Natural Mulches or "Litter" of Grasslands: With Kinds and Amounts on a Southern Prairie

Abstract

terms and crop residue are commonly used by agronomists to indicate *dead material on the surface (Hughes and Henson, '30). Soil conservationists have used these terms in cropland description, and in forest descripton (Bennett, '39). Horticulturists also use the term (Bailey, '33). Foresters have classified characteristic layers of dead materials that occur on forest floors including and unincorporated humus (Hawley and Committee, '44). Soil scientists commonly employ the term AOO horizon to designate an upper layer of loose leaves and debris, largely undecomposed, and the term AO horizon to designate lower layer of debris partially decomposed or matted. Both rest upon the Al horizon where amorphous remnants are found mixed with mineral particles and constitute the upper layer of the true (U. S. Dept. Agric., '38). Range conservationists and grassland ecologists have long been aware of the importance of natural mulches on grasslands though there is no standard terminology and usually no definitiveness as to the portion of total surficial matter so considered. As early as 1913 Barnes ('13) in describing the virgin range stated, The spring snows lay long under the folds of the grass, weeds or brush that covered the ground. Let the wind blow as it pleased, it could not blow the snow entirely off the ground. A certain amount of it was allowed to remain to melt and soak into the ground, thus bringing the green sprouts out early in the spring, and it took a long dry spell to make any great impression on the Sampson ('23) referred to the importance of old growth and unused vegetation. Talbot ('37) stressed the need of leaving some unused forage for soil protection. Weaver and Flory ('34) in referring to mowed climax prairie near Lincoln, Nebraska stated that mulch of fallen leaves, fragments of stems, flowers and fruits, etc., forms a more or less continuous of varying thickness. This may have a dry weight of 50 to 225 grams per square meter on uplands and over 1,000 grams on lowlands. Flory ('36) stated that the amount of on a square meter of grassland was often 225 grams and that it could absorb 650 grams of water. Stoddart and Smith ('43) in their well-documented textbook on range management found it necessary to use not fewer than four terms in referring to surficial residuum on range land, including vegetational debris, protection cover, duff, and litter. U. S. Forest Service ('36) in the comprehensive report entitled, The Western Range, refers to plant cover and organic mulch. It is also stated that On the virgin range dead plants and herbage formed a ground and eventually mixed year after year with the mineral soil. . Allred ('40) mentioned the large quantity of new and semidecomposed litter on a properly managed range. Weaver and Clements ('38) in defining refer only to the forest floor. Carpenter ('38) in his ecological glossary limits use of the term to forest floor description. need for a more specific terminology applicable to grasslands is apparent.