Context-Dependence of Urban Forest Vegetation Invasion Level and Alien Species’ Ecological Success

Abstract

Research Highlights: Urban ecosystems are claimed to be more invaded than natural vegetation. Despite numerous studies, the patterns of alien species occurrence in urban forests are rarely linked to invasion ecology hypotheses. Background and Objectives: We assumed that patterns of invasion level (i.e., neophyte richness) and neophyte ecological success (cover) are context-dependent, i.e., depend on the type of vegetation, and that hypotheses connected with empty niche and biotic acceptance will have the strongest support in urban forests. We also tested biotic resistance, habitat filtering, disturbance, resource availability, and environmental heterogeneity hypotheses. Materials and Methods: Using a random forest algorithm, we tested the importance of factors related to invasion ecology hypotheses in a dataset of urban forest vegetation plots (n = 120). We studied seven types of forest plant communities occurring in Poznań (W Poland) and we assessed the vegetation’s taxonomic and functional composition. Results: We found that models of alien species richness and cover explained 28.5% and 35.0% of variance, respectively. Vegetation type was of the highest importance in both cases, suggesting that the occurrence of alien plant species is context-dependent. Resource availability and disturbance ecological indicator values were also of high importance. Conclusions: Our study supported resource availability and habitat filtering hypotheses as explanations of the level of invasion and ecological success of alien species in an urban forest, with partial support for the disturbance hypothesis. Our study revealed that predictors of invasion level are context-dependent, as patterns of alien species richness and cover differed among vegetation types. We highlight context-dependence of alien species invasion patterns in different vegetation types due to the habitat-forming role of dominant tree species and different availability of resources and disturbance levels, as well as different pools of native species. Thus, prevention and management of biological invasions in urban forests should account for forest vegetation type.

Alien plant invasion hotspots and invasion debt in European woodlands

“…Our results also join an increasing number of studies that found habitat type to be an important predictor of the magnitude of invasions (Chytrý et al, 2008a; Pyšek et al, 2010a; Pyšek & Chytrý, 2014; Dyderski & Jagodziński, 2019). Our study encompassed a smaller set of habitat types than Wagner et al (2017) due to stronger data filtering.…”

Emerging Urban Forests: Opportunities for Promoting the Wild Side of the Urban Green Infrastructure

“…The degree to which alien species are drivers or passengers of change [84] in urban environments likely depends on the characteristics of the dominant species and the particular ecosystem types [85]. Yet there is limited evidence about the role of emerging urban forests in large cities and their domination by native or alien tree species.…”

The Hydrological-Hydrochemical Factors that Control the Invasion of the Black Locust (Robinia pseudoacacia L.) in Succession in Areas with Opencast Mines

“…Based on the species composition, it can be concluded that the adjacent forest resembles the human-cultivated forest Chelidonio-Robinietum Jurko 1963 s.l. [ 43 , 44 ]). Taking into account the relatively small distance from the adjacent forest to the territory of the mine including the sandy habitats, the transport of seeds by the wind could be efficient enough to disperse this plant.…”