50 100 150 200 150 100 50 

 DISTANCE FROM WEST 8 EAST EDGES, m 



FIG. 913 Population (number per m') of hibernating Insects 

 in the soil during the winter at different locations in a 22-hectare 

 (55 acre) rectangular deciduous forest tract (Trelease Woods) 

 in central Illinois. The forest is in contact with grassland on 

 the south side and with farmland on the other sides. The 

 italicized numbers are field and crop insects that have invaded 

 the forest to hibernate, the other numbers are true forest 

 species (modified from Kennedy 1958). 



same, regardless of whether they occur in deciduous 

 or evergreen forest, and regardless of geographic lo- 

 cation (Blake 1926, Dirks-Edmunds 1947). Species 

 occupying these niches dififer, but are often taxonomi- 

 cally related ; related or not, they have similar mores. 

 Thus a predominant, shrub-inhabiting, plant- juice 

 sucking leafhopper in an Illinois oak-maple forest is 

 Erythoneura obliqua, but in a Maine pine-hemlock 

 forest it is Graphocephala coccinea. The common 

 herbivorous woods mouse in Illinois is Peromysciis 

 leucopus, but in the Douglas fir-hemlock forests of 

 Oregon it is Clctlirionoinys occidcntalis. An insectiv- 

 orous hole-nesting chickadee in Maine is Pants 

 hudsonicus ; in Illinois, P. atricapillus ; and in Ore- 

 gon, P. rufescens. 



Coniferous forests have needle leaves ; deciduous 

 forests, broad-leaves. Some special, different niche 

 adjustments are thus required which may not permit 

 a species to successfully occupy both kinds of forest. 

 The tube-building moth attaches its eggs to the pine 

 leaf, and, when the larva hatches, it makes a nest of 



6-15 needles, bound together with silk-like threads. 

 The larva, and later the pupa, is protected within this 

 tube but can come out and feed on the end of the 

 leaves of which the tube is constructed. Deciduous 

 leaves are clearly incompatible with these behavioral 

 patterns, so nicely adapted to the peculiarities of pine 

 needles. On the other hand, the red-eyed vireo ex- 

 periences difficult feeding in coniferous trees because 

 of the arrangement and close position of the needle 

 leaves on all sides of the twig (Kendeigh 1945). 

 While the vireo can feed in coniferous forests, it is 

 considerably more profitable for the bird to confine it- 

 self to the deciduous forest, for which it is better 

 adapted. Some animal kinds inhabit the soil and litter 

 of both deciduous and coniferous forests, but a kind 

 may be more abundant in one forest type than the 

 other because coniferous and deciduous leaves form 

 two distinct types of humus. Because of differences in 

 foliage character, persistence through the year, cli- 

 mate, and the considerable difference in the taxo- 

 nomic composition of the plants and animals involved, 

 coniferous and deciduous forests are separated as dis- 

 tinct bionics, each with a number of biociations in 

 different parts of the world. 



Bird populations are not necessarily consistently 

 higher in one type of forest than in the other (Table 

 9-11) ; rather, population varies with the luxuriancy 

 of the vegetation. Animal populations in both co- 

 niferous and deciduous forests are generally highest 

 in regions where ample rainfall brings rich develop- 

 ment of vegetation as the basic food supply (Odum 

 1950). Population densities of both birds and mam- 

 mals decrease progressively westward from the Ap- 

 palachian Mountains to the eastern edge of the prairie 

 as the climate becomes progressively drier (Wetzel 

 1949, Fauver 1950). The variety of snail species de- 

 creases in a similar manner from moist to dry forest 

 types (Shimek 1930). 



Forest and game management 



The forest productive capacity of greatest eco- 

 nomic interest is the timber yield. Forests are also of 

 great importance to man for the protection of water- 

 sheds against erosion : for such recreational purposes 

 as hunting, camping, and hiking ; and for the inspira- 

 tional values of unspoiled scenery and primitive na- 

 ture. Complete logging, as practiced universally in 

 colonial and even in modern times, destroys the for- 

 est, most of its animal life, and its usefulness for 

 these purposes. Logging on a sustained yield basis 

 converts the forest into a forest-edge community and 

 allows the forest-edge animals to increase in abun- 

 dance, while the animals dependent on dense forest 

 decline. 



38 Habitats, communities, succession 



