The purpose of this document is to provide guidance for collecting soils for testing in the Forest Health Watch program. This document is a working draft. Please send any feedback or questions to foresthealthwatch@gmail.com or complete the contact-us form at https://foresthealth.org/

Microbes and tree roots study

Community scientists are needed to survey the microbes associated with the roots of healthy and unhealthy trees. The aim is to collect information about the microbes interacting with the roots of trees to identify the microbes benefiting and affecting tree health.

Summary of Steps to Participate

Acquire sampling materials
Collect soil samples, tree and site data
(Optional) Add observation of trees to relevant iNaturalist project
Store samples
Submit samples for testing
Stay tuned or follow up about testing

Complimentary iNaturalist Projects

Western Redcedar Dieback Map - Regional project collecting observations of healthy and unhealthy western redcedar trees.
Bigleaf Maple Health Watch - Regional project collecting observations about healthy and unhealthy bigleaf maple trees.
Western Hemlock Health Watch - Regional project collecting observations about healthy and unhealthy western hemlock trees.

Materials Needed

Before setting out to collect soil samples, please acquire the following equipment and supplies:

Hand Trowel or Shovel

We recommend hand shovels that will be easy to clean, avoid shovels that have areas where soil can accumulate and be difficult to remove.

Rag to remove soap from shovel after sterilization.
Zip-top bags (1 gallon or less)
GPS or mobile device to collect coordinates
Materials to remove residual social and sterilize shovel between samples. Any of the following methods or supplies are suitable:

Bucket with scrub brush and soapy water (our favorite)

Note we recommend using biodegradable soap

Disinfectant wipes -

Bleach wipes are okay, but be diligent to remove bleach before collecting next sample

Disinfectant spray - surface cleaners are generally effective at sterilizing the surface, but be vigilant to remove all soil particles.

Soil water, scrub brush, shovel

Shovel, zip-top sample bags, GPS, bucket with soap water and scrub brush

Data Collection

Descriptions about the site and trees will be helpful for analyses. Overall, if you can add an observation of each tree sampled to the iNaturalist projects mentioned above, it will provide most of the requested information below.

Site Data

Multiple samples can be collected from a single site. Generally, if samples are collected within a few hundred feet of each other, these samples can be considered from the same site. However, if samples are from substantially different areas (e.g. top of a slope vs the bottom of a ravine) or if they are spread far enough away to justify a different GPS location, please record it as a different site.

Please record the following information about the site

GPS coordinate - Please record the GPS location or address, or take a note that will help you identify the coordinates from google maps later.
Site description - Please indicate if the site is urban, natural, managed, or a mix.
Disturbance level - please indicate if there have been any activity that may have introduced new microbes to the site (e.g. recent harvesting, trail building, near recreation, etc).
Slope position - Please indicate where the site is in the landscape (ie is it in the bottom of a ravine, in the middle of the slope, or the top of a peak?).

Tree Data

In general, we’re interested in linking the presence or absence of microbial species to the health of trees. Therefore, it is critical to collect information about the health of the tree in addition to the other information listed below.

Please record the following information about the tree

Tree species (is it a Western hemlock, douglas-fir, bigleaf maple, western redcedar?)
Tree size (DBH if you have access, otherwise whether please comment about whether you can wrap your hands or arms around the trunk.
Tree health category (healthy, top dieback, thinning crown, dead)
Tree dieback percent (0 for healthy tree, 100 for dead tree)

Sample Collection

Locate the tree you’re interested in sampling

Collect samples from 4-5 spots around a tree within the canopy area (i.e. stay within 3 meters from the trunk of the tree).

Mix samples into a single sample bag (one sample bag per tree).

Remove litter and duff layers (leaves and decaying plant material) on top of soil before collecting

We want to avoid most of saprophytic microbes that help decay dead plant material

Collect about 500 grams (1 liter) of fine soil particles and small roots

Keep small roots in soil sample
Dig up to 10cm deep into the soil.

Sterilize sampling equipment before collecting next sample

Remove soil particles and sterilize shovels using the methods and supplies listed in the Materials Needed section above.

We recommend carrying a small bucket containing a liter of soapy water and a scrub brush.
Try your best to remove all residual soil particles from the shovel.

Wipe soap residue off shovel using rag or by following below method.

Stick shovel into the soil a few times (not in exact spot to collect sample) to remove soap residue when you arrive at the next tree you want to sample.

Sample Storage

Community scientists can store soil samples before submitting the samples to the lab in order to build a collection that can be submitted together.

Best practices for sample storage:

Keep in a cool dry area that best mimics the temperatures of the natural environment they were collected from.

Do not let the soils get too hot (ie in a car) or too cold. Please do not store the samples in the fridge.

Keep the zip-tops open to allow moisture exchange.

We would rather the soils dry out than trap moisture for molds to grow

Submitting Samples

Send or deliver the below samples to Joey Hulbert (hulbe@wsu.edu) at the WSU Puyallup Research and Extension Center. Samples can be placed in a cardboard box and sent via ground or any other standard method. We have also received samples in old ice-cream containers and paper bags. Please feel free to email Joey with any questions.

Click here for the lab location on Google Maps.

Send samples to:

ATTN: Joey Hulbert

WSU Puyallup Research & Extension Center

2606 West Pioneer

Puyallup, WA, 98371-4998 USA

What to expect from the Lab

Sample processing can take a while depending on lab capacity. A lot of time and funding is required to identify microbes in soil. Feel free to email Joey or foresthealthwatch@gmail.com about the status of your submitted sample.

Sample processing:

The Forest Health Watch program generally uses about half of the submitted sample to test for the presence of Phytophthora first (see below). Phytophthora are a group of microbes notorious for causing many tree diseases, including Port-Orford cedar root disease and sudden oak death.
The other half of the sample is saved for DNA extraction to more broadly identify the community of microbes (beneficial and antagonistic species) present in the soil. More funding is generally needed to complete this second step.

Phytophthora testing

Phytophthora can be isolated from soil because they produce swimming spores. Our lab tests for Phytophthora by flooding the soil samples with water, floating leaves on top of the water as bait for Phytophthora spores, and then growing Phytophthora from infected plant material on petri-plates.

Scheduling Group Hikes

Collecting soil samples can be a fun way to add purpose to hikes and other forms of recreation. It is also a great reason to organize an educational hike or plan an activity with a group. Please contact us if you’re interested in organizing an educational hike to sample an area with a group.

https://foresthealth.org