^nLDLlim iiPJSCTS TTPE OF ^TOH-fCST 



!Rod9nts, ' especid.lly iTxicc euid chiprnuiiks, show a decided preference 

 for seeds of some pines, and studies shov: that among those produced in 

 the California forests the proiorenco was in the follov/in^ order; Sugar, 

 Joffrcv (p inus jeffrcyi) . and poaderosa pines, and after those, v/hitc fir 

 and inconso codar, [ihc ladt nrmod i?- *:atGn in s-nall qiiantitics. Though 

 the preference v.'as in the order of seed si2ie, that is not the deciding 

 factor, as the relative acocptability was the Sc3iiic when fne seeds were 

 reduced to a pastn hy grinding, tossioly the chemical conrposition of the 

 seed Fiay play an important pa:.'t. 



Cutting decrcares tho s-o.pp]y of ru^^-^r pine seed, and the utiliza- 

 tion of the seeds 'by rodents is high. As v. result, nearly all the seeds 

 are taken each yoa.r, Tho few that arc left to germinate find severe and 

 often fatal competition with hur-clover and other plants that increased 

 so markedly after logging operations. 



As white fir seed is abundant an,d only partially consumed "by ro- 

 dents, it reproduces far more readily than does the sugar pine. Incense 

 cedar seed is eaten in small quantities "by rodents and reproduces well. 

 As a result of these conditions the sugar pine is not regenerating and is 

 being replaced by the less commercially valuable white fir and incense 

 cedar. Apparently regeiieration of the sugar pine occurs only at widely 

 separated periods. Probably reproduction is the result of coincidence 

 of a heavy seed crop and a low seed-eating animal population in a year 

 followed by conditions suitable for germination of seedlings. 



Parrow, in his work on rabbits in England, found good indications 

 that these animals have been responsible for the change of many areas 

 from forest to grassland. There is a strong possibility, likewise, that 

 in California some sugar pine -fir-incense cedar associations may give way 

 to fir-cedar because of activities of seed-eating rodents. 



RESULTS OIT CALIPORITIA STUPY APPi.S 



The effects of chaiagcs in forest composition are far reaching. 

 Opening forests by bv.rning or cutting increases food and shelter for many 

 animals. Shrubs valxiable for deer food thrive, more edges are created, 

 and tho deer increase. In 1924, curing the outbreak of foot-and-mouth 

 disease, 22,000 deer were killed in one of the efforts to stamp out the 

 malady. Before and after the deer v;ere killed, lumbering o-oened large 

 portions of the forest, so that the habitat became very favorable. Despite 

 local extirpation, deer are again abundant, and there is a possibility that 

 the summer range has a carrying capacity in excess of that of tlic vdntcr 

 range. If this proves true, over-grazing of the winter range will follov.'. 

 As the cut -over areas grow up to forest trees, conditions for deer on the 

 summer range also will become loss favorable. Good browse species may then 

 show the effects of over-grazing and finally disappear. The sood-eating 

 rodents, by limiting sugar pine reproduction and permitting relative in- 



- o - 



