510 



THE COMMUNITY 



population, I is an individual, and t is a As we have noted with respect to strati- 



time component: fication of communities, the seas, except 



LAi 



etc. 



etc. 



In this revised trophic level system, Ai 

 includes the photosynthetic plants (either 

 or both the higher plants and the 

 photo-autotrophic bacteria), that is, the 

 producers; As includes the herbivores, 

 that is, the primary consumers; j\3 includes 

 the carnivores, that is, the secondary con- 

 sumers; A 4 includes the saprophagous or- 

 ganisms (heterotrophic bacteria and fungi), 

 that is, the tertiary consumers; and /^s in- 

 cludes the chemo-autotrophic bacteria, that 

 is, the quaternary consumers." 



Several variations are to be noted in this 

 system of energetic categories. First, omni- 

 vores encompass both A^ and \3. Second, 

 A.3 must be factored to allow for several 

 predator grades (P) within the level, that 

 is, the Si population feeds on A:, but S2 

 usually feeds on Si, S3 on S:, and so on: 



(Ii 



(Si 

 Pi 



In) 



Sn) 



Pn 



Finally, the trophic level may or may not 

 be synonymous with the food niche (p. 

 516), depending upon the particular com- 

 munity under examination. 



* The growing emphasis upon feeding rela- 

 tionships within the community has been ac- 

 companied by the usual confusion of terms. For 

 example: A 2 includes the "primary consumers" 

 of Jacot ( 1940 ) for terrestrial communities, 

 "browsers" of Lindeman ( 1942 ) for aquatic 

 communities, and "primary consumers" in gen- 

 eral (Lindeman, 1942); A3 includes "secondary, 

 tertiary, quaternary predators" of terrestrial, 

 and "benthic and swimming predators" of 

 aquatic communities, and "secondary con- 

 sumers" of Lindeman (1942); A4 includes "re- 

 ducers" of Thienemann ( 1926a ) , "transformers" 

 in part (Waksman, 1941), and "decomposers" 

 (Lindeman, 1942). 



Naturally, all organisms, whether Ai, or Ao, 

 consume, transform, produce, and otherwise re- 

 arrange and reorganize their protoplasms and 

 environments. The terminology, more or less 

 apt, explains nothing. 



Heterotrophic Chemo-autotrophic 

 bacteria, bacteria 



fungi, etc. 



possibly certain shallow coastal areas, have 

 the photosynthetic level dominated almost 

 exclusively by phytoplankton; almost all 

 fresh-water communities have both a phyto- 

 plankton and a rooted vegetation, while 

 terrestrial communities have this trophic 

 level occupied essentially by rooted, higher 

 plants. In terms of photosynthesis, the fresh- 

 water communities are intennediate in the 

 series. Lindeman (1942) has rephrased this 

 matter in other words. For example, the 

 marine community is "mono-cychc" with 

 microphytic producers; the fresh-water com- 

 munity is "bi-cyclic" with both microphytic 

 and macrophytic producers; the terrestrial 

 community is "mono-cychc" with macro- 

 phytic producers. 



From this point of view, terrestrial com- 

 munities have no structural equivalent 

 to the plankton of aquatic communities. 

 We have seen previously that the phyto- 

 plankton of aquatic communities and the 

 canopy of terrestrial communities are physi- 

 ologically parallel and occupy the same 

 relative stratum in the vertical gradient. 



France (1913, 1914) approached this 

 problem from yet another aspect. He con- 

 sidered the microbiota of the soil (subter- 

 ranean stratum -f- floor, in part) to include 

 bacteria, fungi, algae, protozoans, roti- 

 ferans, tardigrades, and ohgochaetid worms 

 (and should have included mites and 

 micro-insects). These groups of organ- 

 isms France termed collectively the 

 edaphon, and developed the concept that 

 the terrestrial edaphon was the equivalent 

 of the aquatic plankton. Lindeman (1942) 

 took issue with this concept, pointing out 

 that the analogy was misleading, since the 

 edaphon has almost no producers in the 

 trophic sequence and that France's edaphon 

 is much more comparable to the lacustrine 

 microbenthos. 



As with many similar disagreements, this 

 is a matter of the viewpoint from which the 

 problem is examined. From the point of 



