our ‘big tree’ project

Recently, the focus of our weekend hikes has changed to keep step with the seasons. We don’t see many insects now, the birds are less in number, and most plants have died back or dried to their leafless winter state. At this time of the year we turn our attention to those things that might best be studied when the trees are without leaves and the ground mostly bare. We study trees, rocks, lichen, bird and wasp nests, and any other objects that are now revealed.

This autumn, we’ve decided to initiate a personal “Big Tree” project as an appropriate seasonal activity. Out of curiosity, I did some checking around online to see if there’s an Ontario-based project. I found a listing of Champion Trees on a website maintained by the Ontario Forestry Association (OFA). There’s also a listing of Ontario’s Oldest Trees. So, it appears that we could submit trees to an Ontario project if we happen to find some good candidates. We’ll keep that in mind, but for now, our goal is simply to locate, measure and record data on the “big trees” that we come across during our walks.

This weekend, we recorded data on our first tree, a Red Oak (Quercus rubra) that we met along the Sylvan Trail at Murphy’s Point Provincial Park. It’s a decent sized tree – we’ve seen larger Red Oaks – but it provided a good chance to practice our tree measuring skills. For guidance, we followed the Nova Scotia How to Measure Big Tree Size webpage instructions. We began by taking a GPS reading of the tree’s location (that’s what Don is up to in the above photo). Next, we measured the circumference of the tree with a measuring tape. It had a circumference of 111 inches at what is referred to as DBH (And yes, we measured in inches as that’s how our construction tape is marked). I shot photos of the tree, its bark, and the leaf mulch around the base of the tree (see leaf shot below).

I then walked to a spot where I could measure the height of the tree by holding the measuring tape at arm’s length in front of me (to see what that’s all about, check out the Nova Scotia big tree measuring instructions. There’s a diagram and formula there that explain how to measure and calculate the height and canopy width of a tree). After I took the measurements, Don paced off the distance from the tree to me — 47.5 paces — and he can do quite an accurate 3-foot pace, so that gave a distance of 142.5 feet. My “height” measurement of the tree was 25 inches with the tape measure held approximately 28 inches from my eye. All measurements and the GPS reading were recorded in the fieldnote book that we always carry on our hikes.

The final step of the process was completed back home at the computer. The 111 inch circumference was divided by pi (3.1416) to calculate an average diameter of 35.33 inches. The height of the tree was calculated by dividing the height I had measured at a distance (25 inches), by the distance between my eye and the tape (28 inches) x the distance from the tree to the spot where I took the measurement (142.5 feet). So, that goes 25 รท 28 = .89 x 142.5 = 127 feet (btw, I rounded these numbers off during calculation as there’s not much point in trying to be too precise). The canopy width was measured at 12 inches, so approximately 61 feet across (not counting a weird branch that sort of hung way out to one side). By the way, someone (Wayne?) might want to check my calculations and methodology as, quite frankly, I consider myself to be rotten at math. (-:

So, that was our first foray into measuring Big Trees. It doesn’t seem too difficult. What we hope to achieve through this exercise is to:
* compile information on a number of the big trees that we see in our travels.
* sharpen our skills at estimating the height of trees (my eyeball guesstimate was actually not too shabby).
* give ourselves some motivation to get out and about on our favourite trails over the winter when we are at greatest danger of turning into couch potatoes.
* visit some of our favourite trees and see how they’re doing. I make particular mention of this point as so many of our sylvan friends have fallen victim to various forms of pestilence over the past few years – really ever since the ice storm of January ’98 – so, this will help us to monitor everyone’s health a little more closely.

After we get a few trees measured, I’ll set up a web-based chart and post the collected data.

So! Have any of you tried measuring trees? If you haven’t done so, do you feel inspired enough to go out and measure a few trees? If so, please do come back and share some data! (-:


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30 Responses to “our ‘big tree’ project”

  1. Wayne Says:

    It’s very odd, Bev, because I’ve been thinking about doing the same thing, and with the season it seems like a good project now. I do know about DBH!

    We have some marvelous specimens, mainly beech and tulip poplar, but also some white oaks, that we’ve been told by a forester are over a hundred years old. I might have done this earlier but set my self the unachievable goal of documenting *every* *single* *tree*, and that’s just silly. Or is it?

    I’d bet I don’t need to, but I shall go over your calculations, which actually give me some new stuff that I wasn’t aware of.

  2. burning silo Says:

    Wayne – That’s funny that you’ve been thinking about a similar project. I’d actually guessed that you might already have collected data on some of your trees. I’m not really sure what got me interested in this — except perhaps after looking at the Coast Redwoods and thinking that I have no real feel for the size of trees (no point of reference) – of their diameter, circumference, height, canopy width. I’d like to go beyond the vague notion that a tree “looks pretty big” to the point where I actually have a handle on its proportions. Of course, the other part of this is that I believe we’ll actually “look” at the trees a little harder if we’re selecting ones to measure. I’ve always felt that the best way to learn about something is to make a point of watching or studying it as much as you can. We do study trees quite a bit, but in summer, my attention is definitely drawn downward to the point that I probably take trees far too much for granted.
    I think most of the calculations should be correct, but am wondering about the formula for the height measurement and in calculating the inches and multiplying by feet. Does that seem right to you? I guess that the first calculation would actually be creating a percentage which is then multiplied by feet (I think that’s what I mean to say!).

  3. Jenn Says:

    I’m interested in finding out what your GPS unit is. Can you provide a model number? The Garmin site was not particularly helpful.

    I’d really appreciate it, if you’d take the trouble!


  4. Jenn Says:

    Ah. I think I found it, this guy maybe?
    Garmin 010-00560-00 eTrex Venture CX GPS Receiver?

  5. burning silo Says:

    Jenn — I have a Garmin eTrex. I had one almost the same for about 4 or 5 years and it worked very well until it got smashed in a bad fall (it was in a pack that fell and landed on some ice and rocks last winter). It still worked but the top half of the LCD screen got wrecked. I like the bright yellow casing as it makes it easy to find if dropped (it once fell out of the canoe into about 12 feet of water — we probably couldn’t have found it if it had had a dark casing). Anyhow, I finally bought a new one this autumn after putting up with the broken screen. I bought it from Amazon as they had the best price for it. I use rechargeable AA batteries in it and they last fairly well. This unit is easy to use. Doesn’t have all the bells and whistles of the more expensive units, but if you’re just looking for a GPS for recording locations of things, or for finding waypoints, working with a map, etc… it’s excellent for that. We use our GPS. If this one lasts as well as the last one, I’ll be quite happy.
    Edit: The one that you posted a link to has more features than our unit. I think you can load maps into that one. Ours has a lot less features. You should base your decision on how you think you’ll be using your unit. We use ours for recording coordinates for our nature sightings. I also use it for marking out canoe routes on maps and that kind of thing.

  6. robin andrea Says:

    What a great project, bev! I’ve wondered about measuring trees, but have never even googled info for attempting such a thing. I love knowing that you’re out there doing it. We don’t have a gps, so how essential it is to the process? I remember the tape measure thing and the arm’s length from geometry class! Wow, I haven’t thought of that in years. Oh yes, I’m defintely inspired. It’s a great winter project.

  7. burning silo Says:

    robin – I think it would be cool if a few of us were to measure some trees in various parts of the country and maybe share the results. A GPS isn’t actually necessary to the process. We’re using one as that’s just how we keep track of where things are (our nature sightings), but any description that can be used to locate the tree again is about all you need unless you’re going to submit a tree to a tree registry. Even then, I think most of them will accept a description of the location without GPS coordinates. I agree — this is a great winter project. I’m looking forward to visiting a particular forest to measure several trees as soon as hunting season is over. Some of our favourite trees are located there and it will be fun to see how they measure up.

  8. Laura Says:

    This sounds like fun, Bev! Have to admit the math (did someone mention geometry?!?) seems a bit daunting, but it could be a nice way to focus myself on winter walks. Maybe even get the husband out with me, since he knows trees better and is better with tools and measuring. Thanks for the idea.

  9. burning silo Says:

    Laura – We think it’s a fun project – especially for the winter months. The math is actually very easy – trust me on this. While you’re out in the field, just focus on the measuring part and get those numbers down. The calculations are very simple to do once you’re back home. Sounds ideal if your husband would like to go out walking and measuring trees too as I think it’s a little easier and more fun with two people involved. One can stand and take the height measurement, while the other paces off the distance between the tree and where the measurement is being taken, etc… It does require some tree identification skills too as any deciduous trees will probably be leafless at this time, so your husband’s ability to ID trees would come in very handy. Btw, leaf litter can help with identification, which is why I shoot a photo of the leaves around a tree along with the bark and the tree canopy. I know most of my trees quite well, but there are a few (notably the Ash trees) that can give me a bit of trouble.

  10. Wayne Says:

    Bev – regarding the GPS – mine is also a Garmin Etrex. I may not have a cell phone, but I do have a GPS, and I use it frequently. I used it to map out our property, and the most fun is to set it on the dashboard of the car on a long trip to watch the progress of the journey. I’ve also used it to mark locations of discovery, and it has a handy little “find” function that lets you re-locate the spot.

    Having said that, the moment I identified it to our Fire Chief, who also does cartography at UGA, she poo-pooed it as way too insensitive when you’re under a canopy. And she’s probably right, but she’s also a midwesterner and as such wouldn’t give an alternative beyond the criticism (which was sort of de rigueur for her).

  11. burning silo Says:

    Wayne – We do a similar thing when we’re out canoeing — we mark a waypoint at the put-in, and then paddle along on our trip – then use the function that gives us the distance back to our earlier waypoint (I think it’s called “trackback”). Just for fun, we sometimes paddle as fast as we can to see what speed it says we’re going. We have a very light canoe and when we want to, we can really make it fly! (-:
    I’d actually have to say that these GPS units are more sensitive than most people (including your Fire Chief) would credit. We’ve checked coordinates on particular places in the forest and they often come very close to that which we’ve previously recorded on past occasions (within 3 or 4 meters) – and that’s even in summer with quite a bit of canopy. I’m not sure how much more accurate one would need to be than that. However, it is true that we’ve been in forests where it was difficult to get a reading with an accuracy of less than about 10 meters (usually when among immense White Pines). They’re most certainly accurate enough to locate almost anything that is within a few meters of a marked waypoint.

  12. Wayne Says:

    Bev – I managed, in the middle of the most canopy-laden season of summer, to locate all the driven markers that marked our property. And that was using (mathematics) to locate them from a platte. It worked fine. I even marked a big yellowjacket nest.

    So I think the etrex is fine. I’ve enjoyed it immensely.

    I think the FC, who does after all spend a good deal of time beneath canopies far thicker than ours, may have a point, but she’s also a micromanager type who had the opportunity to purchase her superduper GPS off a grant, and so…

    we may discard her opinion. :-)

  13. Peter Says:

    I thought of this post a little late today and didn’t bring a tape measure, but I wanted to give it a shot. I ended up using a relatively straight looking stick which I used to measure, and count my paces. Measured the stick at home to do the proper math. I will go back and try again with a tape measure just to compare.

    Also on GPS units. I have the Garmin iQue3600, which is the GPS and PDA unit in one. I picked it up because it was extremely discounted, but I think I would rather have a more field oriented unit. It does not look very durable and the battery life isn’t the greatest (but comes with car charger). I suppose it would be handy if you wanted to write your notes on it, or use it as a voice recorder or mp3 player, but I require none of those features. I think it is designed more for the road traveler.

  14. Jenn Says:

    Well, this is a great conversation! I am hoping to find an inexpensive GPS unit to do architectural field work with, but I’m not sure such exists at this time.

    Part of my work is going out and measuring buildings for renovations and CAD documentation. Many of these buildings are horribly out-of-square, and I have no current way of determining what points on my drawing are ‘correct’ and which need to move in relation to the where the building actually sits. Very frustrating.

    ‘3 or 4 meters off’ won’t help with what I am hoping to achieve – which is taking point measures off the corners of buildings to translate back to CAD and thereby verify how much out-of-square the building is.

    Anybody out there have any ideas for me, I’m happy to hear them!

  15. burning silo Says:

    Jenn – I don’t think there’s any GPS unit that would do exactly what you’re hoping to achieve. There are several reasons for this. If you go to this wikipedia page and scroll well down the page, you’ll see a section on Accuracy and then several headings explaining what factors have an effect on accuracy.
    This page also has some brief but interesting comments on accuracy.
    And here’s one more bit that may be of interest. There’s been discussion about this among GPS users in the past — that civilian GPS users don’t get all of the accuracy that is possible. This is an older article (2000) and things have changed since then, but it does help to explain why GPS units may not be as accurate as they could be.

  16. burning silo Says:

    Peter – Thanks for posting the info on your unit. I’m not that familiar with what’s out there. I did a small amount of checking around before buying the latest eTrex back in September, but I just went with what I knew. I’ve discussed makes and models with quite a few people in the past and it does seem like the Garmin units are quite dependable and as accurate as most of what’s out there.

  17. Duncan Says:

    A good project Bev. Over here the National Trust has a Register of Significant Trees, one can nominate outstanding trees for inclusion on the register, which if accepted, gives them protection. Living treasures like our ancient trees need it.

  18. Wayne Says:

    I’m late here, but I just got back from the treemeasuring page and jotted down the neat simple directions. Your calculations look just fine, Bev.

    I’m off to do a hickory, a walnut, a water oak, and maybe if it hasn’t started raining, a beech or two.

  19. burning silo Says:

    Duncan – That’s interesting about the special protection for outstanding trees. I’m not actually certain if trees that make it onto the Ontario lists would receive any protection. I must check into that.

    Wayne – I hope you’ll do a post with results of your tree measuring foray. I’m hoping to get out and do a few more trees this weekend. After that, I’ll probably put up a chart to begin posting the results.

  20. Jenn Says:

    Thanks, Bev!

  21. Wayne Says:

    Just got back from measuring the walnut on the knoll (N33deg, 51.650″ x W83deg, 14.496″): 119″ circumference, but “only” 76 feet tall. Canopy is 59’x66′.

  22. burning silo Says:

    Wayne – That’s a pretty substantial tree! I’m now wondering if circumference may be useful in guesstimating the age of a tree. I wonder if anyone has trying to work out a rough formula for the various species? Must do some looking around online to see if anything exists.

  23. Wayne Says:

    Bev – I was thinking exactly the same thing! And it would be species-dependent. I’m sure it would also be climate and environmentally dependent but surely you could get a rough age.

  24. burning silo Says:

    Wayne – I’ve just found a formula on this page. It’s diameter x growth factor. Check out the chart near the bottom of the webpage.

  25. burning silo Says:

    Wayne – according to that chart, it looks like your tree would be roughly 170 years old (if I’ve done the math correctly).
    Edit: I just used the table to calculate the Red Oak that we measured last weekend, and it would be around 140 years old.

  26. Wayne Says:

    Bev – excellent – and your discovery was species specific too. 170 years old suggests that the former inhabitants left the tree growing. We know much of our property was cotton-growing land, so that many of the trees are relatively recent, but how interesting!

    I ran across the “Georgia Champion Trees” website at
    which doesn’t excite you but the search term “champion trees” might. The black walnut champion in Georgia is just a little taller, twice the crown, and an amazing 227 inches in circumference. But ours looks to be extremely healthy – perhaps in another 200 years it will be the champion!

  27. Wayne Says:

    Taking a closer note at that age-estimation website – two things:

    Looks like the growth factor is X years for every inch of diameter. In our walnut’s case, 119/3.14 x 4.5 and as you can up with, 170 years. Good going on the math, Bev!

    The other thing that was interesting was the comment about landscape planted trees. While I appreciate the warning, it strikes me that a lot of landscape planted trees are in danger zones where they’re not like to get very big anyway. Pruning by electric companies that use contaminated saws, acquisition by subsequent owners who don’t particularly like the tree, etc.

  28. burning silo Says:

    Wayne – It’s interesting that former inhabitants probably left the tree to grow. Where I live, there’s a huge White Pine out in the farm field across from us — actually, there are a few more that I can see across the countryside around here — and all are surrounded by farm fields. The farmers have intentionally left these huge trees, even though some of them must have shaded a good bit of cropland at their base. I wonder if they let them stand as shade for livestock, or because they decided not to cut down the last of the great pines in this region.
    Thanks for posting the Georgia Champion Tree link. I was thinking that, when I get my tree chart up online, I’d post links to all of the “big tree” registries that I come across as I’ve noticed some are actually difficult to find. Might be a good resource for others who want to compare trees.
    I agree with you on those landscape planted trees. They might benefit from special care, but I would think they also suffer somewhat from soil compaction around their roots, along with the other indignities which you’ve mentioned.

  29. pablo Says:

    This is exactly the kind of thing I’m supposed to be doing in my woods as part of my membership in the Missouri Forest Keepers organization. I’ve never done it, but this could be a start for me.

    Also, those GPS units are great for an outdoor sport called Geocaching.

  30. burning silo Says:

    pablo – I hope you’ll do some tree measuring and post the results at Roundrock Journal. It would be neat to hear about some of the big trees in the Roundrock forests.
    Originally, we got our GPS to use with our nature observations as we have a biologist friend who keeps a GPS-based database of nature observations for this part of Ontario and we contribute sightings to it. However, we have used it for geocaching. We haven’t actually gone out looking for caches too often, but when were more involved with some community forests, we set up caches at a few sites to get people interested in making use of the hiking trails that had been created. We found that, if we set up a multi-waypoint cache along a trail, it helped to make people aware of the trail’s existence as they would visit to look for the cache, and then come back again in future to just hike.