EQUALIZING INFLUENCE OF FORESTS 



are broken down, and a mass of mud, stones, 

 and rocks invades the valley, destroying 

 everything as it passes. 



Mr. Wolfshiitz, a delegate from 

 Austria, while admitting that excessive 

 floods are not appreciably checked by 

 forests, writes as follows : 



For economical reasons reafforestations 

 will have to be confined to the steeper 

 mountain slopes which are of little use for 

 other cultivation. Here the forest will have 

 a beneficial influence by making the soil 

 firmer and more compact and by preventing 

 erosion and washing down, and thus any 

 excessive alteration and the formation of 

 detritus which would shoal and silt up the 

 water-courses. Such forests further retard 

 the melting of the snows in spring and 

 lessen the violence of spring high water. It 

 is thus advisable in the interests of naviga- 

 tion to spare and to attend to the forest. 

 There is no simpler, cheaper, nor more ef- 

 fective means for securing the mountain 

 slopes and for keeping the pebble shoals 

 down. In this respect, forests have incon- 

 testably had a beneficial influence upon the 

 floods of the large rivers. Beyond this, how- 

 ever, no further measurable influence upon 

 the high waters of rivers can be credited to 

 them. 



As regards the occurrence of high floods in 

 the large rivers, the forests cannot have any 

 noteworthy influence. As regards the in- 

 crease in the ground-water level and in the 

 replenishment of springs the forests have, in 

 the plains, no more influence than the open 

 ground, and it is only in the mountains that 

 this action can be rated at any higher figure. 

 In the mountains, however, the main office 

 of the woods will be to prevent the denuda- 

 tion and erosion of the surface, the formation 

 of detritus, and the silting up of the river- 

 beds with mud, sand, and pebbles. 



Mr. Riedel, of Vienna, is very em- 

 phatic as to the benefits of forests. He 

 shows the terrible results which have 

 been brought about by their destruction 

 in various parts of Europe, and, with 

 reference to Germany, states that * * * 



In Germany, also, reasonable bounds were 

 not everywhere kept to, and the effects of 

 the progressing deforestation made them- 

 selves apparent, on the one hand, in scarcity 

 of timber, and on the other in the impover- 

 ishment of perennial springs and the alarm- 

 ing lowering of the mean water-level of 

 German rivers, and not less so in a gradual 

 increase in the dryness of the ground, caused 

 by the fall of the level of the underground 

 waters. 



The unquestioned circumstance, that a 

 large number of rivers now carry down more 

 loose material than formerly, is a conse- 

 quence of the extensive denudation and care- 



less clearing of the plantations. The slopes 

 of the hills lose a large part of their fruitful 

 soil, and in many cases earth-slides, and even 

 extensive subsidences of whole slopes take 

 place, while considerable areas of ground in 

 the valleys are smothered up and rendered 

 useless. 



The loose material which the tributary 

 brooks carry into the main streams ceases 

 to be carried onward as the declivity be- 

 comes less steep, and in consequence fills up 

 their beds. The streams are then obliged 

 to seek out new courses, by which the most 

 fruitful ground is devastated and the whole 

 bed of the valley is gradually transformed 

 into a barren layer of loose stones. This 

 drawback affects not only the mountain 

 dwellers, but, in so far as the waters are 

 not able to deposit their loose suspended 

 material in large basins on the way, the 

 population of the lower-lying fertile and 

 well-tilled valleys also. Here the damages 

 further include the circumstance that, by rea- 

 son of the often elevated position of the 

 river-bed, overflow-waters are very difficult 

 to get rid of. 



Proofs of the foregoing, and especially of 

 the last-mentioned circumstance, are af- 

 forded by a large number of river valleys. 

 This condition of things is of importance 

 in the cases of those river or stream channels 

 which, by the formation of weirs, are to be 

 made serviceable for purposes of inland nav- 

 igation. Thus on the canalized Oder, be- 

 tween Cosel and Breslau, properties which, 

 though at a distance from the channel, lie at 

 a lower level than the latter, are swamped 

 to the most damaging extent. 



The foregoing is not intended to convey 

 the idea that previous to deforestation, 

 earth slides, damages to river banks, and in- 

 undations did not take place, but it is intended 

 to show that since the decrease of the for- 

 ests all these disadvantages have increased 

 to a serious and disquieting degree. 



Mr. Lauda, of Vienna, compares two 

 similar watersheds of about the same 

 area in Austria, one being much more 

 heavily wooded than the other. He 

 thinks the forests may not exert much 

 influence in high floods, but concludes 

 as follows : 



If, now, the final judgment on the sub- 

 ject of the influence of forests on 'the regi- 

 men of streams be unfavorable to the forest 

 to this extent, that there are denied to it 

 certain of the properties attributed to it gen- 

 erally, it does not follow from this that it 

 is necessary to oppose the rewooding of arid 

 surfaces, the replanting of the basins of 

 streams or the maintenance of plantations of 

 trees. The general utility of the forest is 

 so well settled, the extraordinary apprecia- 

 tion in which it is held, as a means of pro- 

 tecting the soil against landslides, is so firmly 

 established, its great advantageousness, espe- 

 cially for the spring district, in holding back 



