Peterson, R.A. 1962. Factors affecting resistance to heavy grazing in needle 

 and thread grass. Journal of Range Management. 15:183-189. 



Pickford, R. 1966. Development, survival, and reproduction of Camnula 

 pellucida. Canadian Entomology. 101:894-896. 



Piatt, R.B. and J. Griffiths, 1964. Environmental measurements and inter- 

 pretation. Rheinhold Publishing Company, New York. 



Poore, M.E.D. 1962. The method of successive approximation in descriptive 

 ecology. Advances in Ecological Research. Vol. 1:35-63. 



Pfister, R. and S. Arno, 1978. Personal communication. 



Ramensky, L. 1924. The basic lawfulness in the structure of the vegetation 

 cover. Voronezh, pp. 37-73. 



Raunkiaer, C. 1934. The life forms of plants and statistical plant geography. 

 Oxford: Clarendon. 632 pp. 



Redmann, R. 1975. Production ecology of grassland plant coimiunities in 

 western North Dakota. Ecological Monographs. 45(1 ) :83-106. 



Reed, M.J. and R. A. Peterson. 1961. Vegetation, soil and cattle responses to 

 on northern great plains range. U.S. Department of Agriculture Forest 

 Service Technical Bulletin 1252. 79 pp. 



Ross, R.L. and H.E. Hunter. 1976. Climax vegetation of Montana. U.S. 

 Department of Agriculture Soil Conservation Service. 



Ruse, M. 1973. The philosophy of biology. Hutchinson and Company, London. 



Sandoval, F.M., Bond, J., Power, J. and W. Willis. 1973. Lignite mine spoils 

 in the Northern Great Plains--characteristics and potential for reclam- 

 ation. Research and Applied Technology Symposium on Mined-Land Reclam- 

 ation, pp. 117-133, 



Shiflet, T.N. 1973. Range sites and soils in the United States. Arid shrub- 

 lands-proceedings of the third workshop of the United States/Australia 

 Rangelands Power, pp. 26-33. 



Sims, P.L. and J.S. Singh. 1971. Herbage dynamics and net privacy production 

 in certain ungrazed grasslands in North America, pp. 59-124. h^ N.R. 

 French, ed. Preliminary analysis of structure and function grasslands. 

 Range Science Department. Science Series No. 10. Colorado State Univer- 

 sity, Fort Collins. 



Smoliak, S. 1956. Influence of climatic conditions on forage production of 

 shortgrass range land. Journal of Range Management. 9:89-91. 



•> 1965. A comparison of ungrazed and lightly grazed Stipa - Bouteloua 



prairie in southeastern Alberta. Canadian Journal of Plant Science. 

 45:270-275. 



86 



