HISTORICAL. 7 



tribution of our native land animals and plants, and mapping the boundaries 

 of the areas they inhabit. The present report is intended to explain the rela- 

 tions of this work to practical agriculture and to show the results thus far 

 attained. 



"It was early learned that North America is divisible into seven transconti- 

 nental belts or life zones and a much larger number of minor areas or faunas, 

 each characterized by particular associations of animals and plants. It was 

 then suspected that these same zones and areas, up to the northern Umit of 

 profitable agriculture, are adapted to the needs of particular kinds or varieties 

 of cultivated crops, and this has since been fully established. When, there- 

 fore, the natural Ufe zones and areas, seemingly of interest only to the natur- 

 alist, were found to be natural crop belts and areas, they became at once of the 

 highest importance to the agriculturist. A map showing their position and 

 boundaries accompanies this report, and Usts of the more important crops of 

 each belt and its principal subdivisions are here for the first time pubUshed. 

 The matter relating to the native animals and plants has been reduced to a 

 fragmentary outUne for the reason that this branch of the subject is of com- 

 paratively little interest to the farmer and fruit-grower." (p. 7.) 



"The Biological Survey aims to define and map the natural agricultural 

 belts of the United States, to ascertain what products of the soil can and what 

 can not be grown successfully in each, to guide the farmer in the intelligent 

 introduction of foreign crops, and to point out his friends and enemies among 

 the native birds and mammals, thereby helping him to utilize the beneficial 

 and ward off the harmful kinds." (p. 9.) 



"The farmers of the United States spend vast sums of money each year in 

 trying to find out whether a particular fruit, vegetable, or cereal will or will not 

 thuive in localities where it has not been tested. Most of these experiments 

 result in disappointment and pecuniary loss. It makes Httle difference 

 whether the crop experimented with comes from the remotest parts of the 

 earth or from a neighboring State, the result is essentially the same, for the 

 main cost is the labor of cultivation and the use of the land. If the crop 

 happens to be one that requires a period of years for the test, the loss from its 

 failure is proportionately great. 



"The cause of failure in the great majority of cases is climatic unfitness. 

 The quantity, distribution or interrelation of heat and moisture may be at 

 fault. Thus, while the total quantity of heat may be adequate, the moisture 

 may be inadequate, or the moisture may be adequate and the heat inadequate, 

 or the quantities of heat and moisture may be too great or too small with 

 respect to one another or to the time of year, and so on. What the farmer 

 wants to know is how to tell in advance whether the climatic conditions on his 

 own farm are fit or unfit for the particular crop he has in view, and what crops 

 he can raise with reasonable certainty. It requires no argimient to show that 

 the answers to these questions would be worth in the aggregate hundreds of 

 thousands of dollars yearly to the American farmer. The Biological Survey 

 aims to furnish these an.swers." 



Life-zone surveys upon the basis laid down by Merriam have been made by 

 Bailey for Texas (1905) and New Mexico (1913), and by Gary for Colorado 

 (1911) and Wyoming (1917). Bobbins (1917) has made a somewhat similar 

 study of the zonal relations in Colorado with reference to plants alone. Hall 

 and Grinnell (1919:37) have recently published comprehensive lists of plants 

 and animals which are regarded as "life-zone indicators" for California. As 

 with Merriam's life zones, these are floristic and faunistic in character and 

 hence do not necessarily correspond with community indicators. 



