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Results of Exclosure Studies <br />As was the case in last year's report, the emphasis in this report is on the long term trends in <br />the vegetation rather than changes from the previous year. It seems quite apparent that all the <br />exclosures will be a success, barring any serious natural calamities like a 100 year or larger flood. <br />Detailed analysis is now only done on Exclosures 1 and 2 with only photographic monitoring <br />on Exclosures 3, 4, and 5 as well as Exclosures 1 and 2. <br />METHODS - <br />Sampling was done differently this year from prior years. As discussed last year, the transect <br />approach became unworkable in an effective way. This was due to the density of the growth and the <br />difficulty of establishing straight transect lines so data from one year could confidently be compared <br />to prior years. Furthermore, as mentioned earlier, it was time to look at data from the entire exclosure <br />so that could be compared to prior years to see if what was seen on transects holds reasonably true <br />for the entire exclosure. <br />This year a point sample method was used. Although not truly randomized points were used, <br />as that would be extremely difficult to do in this vegetation, a semi - randomized method was used. <br />Basically, starting at one corner data was collected by setting the end of a long measuring rod at a <br />point on the ground and measuring the height of the nearest woody plant while noting whether it was <br />cottonwood or willow and if willow which of the two species the plant was. This provides a good <br />way to measure heights and construct a frequency distribution that could be compared to an idealized <br />curve. It also allows, to a limited degree, comparison of mean, mode, and standard deviations of <br />heights over the entire exclosure to similar values for the transects. It has one additional advantage in <br />that it provides a means to measure the age distribution of the woody vegetation to see whether <br />young trees and shrubs are still entering the community or whether the population is skewing toward <br />only older plants or is still showing the more favorable normal distribution that indicates the <br />vegetation is still dynamic and has not trended toward stagnation. <br />Each of the exclosures have a discussion, and four graphs that show the changes in data over <br />the study duration to this point. Photographic documentation is presented a bit differently this year. <br />Instead of a comparison of the first year to the current year, images of the exclosures for each year <br />are presented on a single sheet for each of the selected viewpoints for all five exclosures. This makes <br />it easier to visually see the changes within the exclosure and sometimes adjacent to the exclosure <br />over the years. It is apparent the changes are often dramatic and with careful examination it is even <br />possible to distinguish good growth years from poor growth years. The photographs also show some <br />of the changes in the many other species in the exclosures, particularly grasses and other herbaceous <br />growth. <br />2011 Annual Report Coal Creek Wetland Mitigation Permit DA 198811488 Page 5 <br />