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United States Department of Agriculture (USDA) 2005

PRESCRIBED LIVESTOCK BROWSING FOR CONTROLLING CONIFER ENCROACHMENT ON FOOTHILL RANGELAND

Conifer Encroachement

United States Department of Agriculture (USDA) Research, Education & Economics Information System (REEIS)

Titre : PRESCRIBED LIVESTOCK BROWSING FOR CONTROLLING CONIFER ENCROACHMENT ON FOOTHILL RANGELAND

Identification : MONB00163

Pays : Etats Unis

Durée : Oct 1, 2005 à Oct 1, 2010

Mots clés : conifer encroachment ; sheep ; goats ; livestock grazing ; supplementation ; tree shear

Partenaire : MONTANA STATE UNIVERSITY BOZEMAN,MT 59717

Objectifs
Several species of conifers are currently invading grasslands and shrub steppe across Montana, including ponderosa pine (Pinus ponderosa), Douglas-fir (Pseudotsuga menziesii), Rocky Mountain juniper (Juniperus scopulorum), and lodgepole pine (Pinus contorta). This research project will evaluate opportunities for using prescribed browsing by sheep (Ovis aries) or goats (Capra hircus) to control encroachment of ponderosa pine and Douglas-fir. Specific objectives are : 1) to determine whether a low-cost nutritional supplement can increase goat browsing of ponderosa pine in winter ; and 2) to determine whether sheep or goat browsing of felled trees (ponderosa pine and Douglas-fir) in late fall can reduce fuel loading.

Descriptif
This research project consists of two experiments (Study 1 and Study 2) to be conducted in west-central Montana on foothill rangeland that has been invaded by conifers. In Study 1, a 2-year, winter grazing trial will be conducted in west-central Montana. For one week in late winter of 2006 and 2007, twelve 1-ha pastures will be grazed at a high stock density with mature female goats (36 goats ha-1). Goats in 4 of the pastures will receive a high cost/high protein/high energy nutritional supplement (Sheeplix) in an effort to help the goats detoxify secondary compounds (i.e., tannins and terpenes) within ponderosa pines. Goats in 4 other pastures will receive a low-cost supplement (alfalfa hay pellets), and goats in the remaining 4 pastures will be unsupplemented. Thus, the study will compare 3 treatments (Sheeplix supplement, alfalfa hay pellets, unsupplemented) during 2 winters (2006, 2007) with 4 replicates (pastures) per treatment. Goats will undergo a 1-week adaptation period immediately before the grazing trial each winter. During the adaptation period, goats in the 3 treatment groups will graze in 3 separate 3-ha pastures that contain similar vegetative composition to the grazing trial pastures. Also, goats in the 2 supplemented treatment groups will receive their supplement during this adaptation period. Response variables for the grazing trial will include : 1) the botanical composition of goat diets, and 2) the amount of browsing damage inflicted by the goats. The study will be completely randomized in a split-plot arrangement, with supplement as the whole plot factor and year as the subplot factor. Analysis of variance (goat diet data) and analysis of covariance (browsing damage data) will be used to evaluate the treatments. In Study 2, a 2-year grazing trial will be conducted on 2 foothill rangeland sites in west-central Montana. Douglas-fir will be the principal tree invader on one site and ponderosa pine will be the principal tree invader on the second site. Young conifer trees will be thinned from within twelve, 1-ha macroplots per study site each year (12 macroplots per study site x 2 study sites x 2 years = 48 macroplots). Thinning will be done in late fall with a tree shear implement mounted on a skid-steer loader. At each study site, 4 macroplots will remain ungrazed, while 4 will receive sheep browsing and 4 will receive goat browsing. Browsing macroplots will be temporarily fenced with electric fencing. Sheep and goat browsing will occur immediately after thinning, with 36 sheep or 36 goats grazing each macroplot for 1 week after thinning. Thus, the study will compare 3 treatments (sheep browsing, goat browsing, no browsing) during 2 years (2007, 2008) with 4 replicates (macroplots) per treatment. Response variables will include : 1) the botanical composition of sheep and goat diets, and 2) the amount of fuel loading and predicted wildfire intensity. The study will be completely randomized, with data from each study site analyzed separately, and analysis of variance will be used to evaluate the treatments.

Présentation : USDA

Page publiée le 14 décembre 2015, mise à jour le 2 novembre 2017