The list of vascular plants for the city of Toronto

1. Urban areas have become epicentres for applied ecological and conservation research and policy. Yet, most urban areas have surprisingly little consolidated information about their biota, including species-at-risk and invasive species. 2. I used multiple data sources to compile a list of vascular plants for the greater metropolitan Toronto region. This data not only includes taxonomic information but also global and national status ranks, growth from, native status, threatened status, abundance estimates and year of first observation for non-indigenous species. 3. The list includes 1937 taxa from 146 families, of which 822 are non-indigenous. The majority of native species were ranked as abundant and widespread both globally and provincially. However, non-indigenous species ranks were bimodal, likely to be either extremely restricted in the province, or very widespread. 4.ThisdatabaseprovidesarobustlistofplanttaxainCanada’slargestcity.Itwillinform global urban ecology analyses and local and regional management and policy.


INTRODUCTION
Urban areas are of increasing scientific and management interest Lepczyk et al., 2017) because of both the impacts of human activity on ecosystems and the realization of the contributions of biodiversity to the delivery of services and benefits to people. Central to understanding both the impacts of urbanization and the potential benefits of biodiversity for urban ecosystem function, and service delivery is an accurate accounting of the species that occur in cities. Even though we know that cities can harbour important biodiversity elements  most city species lists are built from limited and incomplete sampling. Furthermore, cities are hotspots for the importation, establishment and spread of non-indigenous species (Cadotte, Yasui, Livingstone, & MacIvor, 2017). Thus, cities have an extremely important role to play in biodiversity conservation, but more accurate information about their biota are needed.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Toronto is Canada's largest city and supports a human population of about 6.4 million in the larger metropolitan region and covers almost 6,000 km 2 . Toronto sits on the north shore of Lake Ontario and covers a range of different habitat types including ravines, meadows, deciduous forests, wetlands and planted conifer forests. Toronto lies in the transitional zone between the mixed-wood plains and boreal shield ecoregions, and so is naturally situated in a biodiverse region, which is not uncommon for cities to be found in disproportionately biodiverse regions (Schwartz, Thorne, & Viers, 2006).
In the past decade, the city of Toronto has adopted a series of ambitious biodiversity and natural area management policies (City of Toronto, 2019). Yet sound municipal urban ecology policy and management require robust data on the taxa inhabiting a city, especially about the abundances of rare and invasive species. To ensure that adequate data is available for policy, management and urban ecological analyses, I created a master plant taxa list for the Greater Toronto Area, which includes information about the global and provincial statuses, estimates of abundance and time since introduction for nonindigenous species. 6. Herbaceous/shrub: a plant that appears as an herbaceous plant in some conditions and as a shrub in others.

MATERIALS AND METHODS
7. Herbaceous/vine: a plant that appears as an herbaceous plant in some conditions and as a vine in others.
8. Shrub/tree: a plant that appears as a shrub in some conditions and as a tree in others or is at the boundary between shrub and tree growth forms.
9. Shrub/vine: a plant that appears as a shrub in some conditions and as a vine in others.
In addition to species ranks and risk status, estimates of abundance from the number of occurrences of species in the ROM and the GBIF lists were included. I also created a composite abundance measure from the ROM and GBIF estimates by scaling both sets to be between 1 and 100 and taking the average of the two. Either the scaled ROM or GBIF estimates were used if the other was missing. I rounded the combined estimates to the nearest whole number. Further, the first date of observation for non-indigenous (introduced) species in the ROM list was also included.

USAGE NOTES
I did not personally observe all of the species included in this list.

Instead I relied on correct identifications by other botanists, ecologists
and local naturalists. Based on available taxonomic and biogeographic information, I reclassified taxon names based on the likelihood of their being present in the city, and I made the following name changes (independent of taxonomic updates):
While the plant list includes species from both Pteridophytes (clubmosses, ferns and horsetails) and Spermatophytes (seed plants), the sources used more consistently recorded Spermatophytes, and so the list of Pteridophytes is likely to be incomplete. Furthermore, subspecies, varieties, etc., were likely to have been inconsistently identified or included, and so the taxa list underrepresents the full number of these subspecific designations present in the city. It would be prudent to analyse patterns at the species level only.
This plant list can benefit applied management and city policy by providing a baseline inventory and historical information to guide future action, and to provide better estimates of species rarity and invasion in Toronto. As an example, this list is currently being used to implement a non-native species management prioritization assessment (Potgieter, Shrestha and Cadotte, unpublished manuscript). Such lists can be utilized for global scale compendium of both urban biodiversity (e.g., https://sites.rutgers.edu/urbionet/) and urban invasions (e.g., https://cubes-labs.com/gubic/). This list has use for education and outreach to train in the identification of urban taxa.

GENERAL PATTERNS
The Toronto plant list generated includes a total of 1937 plant taxa in 146 families. Most families contain few species in the city, with 105 families each containing 10 or fewer species (Figure 1). The four largest families, Asteraceae, Cyperaceae, Rosaceae and Poaceae, contained more than one-third of the Toronto species (664 species).
Of the 1937 species recorded in Toronto, more than 40% (822)  Most Toronto plants were herbaceous (60% or 1154 species), followed by graminoids (17% or 324 species) (Figure 2(d)). Shrubs (8.1% or 157 species) and trees (7.6% or 147 species) made up about equal proportions of the species list. The remaining five growth form categories all contained fewer than 5% of the species (Figure 2(d)).
Unlike for native species status ranks that were strongly skewed to 4 and 5, the status ranks of non-indigenous species were bimodal (