1902. 



FORESTRY AND IRRIGATION. 



323 



space of time shall elapse between thin- 

 nings. The quicker the growth, the 

 shorter the interval between cuttings 

 during the early life of the tree, the 

 time being gradually lengthened as the 

 trees advance in age. Common sense 

 will have to govern largely on this 

 point. The expense of thinning can 

 be almost eliminated by the sale of the 

 trees to be used in box-board manu- 

 facture, in southern New Hampshire 

 White Pine for box boards being worth 

 from $6 to $10 per thousand. Under 

 no conditions should brush wood be 

 left in the forest, as it greatly increases 

 the danger from fire. If the work of 

 thinning is carefully carried out, a stand 

 of White Pine should be ready for the 

 market in thirty or forty years, while 

 by that time the ground wall be in good 

 condition for a seed-bed. 



Cutting for reproduction should be 

 carried on with considerable care and 

 forethought. A few select trees, vary- 

 ing in number from ten to thirty per 

 acre, may be left on the cut-over area 

 to seed the ground, or a small lot may 

 be cut clear and the ground allowed to 

 seed itself from the surrounding trees. 

 In the latter case the seed trees should 



be left on the windward side, so that 

 the seeds can readily blow into the open 

 (Fig. 4), the cuttings to be made, if 

 possible, when there are indications of 

 a good seed year. 



While the white-pine seedlings are 

 still small, Gray Birch {Dctula popnli- 

 folia) is almost sure to come in, and, 

 as it grows much more rapidly than the 

 pine, soon overtops the latter trees 

 (Fig. 5). The birch should be allowed 

 to remain only as long as it is of mate- 

 rial aid to the seedling as a nurse. Af- 

 ter the pines are old enough to take care 

 of themselves the birch should be re- 

 moved. 



Even aged stands in a natural forest 

 are rare, as the whole of a denuded area 

 is seldom seeded at once. In a natural 

 forest, therefore, cutting should begin 

 by taking out the mature trees first, thus 

 allowing those that remain to quicken 

 their growth through the increased 

 amount of light and space. In sum- 

 ming up it may be said that when the 

 object is to produce quantity, thinning 

 should be early, heavy, and often during 

 the first half of the life of the woods, 

 and more moderate and at longer inter- 

 vals during the second half. 



EXTENT OF IRRIGATION IN COLORADO. 

 AREA RECEAIMED ALMOST DOUBLED DURING LAST TEN YEARS. 



DURING the decade 1889 to 1899 

 Colorado advanced to the front 

 rank of irrigated .states, surpassing Cal- 

 ifornia in the extent of land under irri- 

 gation, but remaining second in the 

 number of irrigators and in the value of 

 irrigated crops. The colder climate and 

 greater altitude of Colorado make it im- 

 possible to raise the high-priced citrus 

 or semi-tropical fruits, or to practice the 

 degree of intensive farming for which 

 Arizona and California are noted. 



The land surface of Colorado com- 

 prises 66,332,800 acres, of which only 

 9,474,588, or 14.3 per cent, were in- 

 cluded in farms in 1900, and 2,273,968 

 acres, or 3.4 per cent, were improved. 

 Of this area, 2,240 acres are included 



in the Indian reservations. Of the total 

 area in farms, 24 per cent is improved. 

 The importance of irrigation as a fea- 

 ture of the agricultural development of *^ 

 the state is shown by the fact that the 

 irrigated land outside of the Indian res- 

 ervations amounts to 1,611,271 acres, 

 or 70.9 per cent of the improved farm 

 land. In 1890 the acres irrigated out- 

 side of the Indian reservations num- 

 bered 890,735, or 48.8 per cent of the 

 improved land. Since then, by the 

 opening of new ditches and canals, by 

 the enlargement of those previously 

 constructed, and by the application of 

 more intelligent methods of water dis- 

 tribution, 720,536 acres of land have 

 been added to the irrigated area of 



