Queries about survey methods

[gunjan_sharma]

Hello,
I am currently engaged in an i-Tree Eco project in New Zealand, focusing on sample plot surveys and data collection within parks. I have a few questions regarding our methodology:

1. Regarding the measurement of Diameter at Breast Height (dbh), is it permissible to measure at heights other than the standard 1.4 meters? For instance, could we measure at 0.9 meters, provided that we clearly document and report this deviation?

2. When estimating ground cover, I'm seeking clarification on what should be categorized as "Herbs." Specifically, how would weeds like white clover and dandelions be classified—as grasses or herbs?

3. The i-Tree Eco project considers anything above 1 cm dbh as a tree. In this context, should we classify botanically categorized shrubs as trees if they exhibit a dbh of 1 cm or more?

4. In cases where branches or stems of the same tree sprout from the base or close to the ground, how should this growth be assessed when evaluating cover under the canopy? Should it be considered as a percentage of shrub cover?
Also, should it be subtracted from the main crown missing value when assessing percent crown missing?

Your insights and guidance on these queries will greatly contribute to the accuracy and consistency of our data collection efforts. Thank you for your assistance.

[Jason.Henning]

Hello,
I am currently engaged in an i-Tree Eco project in New Zealand, focusing on sample plot surveys and data collection within parks. I have a few questions regarding our methodology:

1. Regarding the measurement of Diameter at Breast Height (dbh), is it permissible to measure at heights other than the standard 1.4 meters? For instance, could we measure at 0.9 meters, provided that we clearly document and report this deviation?
Yes you can measure dbh at different heights. There is a dbh height field and i-Tree Eco that you can use to enter the height that the dbh was measured.

2. When estimating ground cover, I'm seeking clarification on what should be categorized as "Herbs." Specifically, how would weeds like white clover and dandelions be classified—as grasses or herbs?
Clover and dandelions would be classified as herbs. Grasses typically have long narrow leaves and are in the family poaceae. Herbs are most other non-wood, low growing vegetation.

3. The i-Tree Eco project considers anything above 1 cm dbh as a tree. In this context, should we classify botanically categorized shrubs as trees if they exhibit a dbh of 1 cm or more?
This is up to you. There is no clear dividing line between what counts as a shrub and what counts as a tree. Sometimes and individual species may grow as a shrub in some of its range and a tree in other parts of its range. Classifying all shrub type growth forms as trees may necessitate the measurement of many small individuals with very low ecosystem services. It is up to you how important these species are to your project and results. You may want to measure an example plot to test your different rules about what counts as a shrub for your project

4. In cases where branches or stems of the same tree sprout from the base or close to the ground, how should this growth be assessed when evaluating cover under the canopy? Should it be considered as a percentage of shrub cover?
Also, should it be subtracted from the main crown missing value when assessing percent crown missing?
Any leaves from the same tree make up the crown of that tree. Usually, these stump or basal sprouts make up a very small amount of the crown relative to the larger tree. For considerations of crown missing it can be helpful to only measure the more typical tree crown (heights and widths) and imagine fitting those disconnected low level leaves as part of the larger crown. So if the larger crown looks like it has 10% missing but you could fill in 5% of that with the leaves from the stump or basal sprouts then you would only record 5% missing. It is important to remember that the percent missing is only measured relative to the crown heights and widths your recorded.

Your insights and guidance on these queries will greatly contribute to the accuracy and consistency of our data collection efforts. Thank you for your assistance.