RODENTS IN SOIL FORMATION GRIN NELL 349 



domestic sheep, the grasslands have become poor — the crop of grass 

 is scrawny — except where gopher workings occur; the sites of these 

 are marked by patches of vivid green. Indeed, on ordinary hill 

 slopes I have repeatedly noted the rejuvenation of the plant cover 

 here and there, traceable directly and obviously to the activity of 

 burrowing rodents. Before the advent of the white man with his 

 cattle and horses a similar service was rendered, though in lesser 

 degree, perhaps, because of the less need for it, when the deer, moun- 

 tain sheep, and bears frequented the same areas. 



The question of damage to forests under natural conditions, for 

 example, injury to young trees, is one that has been raised by for- 

 esters. There is no doubt but that gophers and squirrels do girdle 

 or cut off the stems of many seedlings and thus terminate the exist- 

 ence of numerous individual trees. But the great number of seed- 

 lings observable on parts of any forest floor, vastly more than could 

 ever reach maturity, would seem to indicate that an adjustment in 

 this direction had been reached long ages ago. Plants in general 

 provide for a rate of replacement sufficient to meet the maximum 

 probabilities of casualty, this involving all stages from the seed to 

 the mature fruiting plant. 



In the arable lowlands of California the pocket gopher is well- 

 nigh universally, and of course there rightly, condemned for pur- 

 suing his activities, in making his living, on lands that have been 

 appropriated and cultivated by man. There, man has disturbed the 

 original balance of natural relations between plants and animals; 

 he aims to make the land produce crops of selected plants in the 

 largest measure possible, and to that end he cultivates the ground 

 himself by very effective " artificial " means. He naturally resents 

 the levy upon the land and its products by any other animal. Most 

 of the original quota of herbivorous mammals has been crowded out 

 by his methods ; but the gopher and ground squirrel have been able 

 to persist under the changed conditions. Man's crops have even in- 

 creased their food resources; and they have been able to cope with 

 the other changes. It is clear that we have here, most surely, a 

 reversal of the relationships obtaining in the wild. On wild land 

 there is no cultivation in the " artificial " sense. The crops of wild 

 plants — grasses, herbs, shrubs, and even trees — depend upon what- 

 ever favorable agencies operate in natural ways. The happy rela- 

 tion found by our pioneers was the result of eons of adjustment 

 among all of the elements concerned. 



We grant that the farmer must combat the gopher and ground 

 squirrel in his fields and gardens; we sympathize with him for 

 yearning for the total eradication of the rodents there; and we will 



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