Effects of goats on Tamarix spp. and understory vegetation for riparian restoration

TitleEffects of goats on Tamarix spp. and understory vegetation for riparian restoration
Publication TypeConference Paper
Year of Publication2007
AuthorsTartowski S., James D.K.
Conference NameSociety for Range Management 60th Annual Meeting and Trade Show
Date Published02/2007
ARIS Log Number209036
Keywordsgoats, Rio Grande, riparian, Tararix, vegetation
AbstractGoats were used to reduce Tamarix spp. along the Rio Grande in New Mexico. Seventy 0.1-1.6 ha plots at two locations were either browsed by 400-630 goats for 1-3 days annually, or left unbrowsed. After two annual treatments, nearly every available Tamarix plant in mixed vegetation was browsed (100%), broken (91%) or debarked (60%). Goats reduced the Leaf Area Index of resprouts by about 24% each year. However, nearly all of the Tamarix biomass that was removed regrew between annual treatments. During the second year, goats reduced the mean height of Tamarix by 8% and the mean width by 21% in open-canopy mixed vegetation. Overall, the number of Tamarix decreased by less than 5% after three years of goat browsing treatments. In large, dense, closed-canopy Tamarix, goats opened up the understory, reduced laddering fuels and improved access, potentially reducing costs of subsequent mechanical or manual clearing. Rusian olive (Elaeagnus angustifolia) was heavily browsed and cover declined about 10% per year. Large cottonwoods (Populus deltoides) were not damaged, but small cottonwoods were heavily browsed. Willows (Salix spp.) were browsed and resprouted vigorously. Goats increased the area of bare soil by about 20% and reduced the cover of most understory plant species, including native perennial grasses, such as Sporobolus spp. The cover of native annual grasses associated with disturbance (Bouteloua barbatus, B. aristoides) increased from less than 1% to about 20% one year after browsing, following substantial rainfall. Goats may be useful, in combination with other methods, for controlling Tamarix resprouts or where partial control of Tamarix is desired. Goats may be especially effective in removing understory weeds and preparing the seed bed for vegetation. The use of livestock for land management and ecological restoration, rather than production of agricutlural commodities, offers new economic opportunity for entrepreneurial ranchers.