Abstract
Livestock may provide important service and production functions in agroforestry systems. However, use of livestock in conifer/improved pasture agrosilvopastoral systems is currently limited by concerns about potential damage to trees by livestock. Effects of sheep grazing on Douglas-fir (Pseudotsuga menziesii) trees in two patterns of sheep/pasture/conifer agroforest (cluster and grid plantations) were studied from 4 years after planting (1983) until the first precommercial thinning at age 10 years (1988). Trees averaged over 1 m in height when grazing began in summer 1983. Some browsing of tree lateral branches by sheep occurred regardless of grazing season in 1983–1985. However, the 2 to 10% of current year's lateral branch growth removed by grazing sheep was too low to impact tree growth. Sheep removed the terminal leaders from only 3 to 9% of trees each year during 1983–1985. Most browsing of terminals occurred in the summer when other forages had become mature and were relatively unpalatable to sheep. Less than 13% of agroforest trees were debarked by sheep each year during 1983–1987. By the end of grazing in 1987, less than 8% of agroforest trees had sustained a level of debarking likely to impact future growth (>50% of tree circumference debarked). Grazing had no discernible effect upon tree diameter or height in any year (P > 0.05). Total tree mortality attributable to sheep grazing during 1983–1987 was only 0.9%, including three trees girdled by sheep and two debarked trees which were subsequently attacked by insects. Overall, grazing had no detrimental impact on timber stand growth or mortality.
Similar content being viewed by others
References
Anderson GW, Hawke M and Moore RW (1985) Pine needle consumption and bark stripping by sheep grazing annual pastures in young stands of widely spaced pinus radiata and p. pinaster. Agroforestry Systems 3: 37–45
Beveridge AE and Klomp BK (1973) Grazing before planting and in young plantations. In: Bunn EH, ed, Assessment and Management of Introduced Animals in New Zealand Forests. New Zealand Forest Service, Forest Research Institute, Symposium 14, Proceedings
Brix H and Mitchell AK (1985) Effects of disrupting stem sapwood water conduction on the water status in Douglas-fir crowns. Can J For Res 15: 982–985
Brown D (1968) Methods of Surveying and Measuring Vegetation. Commonwealth Agric Bureaux, Farnham Royal, Bucks, England, 223pp
Carlson DH (1988) Effects of grazing management and tree planting pattern in a young Douglas-fir agroforest. MS Thesis. Oregon State Univ, Corvallis, Oregon, USA, 168pp
Doescher PS, Tesch SD and Alejandro-Castro M (1987) Livestock grazing: a silvicultural tool for plantation establishment. J Forestry 85: 29–37
Doescher PS, Tesch SD and Drewien WE (1989) Water relations and growth of conifer seedlings during three years of cattle grazing on a southwest Oregon plantation. Northwest Sci 63: 232–240
Gillingham AG, Klomp BK and Peterson SE (1973) Stock and pasture management for establishment of radiata pine on farmland. Proceedings NZ Grassland Association, Vol 37, pp 38–51
Knezevich CA (1975) Soil Survey of Benton Country Area, Oregon. USDA Soil Conserv Serv, Albany, Oregon
Knowles RL (1991) New Zealand experience with silvopastoral systems: a review. For Ecol & Manag 45: 251–267
Leininger WC and Sharrow SH (1987) Seasonal diets of herded sheep grazing Douglas-fir plantations. J Range Manage 40: 551–555
Leininger WC and Sharrow SH (1989) Seasonal browsing of Douglas-fir seedlings by sheep. Western J Appl Forestry 4: 73–76
Leininger WC, Sharrow SH and Rhodes BD (1989) Sheep production in coastal Oregon Douglas-fir plantations. Northwest Sci 63: 195–200
Lewis CE (1980a) Simulated cattle injury to planted slash pine: girdling. J Range Manage 33: 337–340
Lewis CE (1980b) Simulated cattle injury to planted slash pine: defoliation. J Range Manage 33: 345–348
Lewis CE, Burton GW, Monson WG and McCormick WC (1984) Integration of pines and pastures for hay and grazing. Agroforestry Systems 2: 31–41
Logan RS (1983) Agroforestry: Growing trees, forage, and livestock together. Oregon State Univ, Ext Circ 1114, Corvallis, Oregon, USA
Monfore JD (1983) Livestock — a useful tool for vegetation control on ponderosa pine and lodgepole pine plantations. In: Roche, Jr BF and Baumgartner DM,, eds, Forestland Grazing, pp 105–108. Washington State Univ, Pullman, Washington, USA
Neilsen WW (1981) Effect of simulated browsing on survival and growth of pinus radiata (d don) seedlings. Aust For Res 11: 47–53
Penaloza R, Herve M and Sobarzo L (1985) Applied research on multiple land use through a sylvopastoral system in southern Chile. Agroforestry Systems 3: 59–77
Rhodes BD and Sharrow SH (1990) Effect of grazing by sheep on the quantity and quality of forage available to big game in Oregon's coast range. J Range Manage 43: 235–237
Steel RGD and Torrie JH (1980) Principles and Procedures of Statistics. McGraw-Hill Book Co, New York, USA, 633 pp
Sharrow SH, Leininger WC and Rhodes B (1989) Sheep as a silvicultural tool to suppress brush. J Range Manage 42: 2–4
Tustin JR (1975) Grazing livestock among young Radiata pine. What's new? No 22, Forest Res Inst, Rotorua, NZ
Winward AH and Rudeen DP (1980) Sheep and deer grazing on pine plantations. In: Research in Rangeland Management, pp 22–55. Oregon State Univ Spec Rep 596, Corvallis, Oregon, USA
Author information
Authors and Affiliations
Additional information
Submitted as Oregon Agricultural Experiment Station Technical Paper No. 9628.
Rights and permissions
About this article
Cite this article
Sharrow, S.H., Carlson, D.H., Emmingham, W.H. et al. Direct impacts of sheep upon Douglas-fir trees in two agrosilvopastoral systems. Agroforest Syst 19, 223–232 (1992). https://doi.org/10.1007/BF00118780
Issue Date:
DOI: https://doi.org/10.1007/BF00118780