422 The Comfiiunitij 



aerated soil influence the depth of root growth. In the temperate 

 forest the tree roots may extend to depths of 3 m, but the bulk of 

 root development occurs in the upper meter. Animal activity is most 

 intense in the upper half meter but the larger burrowing forms pene- 

 trate to depths of several meters. 



Fig. 11.8. Stratification of vegetation in a deciduous forest of the temperate 



region. The vertical subdivisions of the biocenose are: (1) subterranean, (2) 



forest-floor, (3) herbaceous, (4) shrub, and (5) tree strata. 



The forest floor is a complex subdivision of the biocenose in which 

 great biological activity goes forward involving the decay of plant 

 material and a web of predator-prey and parasite-host relationships. 

 Huge numbers of invertebrates inhabit fallen logs and other material 

 on the forest floor, and they are preyed upon by carnivorous beetles 

 and hunting spiders as well as by higher animal types. Saprophytes, 

 including the familiar mushrooms and bracket fungi, are particularly 

 characteristic here but mosses and other low growing green plants 

 may be abundant. In general the density of the population of the 

 floor stratum in the forest is higher than it is in grassland and higher in 

 warmer climates than in colder climates. 



