially Influence the Growth of Native versus Exotic Annual Species in an Arid Ecosystem

“…3a), and actually had higher biomass when grown in combination than when grown alone, suggesting this species was facilitated by growing in a diverse community. Other studies have also found that A. tessellata was robust to exotic competition (Brooks 2009;Abella et al 2011), potentially due to traits such as large seed size and early-season germination (Salo et al 2005). Hence, A. tessellata could be an effective choice for restoration efforts attempting to establish native cover via seeding, especially when there may be potential competition from exotic species present in the seedbank.…”

“…Other studies have also found that A . tessellata was robust to exotic competition (Brooks ; Abella et al ), potentially due to traits such as large seed size and early‐season germination (Salo et al ). Hence, A .…”