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height with a good number of young plants underneath the older plants. As a rule, a wide age <br />distribution is indicative of a system that is establishing a persistent structure. That is, if older, taller <br />plants are killed or die, then there are younger plants to take their places. Still, with respect to height, <br />the plants in Exclosure 1 are well below what should be expected as a maximum height. Looking at <br />other sites along the stream corridor shows that when such assemblages mature there are a few, <br />somewhat stunted cottonwoods perhaps 20 feet tall with a dense understory of willows in a thicket <br />growth and a height of about 7 to 10 feet. The ground level vegetation is composed of grasses and <br />various forbs. That seems to be what is forming here, but it is still only about half way developed. <br />Overall Conclusions: Based on a comparison of the 2006, 2007, and 2008 data, Exclosure 1 <br />appears to be developing toward a willow thicket type of vegetation with occasional cottonwoods <br />that are kept on the low side by the intense competition from dense willow growth. This is more <br />characteristic of growth in the stream channel rather than adjacent to the stream channel where <br />cottonwood is more dominant in the mature growth. It also appears that cottonwoods around the <br />perimeter of the exclosure and on higher ground are the cottonwoods that will eventually form the <br />riparian forest unit itself. On the south end of the exclosure, where the land rises a bit above the <br />general floor of the former pit, cottonwoods seem to be growing better than those toward the north <br />end of the exclosure where the soil is wetter and willow more dense. The fringe trees up high on the <br />bank are probably suckers from adjacent mature trees, but the cottonwoods on the south end high <br />areas will likely become the mature trees originating from actual new plants. To the north the <br />cottonwoods will likely be a bit smaller and be densely surrounded by thick willow growth. <br />The understory of the woody vegetation is currently composed of a wide variety of species, <br />many of which are heliophytes ("sun-loving"). As the cover from willows thickens, many of these <br />will drop out and will be replaced by more shade tolerant grasses and forbs. <br />2008 Annual Report Coal Creek Wetland Mitigation Permit DA 198811488 Page 7