328 Geyer et al.: Rocky Mountain Juniper Seed Source Test bination of the geographic variables gave R-square values of 0.3755 (height) and 0.6721 (dbh) for values significant at the 1% level. Thus, the height model was weak, but the dbh model was relatively strong. Only longitude squared was sig- nificant in the height prediction. Latitude, longitude, eleva- tion, and the squares of longitude and elevation were signifi- cant in predicting dbh. Northerly latitudes, easterly longi- tudes, and elevations lower than those at the Colby site produced larger diameter trees. All but one source came from locations north of Colby. DISCUSSION AND CONCLUSIONS In an earlier study in the Great Plains region (Cunningham and King 2000), Rocky Mountain juniper trees survived bet- ter, were shorter, and had smaller crowns than did eastern redcedar (J. virginiana L.) at 10 years of age. Rocky Moun- tain juniper has better crown compactness for wind reduction than redcedar. In our Kansas study, we found, at 23 years of age that only three seed sources (4611, 4612, and 5851) had a geographic difference from the others sources compared. They were from southwestern Montana and north central Wyoming and were much shorter in height. These sources are not recommended for windbreak plantings in western Kansas. Thus, the general good health, dense crown, and many stems of Rocky Mountain juniper would provide excellent struc- ture, and this species should be selected for use in establish- ing new windbreaks in western Kansas and nearby areas in eastern and western Nebraska. Our findings showed growth at 10 years predicted superior growth at 23 years and in agreement with Schaefer (1995) and VanHaverbeke and King (1990) for 5-year and 10-year relationships. Rocky Mountain juniper is prone to Cercospora needle blight in more humid areas of the eastern Great Plains and is not recommended for windbreak plantings in this area. Acknowledgments. This is Contribution no. 07-69-J from the Kan- sas Agricultural Experiment Station, Manhattan Kansas. LITERATURE CITED Adams, R.P. 1983. Intraspecific terpenoid variation in Juni- perus scopulorum: Evidence for Pleistocene refugia and recolonization in western North America. Taxon 32: 30–46. Comer, C., R.P. Adams, and D.F. Van Haverbeke. 1982. Intra- and interspecific variation of Juniperus virginia and J. scopulorum seedlings based on volatile oil composition. Biochemical Systematics and Ecology 10:179–306. Cunningham, R.A., and R.M. King. 2000. Juniper seed sources in the Great Plains. General Technical Report, RMRS-GTR-51. USDA Forest Service, Rocky Mountain Forest Experiment Station. Fort Collins, CO. ©2007 International Society of Arboriculture Fassett, N.C. 1944. Juniperus virginia, J. horizontalis and J. scopulorum—II. Hybrid swarms of Juniperus virginia and J. scopulorum. Bulletin of the Torrey Botanical Club 71: 475–483. Harlow, W.M., and E.S. Harrar. 1969. Textbook of Dendrol- ogy, 5th Edition, McGraw Hill Book Co., Inc., New York. 542 pp. Schaefer, P. 1995. Ten-year results of an eastern redcedar and Rocky Mountain juniper provenance test in eastern South Dakota. Northern Journal of Applied Forestry 12:30–35. Van Haverbeke, D.F. 1968. A population analysis of Juni- persus in the Missouri river Basin. New Series 38. Lin- coln, NE, University of Nebraska Studies. 82 pp. Van Haverbeke, D.F., and R.M. King. 1990. Genetic varia- tion in the Great Plains Juniperus. USDA Forest Service. Res. Pap. M-292. Lincoln, NE. 8 pp. Wayne A. Geyer (corresponding author) Professor Forestry Division Throckmorton Hall Kansas State University Manhattan KS 66506, U.S.
[email protected] Keith D. Lynch Associate Professor Forestry Division Throckmorton Hall Kansas State University Manhattan KS 66506, U.S. Charles J. Barden Associate Professor Forestry Division Throckmorton Hall Kansas State University Manhattan KS 66506, U.S. Résumé. Trente-six provenances de genévrier des Rocheuses (Juniperus scopulorum Sarg.) ont été plantées dans le cadre d’un test de provenance près de Kolby au Kansas en 1980. La hauteur, le diamètre, le taux de survie, le nombre de tiges, la densité de la cime, l’angle des branches et la vigueur ont étéévalués au moyen de techniques d’analyses de variances, d’analyse de grappes, de cor- rélations simples et d’analyses de régression. Des différences entre les provenances ont été trouvées. La hauteur totale après 23 ans se situait entre 3,6 et 5,4 m, le DHP entre 5,6 et 10,4 cm, et le taux de survie entre 10 et 100%. La croissance en hauteur était faiblement corrélée aux variables géographiques, mais le DHP était reliéà la latitude, la longitude et l’élévation. La sélection de provenances à croissance rapide pourrait se faire à compter de la cinquième année après la plantation en plein champs.
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