Sources of Data - Good and Bad Bob Leverett
Jun 10, 2003 04:27 PDT 
Mike:

    In terms of species distribution, perhaps the choices people made for their witness trees biases the distribution a little. More significantly, wholesale use of fire both in pre and post-colonial America would have had a very substantial impact on the makeup of the forests. We have no counterpart now. My question to Charlie about white oak abundance is directed to that point. Also, white oak is Connecticut's state tree. So the former abundance of white oak in at least Connecticut and Rhode Island is not in question. How far white oak dominance extended northward is the big question. Maybe into extreme southern Massachusetts, but not into the central uplands and definitely not far northward into the Berkshires and Taconics. The extreme southwestern corner of Mass is an anomaly. It seems to have been oak dominated, with white oak being prominent, though not necessarily dominant.

    I would agree with you that the impact of forest practices on current-day species distributions needs to receive a lot of attention and be the subject of scientific inquiry. I think Harvard Forest is looking at that now. I worry about their sources of data, though. How reliable is chapter 132 cutting plans for identifying species and volumes cut in an aggregate sense as opposed to accuracy on individual plans? What would detailed analysis of chapter 132 plans likely reveal? Are there invalid conclusions that could be drawn about species distributions from aggregating the data?

Bob
Re: Sources of Data - Good and Bad Don Bertolette
Jun 10, 2003 20:39 PDT 
Bob-


Aye, there's the rub! The biases...in the western version of land subdivision, a rectangular grid is used as opposed to metes and bounds in the East. It was thought early on that the grid system would function in a more or less random manner and provide some measure of vegetation sampling. And it does. But there are some biases that are difficult to correct, no matter how sophisticated your statistical analyses.
My first forestry job, away from home in eastern Oregon, was original survey corner restoration with the Bureau of Land Management. The GLO (General Land Office) rule book specifies that a certain amount of quadrants shall be represented in witnessing the corner. But the contractor/surveyor got paid by the corner, so there would be a tendency, all other things being equal, that the nearest qualifying tree would be selected.   That's kind of okay, and statistically mitigated, but it was my experience that some trees were preferable to others, distances being equal...too small of diameters (hard to scribe witness information on smaller trees) or too large of diameters (time needed to clear bark increased with thickness/diameter), wood hardness, isolation versus clumps (single tree stands out, makes better witness than clump), etc. I would suspect that the eastern hardwoods would offer
up another set of biases on these counts, to say nothing of the tendency of metes and bounds property lines to follow topography (line runs along ridge bearing SE until point of ridge divide witnessed by 18" red oak, thence NW down drainage until creek where line follows creek NE to tributary of ....as witnessed by 48"sycamore...).
-Don
PS: As a young man, finding original planks (survey notes dated 1880) that the surveyors practiced on before they scribed trees, limbing marks, line tree blazing, scribed rock corners, witness trees that we carefully re-exposed the scribing of, was part and parcel of what forestry meant to me back then...eastern Oregon in 1880 was very much like northern Arizona with reference to the state of settlement.
Re: Sources of Data - Good and Bad Bob Leverett
 Jun 11, 2003 04:31 PDT 
Don:

     Interesting. I had wondered about purposeful selection of species as witness trees that would bias a distribution in favor of one or more species. One might imagine a personal bias also. People being people, we can easily imagine personal biases. Do they average out? I'd think so. Pretty close, but can't be sure.

Bob         
Re: Sources of Data - Good and Bad Paul Jost
Jun 11, 2003 05:22 PDT 

I am curious about the detail of information available in the original
surveys in the east. Was it limited to witness trees only? In
Wisconsin, public land survey records included sample plots that
identified every species and dbh class of each individual recorded in
that plot. I believe that this was done to aid lumber companies in
their quest for their prey. In this century, researchers have returned
to the original survey plots to compare the changes from the early to
mid 19th century data. I have discovered that after some examples of
these were published in the early 1950's with most of the original
trees still there, but only much bigger, the lumber companies moved in
and clear cut them. This seems to have help to lead to the formation
of the Wisconsin State Natural Areas program that protects the few
remaining old growth stands. Lee, do you have more knowledge about the
content of Midwest land surveys?

Paul Jost
Re: Sources of Data - Good and Bad Lee E. Frelich
Jun 11, 2003 06:18 PDT 

Paul:

As it happens I spent a year reading the original GLO notebooks and
transcribing data for a section of northern WI for Craig Lorimer when I was
a senior in college, just before starting graduate school.

The GLO surveys in the Upper Midwest divided the land into square 6 x 6
mile townships, and each township into 36 square mile sections, and
included the dbh, species and distance from the corner of 4 witness trees
at each section corner (generally one tree in each quadrant, although in a
few areas the surveyors got lazy and only recorded 2 trees), plus line
intercept trees, which were all trees that fell on section lines. The
surveyors also ranked the top four species as to importance for each 1-mile
section line, along with timber and soil quality, based on their impression
as they walked the lines. They also recorded recently burned areas and blow
down areas, noting the distance along the line where they entered and left
the disturbed area. They also commonly recorded the distance along lines
where they entered and left swamps, as well as the type of swamp.

Some surveyors were quite good at tree ID and separated things such as
yellow birch from paper birch and red maple from sugar maple, and others
didn't. Dbh was generally done in 2 inch increments up to 40 inches, and 10
inch increments after that, but again there is some variability among
surveyors. Each witness tree was marked with a blaze (i.e. a chunk of bark
facing the section corner was removed with an axe). As it happened, one of
the hemlock witness trees in Sylvania was next to my tent while camping
there to get data for my Ph.D. Thesis. You could still see the scar, which
had healed over but had a different bark texture than the rest of the trunk.

I believe the sample plots you talk about with more detailed data,
including number and quality of logs in the trunk of each tree were done in
a separate survey by the state just for the purpose of assisting timber
companies in getting timber. MN did a similar survey for pine and tamarack
in 1905. I have the one for MN on a CD, but I don't know if the WI one is
available, although I saw a copy of it in the rare book section of the
University of WI library. Tamarack was surveyed because it was used for
railroad ties and telephone poles (or was it telegraph poles in those
days?). Of course, MN had a huge amount of tamarack, even in the upland
forests, and that was cut and used over the entire region.

The FIA (Forest Inventory and Analysis from the Forest Service) survey
began in the 1930's, and has been repeated several times since then, and is
now (since the late 1900s) continuously updated. FIA plots have a lot of
detail but their usefulness accuracy varies from high to low, depending on
what aspect interests you. The FIA data is available to the public through
websites, such as the North Central Forest Experiment Station in St.Paul,
which covers the entire Midwest.

The best data available today for old growth is the CBS (county biological
survey), which is conducted by the Natural Heritage Program in each state.
The data collection is designed and executed by ecologists, so they record
lots of things in addition to tree species, sizes and age structure,
including plant and animal species present. CBS data collection has been
going on for about 2 decades in WI and MN. The CBS usually produces maps
of presettlement vegetation for each county, based on land survey data and
any other historical records available. They also show areas that are still
natural vegetation today.

Lee
Witness trees   abi-@u.washington.edu
  Jun 12, 2003 07:53 PDT 

All,
Thanks to Lee for his wonderful summary of how the GLO surveys were made. I was going to weigh in but have been away from computers for several days.

The pre-settlement vegetation maps for many states (Wisconsin, Minnesota, etc.,) were made almost exclusively using witness tree data. When I moved out west and became involved with the University and GIS, I created a high-resolution presettlement map of Washington, which had never been done. I learned that a branch of the National Archives located here in Seattle had the original books containing the witness tree data. These are huge (~15" x 24") volumes, with each page representing one section. Because the West was not settled until late, these surveys did not begin until 1846 out of Portland and slowly moved north. They were repeated at least once again before 1870.

Washington, however, unlike Wisconsin, does not have a great number of tree species, and therefore the data was less useful. A witness tree recorded as Doug fir, for example, does not tell you much since they grow in nearly every forest type. One of two things that were extremely valuable, however, was that the prairies of Western Washington and the Willamette Valley in Oregon were very well mapped out by these surveys. The boundaries were recorded as they walked the quarter section lines and then a general sketch of that entire section was also included.

Another interesting bit of data was in eastern Washington - a big section of which has no trees. Here, instead of witness trees, there were 'witness bunchgrasses', which may seem silly. Actually, it is an awesome data set since today most of this area is in sagebrush when originally this made up a relatively minor component.

Cheers,
- BVP