DAMAGE CAUSED BY PLANTS. 65 



insects, also find a favourable shelter and abode in a dense soil- 

 covering of grassy tufts, in which the former make their breeding- 

 places. 



Forest weeds do not, however, under all circumstances, exert 

 injurious influences, but can at times have their distinct advant- 

 ages. Thus, for example, they are of direct benefit in the binding 

 of the soil on very steep slopes, and of light soil like drifting- 

 sand, or in the protection which, if of sufficient height and 

 not standing too thick, they (furze, juniper) can afford to young 

 crops against frost and insolation. In many cases they also serve 

 as fodder, being harvested as hay, or utilised as pasturage on a 

 very extensive scale in many localities ; or used as litter or 

 manure (heath, heather, bracken, broom, furze, dry grass) ; or em- 

 ployed for technical purposes (sea-grass) ; or, finally, the fruits of 

 not a few are gathered and often collected for sale in enormous 

 quantities (whortleberry, cranberry, raspberry, brambles, juniper- 

 berries). Even the collection of grass-seed yields here and there 

 a not inconsiderable indirect return. 



And in conclusion, it should be noted that certain forest weeds 

 can carry many a valuable hint to the Sylviculturist in respect to 

 the quality of soil and situation, for they furnish him with facts 

 enabling him to draw tolerably correct conclusions as to the 

 physical conditions, and partially also the chemical properties, of 

 the soil. 



38. Factors determining their Growth ; Names of the more 

 important forest Weeds. 



When close canopy of crops is maintained, and retention of the 

 dead foliage or soil-covering of moss is suitably provided for, few 

 forest weeds, if any, take possession of woodland soil, owing to the 

 iwant of light necessary to their growth. But when the leafy 

 ; canopy of high-forest crops becomes interrupted and broken here 

 ' and there for the purposes of natural regeneration, or when a total 

 [clearance of the mature crop takes place, with a view to artificial 

 : reproduction, a thick growth of grass and rank development of 

 i ! weeds often take place in a very short time; and a similar 

 'observation may be made in the case of crops whose density of 

 canopy has been interfered with as a result of natural causes, or 



E 



