The Pine Orchard: You Know When You Are In It

The Pine Orchard is a well known stand of old growth White Pine and Hemlock near Wells (NY). If you read this blog you know that I'm always on the look out for the big old trees, so a visit to the Orchard was long overdue. I'd read that the Pine Orchard contains trees up to seven feet in diameter but, I have to admit, I was skeptical. I wondered if trees, like fish, get bigger with each telling of the tale. I was prepared to be underwhelmed by the Pine Orchard. Happily, I was wrong. The Pine Orchard is impressive and these may very well be the largest and oldest trees in the southern Adirondacks.

But how big --exactly-- are the pines in the Pine Orchard? I measured a few trees and the largest one I found has a diameter of 51 inches; just over four feet. I took this measurement by stretching a cord around the tree four and a half feet above the ground. The distance on the cord measured 161 inches and dividing that by 3.14 yields the diameter: 51 inches. That's not the six to seven feet that some have reported but I might not have measured the very largest trees. And while measuring the diameter at four and half feet is standard practice in forestry circles, others might have done it differently.

I'm interested in the history of the Adirondack forests and the large old trees have stories to tell. So I look for them when I hike. Over the past several years whenever I've spotted a large tree I've noted the location and estimated the size. Now that I've refined my measurement technique I see that my past estimates may have tended towards the high side (No, Dad, this does not apply to fish I've caught in the past). I carry an old ski pole as a walking stick and I've used the pole as a gauge for estimating tree diameters. I now see that this technique is insufficiently precise. In the Adirondacks, trees with diameters of 36-40 inches are found in many places. Trees of that size will typically be more than 125 years old and a stand containing many trees of that size may have been passed over, or selectively logged, in the first wave of industrial logging. That first wave took place after 1850 and continued into the early part of the 20th century. You can also find trees with diameters larger than 40 inches scattered about in the Adirondacks, but these are much less common. These trees were almost certainly standing before 1850. The really big and old trees, with diameters of 44 inches or larger, are rare. The Pine Orchard contains a number of trees in the 44-48 inch range and estimates that I've seen place the age of the stand at over 200 years. (Note: the correlation between tree size and age varies with species and growing conditions).

Image One: A large White Pine near the point where you first reach the Pine Orchard Stand. The strand of yellow yarn is one foot in length.

The Pine Orchard: Old Growth Forest

The Pine Orchard is old growth. At 200 years without external disturbance the forest has reached the climax stage in terms of ecological succession. For this location, and given whatever circumstances protected it originally, that means mature White Pine with some Hemlock and a few old hardwoods mixed in. Stands of old growth pine are often compared to a cathedral and that description applies to the Pine Orchard. The forest floor is blanketed with a deep layer of pine needles that absorbs sound and this is an airy, quiet, place. I was there on a very warm day and it was pleasantly cool under the cover of the large trees.

Image Two: The cathedral in the pines. The forest floor is covered with a two century accumulation of pine needles. Smaller trees are mixed in but the canopy is dominated by the large White Pines.

The Trail and the Hike The route I followed leaves the Pumpkin Hollow road at the Murphy Lake trailhead. As with the the trail to Wilcox Lake this route is marked and maintained as a snowmobile trail. The 1994 ADK guide to Trails of the Southern Region described this trail as indistinct and hard to follow. That Guide advised that this route should be attempted only by hikers skilled with map and compass and it went so far as to say that the trail was not recommended for parties of fewer than three people.

Image Three: From Google Earth. The entire route covering 5.9 miles each way.

That guide was written over 20 years ago and much has changed. I don't know whether the warning was justified when the book was written, but it is not true today. The route generally follows old woods roads and it for pleasant walking. There are a couple places where arrows (signs) point the way. Not because the trail is indistinct but because multiple old woods roads intersect and it could be difficult to pick the correct route. Interestingly, the warning from the ADK guide was carried over to a much newer map. My favorite trail maps these days are the "Trails Illustrated" Topographic Maps produced by the National Geographic Society. The Northville/Raquette Lake map covers the southeastern Adirondacks and that map restates the warning about parties of "at least three persons" word-for-word.

There is also a meaningful discrepancy in the length of this route as stated on signs and as printed in various guides. As measured using GPS my hike covered a total of 11.8 miles. This included a bit of wandering around so the sign board at the road which states the distance to the Pine Orchard as 5.6 Miles is reasonably accurate. The 1994 ADK Guide lists the distance at 6.6 miles one way. And a third distance, derived by adding up distances seen on signs along the way, yields a total of 4.2 miles. Applied to the round trip, the difference between the shortest and longest mileage is over four miles. That's a serious lack of accuracy.

There are two apparent sources for the uncertainty. The first is that there is no distinct point or boundary to mark your arrival at the Pine Orchard. The lack of a clear "here it is" location accounts for a tenth mile or two of the discrepancy. This is a question of precision. Lacking a distinct end-point it's difficult to measure the distance to the tenth of a mile precision typically used on trail signs. The second consideration is that over the past 30-40 years the trail has been re-routed, probably more than once. The 1994 ADK Guide alludes to this noting that the trailhead had been moved to avoid a crossing of private land. This is also evident in an old sign seen at the junction with the Flatters trail. The sign says that it is 2.6 miles to the "Willis Lake Road" but the trail doesn't go to the Willis Lake Road. That was probably the original starting point. If the sign stated the distance as "a few miles" it would be more accurate but not very precise. As it sits, it is neither.   

Image Four: Stanton Miles: When our children were young we would take them hiking and the first thing they wanted to know was; "how far is it?" To which I would respond "a couple of miles." It took only a few outings for them to realize that my "couple of miles" could be anything from two to five miles. That answer is accurate but not very precise and my scale became known in the family as "Stanton Miles." If you use Stanton Miles the difference between what appears on the sign and the actual distance of four miles is accounted for.

Uncertainty, Accuracy and Precision

Measuring the diameter of a tree is pretty easy. And collecting measurements from many trees is a straightforward process:

• Measure the tree
• Record the location
• Record the species
• Note unusual or complicating factors
• Repeat

That sounds easy enough, and it is easy. Which is why I am continually surprised by all the different ways that uncertainty creeps into the data. Part of it comes from doing this work in the Adirondack Biting Insect Preserve. During the warm months you encounter many many small complications and distractions and for the rest of the year your fingers will be numb making it difficult to write out notes. But sometimes I run into more specific issues:

• Diameter: What about double-trunk trees? Or trees in difficult locations? What if there is a branch or some other oddity at the 4.5 foot height where I want to measure?
• Location: Assuming that the accuracy level of your GPS device is good enough, and assuming that you have a good signal from several satellites, and assuming that you correctly note which location goes with which tree, it nothing more than the push of a button.
• Species: I'm familiar with most tree species seen in the Adirondacks, especially the species that get to be big. Still, when I have gone back and looked at the same trees a second time I've found that I get some of the them wrong.
• Notes: Some days I do a good job of recording the unusual or complicating factors and some days not so good. And this information often turns out to be important when trying to draw conclusions from a body of data.

On one point I have no doubt. All non-trival data contains errors and considerations of precision and accuracy are relative to the intended use. These are the sources of uncertainty.

A Couple of Miles: I was just being accurate

As often happens, the use of a tool under less than ideal conditions leads to a deeper understanding how the tool works. Using GPS to record locations and to record the tracks I've follow has given me a deeper understanding of how the system works. I'm going to return to this topic in the future but a few key points go right along with the theme of this post. First, take a look at image five. The lines show a short section of the track captured by my GPS receiver on the hike to the Pine Orchard and back. The line on the left was from the inbound leg of the trip and the line on the right is from the return trip. I walked the same path both ways so it's odd that the the lines are so far apart. To get to the bottom of this you need to know something about how I hike.

I took much longer to complete the trip to the Pine Orchard then I did on the return and this is typical for me. And this was not because of the terrain. The route crosses a couple of small ridges but there is very little difference between the elevation at the turn around point. It's counter intuitive, but I typically travel at a slower pace on the way in because I'm fresher. On the way in I stop to record measurements, I take photos and I generally take more time to enjoy the forest the scenery. On a hike of this distance by the time I'm half way back to the car I'm starting to get tired. And this is the counter-intuitive part, I tend to walk faster and I move along without stopping. On this particular day, it was hot and by the time I reached the area shown in image five I'd been hiking for over five hours. It was also into the early afternoon and I was I not hiking alone. I was traveling with dozens of new (and now really annoying) friends that I'd made along the way. Deer flies, midges, mosquitoes and a few too-stupid-to-just-give-up-and-die black flies. The bug spray that had been mostly effective earlier in the day was no longer working. 

Image Five: GPS Accuracy 
The lines in the image show a short segment of the track captured by my GPS receiver on the hike to the Pine Orchard and back. The line on the left was from the inbound leg of the trip and the line on the right is from the return trip. I was walking on the same path for both legs of the journey, so you might expect the lines to be very close to each other. (Map Image from Google Earth)

A GPS track like the one shown in the image is recorded as a series of points. Every second or so (this will vary based on the device) the GPS receiver calculates your location and stores the coordinate pair representing that location.  When you stop the receiver gets extra time to correct for errors so stopping periodically improves the accuracy of the track overall. This is especially true when walking through a dense forest where the strength of the signals is reduced by foliage. In image five I added a note to a place where it looks like I took a short side trip off the trail. But I know that that never happened. What did happen is that the GPS recorded a couple of points with much lower accuracy and those points became part of my route. If I was planning to use this track as data I would need a method to clean up these kinds of errors. 

There are many factors that limit the best case accuracy of GPS. A GPS receiver captures signals sent by satellites orbiting the earth and when the receiver has signals from at least three of these satellites it can calculate your location. The U.S. GPS system uses a constellation of 32 satellites positioned so that there should always be at least three satellites above the horizon and "visible" to a GPS receiver located anywhere on the earth. Under good conditions a typical consumer GPS receiver can fix your location to within about 10 yards -30 feet- using signals from three satellites (four are required to also calculate your elevation). At that accuracy level you use the coordinates calculated by the receiver and place a point on a map. Then you draw a circle with a diameter of 30 feet around the point. Your actual location lies somewhere in that circle. 

Depending on what you are trying to do that may or may not be accurate enough and it's usually possible to get much more accurate data. For instance, it's common for there to be more than the minimum of three satellites available to your receiver. Modern GPS receivers including the ones found in most smart phones, use the "extra" satellites to average out some of the errors that otherwise limit GPS accuracy. For example, when I save a waypoint (the coordinates for a single location) using my Garmin GPS it tells me how accurate the fix will be based on the set of satellites available to it. The use of additional satellites and averaging commonly improves accuracy into the ten to twenty foot range. On the other hand, dense foliage, cliffs, mountains and other obstructions reduce accuracy or prevent the receiver from getting any fix at all.

The point is that data taken from measurements is always uncertain to some degree and the level of uncertainty varies based on the specifics of how you gather the data and your intended use. You have to ensure that your data is accurate enough for the intended use and you have to avoid mis-representation by overstating the level of precision. When I use a cord to measure the circumference of a tree, if my measurement is accurate to within one inch then I can state the diameter in inches. Dividing the circumference by Pi to get the diameter will almost always yield an answer with a remainder, something like 45.3. But the .3 must be thrown away. The accuracy level of my measurement does not support that level of precision. If a trail sign states a distance as 2.6 miles, then assuming typical rounding to the nearest tenth we can say that it's accurate if the actual distance is between 2.55 and 2.65 miles. Assuming, of course, that it's the correct sign for the trail you are on. My GPS gives me coordinates with 6 decimal places of precision. That's precise enough to separate locations that are just inches apart. But the device is not nearly that accurate and the last digit (and maybe the last two) should be discarded. The extra precision is meaningless at best and misleading at worst. Whenever we take measurements there is uncertainty and the level of precision we use should not overstate the accuracy of our technique. 

You see kids, when I said it was a "couple miles" I was giving you the most accurate answer that I could.