Sencenbaugh Lilly, Maxwell Bruce D, Rew Lisa J
Land Resources and Environmental Sciences Montana State University Bozeman Montana USA.
Ecol Evol. 2025 May 19;15(5):e71458. doi: 10.1002/ece3.71458. eCollection 2025 May.
Competitive interactions between co-occurring invasive species can have detrimental impacts on native communities and cause counter-effective responses to management. Targeted removal of one invader may allow for the release of a subdominant invader, causing a secondary invasion. The goal of this research was to elucidate competitive dynamics between and two invasive winter annual grasses found in the western United States We quantified the impacts of (1) intraspecific competition on and as the density of conspecifics increased and (2) interspecific competition between the two at varying proportions. The two species were grown at increasing densities and proportions (addition series) over 10 weeks in a greenhouse. Aboveground biomass was harvested and weighed. We derived the intraspecific and interspecific competitive effects on each species with a nonlinear analysis and used these coefficients to determine relative competitive ability (RCA). Both species were impacted by interspecific competition and intraspecific competition. More conspecifics were required to cause a decline in both species' biomass relative to the number of allospecifics that caused the same response. Interestingly, the number of allospecific individuals to imposed an impact was similar. The RCA values for both species were < 1, which indicated that interspecific competition had a greater influence on both species than intraspecific competition. This suggests that the replacement of by is unlikely to be caused by aboveground competition alone. However, there are differences in germination timing between the two species; both germinate in the fall, but also germinates in the spring. Management that targets fall-germinating individuals may reduce and fall-germinating but not impact spring-germinating which may release these individuals from competition. Understanding the competitive interactions between these species provides insight into invasive species impacts and management.
同时出现的入侵物种之间的竞争相互作用可能会对本地群落产生不利影响,并导致管理上的适得其反的反应。有针对性地清除一种入侵者可能会使次要入侵者得以释放,从而引发二次入侵。本研究的目的是阐明美国西部发现的两种入侵性冬季一年生禾本科植物之间的竞争动态。我们量化了(1)随着同种个体密度增加,种内竞争对这两种植物的影响,以及(2)这两种植物在不同比例下的种间竞争。这两个物种在温室中以增加的密度和比例(添加系列)生长了10周。收获并称重地上生物量。我们通过非线性分析得出了对每个物种的种内和种间竞争效应,并使用这些系数来确定相对竞争能力(RCA)。这两个物种都受到种间竞争和种内竞争的影响。相对于导致相同反应的异种个体数量,需要更多的同种个体才能使这两个物种的生物量下降。有趣的是,施加影响的异种个体数量相似。这两个物种的RCA值均<1,这表明种间竞争对这两个物种的影响大于种内竞争。这表明,[物种名称1]被[物种名称2]取代不太可能仅由地上竞争引起。然而,这两个物种在发芽时间上存在差异;两者都在秋季发芽,但[物种名称1]也在春季发芽。针对秋季发芽个体的管理可能会减少[物种名称1]和秋季发芽的[物种名称2],但不会影响春季发芽的[物种名称1],这可能会使这些个体从竞争中解脱出来。了解这些物种之间的竞争相互作用有助于深入了解入侵物种的影响和管理。