FOREST PROTECTION 



187 



fire, disease, insects, animal damage, and weather 

 effects, trends in reducing losses will be easier to 

 measure in the future. 



Methods of all agencies reporting fire statistics 

 have been on a systematic and fairly comparable 

 basis for many years. Thus, the nationwide 

 figures on fire occurrence and acreage burned are 

 on a comparable basis in the three timber ap- 

 praisal reports preceding this one. A review of 

 the estimates of annual timber drain from fire 

 shows a progressive reduction in damage from this 

 cause. 



The earlier appraisals reported timber destroyed 

 by insects, disease, wind, and other destructive 

 agencies to be from 3.4 to 3.9 billion board-feet a 

 year, or from 2}^ to 4 times the damage from fire. 

 In their earlier appraisals, the estimate of timber 

 destroyed by disease, insects, and windstorms in- 

 eluded only epidemic losses not salvaged, and 

 omitted the much greater but unestimated normal 

 losses that continuously occur in the forest. The 

 present appraisal includes not only the epidemic 

 losses but the ordinary losses as well. Because of 

 this change to a more comprehensive and realistic 

 definition of mortality and a stronger base for es- 

 timating it, the present appraisal of total mortality 

 from causes other than fire is more than triple 

 that of earlier estimates. 



In addition, the damages defined in the concept 

 of growth loss have been added, so that the total 

 growth impact in cubic feet, from destructive 

 events otlier than fire, is more than nine times 

 that of the mortality loss given in the national 

 timber appraisal of 1946. Through the State by 

 State appraisal of each element of mortality and 

 growth loss, by causal agency and by the major 

 tree species involved, there is no doubt that the 

 growth impact data in this report far more nearly 

 approximate the loss from destructive agencies for 

 a given year than the partial figures on mortality 

 alone presented in past appraisals. 



It is emphasized that comparison of losses esti- 

 mated in 1952 with those previously reported 

 should be made with caution. Fire losses are sub- 

 stantially lower than those cited heretofore, pri- 

 marily because of the progress made in fire con- 

 trol. However, the fact that fire losses are lower 

 does not lessen the importance of the substantial 

 impact this agent causes. Neither does it imply 

 that any slackening in the effort toward better fire 

 control can be accepted. Moreover, there is 

 strong justification for more effective fire control 

 because of the watershed, grazing, and recreation 

 values involved. 



A comparison of past and present figures on 

 timber losses might lead one to the conclusion that 

 no progress has been made in the control of in- 

 sects, disease, and damage other than that due to 

 fire. Such a conclusion would not be justified, for 

 substantial progress has been made in controlling 

 many of the more serious insect and disease 



epidemics. Control can be and to some extent is 

 being achieved indirectly through sdvicultural 

 measures that remove high-risk trees. Fire has 

 been used effectively to control brown-spot disease 

 in the South. A number of successful direct con- 

 trol projects have been completed throughout the 

 Nation as well. 



The differences in scope between losses presented 

 in past reports and in this appraisal make direct 

 comparisons of little value. The conclusion is 

 warranted, however, that a tremendous volume of 

 timber continues to be lost every year by the usual 

 as well as the unusual occurrences of fires and the 

 activities of insects, disease, weather, and other 

 natural agencies. The need for effective forest 

 protection is again emphasized by the evidence 

 given in the present report. The only change is 

 that the size of the problem of reducing the losses 

 or utilizing the timber destroyed by destructive 

 agencies is much greater than had been previously 

 supposed. 



THE GROWTH IMPACT OF FOREST 



DAMAGE OCCURRING IN 1952 



Destructive Natural Agencies 



Take Heavy Timber Toll 



The total growth impact from destructive 

 agencies on commercial forest lands of the United 

 States and Coastal Alaska in 1952 is estimated at 

 11.2 billion cubic feet of growing stock, including 

 43.8 billion board -feet of sawtimber (table 113). 

 These losses are equal to 92 percent of the net 

 sawtimber growth and 90 percent of the sawtimber 

 cut in 1952. Comparative amounts in billions 

 of board-feet are: total growth impact, 43.8; net 

 growth, 47.4; total cut, 48.8. Such destruction 

 indicates that a combination of better prevention, 

 control, and utilization of loss would go far toward 

 meeting future timber demand. 



Of the total impact on sawtimber growth, 45 

 percent is estimated as due to disease (fig. 71). 

 Insects caused 20 percent of the loss, fire 17 

 percent, and all other agencies 18 percent. The 

 wood used from dead trees in 1952 was 22 percent 

 of the 1952 mortality to growing stock, which is 

 equivalent to only 7 percent of the total impact. 



Fire is generally recognized as the greatest 

 enemy of forests, because of its capacity to destroy 

 timber and other forest values over vast areas in 

 a very short time. Largely because of the pro- 

 tection from fire given most of the forest lands in 

 this country, the loss from fire was lower than that 

 from insects or diseases (table 113). 



Insects are charged with having killed the most 

 sawtimber. They accounted for 5,041 million 

 board-feet or 40 percent of the total mortality. 

 They also caused a growth loss of 3,576 million 

 board-feet, so that their total growth impact was 

 8,617 million board-feet. 



