Laserfiche WebLink
The irrigated pasture reference area is a typical irrigated pasture in the Nucla area. Vegetation is <br />almost entirely herbaceous species, mainly introduced perennial pasture grasses planted for <br />livestock forage. Flood irrigation results in uneven water application, and as a result the species <br />composition within the reference area varies with soil moisture. On most of the reference area <br />where soil moisture is moderate, at least 8 species of upland perennial grasses are dominant, with <br />Kentucky bluegrass, tall fescue, wheatgrasses, and meadow fescue the most dominant <br />(Attachment 2.05.4(2)(e) -5 shows production and cover summary data from 2007 vegetation <br />sampling, and scientific names of plants). Desirable perennial forbs are much less common, and <br />include mainly Alsike clover with minor amounts of dandelion. In shallow drainageways the soil is <br />saturated during the growing season and wetland plants dominate primarily various species of <br />sedge and rush with minor amounts of tufted hairgrass, buckhorn plantain, common plantain, and <br />rarely cattail. <br />In June 2007, mean cover of total vegetation measured at 15 transects was 71.9% (see <br />Attachment 2.05.4(2)(e) -5). Most of the remaining cover was litter, with very little bare ground <br />(3.5 %). Most of the vegetation is desirable (perennial grasses, grass -like plants, and forbs, <br />excluding noxious weeds), comprising 68.6% cover. Of these, Kentucky bluegrass and tall fescue <br />contribute nearly 48% relative cover (the fraction of total vegetation cover), and sedges, rushes, <br />and wheatgrasses comprise 32% relative cover. Among life forms, desirable perennial grasses <br />(including sedges and rushes) are dominant by far (64% cover, 89% relative cover), and desirable <br />perennial forbs (primarily Alsike clover) are next (4.5% cover, 6.2% relative cover). Undesirable <br />species together comprise total cover of 3.3% and relative cover of 4.6 %. These include shrubs <br />(gumweed), a few weedy annual forb species, and the noxious weed field bindweed; each of these <br />life forms contributes 1.5% or less total cover. <br />Mean total production measured in June 2007 at 44 plots was 2,677 lb/acre for all vegetation, and <br />2,513 lb/acre for desirable vegetation. Perennial grasses (including sedges and rushes) contribute <br />most of the production, at 2,436 lb/acre (97% of desirable production and 91 % of total production). <br />Forbs made up most of the remaining plant production, with a minor contribution from shrubs <br />(gumweed) and the noxious weed species field bindweed. <br />The reference area pasture is in good ecological condition. Soil erosion is minimal, there are no <br />significant gullies or rills, and very little bare ground. Desirable plant species composition is <br />Revised April /09 TR58 2.05.4(2)(e) -19E <br />-rR 58 <br />Approved <br />) 3 Al ay <br />