Invasive Lupinus polyphyllus Alters Functional Traits and Life Strategies of Native Species

The primary trait of invasive plant species is their enhanced competitive ability compared to native flora. Consequently, in ecosystems they invade, native species diversity often declines. However, some native plants may allocate resources to developing traits that support their coexistence with invasive species. We conducted an observational experiment to assess how the functional traits of native plants are influenced by the invasion of Lupinus polyphyllus, how the Competition-Stress-Ruderal (CSR) strategies of native species shift during this process, as well as whether environmental factors modify these relations. We selected eight species (four herbs and four grasses) commonly found in the grasslands of the Sudety Mountains (Poland). Plants and soil were sampled from grasslands dominated by L. polyphyllus (> 50% cover) and from adjacent patches free of invasive plants. We measured plant height, leaf area (LA), specific leaf area (SLA), and leaf dry matter content (LDMC). Subsequently, we evaluated each species' allocation to a particular life strategy using the CSR framework. Our findings show that native grassland species growing alongside L. polyphyllus tend to be taller, have larger leaves, exhibit higher SLA, and have lower LDMC compared to those in noninvaded areas. Simultaneously, L. polyphyllus presence is associated with reduced impacts of K and moisture on herbs' functional traits; C, N, C/N, and heat exposure on grasses' functional traits; as well as low pH and clay content on both groups' functional traits. These shifts in leaf traits among plants interacting with the invader suggest a reduced investment in stress-tolerance strategies, accompanied by increased investment in competitive or ruderal strategies.