Wednesday, January 07, 2026

December 2025 Survey Volunteers Email

Hi, Survey Volunteers for Fairfax Tree Rescuers PRISM,

Thank you all so much for volunteering to do surveys of invasive plants. We commend those of you who have worked through the detailed instructions and started surveying the parks!

To make it easier to find the instructions later, you can now see links to them on the Surveying Invasive Plants page of the Fairfax Tree Rescuers PRISM website.

Here is something new we hope you will do.

Site-level Surveys

iMapInvasives is great for marking major infestations of individual species, but it doesn’t tell us much about the park as a whole. For that, we now have a separate, user-friendly questionnaire and would be grateful if you could bookmark the form and fill it out for any park you have covered. This will tell us how many trees are at risk and how the invasives are affecting access to the park for people and wildlife as well as the overall quality of its habitat. Knowing this information will help us as we approach neighborhoods and businesses to adopt the parks.  We plan to display the results on a map on our website (You can get a feel for the map here, although this is not the final version.)

And here are a few reminders.

Levels of expertise

Invasive plant surveys aren’t for everyone.  We need relatively robust identification of the species to effectively develop management plans. So, if your tolerance for new technology is low, and/or if you have little plant ID experience, don’t feel obligated to do comprehensive park surveys. You can instead do a great service by doing simple residential tree counts, dropping off door hangers as you do it. Details and instructions are on the Plant NOVA Trees website. Please just let us know so we can update our records.

If you are still motivated to survey, and your plant ID skills need some work, please use a plant identification app like iNaturalist, Seek or others to validate your identification. These apps are a great way to hone your skills. Over time, you’ll find yourself quite good at it. The more people in Fairfax who know these plants, the more effective we will be!

Using iMap in Winter

For volunteers with a lot of experience with winter plant identification, this can be the perfect time to assess woody species. For those with less winter plant id experience, it is still a great time to assess certain species including English Ivy, Wintercreeper, Japanese Barberry, Multiflora Rose, and evergreen groundcovers. In either case, a second visit to each park in the spring would be very helpful to complete the full assessment.

By “severe,” we mean really severe!

Your apps should be set up to default to tag your observations as “severe invasive plant infestations.” If you are observing something less than that, please be sure to change that project tag by unchecking “severe invasive plant infestations in the iMap 2 Projects field! We spell out what we mean by severe in the instructions, but in brief, it means an area that is dominated by invasives to the great detriment of everything else, more than just a few trees or shrubs in a row.

Clear photos

If you are using the simpler of the iMap mobile apps, it only allows you to give us one photo. Please make it a clear one, close up, of the right part of the plant for us to be able to confirm the identification and add the observation to our dataset. Since we can’t tell severity from that sort of photo, be sure to spell that out when you fill out the rest of the form, including using the comments as needed.

iMapInvasives Mobile App is not compatible with recent model Androids

We recently learned that the iMap mobile app is no longer compatible with some very new Android phones. We have been in contact with the developers, and they say it will take several weeks to update the app.  If you find that you cannot use the app, you have two choices.  Try using the Survey123 IMapInvasives app (see instructions in Detailed Surveys below), use the online version at iMapInvasives.org, or wait until Spring when everything should be fixed.

The map is not displaying on the iMapInvasives Mobile App, but the GPS IS working.

This has been the case for several months and the developer is working on it with their map vendor. Keep the GPS box checked to enter the location data.  For now, we can’t enter observations in the field if there is not a good signal.

Priority species

If you see Asian Wisteria, Kudzu, or Five-leaved Akebia anywhere in the county (parks or elsewhere), please add them to the map and use the same “Severe invasive plant infestations” project code that we do for park surveys. We want to get on top of these species, which are devastating but not yet so common that we can’t get a grip on them.

We are all new to this process, but please bear with us! You have already made great progress. Here are some statistics.

Survey Updates: As of November 16, 2025

Volunteer Engagement

  • Expressed initial interest : 135
  • Engaged in some way after contact :82
  • Created an iMap survey account: 53
  • Signed up to survey specific parks: 39
  • Completed at least one survey (uploaded records in iMap: 17

Parks Survey Coverage

  • Parks assigned to volunteers: 85/427 (20%)
  • Parks with observations: 38/427 (9%)

Total Number of “Severe Infestation" Observations: 712

Top 10 # Species with of Severe Infestation Observations

  • Porcelain-berry: 162
  • Wisteria (both species): 99
  • English ivy: 51
  • Japanese stiltgrass:45
  • Oriental bittersweet:44
  • Amur honeysuckle: 41
  • Multiflora rose:33
  • Japanese honeysuckle:32
  • Kudzu:22
  • Autumn olive:22

Note: This does NOT necessarily mean these are the most abundant invasives in the county.  Observer bias and ease of identification and affinity of some species for light gaps near trails may skew results. Also, with the exception of Wisteria, most surveys began after June 2025, so species that are most obvious in spring and early summer may not have been detected.

Areas Most in Need of Additional Surveyors

Western / Central Fairfax

  • Chantilly
  • Greenbriar
  • Bull Run

Northern Fairfax

  • Tysons/McLean

Southern / Southeastern Fairfax

  • Franconia
  • Springfield
  • Newington
  • Mount Vernon

Volunteer Needs

  • More Surveyors!