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Cover: Overall cover in Exclosure 2, as shown by the photographs, has increased <br />dramatically while tree cover remains about the same. Trees are still gaining in height rather than <br />spread and therefore much increase in tree cover would not be expected at this point. In 2010 though <br />it does appear that tree branches are starting to show some additional spread, although it is not <br />apparent enough to say it is occurring on a wide spread basis. Nevertheless, it did increase simply <br />because as the trees get taller they naturally spread out a bit more. Where trunk dimensions are <br />greater there does seem to be more branch spreading. Multiple stemmed cottonwoods are not unusual <br />here, but that growth form is restricted to only the older cottonwoods. Newer trees are developing in <br />a more normal growth form with a single, central trunk. <br />Change in Height: As discussed previously, the slow but steady annual gain shows <br />promise, but it does leave room to wonder if the site is in a precarious, marginal habitat that could <br />result in major losses of trees in the event of a multi-year drought. At this point though, there does <br />not seem to be much need to worry about the future as steady gains are still being made. It is <br />expected that gains in height will remain in the 25% per year range for at least a couple more years. <br />At some point though gains in height will slow while gains in width becomes the dominant growth <br />pattern. It appears the point where the trees begin to spread may be controlled by the trunk <br />dimensions. As the trunk thickens the tree can biomechanically support more branch spreading. <br />Examination of the trees seems to indicate this point is when the trunk diameter reaches about two to <br />four inches a foot or so above the ground. <br />Overall Conclusions: Exclosure 2 is clearly on the dry end of the favorable habitat regime <br />for cottonwood and spectacular growth would be unreasonable to expect. The soil is very sandy and <br />is at an elevation that is somewhat marginal with respect to access to groundwater. Nevertheless, <br />steady growth gains each year have been seen and the first year gains were the only ones that could <br />be called spectacular. Those first year gains were undoubtedly a response to the removal of <br />browsing. Unlike Exclosure 1, there isn't an adjacent area that can be used for comparison to see <br />whether another, slightly more moist habitat of the same age would make even greater gains and thus <br />move ahead of the growth in the exclosure. In a word, the results have to stand on their own merits <br />for this exclosure and, at this point, it is continuing to show considerable promise. Probably more <br />revealing than the graphs or even careful examination of raw data for this site is a careful <br />examination of the photographs. Here the photographs say far more about what is happening than <br />would be seen if the amount of data collection was doubled or tripled. <br />In this year's annual report a new set of photographs are presented that show the changes <br />along the three individual transects. These photo pairs show the transect when first established in <br />2006 and how the transect appeared in 2010. This kind of presentation is not provided for the other <br />2010 Annual Report Coal Creek Wetland Mitigation Permit DA 198811488 Page 15