Invasive grass litter suppresses a native grass species and promotes disease

Abstract

Plant litter can alter ecosystems and promote plant invasions by altering resource availability, depositing phytotoxins, and transmitting microorganisms to living plants. Transmission of microorganisms from invasive plant litter to live plants may gain importance as invasive plants, which often escape pathogens upon introduction to a new range, acquire new pathogens over time. It is unclear, however, if invasive plant litter affects native plant communities by promoting disease. Microstegium vimineum is an invasive grass that suppresses native populations, in part through litter production, and has acquired new fungal leaf spot diseases since its introduction to the United States. In a greenhouse experiment, we evaluated how M. vimineum litter and its pathogens mediated competition with the native grass Elymus virginicus. M. vimineum litter promoted disease on E. virginicus and suppressed establishment and biomass of both species. Litter had stronger negative effects on E. virginicus than M. vimineum, increasing the relative biomass of M. vimineum. Live plant competition reduced biomass of both species and live M. vimineum increased disease incidence on E. virginicus. Altogether, invasive grass litter suppressed both species, ultimately favoring the invasive species in competition, and increased disease incidence on the native species.

Suppression of Seedling Survival and Recruitment of the Invasive Tree Prosopis juliflora in Saudi Arabia through Its Own Leaf Litter: Greenhouse and Field Assessments

“…Second, increasing litter depths reduces seed germination and large amounts of litter (8 cm litter depth) can eliminate germination completely. Similar results have been reported in studies assessing the influence of leaf litter on seed germination of many native plant species [ 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 ].…”

“…Non-native woody plant species (shrubs and trees) often produce an abundant and thick leaf litter layer which can inhibit the germination, survival, and recruitment of native seedlings in native plant communities [ 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 ]. For many of these non-native species, the suppressive effects of a thick litter layer are amplified by the production and release of allelopathic compounds from this accumulated litter layer and other tissues (i.e., the “Novel Weapons Hypothesis”) [ 51 , 52 , 53 , 55 , 56 ].…”

“…The effects of leaf litter on plant populations and communities are determined by a complex set of interacting factors: habitat type, which species are present, litter depth or abundance, the chemical composition of litter, seed characteristics, and the position of seeds in the litter [ 9 , 10 , 11 , 24 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 ]. Chief among these factors is litter abundance and depth [ 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 ]. Thus, in this study, we tested the effects of four P. juliflora leaf litter depths (1–8 cm) on seedling emergence, seed germination, and seed viability of P. juliflora , under greenhouse and field conditions.…”

“…This can occur when invasive plants form extensive monocultural stands, produce large amounts of biomass, and generate an abundant and thick litter layer [ 36 , 37 , 49 ]. Thick litter layers produced by numerous invasive plant species have been reported to suppress the emergence, survival, and recruitment of native plant seedlings [ 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 ]. In some cases, the litter of invasive species also contains allelopathic compounds that are released into the environment as their litter decomposes and these compounds inhibit the seedlings of native plant species [ 51 , 52 , 53 ].…”

Effect of litter decomposition on mowing and plant composition change during Solidago stand restoration

“…In a pot experiment conducted in China, a positive plant-soil feedback for soil nutrients and a negative plant-soil feedback for growth in native Sphagneticola calendulacea resulted from the breakdown of litter from the invasive Sphagneticola trilobata (Sun et al, 2022b). However, invasive grass litter has been shown to stunt development and increase disease in native species (LaForgia, 2021;Benitez et al, 2022). Through interactions between microbial and microfauna, invasive plants can accelerate the degradation of organic P (Sun et al, 2022a).…”