Severe Infestation Surveys
Fairfax Tree Rescuers PRISM
Updated 6/15/2025

We are hoping to survey every park in Fairfax to find and document the most severe infestations, mapping them as Presence Records in iMap. To keep track of which areas have already been surveyed and are clear of severe infestations, we will also use the Not Detected option.

Please first see general instructions for using the web-based and mobile app versions.

Reminder: Surveyors should create one iMap location record for each species surveyed.

1. Before you go out, look at the map and see whether the park has already been surveyed for severe infestations.
   1. Log in
   2. On the right, click on Layers On/Off and turn on Search Areas.
   3. At the top, click on Filter Records. Under Project, type in “Search for severe infestations.”
   4. Zoom in to the area of interest and wait until the little circle stops spinning, which may take a minute.
2. Methodically walk through your chosen park or section of park, looking for severely infested areas (see below). There are two ways to do this.
   1. Easiest: Take a walk
      1. Walk along a trail or road.
      2. Photograph the infestations as you go along.
      3. When you get home, open the map on the web and draw a line to show other people where you have already looked for severe infestations.
         1. Create Record
         2. Use the Mutli-record Search Area for this one purpose.
         3. In the first field (Searched Area), choose “Line” (as opposed to point of polygon.) Draw a line along your route.
         4. Select “Buffer” and indicate the relative distance from the trail you were searching. If you were just looking about 2 meters from the trail, enter “2”. If you were searching for and detecting trees 20 meters from the trail, enter “20”. Approximate distances are fine.
      4. Add Presence Records
         5. You can now enter the species you saw by selecting “Point”, “Line” or “Entire Searched Area” Use Points for individual observations of species that have smaller areas (like a grove of trees covered in ivy) Use lines for linear features like a long bank of multiflora rose that is almost continuous along the trail. Place your presence record anywhere in your buffered search area.Make multiple records for species that you see in multiple places along the trail, such as Japanese Stilt Grass or Japanese Honeysuckle.
         6. Under Tagged Projects, use the location project (such as FCPA). Add another tag to indicate “Severe” vine, tree or ground layer infestations.
         7. In the comment section, note which kind of infestations you were not able to search for, either because it was the wrong time of year or you don’t have the experience. A beginner, for example, might say “Only looked for severe vine infestations on trees.” An expert still couldn’t see some ground-layer plants such as Lesser Celandine in the winter.
      5. “Create Record” from scratch for each severe infestation (if there were any) using the Presence function this time and either points or polygons (polygons are best for large areas). See How to Map Severe Infestations (below).
   2. More methodical: Survey a polygon
      6. Same as above, only use a polygon for the initial searched area instead of a line.
3. How to map severe infestations
   1. Create a separate record for each severe infestation. Use polygons for larger areas. Approximation is fine.
   2. In infestations consisting of a mix of species, choose the one that is most dominant. (You could mention the others in the comment box if you like.) If you are unable to identify the most dominant species, either because you are viewing it at a distance or because you don’t yet have the knowledge, use “A Fake Species” and say something about what you saw in the comment box. “A Fake Species” is currently only available in the web version and not on the Survey 123 app. If you are using the app, you can edit the species name when you get back to your computer.
   3. Choose one of the four severe infestation Project codes below plus the appropriate location code. TIP: If you upload your photos to Google Photos, you can get a map that shows where the photo was taken.

How do we define “severe?”

• Severe vine infestations: English Ivy or Wintercreeper reaching up high into multiple trees. Strangling vines severely affecting multiple trees. Smothering vines blanketing the canopies. We always consider Wisteria and Kudzu severe, even if there isn’t that much of it. The most common other examples are Japanese Honeysuckle, Porcelain Berry, and Oriental Bittersweet.
• Severe tree infestations: Large areas dominated by invasive trees. The most common examples are Callery Pear and Tree-of-Heaven.
• Severe shrub infestations: Large areas where invasive shrubs are covering almost everything underneath. The most common examples are Multiflora Rose, Amur Honeysuckle, Japanese Barberry, and Burning Bush.
• Severe ground-layer infestations: Large areas where the ground-layer is almost entirely occupied by forbs (annuals or perennials such as Lesser Celandine) or grasses (such as Chinese Silvergrass).

How do we define “large?” Use your judgement.

Project numbers:

• 1625 VDOT rights of way - all
• 1626 VDOT rights of way - inaccessible to volunteers
• 1634 City of Fairfax Parks
• 1633 Clifton, VA parks including CBA
• 1629 Commercial properties
• 1630 Fairfax Board of Supervisors land
• 1635 Town of Herndon parks
• 1637 Town of Vienna parks
• 1640 Faith communities
• 1636 Falls Church, VA parks
• 1627 FCPA properties
• 1632 FCPS (Fairfax County Public Schools)
• 1628 HOA common land
• 1631 Multi-dwelling unit common land
• 1638 NOVA Parks
• 1639 Single family home properties
• 1642 National Park Service (NPS)
• 1643 Military
• 1644 Railroad rights of way
• 1645 Federal lands
• 1646 State parks
• 1647 Severe vine infestations
• 1685 Severe tree infestations
• 1686 Severe shrub infestations
• 1687 Severe ground-level infestations
• 1690 Search for severe infestations