Tightly Packed Tree Groups   John Eichholz   Mar 29, 2004 20:48 PST  Dale, Bob, Gary,: I like the idea of studying trees in relations or groups.   Many of our questions have to do with the relationship of the tree to the site conditions. General terrain conditions, such as aspect and slope, proximity to streams, latitude, and overall age or history are common to the stand. GIS mapping has been presented as a way to quantify this. The threshold of GPS or survey for every tree may be too high a barrier if we want to have widespread sampling. But a stand can almost always be assigned a location, just from the map if need be. A single cove or terrace, a hillside, or any reasonably well defined small area contains the trees in the group. The area itself should be easy to locate, perhaps by GPS on a prominent feature. Written notes describing the lay of the land and the relation of the trees to each other and to landmarks, combined with identifying features might be as useful as GPS to locate individual trees. Tagging and GPS can take place if desired to identify specific trees. The stand moniker can also serve to mask the ID of a specific tree when needed, while still giving information about the site. What does this mean for data collection? While we continue to collect data for individual trees, we would also collect data on the grove as a whole. Trees and groves both become individuals. They have relationships to each other tree to tree, tree to grove and grove to grove. The levels of tagging and measuring, grouping in stands, and locating stands might be a workable, efficient way of associating trees with site conditions. Also, a tree can belong to more than one stand. For instance, "Zoar gap cove, flat area at base of rocks" and "Clark ridge" are both valid stand names for the 120'+ black cherry trees I measured. Data-wise, a stand is a collection of trees, (rather than, a tree is in a stand.) Stand measures can be associated with site attributes, and vice versa. Kind of abstract, I guess. What do you think? BTW by my reckoning a thousandth of a minute (the 1 and the 6 on 42 3.071N x 80 11.756W respectively) is only 5 or 6 feet. That must be a pretty tight stand of maples? Those coordinates lie in a 25' square! John   From: Robert Leverett Sent: Monday, March 29, 2004 2:34 PM Dale:    One lesson that I've learned the hard way is that in tightly packed pine stands, if one tree is above 150, there's a good chance that several are. In the Trees of Peace, several trees made it into the club this past growing season, but I had thought they were around 3 feet shorter and so I was disinclined to put the extra energy into sorting out their crowns for a couple more years. However, Lisa Bozzuto and Susan Benoit's fine work of tagging the trees for our long term growth study for DCR necessitated measuring the tagged trees and that necessity led to Howard and I going after the residuals in the Trees of Peace Grove. Well, guess what we found?    On Sunday, the extra 150s in the Encampment Pines came as a fine surprise although one reason we went there was to search for another 150. The two new 150s in the ENTS Grove of the Encampment Pines are on the up-hill side of the trail and are mixed in with trees in the low and mid-140s. It was sheer luck that John Knuerr spotted the crown of the Lee Frelick Pine through a peep hole. John immediately recognized its potential. He did a quick measurement and was in the 157-foot range class. That illicited an ape call from yours truly. When we took careful measurements and adjusted for the base, we were in the 155 - 156-foot class. A new spot from high ground confirmed at least 156.1. It could we have a higher top. We'll try to establish that this coming Sunday. Could there be a fourth 150 in the Grove. Yes, there could.     As mentioned previously, the other 150 is up for grabs as to its name. The Tree Amigos have put it out to the ENTS list for a vote. I prefer not to be a candidate. I get enough attention as it is.     Next Sunday, I'm hoping we can spend another day in the ENTS Grove identifying all the candidates for naming. Trees above 140 are all available. I think there are between 10 and 20.     So presently, ENTS president Will Blozan and vice president Lee Frelich have trees named for them in the ENTS Grove. Will's tree is the larger in girth. Lee's tree is the taller. Hmmm.    Bob RE: What's the number?   Gary A. Beluzo   Mar 30, 2004 06:31 PST  Hi John, The method of mapping trees that keeps coming up in my literature search is the INTERPOINT method developed by Boose, Boose, and Lezberg in the April 1998 issue of Ecology. The method is a simplified, and improved, technique based on a 1978 Rohlf and Archie paper. If you are any other one on this list wants me to send the INTERPOINT files let me know. I think it would be a good protocol for ENTS to use, would allow for us all to use a standardized method, and it would facilitate the movement of the data into a GIS database like ArcView or ARCGIS easily. Here is a basic overview of the method (from the Ecology paper): 1. Establish three (or more) bench marks on the periphery of the stand such that one is on a corner (#1), a second is say 15m down one side, and the third is 20m down the other side from #1. Spend the time to get accurate GPS coordinates of these permanent benchmarks since these will be the primary references for all other measurements in the stand. 2. Each tree to be mapped is labelled and measured for dbh to the nearest 0.1 cm. Aluminum tags at dbh height (1.37M) are convenient reference for setting the height of the measuring tape for each tree-to-tree measurement. 3. Beginning in the vicinity of the bench marks, and moving gradually across the plot, each target tree (called subject trees by Susan Benoit at MTSF) is located by measuring the horizontal distance (may need a plumb bob) to the three benchmarks (or later three other REFERENCED trees). The three points should be more than 1M apart; pairs of reference trees that subtend an angle of <20 degrees or >160 degrees at the target tree should be avoided. Distances are measured from bark to bark to the nearest 0.01M. After each tree has been measured to the three reference points (initially the three benchmarks but deeper in the stand other reference trees that have already been measured)the target tree should be tagged so that you can identify it as a potential reference tree. 4. At the end of the field day the measurements are entered into a computer, plotted and the error analyed using the INTERPOINT programs. The resulting plot can then be imported into a GIS database. All of the details can be found in the Ecology paper. I also have loaded a new extension to ARCVIEW 3.2 on my laptop called AVCAD which allows me to plot trees based on combination of angle and distance measurements (at home or real time in the field!), so I am going to plot up Susan Benoit's data sometime this week. I would love to work with folks to get the whole process standardized and efficient. Gary Gary A. Beluzo Professor of Environmental Science Holyoke Community College 303 Homestead Avenue Holyoke, MA 01040 Re: What's the number?   John Eichholz   Mar 30, 2004 10:44 PST  Hi Gary, Thanks for the very detailed reference. I would be interested in reading the original papers. I think your general approach can be very useful both at the tree level and at the stand level. I am still thinking about mapping an object called a "grove" on the map, using your method or direct GPS to a monument within the grove. Each grove has its own characteristics, for example, a Rucker index or a basal area per acre. Groves stand in relation to each other in space as well. Perhaps a minimum definition of a grove would be the three required initial benchmarks, with the one benchmark chosen as the grove location. How well would the process work at +/- 1 yard distance precision? John RE: What's the number?   Gary Beluzo   Mar 31, 2004 10:14 PST  Dale, You need to use GPS to establish accurately the coordinates of your three initial benchmarks (on the periphery of the stand where you CAN get GPS measurements) and then once target trees have been accurately located with the method those trees can and do become reference trees as you map further into the stand. The important thing is that you begin with three properly located benchmarks (can be trees as long as you can determine the coordinates of the center...the method assumes a dbh of "0" for the three benchmarks). Gary Gary A. Beluzo Professor of Environmental Science Holyoke Community College Re: What's the number?   John Eichholz   Apr 05, 2004 20:39 PDT  Gary, Bob: (long) Summary: I have an idea for a mapping protocol that uses at least three GPS located monuments and a rangefinder and clinometer for measurements. The resulting data can be loaded into interpoint, and formatted GIS data obtained as output. This output should be accurate to +/- a yard or so under field conditions. The motivation for this protocol comes from your idea of locating some of the MTSF trees for the purpose of placing them on a GIS layer, which could open up a world of data to correlate with each tree. The Interpoint reference was very helpful. I found the complete text of the article on the Harvard Forest website, along with a downloadable copy of the INTERPOINT software. I was surprised that it was only about 50k in size, including the executable, a readme file and a set of test data for 1000 trees. I wanted to come up with a simpler protocol that would use a rangefinder and clinometer instead of tapes, to accomodate the often widely spaced trees in the areas we study. This protocol could be easily tested with a small data set generated for several trees in a day. The three or more benchmarks would be set up within view of the subject trees, and at least 20 yards distant. Then we would take GPS readings at the benchmarks. The cartesian coordinates (in yards) of the benchmarks (needed as input) can conveniently be figured out using the triangulation program provided with INTERPOINT. The distance from each benchmark to each subject tree is measured using a rangefinder to the nearest yard, and corrected for slope using the clinometer and the cosine formula. (Cosine of the angle times the distance equals the horizontal distance.) The circumference is measured in feet then converted to yards (same units as distance). There is then enough data to set up an input file for INTERPOINT. You get the formatted output from INTERPOINT, and there you go. When I ran a subset of the INTERPOINT test data (the first 66 rows) unmodified, the results came within 7cm of true for every tree. I then rounded the location data from 3 digits to 2, and was able to see the effect on cumulative error (not much). The trees were then located within 13cm of true. This data is similar to what you get using the protocol as you described it. I modeled the simplified process using graph paper and a ruler. I established three benchmarks along the edge, and randomly located 8 dots within. I invented cbh for these trees in decimal feet, then converted to cm. Scaling up the measurements to about a 20-90 meter spacing from the benchmarks, and rounding to whole meters, I set up a data file and ran INTERPOINT. The results came within 58cm, with all but 2 of 24 results within 25cm. The key was that all readings were taken from a benchmark, so there is no more than a single error to add in. I imagine that the error from chaining measurements from tree to tree like in the original protocol, would be at least additive for the first few. If it would seem reasonable for our purposes to have tree locations within a couple of yards on the GIS map layer, and we could verify with a ground test, this method might be useful. Once enough GPS monuments were once set, trees could be added to the data bank using a rangefinder and clinometer at any time. And, you could do it solo. What do you think? Would you like to try this process at the ENTS grove, as well? John RE: What's the number?   Gary A. Beluzo   Apr 06, 2004 07:03 PDT  Hi John, I am very interested in Terrain Shape Index (TSI) (and Landform Index in larger areas) and would like to see your thoughts about it..It is a simple field method that Henry McNab developed published in the early 1990s. Here is the basic method excerpted from the Forest Science, Vol 35, No. 1 article entitled "Terrain Shape Index: Quantifying Effect of Minor Landforms on Tree Height" pp 91-104. : In essence the index represents the mean relative difference in elevation between the center of the plot (i.e. stand, grove, or cluster of trees) and its boundary. Elevation of the observer, Zo, defines a fixed horizontal reference plane. The plot radius, R, when projected on the cone's surface below the observer, defines a sloping elliptical plane with a boundary ranging between maximum and minimum elevations at points Z1 and Zn. The mean difference in elevation between the observer and the plot boundary is: Zmean= (Z1-Zo) + (Z2-Zo) +...+ (Zn-Zo) /N For convex topography the sign of Zmean will be negative because the mean elevation of the plot boundary is less than the elevation of the observer. Similar logic is used in visualizing a plot situated on concave topography, except the value of Zmean is positive. A value of Zmean near "0" would indicate a nearly linear, but not necessarily level, surface shape, such as might occur on a side slope. Although the plot side does not enter into determination of Zmean, the gradient of surface curvature varies, depending on the size of the area being described. Standardizing the index for plot size yields: Terrain Shape Index (TSI)= Zmean/ R Where Zmean= mean elevation of the sample plot boundary           R= plot radius measured in the units used for elevation ------------------------------------------------------------------------ ------------------------------------------------ The TSI is thus equivalent to the mean slope gradient of the plot boundary as viewed from the plot center, with units of meters change in elevation per meter of plot radius. The TSI gives an indication of the amount of "concavity" or "convexity" of the plot center. This can be determined at a pixel by pixel basis (at whatever radius from each pixel you want to use)for the entire USGS quad using GIS! McNab found that in the Southern Applachians, the distribution and growth of trees was highly correlated with local topography. Application of the TSI in three even-aged stands of yellow-poplar on high quality uniform sites shows that it is highly correlated with total height of the trees in a stand, with r2 ranging from 0.45 to 0.74. In comparisons amopng the stands, TSI accounted for an average of 51% of the variation in site index. SO, it would be interesting to apply the TSI to our groves in MTSF and other sites to see how much of the superlative height may be explained by terrain topography (which of course influences variables like moisture availability). Also, we may be able to use TSI in combination with other GIS layers to predict where other superlative trees may be growing. Gary Gary A. Beluzo Professor of Environmental Science Holyoke Community College RE: What's the number?   Gary A. Beluzo   Apr 06, 2004 07:16 PDT  John, Yes..yes..yes...sounds wonderful. You are right of course, that we need a simple method that folks working SOLO can use to document the location of trees. I like your idea of simplying the field protocol by using our standard field tools- the clinometer and laser rangefinder. My only concern is that the laser rangefinder provides measurements to the nearest yard rather than centimeter and some of the rangefinders do not provide distances less than 18 yards or so (so what about trees that are relatively close to the benchmarks or densely packed?)...but if we are willing to accept these shortcomings with our existing equipment then by all means go for it. As soon as I receive the first grove data set (LATLONG in decimal degrees preferred, Massachusetts State Plane NAD 1983 the best..that's what MASSGIS uses and what our GIS database is now in) I'll plot it up and send you a JPEG with some different background layers so you can see what the ARCGIS and ArcView 3.2 software programs are capable of. Right now the main limitation for getting this GIS tree database going is..as always.. the field data; I have access to all of the MASSGIS data layers which include color digital orthophotos (0.5M resoluton), digitized USGS quad sheets, bedrock geology, surficial geology, soils, forest type (very coarse resolution though), major roads, major streams, watersheds, ACEC, etc. I will use USGS Digital Elevation Model files to create 3D models of each site over which we can "drape" whatever data layers (including any tree attributes like height, girth, health, etc) we want. I can also generate the various derivative terrain layers (slope, aspect, Terrain Shape Index, Landscape Shape Index)from the DEM files. Once the trees are plotted we can do many types of population, neighborhood, and other statistical analyses. The sky is the limit! Thanks for all of the time and expertise you are putting into this...once we standardize the field measurement method so that any of our ENTS folks can document individual trees easily and in a format that facilitates inclusion into the GIS database, we'll be entering a new phase of the work. These are exciting times! BTW, Tuesdays and Saturdays are good field days for me and after I return from the Smokies trip on April 26 I can get out on many Sundays. Feel free to call me at home 413 467-1531 or on my cell 413 210-7150. Gary   Home