Fixed Area Plots/ Rucker Index Analysis   John Eichholz   Nov 14, 2006 09:57 PST  Bob, ENTS If we are going to produce further improvements in the data, we ought to structure it to allow analysis like Lee Frelich is proposing. As our corps of tree measurers are aware, tree heights are maximized in a very localized pattern. Overall, a forest can have many primo sites, and in the vicinity of any tall tree are often several others of the same species and sometimes of different species. Move away from that tree a couple hundred meters and everything changes. In some cases, you can move a few hundred meters more, into another high growth area, and the pattern repeats. We gain a sense for where this will happen, but not only are we sometimes wrong, but we don't know enough about what makes a site support high tree growth. One idea I am working with is to consider the local site conditions at each area that contributes a tree to the Rucker index. In order to support this research, I am delimiting the topo map for MTSF into even-sized sections, using the UTM grids on the map. Those are 1km by 1km, there are 15 to 20 of them in the forest, and they could usefully be further divided into 250m by 250m quadrants. On a first pass, most of our contiguous high growth areas would each fit into one or two quadrants. Many quadrants have high growth areas, but fewer quadrants have Rucker iteration members in them. An initial project would be to map as many trees from the top 25 iterations onto the grid system as we can, then look for patterns. We can revisit an area to supplement other data we have about a quadrant identified in this search. We can make standard characterizations about the quadrant, and perhaps contrast tree populations from other quadrants with similar characteristics. This process of picking areas to go back to is one way I use to increase the Rucker index. Right now I am looking at a cluster of data showing high concentrations of tall hemlocks in the area of Black Brook/Cold River confluence. The tallest hemlocks are located in or next to streams, within 200' to 300' elevation above the main river. The tallest trees are located where slopes are 35 degrees or less. While 40 to 45 degree slopes exist adjacent to these areas, mostly at higher levations, there is a 20' reduction in maximum observed heights in those areas. Also present near the tall hemlocks are a significant population of really nice Yellow Birch, including most of the known examples that exceed 100' in height. Sugar Maple and to a lesser extent, American Beech grow quite tall in these areas, but not to record heights. White Ash does intermix with hemlock, but outside the hemlock areas it grows much taller. Across Cold River but within sight, is the famous Ash Flats, with champion White Ash and Bitternut Hickories.     Of the top 25 hemlocks found, 9 occur in this area. 10 more occur in the Trout Brook basin, and 4 near the entrance to the park. At least 80% of the tallest Hemlocks found at MTSF occur south of the Cold River, and would probably lie within the boundaries of 9 quadrants (out of 60-80 total in MTSF.) Another idea we are working on is time series measurements of selected trees, to establish growth rates. We have some time series data for MTSF, but it seems like only the beginning. John RE: Skiffley Creek and Dry Branch   Robert Leverett   Nov 22, 2006 05:35 PST  Josh, Jess, Mike, The amount of acreage in the southern Appalachians with a RHI above 140 may cause us to have to introduce an area variable and begin looking at the results of Rucker indexing through physical areas with indices reaching thresholds to get a better appreciation for the extent of the high canopy forest in various areas. We may be moving more toward a calculus-like approach to Rucker Index Analysis (RIA) to better describe an area. I have thought about mapping MTSF via the RHI as a series of limited fixed-area plots chosen to capture different growing habitats. More on this idea to come. Bob      RE: Skiffley Creek and Dry Branch   Joshua Kelly   Nov 22, 2006 10:09 PST  Bob, Identifying and mapping the areas of highest RHI, RCHI, basal area, wood volume, etc. is a very cool idea. By identifying such sites and quantifying the physical properties that lead to their productivity and the tree dimensions found there, much could be deduced about the way forests function - at least in 2nd growth circumstances. I'm not sure the data set is complete enough for the primary forests of our region. I also like the idea of RIA's. I'm imagining maps with colored zones that delineate the known potential canopy heights of different areas of forest. Perhaps ENTS should invest in some GIS software? That would be fun, and expensive. Josh Fixed area plots was: RE: Skiffley Creek and Dry Branch   John Eichholz   Nov 24, 2006 17:59 PST  Bob, I have been thinking similarly (see my 11/14 post), that MTSF should be divided into a series of plots that represent distinct growing areas, especially areas that are contiguous areas of high growth, bounded by lower growth areas. It seems at first that each grove would have a much lower Rucker index than the forest as a whole, and would represent a pinnacle of a particular soil/aspect/moisture/history that supports a distinct forest type. I am thinking of forest type distinct from the usual classifications such as "northern hardwoods", since we would be looking at much more detail. I have started to enumerate subsites as I explore a site, carrying a topo map printout to mark up. In the Cold river basin I found the natural site boundaries to be a couple of hectares extent. In Trout brook, they might be 2-5 hectares, enclosing a particular hot spot or region of interest. That is not to say that adjacent areas are always dull, but that they are of a different focus. Anyway, I am looking forward to what you are thinking, and I will keep developing the idea as well. John Eichholz p.s. Too bad our areas are not as big as the southern apps.   Home