22 



ANIMAL ECOLOGY 



succession. The same thing is well known to occur in a great 

 many places when heather or grass is protected, the important 

 animals varying in different places, being usually cattle, 

 sheep, horses, or rabbits, or even mice. 



6. We begin to see that the succession of plant communities 

 does not take place at random, but in a series of orderly stages, 

 which can be predicted with some accuracy. The exact type 

 of communities and the order in which they replace one another 

 depend upon the climate and soil and other local factors, such 

 as grazing. It is possible to classify different series of stages 

 in succession in any one area, the term " sere " being used to 

 denote a complete change from a bare area in water or soil up 



Pine WOOD 



'Before. fcUfng Aftzr felling 





Boc; Societies y 



kMouniA 



CONSOCIES 



MOLINIA -JoNCUS. 

 ECOXOME 



4- 



JUNCUS. 



Mixed Wood 



,1 ( loeaUy) 



.jBrhCH' 



I 



s.i--.-_r.^ 



Assoc I es" 



^ z^Sphaqnuh 



Boq 



■^ C+t^ier has occu-T-rci or m /brogrts^ 

 •> "ProbAble JroM observations (sccTiKt) 



*/Newoo'D 



Fig. 2. — The diagram shows the stages in ecological succession follow- 

 ing colonisation of damp bare areas formed by felling of a pine wood on 

 Oxshott Common. The succession is different on the drier areas. (From 

 Summerhayes and Williams.^ 2°) 



to a climax like pine wood {cf. Fig 2). Each type of soil, etc., 

 has a different type of '' sere " which tends to develop upon it, 

 but they all have one character in common : bare areas are 

 usually very wet or very dry, and the tendency of succession 

 is always to establish a climax which is living in soil of an 

 intermediate wetness — a type of vegetation called " meso- 

 phytic," of which a typical example is an oak wood. Thus a 

 dry rock surface gains ultimately a fairly damp soil by the 

 deposition of humus, while a water-logged soil is gradually 

 raised above the water-level by the same agency, so that there 

 tends to appear a habitat in which the exjpenditure by plants 

 and by direct loss from the soil is suitably balanced by the 



