IPC Programs
Projects & Resources
Yellow Starthistle Mapping Project: Cooperative Survey 2000
Introduction
The Yellow Starthistle (YST) Mapping and Assessment Project is a long-term inter-agency/organization effort aimed at:
- Measuring the eastward and upward movement of YST in west Sierra Nevada watersheds and
- Producing a plan to stop (or reverse) further spread.
Integrated control of YST, in areas where it is heavy, is not the focus of this project. The search for YST, and its mapping, will be a joint effort by professional field personnel and private individuals from all agencies and organizations in the Sierra Nevada. This project will serve as a conceptual umbrella for all currently existing local YST mapping projects underway, and will attempt to encourage local people to fill in the "gaps" between these ongoing projects. If you live near or visit this area and want to help with this effort, please read the following instructions and contact the appropriate Weed Management Areas (WMA).
Inventory of YST will be focused in the zone where it transitions from being wide-spread to very patchy or isolated. Outlier populations - those which are greater than a mile away from other known populations and are smaller than an acre in size are especially important to identify because they can be easily eradicated before they spread to adjacent areas. If you find such a population please use the Outlier Form to fill out the necessary information and send the form to the project contact or local WMA.
Mapping should not be carried out on private property without the owner's permission, except for what can be observed from a public access right-of-way.
Do not enter a private parcel for detection purposes without the owner's permission! Private land inventory will be coordinated locally by the County Agricultural Commissioner, the Resource Conservation District, the Weed Management Areas, and/or other local landowner or agriculture groups.
Mapping Instructions
MAPPING WHERE YST ISN'T IS JUST AS IMPORTANT AS MAPPING WHERE IT IS!!
In other words, keep track of where you have searched and not found YST. This will allow us, over time, to know which areas have not been surveyed for this project. It will also allow for analysis of spread and help measure the effectiveness of this project.
Send data to your local county mapping coordinator or to CDFA state office in Sacramento.
HAND MAPPING
Yellow starthistle (YST) occurrence and areas that have been surveyed can be hand drawn onto USGS "Topo" or 7.5' Quad maps, US Forest Service maps, local AAA maps, county "blueprint maps", assessor parcel maps, etc. For the regional mapping desired accuracy is approximately 100 meters or 1/15 mile. USE A YELLOW "HIGHLIGHTING PEN" TO MARK AREAS THAT WERE SURVEYED BUT NO YST WAS FOUND. Project maps are available.
Point Infestations:
Point infestations should be identified by an X, a triangle or a square drawn directly on the base map.
Use green or red ink (or any color but black). (Greater than five acres draw as a polygon)
X = less than 0.1 of an acre
= 0.1 to 1 acre
= 1 to 5 acres
Line Infestations:
Line infestations are used when weeds follow linear features such as roads or streams. The lines can be any length. When identifying lines, include the line width (real world width of the infestation) and center the line on the middle of the infested strip.
Area Infestations:
Infestations larger than 5 acres should be outlined on the map. A square, five acre infestation is 217,800 ft2, or approximately 467ft on a side. Therefore, a five acre infestation drawn on a 1:24,000 or "quad" topo map would be about ¼ in. or 0.6cm on each side. The map set distributed with this project is gridded with section lines. Each section contains approximately 128 5-acre parcels, or around 11 on a side. Since most weed infestations aren't uniform and square, do your best to draw an approximately sized area that will depict the infestation's true size and shape.
= areas larger than 5 acres should be outlined directly on a map
Cover Class:
Weed cover class is an important way to estimate and describe the density of YST averaged over a population being mapped. To determine cover class, estimate the percent of the ground that is covered by YST in the infestation being mapped. Estimate an average value if the density is variable. Next to the map symbols write in one of the following cover estimates.
T = (Trace, rare); less than 1% cover.
L = (Low, occasional plants); between 1% and 5% cover.
M = (Moderate, scattered plants); between 5% and 25% cover.
H = (High, fairly dense); between 25% and 100% cover.
* These guideline are taken from the Montana Noxious Weed Survey and Mapping System Handbook.
GPS MAPPING
Data can be collected conveniently and accurately with a Global Positioning System (GPS) unit. There are 3 different options for submitting location data which originates from a GPS receiver. Always submit a map to go along with GPS readings.
- The latitude and longitude of a point location can be read from the GPS unit and transferred to a data sheet or written on a map. GPS units can display latitude and longitude in a number of different datums (eg., NAD27, NAD83, WGS84), which can produce different longitudes and latitudes for the same location. For this reason, please provide the datum in which the data was collected.
- GPS units made by manufacturers other than Trimble:
If the GPS can save readings and upload them to a personal computer, it may be possible to submit a file containing the readings. CDFA's Noxious Weed Information Project uses MapInfo for our GIS, so if your GPS software outputs data in a format suitable for MapInfo (.mif or .dxf files), that is one possibility. We can also convert ArcView shape (.shp) and ArcInfo export (.e00) files. Otherwise, if possible, provide an electronic list of latitudes and longitudes (and any data notations) in a plain text (ASCII) format. Provide an explanation of the data structure and the datum in which the data was collected. Also note whether the data were differentially corrected. - Trimble GPS units:
CDFA's Noxious Weed Information Project uses Trimble products. If the readings were taken with a Trimble unit (GeoExplorer, Pathfinder Pro XL, XR, XRS), the most useful format is a differentially corrected .cor file. An uncorrected .ssf file is also adequate. A word on datums and projections:
Save GPS digital files in their default datum and projection. This info needs to be submitted. For export files (see GIS Mapping below) record and submit datum and projection information. If datum and projection are not available, contact Rosie Yacoub or Pat Akers (916-654-0768).
GIS MAPPING
Data that has been entered into a GIS can be submitted in one of the following formats:
ARCVIEW Project format = *.apr
Shape format = *.shp
ARCINFO Export format = *.e00
-single precision only
-NOT ArcInfo compressed
MAPINFO Table format = *.tab
Export format = *.mif
Other: Where possible, data should be exported to one of the above formats. If you are limited to another format not included above, call Rosie Yacoub or Pat Akers (916-654-0768).
Note: Using pkZIP to compress files is OK.
Be sure to include all accompanying files. For example, MapInfo export format (.mif) usually has a second file with the same name and a (.mid) extension. MapInfo (.tab) file will have three or more files that accompany it using the same file name and different extensions.