than 5-fold over a shorter 7-year period that did not include 

 the year of lowest forb production. Additionally, an index of 

 tree growth (Tree Ring Laboratory, University of Arizona, 

 Tucson, C. Stockton and D. Meko, personal communication), 

 indicated that over the 21-year (1960-1980) period, which 

 encompassed most of the study, annual growth of Douglas Fir 

 trees varied 10-fold from the poorest (1961) to best (1978) 

 year. For a 100 year period (1881-1980), annual growth varied 

 21-fold from poorest (1956) to best (1916) years. 



Most of the variation was inherent in the environment, 

 controlled by climatic/weather factors (temperature and 

 precipitation) , and independent of influences of deer use or 

 density. The maximum observed difference in deer numbers for 

 the same season (3-fold) or among seasons over all years 

 (4.4-fold) was considerably less than the variation in forage 

 conditions . 



The data also indicated that, during most years, fawn 

 production and survival to December was directly related to an 

 index of forage production; population change was directly 

 related to fawn production and survival. There were several 

 reasons why population numbers did not vary as widely as 

 forage production. Biologically, fawn production and survival 

 is limited and cannot exceed certain levels in any year 

 regardless of how good forage conditions may be. Similarly, 

 fawn survival can only decline to zero, no matter how poor the 

 conditions, though adult mortality may increase. Also, 

 relieved of lactation, adults can survive on poorer quality 

 forage than lactating females require. Time-lag responses to 

 wide fluctuations in forage production could occur as 

 exceptionally good conditions result in fat accumulation, and 

 exceptionally poor conditions result in fat depletion. 



Further examination of our data, however, led to the 

 conclusion that it was unlikely that fawn survival and 

 population performance was directly related to forage 

 quantity, or that deer numbers (density) influenced subsequent 

 forage production. Very conservative estimates of annual 

 forage production during the period 1976-1986 indicated that 

 annual forage quantities were adequate to support 2-10 times 

 the numbers of deer that occurred on the area during summer 

 and autumn. A possible exception occurred during 1985, though 

 given the conservative estimates and an "autumn green-up" it 

 is also unlikely that the quantity of forage was deficient 

 during 1985. Furthermore, the leaves and buds of fragrant 

 sumac, snowberry, rose, and choke- cherry were never observed 

 to be close to completely utilized. Those forages, which were 

 important summer forages for deer, were nutritionally adequate 

 to supply at least maintenance requirements (8-13% protein, 

 Eustace 1971, Pac 1976, Mackie et al. 1979) for adults during 

 most years . 



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