You Can’t See the Woods for the Trees: Invasive Acer negundo L. in Urban Riparian Forests Harms Biodiversity and Limits Recreation Activity

Abstract

Public access to high quality green environments has become a key issue for city managers and a matter of environmental justice. Urban pressures on ecosystem remnants may act to favor the expansion of some invasive species in cities. Whilst the negative impacts of invasive species on ecosystem function is well documented, little is known about how invasive species influence the use of green space by people. Here, we examined one of the few remnants of urban riparian forests in Europe, the Vistula river valley in Warsaw, which has recently become an attractive recreation site. Despite their high ecological value, the poplar and willow forests have been increasingly taken over by the invasive tree species Acer negundo. We examined the status of the invasion process and the relationship between recreational ecosystem services and the characteristics of the tree stands—tree species, tree density, and age and NDVI values. We found the willow forest to be more susceptible to invasion by A. negundo than the poplar forest, which was revealed in significantly higher share of the maple individuals and their greater volume per unit area. Ash-leaved maples also prevailed in numbers in younger stands (<10 years) than in older ones. The presence of A. negundo affected biodiversity, resulting in decreased undergrowth density and biodiversity expressed in number of species. The use intensity by the public, assessed on the basis of soil compaction of existing informal tracks, as revealed by GLM analysis, was related to volume of invasive maple and distance from the main track. This study highlights the need to integrate invasive species management into green infrastructure planning and management.

Significance of Urban Vegetation on Lawns Regarding the Risk of Fire

“…If the biomass dries out toward the end of summer and at the beginning of autumn in association with the end of the growing season, fruits and seeds ripen and above-ground parts of plants gradually die. In this period, the representation of dicotyledons such as Acer negundo, Artemisia vulgaris, Medicago sativa, Melilotus officinalis, and Rosa canina is particularly important [48][49][50]. The biomass of these species increases the risk of fire.…”

The Hidden Potential of Informal Urban Greenspace: An Example of Two Former Landfills in Post-Socialist Cities (Central Poland)

“…The first group of analyses addresses all urban degraded areas, both built-up post-industrialised and lost or uninvested open spaces [51]. Most of the evaluation studies also discuss specific issues such as the accessibility assessments of these places [52], economic and recreational values [53][54][55][56][57][58][59][60][61][62] and only natural values or quality of the natural environment of abandoned urban spaces [1,27,63]. The second group of analyses concerns public spaces on the city scale, which might be used for comparative analyses of other similar areas or in the context of ecosystem services [6,21,22,[64][65][66].…”

Roślinność wieloletnich nieużytków miejskich – systematyka zbiorowisk, ich struktura i pełnione usługi ekosystemowe = Vegetation of perennial urban wastelands – syntaxonomy, structure and ecosystem services

“…Roślinność łęgów Populetum albae var. Acer negundo w strefie miast jest szczególnie silnie podatna na antropopresję (Dyderski i Jagodziński, 2019a;Sikorska et al, 2019). Zanik epizodycznych zalewów spowodowany zmianami klimatu i regulacjami koryta górnego biegu, postępujący proces grądowienia i wynikający z tego ciąg sukcesyjny prowadzi do regresji zespołu.…”

“…Zagęszczenie zdrewniałych pędów roślin w nieużytkach znajdujących się w dolinie rzecznej jest zbliżone do zagęszczenia spotykanego w łęgach o podobnym wieku (Sikorska et al, 2019). Może to wynikać z powszechnie występujących na tych nieużytkach topól i wierzb, które dzięki bardzo dużym obwodom pni zawyżają ogólne zagęszczenie zdrewniałych pędów.…”