Analyzing the landscape characteristics promoting the establishment and spread of gorse (Ulex europaeus) along roadsides

Abstract

The International Union for Conservation of Nature listed gorse (Ulex europaeus, Fabaceae), a heliophilous evergreen shrub, as one of the world's 100 worst invasive species. Over the years, multiple attempts have been made for controlling gorse, including biological methods, but they have not been fully successful. This study aims to investigate some aspects that still remain unexplored such as the relationship between anthropogenic disturbances with the spatial mechanisms of species spread. We aimed to fill this gap by analyzing the role of transportation network configurations and landscape context on gorse propagation. We surveyed the presence of gorse in southern Brazilian forest‐grassland mosaics by completing landscape‐level road transects coupled with remote sensing, to evaluate land use and landscape structure. A binary logistic regression model was performed to test the influence of independent variables (e.g., road orientation, type and category in addition to distance to the nearest habitat patch of forest, grassland and anthropogenic area) on gorse occurrence. Our results showed that the structure of road networks can facilitate the spread of heliophilous taxa like gorse. Specifically, local, paved, NWSE and NS‐oriented (which exhibited high light exposure) roads had the highest probability of finding gorse. This suggests that human transportation activity (traffic, road construction, and maintenance) constitutes a significant dispersal agent for the species. In addition, the landscape matrix context also played a significant role; gorse was most prevalent along roadsides close to urban or agricultural areas than to forests and grasslands. No area was completely free from disturbances, such as fire, livestock grazing, and silviculture, in these seminatural landscapes. We concluded that, disturbances affecting small‐scale processes, at roadside and adjacent habitat patches, were probably as important factors explaining gorse occurrence as the urban impact. Furthermore, the current work also emphasizes the need of understanding the complexity of interacting factors. Our work has important implications for ecosystem conservation and habitat management, and consequently should be considered a prior step in establishing new approaches for gorse control.

Landscape correlates of forest plant invasions: A high‐resolution analysis across the eastern United States

“…Despite the limitations of observational data, most investigations of the role of roads in invasive plant ecology have used field survey or plot data. Many of those studies have been site-specific (e.g., Barton, Brewster, Cox, & Prentiss, 2004;Parendes & Jones, 2000;Underwood, Klinger, & Moore, 2004) or species-specific (e.g., Cordero, Torchelsen, Overbeck, & Anand, 2016;Davis, Singh, Thill, & Meentemeyer, 2016;Nielsen, Hartvig, & Kollmann, 2008). Survey designs to quantify the effect of distance from a road have included transects perpendicular to a road (e.g., Flory & Clay, 2006;Honu & Gibson, 2006;Pauchard & Alaback, 2004), comparisons of "road" locations with "control" locations (e.g., Christen & Matlack, 2009;González-Moreno, Pino, Gassó, & Vilà, 2013;Hansen & Clevenger, 2005;Yates, Levia, & Williams, 2004) and comparisons of road distance to "found" locations (e.g., Vieira, Finn, & Bradley, 2014;Western & Juvik, 1983).…”

Landscape structure and climate affect plant invasion in subtropical grasslands

“…Medeiros & Focht ; Rio Grande do Sul ; Guido & Guadagnin ; Cordero et al. ; see Appendix S2): Eragrostis plana, Cynodon dactylon , Senecio madagascariensis and Ulex europaeus . E. plana is also invasive in other regions of the world, with high potential for expansion, mainly in southern South America (Barbosa et al.…”

“…Spread of U. europaeus has been associated with the structure of road networks, suggesting that local and paved roadsides close to urban or agricultural areas and adjacent natural vegetation had the highest probability of invasion (Cordero et al. ). Less is known about C. dactylon and S. madagascariensis invasion mechanisms in south Brazil grasslands.…”

Biology, distribution and control of the invasive speciesUlex europaeus(Gorse): A global synthesis of current and future management challenges and research gaps

“…Weedy plant invasions have been recognised as one of the main causes of biodiversity loss around the world and of concern here is that although U. europaeus has been widely researched it is still widespread, problematic and a spreading weed that significantly impacts ecosystem functions and services across many landscapes (Altamirano et al, 2016;Atlan and Udo, 2019;Broadfield and McHenry, 2019). Extant research has focused on biological control (Ireson et al, 2003): burning for management (Anderson and Anderson, 2010); evolutionary change throughout the landscape (Cordero et al, 2016a); the effects of grazing (Gouldthorpe et al, 2006); the efficacy of herbicide application (Clements et al, 2001); and the mechanisms of seed germination (Udo et al, 2017). Previous reviews and literature on the management of U. europaeus have also been conducted and strongly focused on the species biology and management success in selected regions (King et al, 1996;Clements et al, 2001;Gouldthorpe et al 2006;Cordero et al, 2016a;Atlan and Udo, 2019;Broadfield and McHenry, 2019;Christina et al, 2019).…”

“…Extant research has focused on biological control (Ireson et al, 2003): burning for management (Anderson and Anderson, 2010); evolutionary change throughout the landscape (Cordero et al, 2016a); the effects of grazing (Gouldthorpe et al, 2006); the efficacy of herbicide application (Clements et al, 2001); and the mechanisms of seed germination (Udo et al, 2017). Previous reviews and literature on the management of U. europaeus have also been conducted and strongly focused on the species biology and management success in selected regions (King et al, 1996;Clements et al, 2001;Gouldthorpe et al 2006;Cordero et al, 2016a;Atlan and Udo, 2019;Broadfield and McHenry, 2019;Christina et al, 2019). However, notwithstanding the contributions of their research, some management strategies may not be appropriate to all infested regions around the world due to the complex landscape heterogeneity associated with this species, in addition to the difference in climatic conditions, soil types and cultural or economic circumstances associated with the invaded land areas (Cordero et al, 2016a;Kariyawasam and Ratnayake, 2019).…”