Nitrogen deposition enhances Bromus tectorum invasion: biogeographic differences in growth and competitive ability between China and North America

Abstract

Increased resource supply commonly facilitates invasion by exotic plants, raising concerns over atmospheric nitrogen (N) deposition; fast‐growing annual invaders may have exceptional abilities to outperform native perennials in response to N pulses. However, it remains unclear whether this advantage is due to growth differences or to shifts in competitive outcomes, and whether annual invaders are favored by N deposition in their introduced range over native range. We conducted an experiment to compare the growth and competitive ability of Bromus tectorum and its native perennial grasses either at three different N regimes or between China and North America. The soil used in this experiment was from mountain grasslands as a neutral growth medium. The total biomass of three natives from China and North America did not increase along the N deposition gradient. Nitrogen addition enhanced the growth of North American B. tectorum instead of Chinese B. tectorum. Nitrogen addition increased the competitive ability of B. tectorum, but had no effect on that of natives. North American B. tectorum was bigger and had greater competitive ability and root weight ratio than Chinese B. tectorum. In contrast, North American natives were less competitive than Chinese natives. There was a significantly positive correlation between the growth of B. tectorum grown alone and its competitive ability. These findings suggest that N deposition may enhance the B. tectorum invasion through disproportionally increasing the growth and maintaining inherent competitive advantages of North American B. tectorum, further increasing threats to introduced ranges. There were differences in the growth and competitive ability of B. tectorum and natives between China and North America, which explains why B. tectorum is a minor component at home and becomes a successful invader abroad.

A Congeneric Comparison Shows That Experimental Warming Enhances the Growth of Invasive Eupatorium adenophorum

“…This similar phenomenon has been found in recent studies [15], [28]. Because there are correlations between growth and competitive effects of invaders, their growth can predict their competitive effects [29]. Thus we propose a hypothesis that the growth advantage of E. adenophorum due to climate warming may allow it to become a good competitor.…”

Science synthesis to support socioecological resilience in the Sierra Nevada and southern Cascade Range

“…nitrogen can promote invasive grasses (Fenn et al 2010), including cheatgrass (Bromus tectorum) (He et al 2011), which can in turn have transformative effects on ecosystems by altering fire regimes, reducing carbon storage, and degrading forage quality (Bradley 2009).…”

Nutrient enrichment alters impacts of Hydrocotyle vulgaris invasion on native plant communities

“…The competitive effect of H. vulgaris was calculated as: competitive effect = ln (biomass of the native community not invaded by H. vulgaris /biomass of the native community invaded by H. vulgaris )3259. A positive value suggests competition between H. vulgaris and the native plant community, while a negative value indicates that H. vulgaris invasion promotes the growth of the community59.…”

“…Post-industrial anthropogenic activities have amplified nitrogen and phosphorus cycles by 100% and 400%, respectively30, and rates of nutrient deposition have increased dramatically31. Higher rates of atmospheric nutrient deposition can enhance plant invasion32. Native species have different nutrient-acquisition strategies and are key functional components of vegetation.…”