I got a call today to do a 22 acre tree survey proposal. I have never done a tree survey of appreciable size and it makes me nervous coming up with a number. Seems like a good many variables that could effect the time it would take to do one. In this particular case, they want 4 inches and up and it is a fairly mature oak hardwood forest. I took an educated guess of a week using the grid lines that I already would have cut for the topo.
What are the usual techniques for doing a tree survey efficiently?
> What are the usual techniques for doing a tree survey efficiently?
I have no magic to give you. I'm not sure just how thick the underbrush is in your area but you may be surprised just how little control is need to do these. Judicious use of offset shots helps a lot.
Do not paint the trees. Tie a ribbon all the way around the trunk at eye level as each one is tied. That way you can see which ones are done, which ones are left to be tied.
This it a good job for a 3 man crew, rodman, instrumentman, flagger.
> I got a call today to do a 22 acre tree survey proposal. I have never done a tree survey of appreciable size and it makes me nervous coming up with a number. Seems like a good many variables that could effect the time it would take to do one. In this particular case, they want 4 inches and up and it is a fairly mature oak hardwood forest. I took an educated guess of a week using the grid lines that I already would have cut for the topo.
>
> What are the usual techniques for doing a tree survey efficiently?
If I were to map the trees on a tract of the size you describe, which sounds like perhaps 500 to 600 trees, the first thing I'd do after cutting out the cross-section lines through the tract is go through and tag them all with numbered tags, noting the caliper, species, and canopy (if required) for each so that all you have to enter when you locate the tree is the tag no.
Set temporary lath (48" long pieces of 1/2" PVC irrigation pipe if you're me) approximately where you think you'll need an instrument station and tag trees with the tags facing that point, working clockwise around the circle so that all of the trees can be located later more or less in sequence.
Then move up along the cross-section line and repeat.
This is copied from a post I replied to a few months ago.
Here is a tree topo estimating method that I learned while working in georgia. You have to go out to the site and walk it.
1. Walk out into the site, far enough that you can barely see out to the road. Keep up with your pace so you have an idea of the distance.
2. Now just start counting the trees that you can see.
example: you count 85 trees in a 200' radius.
so there are 85 trees per 125,663 square feet, or 85 trees per 2.88 acres. that boils down to 29.5 trees per acre.
keep walking and do a few more counts to get a good average.
while walking, keep an eye out for topo features that will need special attention.
Now that you have an idea of how many trees you need to locate, you can estimate how much time you will be on the site.
based on the distance you could see, you can estimate how many set-ups will be required.
ex: if you can see 200' radius, you can topo 2.88 acres per set-up. so thats 28 set-ups.
now estimate how long the crew will take to finish a setup. lets say 3.5 hours. comes out to be 98 hours on site.
add 20% for office time and your at 118 hours.
I would make sure to include some language that my proposal was good for 30 days. or less.
Hope that helps you. I made a spreadsheet for this, so now all i have to do is plug in the sight distance average, ann job size, and it spits out the time on site.
I agree that you do not want to paint the trees.
If the town does not require numbered aluminum tags, the get a 'Chalk Tree Marker' from Forestry Suppliers, found here:
http://www.forestry-suppliers.com/product_pages/View_Catalog_Page.asp?mi=1231
The chalk lasts a week or two, unless it rains hard for the next few days and you don't make it back to pick up where you left off for a while....
It really works well. Also handy when doing a topo in a residential yard; helps you keep track of what was mapped and the marks fade in time.
As for how many, there always seem to be more trees to locate than you think, and the client almost never needs a tree survey when the leaves are down (but that may not apply in Florida, it sure matters in NY).
A folding biltmore stick can come in handy for estimating the diameters, or just keeping your eye calibrated. Remember that trees come in 2" diameters - there are no 7, 9, or 11 inch trees; that makes it simplier.
The suggestion to use offsets, within reason, is a good one.
What are they to be used for? A count to satisfy some EIS that 'X' trees will be removed in clearing the whole site, or will someone be designing to your locations so they better be right? Map accordingly.
> I got a call today to do a 22 acre tree survey proposal. I have never done a tree survey of appreciable size and it makes me nervous coming up with a number. Seems like a good many variables that could effect the time it would take to do one. In this particular case, they want 4 inches and up and it is a fairly mature oak hardwood forest. I took an educated guess of a week using the grid lines that I already would have cut for the topo.
>
> What are the usual techniques for doing a tree survey efficiently?
Great posts! Let me ask you this. Would you try to do the topo and tree survey simultaneously?
> Would you try to do the topo and tree survey simultaneously?
Sure, as long as you have some grid lines cut out to keep track of what you're doing, why not? Just keep track of the start and stop limits.
BTW, you didn't ask, but in a situation where you have lots of setups to make along brushed-out cross-section lines, using two-point resections would be my preference for locating as many of the instrument stations as possible. That way, you can leave prisms and targets on the two control points, move the instrument and you're ready to go after resecting. While you're doing that, your assistant can be eyeballing the sequence of trees that are to be located from the station.
I usually charge my clients per tree with a not-to-exceed price. If you think it will take 5 days then make your not-to-exceed price be whatever you charge for 6 (just in case) days of field time plus the office time. I usually charge $8/tree, but due to the size of the survey (22 acres) I would probably reduce that to $6/tree. I also tie flagging around the at breast height.
FWIW, I usually start a new coordinate file so I can start locating the trees at point number one. This makes it easy to create a chart in excel or autocad. I usually label the trees as a point number on the map then place a chart off to the side (or add another sheet if needed. I have also found that it saves a lot of time to code them with abbreviated codes, then use Find/Replace.
for example:
24tp = 24" tulip poplar (just replace "tp" with "tulip poplar"
12hi = 12" hickory (replace "hi" with "hickory"
I also use the distance offset command a lot... you already have a tape in your hands!
After a couple of inefficient attempts at tree location, I found it was easier to flag all of the desired trees before breaking out the instrument, and then pull the flagging off as I shot them.
In my opinion, it's much easier to tell if you have shot all of the trees from a particular setup by standing at the instrument and looking for any remaining pink flagging, instead of trying to pick out an unflagged tree from the forest.
My two cents,
Doug
Or you can get the 2013 Carlson Survey software and code the points to label the size of the tree, the type of tree, draw the trunk diameter to scale and draw the drip lines, all during a pass through Field to Finish. They have a special toggle for Tree Surveys that is something to see.
You can draw EVERYTHING concerning the trees and all your plan data all at one time. Then build the surface, contour and label and you are done.
I think there's a couple of training films on their web site that will show you how to do it. Saw a demo Tuesday and was VERY impressed.
:good: I use Civil 3D to import my linework and symbols. I know everyone doesn't use ftf, so I just dumbed down what I do.
> After a couple of inefficient attempts at tree location, I found it was easier to flag all of the desired trees before breaking out the instrument, and then pull the flagging off as I shot them.
>
> In my opinion, it's much easier to tell if you have shot all of the trees from a particular setup by standing at the instrument and looking for any remaining pink flagging, instead of trying to pick out an unflagged tree from the forest.
Yes, and if you're pre-tagging them, you can nail the tag through a streamer of flagging facing the instrument station. On large diameter trees, it's a bit faster. I agree that deflagging as you go is the more efficient method.
deflagging is probably also more environmentally friendly than leaving meters of pvc flagging hanging around the trees, as long as you dispose of it responsibly.
Trimble access as a routine to measure the the center of a circular object and calculate the radius, but it needs two measurements, you measure a point on the tree trunk at chest height, dead center, it records angles & distances, then it asks for the horizontal angle to the edge of the tree, you turn the instrument to the edge , it records the Ha, and calculates the center co ordinate of the tree and the radius.. this data comes into your cad plan.
For consistency you need to measure the trunk at the same height , which is not always possible. So it is not perfect, bit very useful.
So it needs two measurements, which will add a bit of time, but the shot to the tree edge for Ha is very quick and easy
The routine had a bug in it the first time I used it, it turned out to be a south azimuth thing, the software was subtracting the tree radius from the initial center topo shot instead of adding it to the shot, so all my trees were plotting off center by the tree radius.
I picked it up as I did a couple of 3 points on a curve, tree trunk shots for backup and could see the error when plotting.
This problem was back in survey controller 12,2 I think and was fixed, I got off easy as I picked it up only on trees , a fellow surveyor I know was not so lucky, he did an as built of circular concrete columns for a major upgrade to a shopping center, when the contractor got to site to build, nothing was would tie in, took a structural re design to fix..... not sure of the outcome either.
> After a couple of inefficient attempts at tree location, I found it was easier to flag all of the desired trees before breaking out the instrument, and then pull the flagging off as I shot them.
>
> In my opinion, it's much easier to tell if you have shot all of the trees from a particular setup by standing at the instrument and looking for any remaining pink flagging, instead of trying to pick out an unflagged tree from the forest.
>
> My two cents,
> Doug
Seems like a lot of extra work to visit every tree twice.
Also, when you do a tree survey, do you pretty much have to bet on clearing the underbrush over the whole site to provide enough visibility to shoot all of the trees.?
> Also, when you do a tree survey, do you pretty much have to bet on clearing the underbrush over the whole site to provide enough visibility to shoot all of the trees.?
Not on any site I've ever mapped. The main variable is the average radius of sight length that will be most efficient.
> Seems like a lot of extra work to visit every tree twice.
It's actually not for a two-person field party. Otherwise, you have the person at the instrument just standing around while the person on the rod measures up the tree and/or its canopy.
If you're measuring canopies, that's almost always easier with two people, ditto the tagging and flagging element.
The most efficient way of locating trees hardly ever seems quick and easy if you're collecting the full set of information.
> ... Would you try to do the topo and tree survey simultaneously?
Sure, why not? If the crew is inexperienced I might have them stick to one thing at a time but in most cases, why not?
I don't usually cut grid physical grid lines for woods topo as Kent suggests. If the underbrush is very thick it is sometimes necessary, but usually I use a virtual grid on the data collector screen to keep me on a pattern.
Located of thousands of trees...most years...
We locate them and fill in topo between as needed, tagging and flagging as we go.
We take into account the rise around the base of a large tree with our rod heights, to keep consistent ground topo.
We also turn to the center of each tree, or call out an offset.
Our code for Carlson, imported into Civil3D is like this:
FIR 48 TDL BEG CIR35
(type) (size) (dripline line code) (circle command with radius in feet)
And... We don't leave meters of flagging, maybe yards...
Tree Tags
I noticed that some of you mention tagging the trees you locate. I suppose you mean those numbered aluminum tags that you can by from forrestry supply stores. What is the purpose of these tags. On the few tree surveys I have worked on, we did not tag. Just tied and showed on a map.
