Based on the attribute list, we had to find appropriate sources to acquire the attribute data for this project.
The INVADERS Database System (invader.dbs.umt.edu) is the largest
compiled historic data set on the distribution of exotic plant
species for a contiguous region in the U.S. (Montana, Wyoming, Idaho, Oregon, and Washington). This data source
consists of more than 88,000 distribution
records for approximately one thousand species exotic to North America. Each distribution record minimally consists of
the plant scientific name, county, and the year it was found. Other tables include where in North America a
plant has been declared noxious, life form, and scientific names of all native vascular plants found in those
five states. INVADERS provided data for the following attributes:
the studies outlined above rely on geographic data from native origin areas,
we decided to use the online source Flora Europaea (Pankhurst, 2002).
Flora Europaea provides
a list of countries in Europe where each plant is found. Every list also
indicated whether plants are native or exotic in those countries, or their origin
is unknown. Flora Europaea provided most of the data for the following attributes:
- Native genera: The data for this
variable was collected by counting the number of native
species for each genus.
- Number of counties: The data for
this variable was collected by counting the number of
counties where the exotic plant was reported.
- Number of records: The data for
this variable was collected by counting the number
of distribution reports in INVADERS.
- Life Form: Forb, tree, shrub, grass-like
or spore-bearing vascular plant.
- Spread rate: Calculated by the
number of occupied counties over the number of years since
- Noxious elsewhere: The data for this variable was acquired by counting the number
of states/provinces (outside of ID and MT), where the exotic plant is listed as noxious.
The attribute data was acquired by parsing the list
of countries and calculating the numeric data from the results. If Flora Europaea listed a plant either as native, exotic, or unknown in a
country, that value was parsed as either N, E, or U in an appropriate field carrying each country's name. Latitudinal
limits and area covered by each European county were determined from various map sources, often using
ArcView. Afterwards, the appropriate calculations were performed to determine the count, range, and total area where plants are native or exotic.
- Native range.
- Native count.
- Native area.
- Exotic range.
- Exotic count.
- Exotic area.
- Absolute range.
- Absolute count.
- Absolute area.
major difficulty with using this source was determining the
territory covered and latitudinal ranges of the former Soviet
Union floristic provinces as described in Flora Europaea. In
this particular case, we used Flora USSR (Komarov, 1968).
After reading Komarov’s descriptions of the former regions of
the USSR and reading a very old map, we outlined the Soviet
regions using Arcview 3.1, thus giving an estimate of
geographic ranges and territorial coverage. In order to obtain
geographic attribute data (such as latitude, boundaries and
area calculations) we used ArcIMS data set from ESRI
(producers of GIS and mapping software).
The Global Compendium of Weeds proved to be an invaluable source for acquiring data for the following attributes:
- Literature Count: The number of known weed literature sources as listed in The Global Compendium of Weeds----after parsing the data into a suitable format,
all literature sources were counted.
- Status Count: The number of statuses as listed in The Global Compendium of Weeds--after parsing the data into a suitable format,
all statuses were counted (Note: "Exotic" and "Casual alien"
- Cultivated: Whether or not a plant is cultivated or promoted for cultivation.
In order to obtain the vegetative reproduction status, we used a number of sources:
- ILPIN—the Illinois Plant Information Network
- INVADERS Database system
- Bailey, L.H. 1976. Hortus Third: A
Concise Dictionary of Plants Cultivated in the United States
and Canada. Liberty Hyde Bailey Hortorium, Cornell
University, NY. 1290 pgs
- Hitchcock, C. Leo, and Arthur Cronquist. 1973. Flora of the Pacific Northwest: an Illustrated Manual. University of Washington Press, Seattle, WA.730 pgs
The life history for all plants was obtained through John Kartesz’ Sysnthesis of the North American Flora.