DISOPERATION 157 



DISOPERATION 



Nature and Scope. As suggested previously, the harmful effects 

 arising from aggregation or crowding may well be termed disoperation. 

 This stands in direct contrast to cooperation in consequence, but it 

 is less clearly distinguished from competition. However, the essence 

 of competition is the attempt to secure more than a proportionate 

 share of a limited supply of something, e.g., raw materials, food, space, 

 or material for construction. In comparison, disoperation includes 

 chiefly those harmful effects that have to do with changed conditions 

 or behavior, as in the accumulation of carbon dioxide, toxins, or ex- 

 creta. Since all coactions may be classed as beneficial or harmful with 

 respect to the needs of a species, it is evident that no absolute line can 

 be drawn between them, since even cooperation may present disadvan- 

 tages. Nevertheless, the four main types of coaction, namely, coopera- 

 tion, disoperation, competition, and destruction, correspond to definite 

 differences in process and outcome, and hence serve a useful purpose 

 in the analysis and organization of the myriad of interactions between 

 organisms. 



As with other coactions, disoperation may concern plants or ani- 

 mals, or both may be involved in the same process. IMoreover, it may 

 be combined with other types of coaction in some measure, or it may 

 be a secondary effect of any one of them. 



Disoperation in Plant Communities. Disoperation among plants is 

 largely an outcome of additive reactions, as in the production of car- 

 bon dioxide or other toxins in the soil. This occurs, as a rule, only in 

 colloidal or waterlogged soils, where it is a concomitant of competition 

 for an inadequate supply of oxygen, with the consequence that the two 

 effects are difficult to separate. Acids and other more or less dele- 

 terious substances are produced by the decay of plant remains in wet 

 climates especially and may serve as a physiological barrier to certain 

 invaders or lead to the actual elimination of some species (cf. Clem- 

 ents, 1921 b) . The accumulation of leaves in forests may be disoper- 

 ative to a high degree in dry climates, or wherever a thick layer of 

 duff is produced or a dense interwoven carpet of pine needles is formed. 

 Such conditions not only render germination difficult or fruitless, but 

 they likewise hinder seedlings from rooting in the mineral soil beneath, 

 with its proper supply of water and nutrients. 



Disoperation may also act through the canopy of forest or thicket 

 by decreasing the light intensity or the effective rainfall. The light 

 effect is felt in the competition between individuals of the canopy 

 (e.g., Fig. 34) or of the layers below, but it results also in a direct 



