170 ILLINOIS STATE ACADEMY OF SCIENCE 



The inhabitants of near.by dwellings also use the pond 

 as a dump. It is not uncommon to find all sorts of debris 

 when raking up material for laboratory examination. 



The region that is of most interest to the ecologist is 

 not that in which he finds one stage predominant. His 

 real interest is in the contested ground, "no plants land" 

 as it were. In the interzonal areas the conditions are 

 such as to permit the development of species from the 

 two zones on either side of it. No species or type can, 

 however, predominate because of the presence of the 

 other and the conditions that do not favor maximum de- 

 velopment. No more valiant fight ever was staged on 

 battlefield or gridiron than is being fought every year 

 in these regions. The receding species do not give up 

 easily ; they contest every inch. 



The arrow head, because of its adaptibility, is one of 

 the more aggressive types. It seems to defy the deep 

 water on one side and the smartweed on the other. Each 

 spring during the flood period, it takes a grip on part of 

 the lower flood plain and when the water recedes, it re- 

 mains. The sand bar willow is struggling for a foothold 

 on the lower flood plain. Last season a row of seedlings 

 were established on the west end of the south side. This 

 spring they are on the water's edge and a few are par- 

 tially submerged. This season will determine whether 

 or not the year old seedlings can survive such conditions 

 even temporarily. Last year, a few willow sprouts were 

 seen on the edge of a partially submerged row boat near 

 the west end of the lake. This spring, there is no sign to 

 indicate that they have survived. So the struggle goes 

 on, the plants slowly changing the conditions of the area 

 and the conditions determining the plants that shall sur- 

 vive. 



IN CONCLUSION 



Lake Knox, an artificial pond, was abandoned several 

 years ago and, with the exception of man's influence men- 

 tioned, nature was allowed to take her course. At the 

 present time, the lake is being filled in slowly with the 

 silt and humus carried in by the inlet and the humus 

 formed by the plants that live within and around its 

 borders. Here we have a striking example of nature's 

 developmental changes within a limited area. 



