Sometimes forest events occur over part of a stand instead of the entire stand. Some examples would be:
- A low pruning event has only been completed over part of a stand because of growth rate differences in the trees, with the remainder scheduled to be pruned next year, or
- Areas of a stand where thinned in different years because of budgeting constraints
- Only some area has been production thinned due to terrain access constraints.
- You want to plant up an area that has been clearfelled, even though the entire clearfell operation has not finished yet.
- You have sprayed part of the stand for weeds or disease only where they occur (roadside or aerial spraying).
In these situations you have a couple options depending on the event type and end result. In most cases its is just a matter of splitting the stands underlying patch layer into a couple of patches to describe the event on the basis of work partially completed, therefore reflecting the area treated. This is what I will describe here and is often what is done for the examples 1 through 4 above. Some events such as aerial or roadside spraying (example 5) would be better described using a “GIS Managed Event” which I will cover in a later post (where it would be cumbersome to split the stand into a large number of patches over time).
EXAMPLE OF SPLITTING PATCH FOR A PARTIAL THINNING EVENT.
In the quick example below a thinning event was entered into GeoMaster covering one stand however during the course of the event not all the stand (in this case one patch) ended up being thinned; with the remaining area to be completed the following year and be entered as a separate event.
Digitise a polygon in a ‘Work In Progress’ layer representing the work completed for the event – as shown by the black polygon in figure one below. You may have walked the boundary of the treated or untreated area with a GPS and can import a GPX waypoints file into Arc Map (points shown yellow in map below) in order to accuracy map the split. Make sure the polygon extends over the outside of the patch you are wanting to split. In this example the area covered by the ‘Work In Progress’ (black) polygon is the area thinned and the patch is to be split along the boundary between thinned and un-thinned.
Figure One: Completed Polygon in the ‘Work In Progress’ of Area thinned – Excluded area is the Un-thinned Area
Save you edits and select just the ‘Work In Progress’ polygon then under the GeoMaster tool bar select Event/Split Treated (figure four). This will identify any ‘in-progress’ events in GeoMaster for the stand under the polygon. If one is found then you are asked to confirm that is the right event, if several are found a picklist of events is presented for you to choose from.
Figure Two: Split Treated Tool in GeoMaster
A Patch Subdivide form will appear and GeoMaster will display how many patches will be split based on the selected polygon (in this case one). You can see in this example the sub-divide creates two new patches, one 22.34 hectares and one 3.06 hectares from the original patch which was 25.40 hectares. The patch with the greyed out tick is the patch the event will be associated with. You can add a note as to why the patch is being subdivided. The date is set to the beginning of the event. Click the red tick.
Figure Three: Patch Subdivide Form
Once you click the red tick ton confirm GeoMaster will present the Event Form with the newly split patches. The patch(es) covered by the ‘Work In Progress’ polygon will have progress set to 100% and those not covered will have a progress of 0%. Set the activity date to the date at which the event progress was completed, then double click the finish date to copy the activity date to the finish date. This signals that the event has been completed. On saving the event all the patches not treated (with progress of 0%) will be removed from the event. Note if you set the finish date before the activity date GeoMaster will assume that the event was finished after the last activity and will set all patches to 100%.
Figure Four: Stand now made up of two Patches
So now the stand has been split into two patches. A separate thinning event can be added into GeoMaster to thin the currently un-thinned patch as needed.
If you want more information about GeoMaster Harvest Manager provided by the cloud services at Interpine feel free to contact us.