survey design

[wdmn]

Hi all,

I'm working on a survey of a bunch of different sites in order to assess viability for tapping.

The original instructions were to measure each tree in the area (of the appropriate species), in order to map where good locations might be to tap.

I'm thinking there has to be a smarter way of doing this. Couldn't we set up a bunch of points throughout the stand, do prism sweeps, counting only relevant tree species, and then calculate basal area? points with highest basal area will be good areas to tap?

Thanks for the advice.

wdmn

[beenthere]

Would think it will depend on what accuracy you want for the survey.

Have to weigh the cost to survey against the quality of the results.

Seems worthy of a look, but would suggest some quick trials to decide for sure.

Click your forum name, and it will take you to where you can update your profile with your location. Would maybe help us with your questions.  Could guess the mn in the name is for Minnesota. The "french" maybe France, or Quebec..  but don't like to guess. ;)

[Magicman]

You hit on each side of Ontario with those two guesses.   ;D

[clearcut]

If you are only measuring diameter and tappable species, this should work, basal area is derived from diameter.

I would include the other species, lumped together as "other" in the sweep to get a total basal area and the proportion of basal area in tappable trees.

You can calculate the quadratic mean diameter from basal area - as the diameter of a tree of average basal area.

I agree with the quick trials comment to make sure that you are collecting sufficient data.

[Ron Wenrich]

What you're looking for is an inventory.  If I was doing that survey, I wouldn't hesitate to use a prism for giving a good estimate.  It iwill give you the best bang for the buck. 

My typical design for a prism inventory is to take one every 200' on a grid line.  That gives about a 10% sample.  I always work from a map of the property that I'm working.  At each plot, I would note the species and diameter.  You could throw in other classifications that might be important.  I know little about tapping, but I would think that a dominant or co-dominant would put out more sap than a suppressed tree.  Maybe diameter isn't as important as crown.  There may be other information needed, such as tree height, etc.

On the map, I would note areas where the timber type would change, physical attributes like roads, trails, streams, terrain, etc., and where each plot is located. 

The office work would include doing each plot separately.  You will have to classify each plot with the criteria that you want.  The percentage of tappable trees could be one, size distribution, or whatever criteria you need.  Plug those into the plot numbers, and you'll have a map of the area where the trees are most likely located and where the access is at.  Your map may have several different types as there are many variables across a stand of timber.  I'm not sure what they use to find area nowadays, but I have always used a dot grid on my map to give me pretty good acreage estimation.

Your final analysis would lump all those plots into a similar unit.  You will come up with the approximate number of trees and at what diameters, the size of the unit and the location. 

At least, that's the way I would do it.

[wdmn]

Thanks everyone for the help. Here is my plan so far, without having fully digested all of your good advice:

(I'm in north eastern Ontario) Set out 1 hectare grid on all of the sites. Maybe do a checker board pattern and do 3 sweeps per hectare.

I'm pretty sure the ministry of natural resources here has a conversion table that allows you to estimate the diameter distribution based off of reloscope samples. If I can get that I can do an estimate for each sweep and then take a mean for each hectare and map it.

Criteria will include health of the tree diameter, proximity to road, etc.

Thanks again;

wdmn