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4.15.4. "fCC hereby request the CMLRD to suspend [he requirement for mulch on the proposed Foidel Creek <br />• Mine permit area in light of [he above facts. <br />The mulching variance request presented herein is based upon a comprehensive literature review and field data <br />collected adjacent to the proposed permit area. Results from these studies provide evidence indicating that the <br />application of mulch would not be beneficial. <br />Application of either straw or annual grain mulches intercepts much of the needed plant moisture and renders it <br />unavailable for plant growth. Various researchers have documented this fact. On the Northern Great Plains, <br />USDA-ARS-NDSU (1975) reported that the application of straw to respread topsoil significantly lowered the <br />amount of plan[ available moisture. Topsoiled plots receiving straw were found to contain a negative 0.01 inches <br />of water while the same plots receiving no straw contained 1.03 inches of water. In Colorado's Piceance Basin, <br />researchers at Colorado State University (1978) reported dta[ application of mulch significantly reduced grass and <br />forb densities and grass heights. They concluded, "there appears [o be an overall depressing effect of Silva-fiber <br />mulch on grass and forb establishment." During the second year of this study, Colorado State Universih• (1979) <br />researchers concluded that, "Mulch may retard the establishment of grasses in both the native and introduced grass <br />and grass forb mixtures." In terms of biomass, it was reported that, "mulching has no significant effect on the <br />biomass of seeded plants." <br />Similar conclusions relative to the negative effect of straw or annual grain mulch on plan[ growth and survival are <br />demonstrated in another study conducted in Western Colorado by researchers of the USDA. Frischnech[ and <br />Ferguson (1979) reported that first year survival of transplanted shrubs and forbs on processed oil shale was <br />highest on treatments receiving topsoil (82 percent) and lowest on plots receiving barley straw (36 percent). Not <br />only was plan[ mortality highest, but also plant heights lowest on plots receiving barley straw. <br />• Another study conducted in western Colorado (Rio Blanco Oil Shale 1977, 1978 and 1979) revealed that <br />application of straw, straw netting or hydro-mulch did not increase seedling survival of planted species. In every <br />instance topsoiled sites receiving straw mulch produced from 12 to 13 percent lower seedling survival than did the <br />topsoiled controls. <br />At the Colowyo Mine, Herron and Berg (1977) reported considerably lower shrub seedling survival for mulched <br />plots in their shrub management practice study. Shrub seedling mortality on unmulched plots was 52 percent <br />while plats mulched with 2 tons per acre of alfalfa experienced a mortality rate of 75 percent for seeded shrubs. In <br />another study reported by Herron and Berg (1977), percent vegetative cover of seeded herbaceous species on a <br />control plot declined 24 percent from 1976 [0 1977 while a straw mulched plot undenven[ a 68 percent reduction <br />in plant cover for the same period. <br />Data and observations collected on the CYCC mulching plot studies conducted on Lease C-20900 during the <br />sununer and fall of 1980 indicate no superiority of mulching either with barley straw or annual grains over direct <br />seeding to perennials. Plant cover was not different and a significant amount of runoff did no[ occur on mulched <br />or non-mulched plots. <br />One of the immediate concerns relative to [he use of a cereal grain mulch deals with the competitive exclusion of <br />the desirable native species which normally volunteer from respread topsoil. An inspection of [he site in CYCC <br />Area 10, where winter rye had been planted, revealed that few natives volunteered from respread topsoil. Ran,e <br />transect data collected from this area during the summer of 1981 are presented in Table 56, Species Densiq~ and <br />Diversity Values Obtained on Mulched Versus Non-Mulched Sites. <br />A comparison of plant densiq• and diversity values benveen the non-mulched and mulched sites reveals the <br />negatve effect gram mulch had on the desired perennial plants. Perennial plant densities are 3? times higher far <br />grasses, 173 times higher for forbs and 9.6 times higher for shrubs on the non-mulched sites. The means were <br />MR 97-154 205-I 13 Revised 9/9/97 <br />