6 AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS. 



susceptible to serious and permanent injury. The effect of fires in 

 somewhat older stands is to kill many but not all of the trees, causing 

 the stand to be open and liable to attack by borers and disease. Dense, 

 well stocked stands twenty years of age and over are not usually found, 

 except in old fields or on scattered areas where fires have been excluded. 

 The rate of growth of second growth pines is remarkably high when 

 protected from fire. 



Thin barked hardwoods like ash and hickory and those which do not 

 sprout easily are destroyed during the seedling stage. Scrubby, upland 

 oaks, sweet gum and many inferior hardwoods, however, develop from 

 sprouts with unusual ease and at almost any age, and as a result of 

 successive fires will often fill the woodlands with useless scrubby growth 

 to the exclusion of better timber. 



RESULTS OF HUMUS DESTRUCTION. 



The most notable characteristics of our woodland soils today is the 

 absence of humus and decaying vegetation, which should, under normal 

 conditions, cover the surface. Repeated fires are almost entirely re- 

 sponsible for this absence of humus, and as a further effect of them, 

 the exposed surface soil is baked and hardened and becomes impervious 

 to water. Without a humus covering and in this compact condition 

 the rainfall is not absorbed by the soil but passes rapidly down the 

 slopes, gullying and washing them and carrying the surface soil into 

 the rivers and streams. This rapid increase in the volume of the 

 streams causes overflow and injury to farm property. The washing of 

 the soils fills the streams with sand and mud, making them shallow 

 and impeding navigation. During periods of little rainfall springs 

 and small streams become dry, larger rivers are low and water supplies 

 fall, because over the vast areas of forest, cut-over and waste land, 

 devoid of humus because of fires, there is no means of absorbing and 

 holding the rain which has previously fallen. Extremes of high and 

 low water are guarded against through this water absorbing property 

 which humus has. The land surface without humus may be likened to 

 the roof of a house which quickly sheds the rain and as quickly becomes 

 dry when the rain is over. But cover the roof with a mat of decaying 

 vegetable matter and the water cannot pass off until the spongy mat 

 is thoroughly saturated and only then in the form of slow seepage 

 from beneath the mat. It is not a matter of wonder that the springs 

 dry up on the farms; the soils wash into streams and clog them, and 

 the streams overflow their banks after heavy rainfall and are dry at 

 other times. The damage from floods in the Trinity, Brazos, Colorado 

 and other rivers is too well known to require comment. The govern- 

 ment has spent nearly four millions of dollars to improve the rivers 

 and harbors of Texas. The damage has been due in large measure to 

 forest and humus destruction. Next to a humus covered forest soil, 

 farm lands in a good state of cultivation and managed so as to pre- 

 vent soil erosion are the best conservers of moisture. Today, however, 

 the well tilled and managed areas are separated often by wide stretches 



