Using Satellite Data to Find Old Growth    Ernie Ostuno
   Jun 02, 2006 23:30 PDT 


I think it would be a very worthwhile project to use the terraserver or
google earth sites to try and track down these undocumented old growth
fragments. About seven ago I took a course on satellite mapping at Penn
State and used some software that was capable of plotting different
ground cover types. From what I recall it worked like this: you take a
high resolution (3 meters I think) satellite photo and zoom in on a
section of known groundcover, such as asphalt. You sample a section of
it and assign it a value and the software maps all similar cover over an
area, so that you see a map of roads, parking lots, etc. Then you repeat
the process for other types such as grass, trees, etc., choosing a
different color for each until you have all sections of the map plotted
in various colors. It would be interesting to see if the satellite
signature of old growth hemlocks such as those seen on the link below
would be tagged differently than younger hemlocks.


Robert Leverett wrote:
Ernie, et. al.,

   If we can find plenty of previously undocumented old growth spots in
western Massachusetts, and we have, I'd have to believe that
Pennsylvania has many, many more. In western Massachusetts, areas of an
acre or less frequently pop up at property boundaries, around rock
ledges, and near waterfalls.


Ernie Ostuno wrote:

Ed provided a link to terrasever imagery of Beech Bottom Hollow, to
which I got the following photo link from:
RE: Forest Dutlinger Natural Area, PA   Ernie Ostuno
  Jun 02, 2006 23:54 PDT 

Years ago I entertained the idea of using an ultra-light to fly over the
ridges and identify old growth stands, but alas, technology now allows
us to do the flyovers from our easy chairs. Many times during the winter
months I would spot a patch of evergreens on the ridges of central PA
while driving through the valleys and wonder how old they were. Several
times I would look at them through a pair of binoculars and see the
conical tops of what appeared to be mature, if not old growth hemlocks.
Only once did I actually hike up the ridge to check them out and in that
case they did indeed turn out to be old growth.

Check out this view of part of Potter County:

It's amazing at how thorough the cutting of hemlock in the stream
valleys was back in the logging era through the Hammersley area, but you
have to think that in an area as big as this a few stands of trees may
have survived. Yet I have never seen any mention of there being old
growth in all of Potter County. Let's zoom in on a couple interesting
locations here:

There's a few dark patches here, let's go closer in:

Definitely intact stands of evergreens on the valley sides and near the
ridge tops but is there any way to discern the age or species of these

Here's another interesting area:

Zoom in of the evergreens:

At least these seem like they could be observed from a car, as there are
roads nearby. This seems like it would be an interesting endeavor for
those with the time and inclination.

RE: Forest Dutlinger... (Satellite Photos)   Anthony Kelly
  Jun 03, 2006 05:56 PDT 


Thanks for the detail on the location of the Dutlinger Natural Area
old-growth area. I'll definitely explore that area better on my next trip
there which will probably be with some of the other PA ents. If you can
scan that map and sent it to me, I'd be gratefull. Thanks.

As far satellite photos go, I've mostly been using them just to navigate and
get an idea of the lay of the land before I arrive. For this trip we knew
that you and Dale had already found old-growth hemlocks, so we used the
photos (which were taken in April of 1994, i.e. leaves off), to find conifer

Whether satellite photos of old-growth areas, in general, LOOK any different
than photos of advanced secondary growth, I don't know. I understand that
David Stahle and others at the University of Arkansas have used NASA's
Landsat images to search out possible old-growth locations. Exactly how
they analyse them I don't know. I would imagine that they do some sort of
spectrographic analyses.

I've looked over satellite photos of known old-growth areas trying to
discern any differences detectible by the naked eye, but really haven't
noticed any. Uneven aged canopies should be detectible. If you look at
satellite photos of Cook Forest, for instance, you can see this.

Cook Forest is dominated by conifers. Terraserver photos are almost always
taken in early Spring when the leaves are off, so they are mostly only
useful for spotting and examining conifer stands. Below is a link to the big
woods area at McConnells Mill State Park.

The area contains a huge chunk of old-growth hardwoods. Looking at the photo
you can see the outlines of some early-succesional old-field areas and some
hemlock-filled ravines (definitely useful information), but theres nothing
about the other areas (that I can see) that indicate where the old-growth
lies. Perhaps summer, leaves-on photos, especially color ones, might show
some differences. I haven't yet tried any other online sources of color
satellite images.

If anybody knows of any old-growth characteristics that can be spotted on
satellite photos, I'd be interested in hearing about them.

Anthony Kelly
RE: Forest Dutlinger Natural Area, PA
  Jun 03, 2006 12:37 PDT 

In the part of NJ I'm from, google earth has much higher res data and I can
clearly spot that the trees behind our house are bigger than those in the
adjacent property and I can also see an area farther back in where I recall
seeing large trees a that also look noticeably larger. It is not easy, but
to an extent, the areas where they have super high detail, can reveal a
least a bit about actually stand maturity.

Re: Forest Dutlinger Natural Area, PA   Edward Frank
  Jun 03, 2006 16:39 PDT 


These areas may be worth checking out. In general I would observe that the
coarser the apparent texture of the trees, the larger the individual trees.
An old growth area may have a stand of mixed sizes of trees, rather than the
uniform smooth texture of a younger single aged stand. Some coal mining
reached into Potter County, but not much. Pine trees were commonly used to
revegetate strip mined areas because of their tolerance for the more acid
soil and sub-soil turned up by the mining operation. These would appear as
stands of evergreens on the photos, but would tend to be young and small.

The other question to consider is whether there is some physiographic reason
why these patches of trees might have been left here? A steep valley wall
in a relatively inaccessible area might be an indicator of a section not
timbered for economic reasons. The locations of sections left by boundary
disputes would be erratic and unrelated to topography.

Re: Forest Dutlinger Natural Area, PA   Don Bertolette
  Jun 03, 2006 20:08 PDT 

Yeah, I liked EarthGoogle so well in the trial version, I bought into the
midlevel subscription, and always get a kick out of it...of course, Grand
Canyon is featured with fine resolution imagery, and it's a treat! And I
can "fly" from the North Rim to my home south of Flagstaff in just minutes!
Just change the angle of incidence, zoom up to get over the San Francisco
Peaks and you're off and running, err, flying! Many large cities have fine
resolution...recently I flew from Chicopee to the Great Smokies and was
absolutely entranced...
RE: Forest Dutlinger Natural Area, PA   Ernie Ostuno
  Jun 03, 2006 21:59 PDT 


All excellent points. Some of the dark patches I zoomed in on did have
the appearance of evenly-aged pine plantations. The neatness to the
edges seemed to be an indication of that.

Some software used to analyze satellite data maybe be capable of
discerning between old growth and second growth hemlocks. Even seven
years ago, the software seemed on the verge of being able to discern
such subtle differences in ground cover. I do notice the slight
differences in the appearance of the old growth hemlocks in the
Dutlinger N.A. just from looking at the close up satellite photos, where
individual crowns of trees can be seen. One place that would be
interesting to look at would be the Tionesta Scenic/Recreation Areas to
compare the intact old growth hemlocks with the blowdown areas.

Of course, there will still be the need for ground truthing the
inferences made from satellite data. And given the remoteness of the
Hammersley Wild Area, that ought to be the real "fun" part.

Re: Forest Dutlinger... (Satellite Photos)   Don Bertolette
  Jun 03, 2006 23:58 PDT 

I tried using Landsat back in the late '70s to identify old-growth in
Massachusetts...excellent spectral resolution (color range) but inadequate
spatial resolution...pretty much have to get airborne platform digital
imagery to get to the spatial resolution you need...a remote sensing guy
here in Flagstaff (Pat Chavez at USGS) has a quick attaching digital camera
(variable three band) that is wonderful for detecting water stress/bug kill,
AND sub meter spatial resolution...of course, you have to have a lot of
flight lines for larger areas!
RE: Forest Dutlinger... (Satellite Photos)   Ernie Ostuno
  Jun 04, 2006 02:28 PDT 

There may well be satellite data with that much resolution, but I
haven't seen it on the web...yet. Google Earth is the highest resolution
I've seen so far and individual trees can be made out clearly.

The photos of Cook Forest and McConnells Mill didn't appear to my
untrained eye to be discernable as old growth, and the bare deciduous
trees all looked the same to me. Maybe there is some level of pattern
recognition that can be attained after some hours of study, but I assume
the spectrographic analyses would probably work better.