Climate change, snow mold and the Bromus tectorum invasion: mixed evidence for release from cold weather pathogens.

TL;DR: In this paper , a 15-year monitoring dataset of more than 53,000 seedlings in a temperate forest was used to examine the role of interannual climate variability in driving local community dynamics.

Abstract: The enemy release hypothesis proposes that invasion by exotic plant species is driven by their release from natural enemies (i.e. herbivores and pathogens) in their introduced ranges. However, in many cases, natural enemies, which may be introduced or managed to regulate invasive species, may fail to impact target host populations. Landscape heterogeneity, which can affect both the population dynamics of the pathogen and the susceptibility and the density of hosts, may contribute to why pathogens fail to control hosts despite established negative disease impacts. We explored patterns of post‐fire infection of the fungal head‐smut pathogen Ustilago bullata on the invasive annual cheatgrass Bromus tectorum, which has caused the notorious grass‐fire cycle and ecosystem degradation across Western North America. We asked whether infection level was a driver of host density or vice‐versa, and how weather affected infection and how spatial patterns of infection varied with time since fire, using a combination of structural equation modelling (SEM), proportional odds modelling and entropy‐based local indicator of spatial association (ELSA) on data from >700 plots spanning >100,000 ha remeasured annually for 4 years. Observed infection levels increased with greater prior‐year cheatgrass cover, and disease severity did not suppress cheatgrass populations. Warm, humid fall/winters and proximity to fire refugia (unburned patches) were associated with more infections. Infection clustering was most evident 2–3 years following fire with warm‐wet fall–winter conditions and decreased after two drier, colder winters. Synthesis. Severity of fungal disease did not result in measurable reductions of populations of a non‐native, invasive host species, cheatgrass, which suggests that natural enemies may not strongly regulate cheatgrass in its introduced range. Landscape heterogeneity associated with disturbance and weather limited population‐level infection of hosts by the fungal pathogen. Disturbance (specifically wildfire) and variable weather are key components of this and similar invasion systems, and likely need to be considered when evaluating disease dynamics and potential for natural enemies to influence invasion potential.

TL;DR: Ricks et al. as discussed by the authors found that plant salinity adaptation depends on interactions with soil microbes, and found that the salinity of plants adapts to salinity changes with the amount of salinity in the soil.

TL;DR: A systematic literature review as discussed by the authors evaluated how well peer-reviewed journal articles and formal technical reports published between January 1, 2015, and December 31, 2020, addressed six needs (hereinafter “Needs”) identified under the Invasives topic in the IRFMS.

TL;DR: In this article, a model is described in an lmer call by a formula, in this case including both fixed-and random-effects terms, and the formula and data together determine a numerical representation of the model from which the profiled deviance or the profeatured REML criterion can be evaluated as a function of some of model parameters.

TL;DR: In this article, a model is described in an lmer call by a formula, in this case including both fixed-and random-effects terms, and the formula and data together determine a numerical representation of the model from which the profiled deviance or the profeatured REML criterion can be evaluated as a function of some of model parameters.

TL;DR: Biological invasions into wholly new regions are a consequence of a far reaching but underappreciated component of global environmental change, the human-caused breakdown of biogeographic barriers to species dispersal.

TL;DR: It is concluded that in order to reliably predict the effects of GEC on community and ecosystem processes, the greatest single challenge will be to determine how biotic and abiotic context alters the direction and magnitude of G EC effects on biotic interactions.