2010-12-29_REPORT - M1988044 - Laserfiche WebLink

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youngest of the five exclosures are developing well and reaching toward the goals, but the growth is not yet there. Photographic monitoring is provided for the other three exclosures. In 2010 it was found that Exclosures 1 and 2 continued to show significant gains, but seem to be developing in different directions. New tree seedlings are still found, as would be expected, and this is especially true in Exclosure 1. Exclosure 1 is continuing to shift strongly toward a willow dominance that is probably reducing the growth rates of the cottonwood. Nevertheless, cottonwood still makes significant gains where the local microenvironment is more suited to cottonwood. In wetter soils though willow seems to be winning the competition battle. In Exclosure 2 where willow forms a far less dominant cover and density, cottonwood continues to make strong gains, but once again only in the somewhat drier portion of the exclosure. Here the main competitor with both willow and cottonwood are herbaceous wetland plants that dominate the western edge and the northwestern corner of the exclosure. Elsewhere, cottonwood and willow made significant gains in height, but density did not change very much, if any. The 2010 Growing Season: The winter of 2009/2010 was unusual due to the effects from a fairly strong El Nino cycle in the equatorial Pacific. Early winter was unusually wet with prodigious snowfall in October and November. In Denver, nearly half of the annual snowfall had been received by December when winter actually began. This is fairly typical of El Nino years. However, the usual January thaw did not come in 2010 with only moderate warmth and continued occasional snows that maintained the soil moisture that had accumulated earlier in the autumn and winter. Thus spring began with a surplus of soil moisture that resulted in rapid greening of the prairies with strong growth of native grasses as well as winter wheat crops. By mid-2010 the El Nino rapidly declined to a neutral condition and then quickly shifted into a La Nina pattern and its usual decline in precipitation east of the mountains. Moisture increased some in the late summer but a strong monsoon never actually developed and autumn began with a moisture deficit that continued well into December. In contrast to 2009, the October to mid- December period resulted in only about 1.5" of snowfall in Denver for the entire period and practically no rain. This site received a bit more snow and rain during this period, but it was still essentially a complete reversal of the same period in 2009. This is typical of La Nina years where it is quite dry and warm east of the mountains but the mountains receive prodigious if not record snowfalls. By mid-December the snow pack in the mountains was well above 100% of normal and even reached nearly 150% in some drainage basins. Meanwhile the east side of the mountains plunged into drought conditions. Not all is lost, however, as it is also typical of La Nina years that late winter and spring moisture is abundant east of the mountains, sometimes with record breaking snow storms. At the time of this writing (mid-December), however, long range models are not predicting a significant change in this pattern until perhaps the second half of January. So long as the La Nina continues to 2010 Annual Report Coal Creek Wetland Mitigation Permit DA 198811488 Page 2