Resources
Use the resources below to help you establish and monitor a Hemlock Health Monitoring Plot.
There are three steps to establishing a Hemlock Health Monitoring Plot:
- Select a site to establish a plot or plots
- Tag your trees and conduct your initial survey
- Survey all dead trees in your plot(s)
After you have completed these three steps to establish your plot, your only task is to revisit it annually for a survey. We are in the process of developing an app to help you easily collect and submit data on your plot establishment and survey. In the meantime, we have developed datasheets for each step that you can print out and bring with you into the field to collect data. If you would prefer to instead collect data using Survey123 or another app, you are welcome to do so. Until the app has been developed and released, all data (whether collected on printed datasheets or through a different method) should be transcribed into the spreadsheet linked below and emailed to statonlabapps@gmail.com.
Hemlock Health Monitoring Plot DIGITAL Datasheet
In our printable datasheets, the first year’s survey is included in the tree tagging and setup datasheet so that you can collect data on your trees as you tag them. There is a second datasheet you can use for annual surveys beginning in the second year that omits data that will remain consistent year-to-year (such as the GPS coordinates of each tree) and adds data that would be redundant in the first year (such as whether you found your tree and it is alive). The following printable protocol may be useful for data collection; you may wish to print it out to bring with you into the field.
Hemlock Health Monitoring Plot Protocol
The rest of this page covers plot establishment and surveying in depth, including guidance on how to estimate the level of HWA/EHS infestation and crown health. The four associated datasheets are linked individually after each descriptive section. You may also download all the datasheets simplified into a single, printable pdf by clicking the button below:
Hemlock Health Monitoring Plot Datasheets
Our digital training video (below) shares tips and tricks for plot establishment and data collection.
Step 1: Site selection and plot establishment
In this protocol, a “site” refers to the general area where you are establishing a plot or plots, such as a property you own or manage. The first steps on this datasheet are to enter the address of the property and sharing information about its management, ownership, and rules of access.
Once you know the general area where you will operate, you can establish your plot or plots. Each site can have up to 3 plots as long as these plots are at least 50m or 150ft away from each other. You may choose to establish more than one plot if you have extra capacity or unique habitats within a single property. Establishing a plot involves marking its boundaries, collecting a central GPS coordinate, and answering questions about the plot’s habitat, slope, soil type, and history of infestation by HWA and EHS.
Click the button below to download the datasheet used to collect information on your site and associated plot(s).
Basic Information and Setup Datasheet
Step 2: Tree tagging and initial survey
Once you know where your plot will be, you can begin tagging trees. As you tag trees, take a GPS coordinate at each tree. You can also collect your first annual survey at this time, which involves measuring each tree’s DBH (diameter at breast height) recording the level of infestation of HWA and/or EHS at each tree, estimating each tree’s crown health, and reporting each tree’s canopy position.
Please only include trees that are at least 4″ in DBH. In our datasheets, DBH should be reported in inches to the tenth of an inch. If you measure your trees’ DBH in centimeters or measure the diameter for later conversion, please be sure to send in your final data in inches to the tenth of an inch.
You will be asked to record the level of infestation on each tree by HWA and EHS as heavy, moderate, light, or uninfested (see example photos below). If you are unable to see any twigs on a tree, you may also write “I’m not sure.”
HWA Infestation Level
EHS Infestation Level
The next datapoint you will be asked to assess on each tagged tree is crown health. For this protocol, there are three potential categories of crown health: healthy, in decline, or severe decline. A hemlock tree with a healthy crown would have at least 80% of its original crown density. It should have deep green, dense foliage, and if you look up through the tree, most of the sky should be blocked by its needles (see the photos below).
Hemlock trees with “healthy” crowns
The “in decline” crown category is a spectrum; a hemlock tree in this category could have anywhere between 20% and 80% of its original crown density. The tree’s foliage will be beginning to thin and green-to-greyish in color. When looking up into the tree’s canopy, some light from the sky will be visible through its needles (see the photos below).
Hemlock trees with “in decline” crowns
A hemlock tree with a crown in “severe decline” will have less than 20% of its original crown density. These hemlock trees will have many dead limbs and sparse foliage. You may see the telltale “lollipopping” in these trees, in which they retain only the needles at the very top of the crowns. The sky will be highly visible when looking up through the tree (see the photos below).
Hemlock trees with crowns in “severe decline”
Finally, report each tree’s canopy position as “dominant,” “co-dominant,” or “overtopped.” A hemlock in the dominant canopy position is taller than all those around it. A co-dominant hemlock is the same height or nearly the same height as those around it. Hemlocks in the understory should be entered as “overtopped,” meaning that they are shorter than all the trees around them. If you include any trees that are isolated, you may be unable to assess their canopy position and can instead write “not applicable.”
Canopy positions
The datasheet below has space to record these data about 40 trees, or the number we hope you will include in each of your plots. Please use one row to record each tree and all its associated data.
There is one additional page at the end of the document. You may use that page to record additional information about your plot, such as the presence and species of seedlings or saplings, the presence of predators used for biological control of HWA, or any ongoing forest management in your plot. Collecting this additional data is optional–we do not require it for our purposes of tracking hemlock mortality. However, collecting data on these facets of your plot may help inform any future plot management you wish to do; a plot where the dominant regenerating species are all invasive or shrubby may require more intensive intervention as the hemlocks die than a plot with strong native tree regeneration in the understory.
Initial Tree Records and (Optional) Plot Information
Step 3: Dead tree survey
Your final step before submitting your first year’s data is to survey all the dead trees within your plot’s boundaries. This step is important to establish the baseline level of hemlock mortality in your plot. Without knowing the percentage of hemlock mortality at the beginning of the plot, we will not know when it has reached 80% of that mortality to begin monitoring for lingering hemlocks.
This survey is simple. First, measure each dead tree’s DBH if possible (e.g. if the tree is not lying on the ground half decomposed). Next, indicate whether the dead tree is standing or fallen. Finally, please let us know if there are signs that the tree is decomposing. This may look like bark falling off the tree, rotting wood, or the presence of fungi.
Use the datasheet linked below for your dead tree survey. There is no need to tag dead trees.
The data from your site selection and establishment, tree tagging and initial survey, and dead tree survey can be easily transcribed into the following digital datasheet. Once you have done so, please send it via email to statonlabapps@gmail.com.
Hemlock Health Monitoring Plot DIGITAL Datasheet
Annual Surveys: Year 2 and Beyond
In future years, the only step to complete is an annual survey of your now-established plot. This survey is very similar to your initial tree survey. However, there are a few key changes:
- There is no need to re-collect GPS coordinates for your tree locations. If you struggle to locate any previously tagged trees, you may benefit from referring back to your first year’s survey.
- Similarly, there is no need to re-identify the species of your hemlock trees. This is particularly true if you are north of Virginia, where the only hemlock trees present are eastern hemlocks (Tsuga canadensis).
- We have added columns to indicate whether you are able to locate each tree from the previous year and whether that tree is alive. If you plot(s) are in a location that is beginning to decline from HWA infestation, some trees may die and fall. If you are unable to locate them or if they have died, you may indicate that in these columns. You can omit lost/dead trees from future years’ surveys.
- We have also added a column to indicate whether or not each tagged tree has received chemical treatment. We can most accurately track natural hemlock mortality if the trees in these plots do not receive chemical treatment, but we recognize that these difficult decisions may need to be made. If a tree in your plot does end up receiving treatment, we simply ask that you take note of it in your annual survey so it can be omitted from the mortality assessment.
Annual Tree Survey and (optional) Plot Information
To help you visualize the process of plot establishment, we are working on developing a training video. Once it is ready, it will be linked with the button below.