Author Topic: How do I calculate this? (Read 2663 times)

crtreedude · « **on:** July 09, 2005, 07:07:22 pm »

Hi all,

I have an idea that I would like to do. We plant trees - quite a few at a time. What I would like to do is be able to walk around an area with my GPS and mark the outside. Then, I would like to load this information in something and estimate the area.

Since we plant on a 3.5 meter grid, I should be able to estimate the number of trees within an area. The best would be if I could then mark off on the computer these areas groups of trees. Usually a group of trees would be 100.

So, any ideas? Is there anything out there or do I have to write it myself. (I am a geek with more than 20 years software development background).

Also, I am looking for suggestions for inventorying a new property we have. It has lots of trees and I would like to monitor their growth and health.

As you can probably tell - I am not a forester - but plantation owner. I do hire forestry engineers down here - and perhaps I should ask them, but I figured I would start here.

Fla._Deadheader · « **Reply #1 on:** July 09, 2005, 07:26:57 pm »

We youster do a MOB (Man over board) and that would be our Go To mark. That was a long time ago.

We could also set a distance from any MOB and the GPS would keep us exactly at a set distance, if we paid attention.

Being as you are a Research Junkie, go to Garmin or Magellan, and see how they recommend to do it.

We had "Differential", and could get within 10 feet of an object with accurate numbers.

Things might be more accurate, now.

SwampDonkey · « **Reply #2 on:** July 09, 2005, 07:32:44 pm »

crtreedude, do you use a garmin GPS?

crtreedude · « **Reply #3 on:** July 09, 2005, 07:35:17 pm »

Yes, I have a Garmin.

crtreedude · « **Reply #4 on:** July 09, 2005, 07:36:35 pm »

Harold - I have actually written code before to interface with the Garmin - you know I am a geek.

This IS part of my research...

SwampDonkey · « **Reply #5 on:** July 09, 2005, 07:38:05 pm »

If your planting trees at 3.5 meter grid spacing then:

3.5 x 3.5 = 12.25 m^2/tree , then how many 12.25 m^2 will fit into 1 hectare

10,000 m^2/ha divided by 12.25 m^2/tree = ~ 816 tree/ha or 330 trees/acre

SwampDonkey · « **Reply #6 on:** July 09, 2005, 07:41:47 pm »

crtreedude, your garmin will give you area, right on the screen.

Go into tracklog and go to your starting position, then clear the new track log. Then start walking the perimeter. When you get back to the start just save the track log. You should be able to load that track up and see the diagram of the track with an area. In that screen you can set metric or imperial. Is it a eTrek Garmin?

You can zoom in and out on your track to see it on your built in world map. When you move away from the area, say 10 miles, you'll have to zoom out to see the tract.

You cna get the Minnesota DNR Garmin utility to get the track log off your garmin and it saves it as a GIS shapefile (a proprietary file format by ESRI). And there is a link in this forum to a free GIS program that will read in that file and you can make printable maps with it. Let me pull up the link to the free GIS program. Do a google for Minnesota DNR Garmin to find the file transfer util.

SwampDonkey · « **Reply #7 on:** July 09, 2005, 07:53:38 pm »

Link to free GIS

SwampDonkey · « **Reply #8 on:** July 09, 2005, 08:10:45 pm »

DNR Garmin Extension - It can be used stand-alone

SwampDonkey · « **Reply #9 on:** July 09, 2005, 08:21:07 pm »

There are calculators for estimating tree volumes on the forum, it the Forum Extras. Ron W can help you out better with those, than I can.

I use timber volume tables developed for different growing sites (site index) in my area.

I would think that it would be best for you to use taper tables for species down there and estimate tree heights with a clinometer and measure tree diameters at 4.5 feet. Then make volume equations using statistics of trees for your area. Your foresters must have taper tables or volume tables for your species. You'll find the volume increases rapidly, then levels off over time, then declines as the trees reach over maturity.

That's enough stuff to confuse even me

crtreedude · « **Reply #10 on:** July 09, 2005, 08:22:47 pm »

Thanks SwampDonkey.

Yep, believe me I know how many trees fit in an Hectare! However, knowing how many hectare is in a particular area is a little harder since the shapes are irregular.

I think we are getting there - my application is a little odd since I need to mark out trees by groups of 100. Shouldn't be too hard since the grid is known.

crtreedude · « **Reply #11 on:** July 09, 2005, 08:26:15 pm »

Yes, I have a lot of this information, growth rates and even when they start to level out - in tropical trees it tends to be at about 80 years or less.

The amount of lumber is secondary to the increase in size per year. I think I am almost ready to hire a full-time forestry engineer - they aren't very expensive here and they do very good work. Also, you don't even think of harvesting wood down here without one since to cut and haul most types of wood requires a permit. They aren't expensive - unless you don't have one.

SwampDonkey · « **Reply #12 on:** July 09, 2005, 08:27:45 pm »

I don't have a Garmin myself but I've looked at eTreck and Map76 models and they all work pretty much the same. If you can get to that track log screen and start a new track then zero it out (clear track log ?) at your start position. You can make a map by walking the perimeter and return to your start. Save the track, then open it up and it displays perimeter and area in a new screen. You can rename the track log there too, and I think you can have 10 tracks.

SwampDonkey · « **Reply #13 on:** July 09, 2005, 08:34:17 pm »

When we cruise up here, we look at total merchantable volume and not just the sawlog volumes. Sawlog volumes don't mean to much to folks up here until they are scaled on the yard. That's because what you estimate from looking on the outside of the tree is more often then not blown away from what you can actually recover as sawlog volume.

crtreedude · « **Reply #14 on:** July 09, 2005, 08:41:31 pm »

I have an older Garmin -= GPS 12 are you saying it would be nice to upgrade? (pretty please.

) It will do a track, but that is about it - so I figure by downloading into software I should get what I need.

I really don't need to be too accurate - I just want to be able to estimate overall growth. I will be figuring when to thin based on canopy coverage more than amount of marketable wood. At least that is my current plan.

SwampDonkey · « **Reply #15 on:** July 09, 2005, 08:48:35 pm »

All ya need is an inexpensive Garmin Etrek for your purpose and use the programs I've linked to print out a map. You can download the track from your old unit using the DNR extension. You'll just have to be sure to clear the track log before you walk the perimeter or you may have a line from where you started the GPS (lets say the house) to where the stand is. This will mess up your area. Be nice to see the track displayed on screen afterward, and see the area with perimeter also.

I compared the accuracy of Garmin's Map 76 with Trimble's $8000 GEO3 and I never saw any difference. It's just that Trimble's software is alot easier to use than third party Garmin software. Garmin's units even have 4 more sat. channels than does the GEO3.

crtreedude · « **Reply #16 on:** July 09, 2005, 08:57:40 pm »

You're no fun! How am I going to explain to the CFO (my wife of course) that I need a new fangled piece of equipment?! $:-\$

We are supposed to stick together here.

Honest, thanks for the information - I suspect my Garmin will do it too.

SwampDonkey · « **Reply #17 on:** July 09, 2005, 09:07:42 pm »

Here's the Garmin 12 manual.

http://www.garmin.com/manuals/GPS12_OwnersManual.pdf

I'm on dialup and it takes for ever to load, so I thought I see if you had it to read through. Look for a page that displays a track with an area, then read up on it.

Sometimes those screens take about 5 presses of a key to get to.

crtreedude · « **Reply #18 on:** July 09, 2005, 09:29:08 pm »

Thanks, I have 1024/256 ADSL so it download in a couple of seconds.

Costa Rica may be third world, but we sure have good internet in some areas!

johnjbc · « **Reply #19 on:** July 09, 2005, 09:36:31 pm »

This thread shows how I did it.

http://www.forestryforum.com/board/index.php?topic=10300.msg141723#msg141723

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Author Topic: How do I calculate this? (Read 2663 times)