Oct.-Dec. 1921.] 



The Canadian Field-Naturaijst 



123 



so encloses a sheet of water 150 200 

 yards wide and 200-300 long. The on 

 farther from the island runs almost due 

 east for nearly 500 yards and gives off at 

 its extremity another smaller spit about 

 170 yards long pointing to the north. This 

 second spit, therefore, encloses a still lar 

 ger bay which includes the former spit. 

 and this bay and its eastern end come over 

 to within about i/4 mile of the southern ex- 

 tremity of the island. In this way there is 

 formed a very good harbour known to the 

 fishermen as Swampy Harbour and for 

 this reason the whole island is sometime.'^ 

 erroneously referred to as Swampy Island 



The main ridge and its side spits form 

 an environmental complex that is in many 

 ways similar to that on the shores of Lake 

 Michigan in the vicinity of Waukegan, and 

 its biota (total life content both animal 

 and plant) must be on the whole fairly 

 similar save for the effects of its more 

 northern position and the somewhat dif- 

 ferent forest associations with which it is' 

 sur: ounded. 



The observations were made on this se- 

 cond spit which has the form of an L and 

 may be treated as a small ecological unit. 

 Its long stem coming off from the main 

 spit runs east by a trifle south, and is about 

 500 vards long bv 100 vards wide. On 

 each side it slopes off very gradually 

 under the water, on the north to the inner 

 bay and on the south to the outer bay. It 

 has three crests running along it, the high- 

 est of which is about 7i/2 feet high and lies 

 near the .southern side. The short stem of 

 the L is about 170 vards long bv 23 vards 

 wide and runs north by a trifle east. On 

 the west side of this the water (of the inner 

 bay) is very shallow, but on the east side 

 it is deeper, particularly at the heel of the 

 L, so that the fisheries steamer "Lady of 

 the Lake" i^ able to run alongside a veiy 

 short pier. At this point are the cleaning 

 shed, the store house, bunk house and cook 

 house used in both summer and winter 

 fisheries by about a dozen men. The short 

 stem of the L is used for work on the nets 

 and boats, etc., and is sandy without any 

 vporptation. Our own camp was pitched 

 dDout half way along the spit. It is quite 

 obvious that the spit is much younger than 

 the main ridge from which it springs, for 

 while the latter has several groups of fair- 

 sized poplars, Popidus halsamifera, the 

 former has only much smaller ones, and 



the largest of these occur at the place where 

 it comes off the main stem. It therefore 

 represents a comparatively recently form- 

 ed spit of sand and fine shingle that is 

 being established and overgrown by ve- 

 getation. 



The m(\st st iking feature is the manner 

 in whicli the plants are arranged in rows 

 parallel with *he axis of the spit, each row 

 characterised l)y the presence of a part- 

 icular species or grouj) of species. On 

 standing at either end and looking along 

 the .spit this cannot fail to be remarked, 

 for it almo.st looks as if it we:e arranged 

 and was commented on by two of the fish- 

 ermen quite independently. About eleven 

 of these zones can fairly readil.y be dis- 

 tinguished and may be named according 

 to the prominent vegetation characterising 

 them. Thus, starting on the south, we 

 have : 



A 23 feet shore sand zone 

 B 21 " zone of soft sand 

 C 25 " artemisia zone 

 D 29 " vetch zone 

 E 28 " golden-rod zone 

 P 25 " rose zone 

 (j 31 " astralagus zone 

 H 21 " second vetch zone 

 J 45 " willow and poplar zone 

 K 13 " grass zone 

 L 40 " shore .sand zone 



To which may be added 

 M the water zone on the inner side. 



The grasses extend through nearly all 

 the zones, but in K they are very close and 

 are the only noticeable plants; they form 

 the main part of the vegetation of zone J. 

 The two shore zones are partly covered 

 when the water is liigh, and were probably 

 submerged in 1916 and 1917 when the 

 whole lake level was sliirhtly higher than 

 :n 1918. 



""he following table gives an idea of the 

 zonation. It provides a list of the plants 

 found and the zones in which they were 

 distributed. To convey some idea of the 

 amount of vegetation present, letters have 

 been employed. They are by no means ac- 

 curate, but time was too short to allow of 

 taking unit counts. Thus "extremely 

 common" means that the area was well 

 covered with the species and n. c. means 

 that examples only occurred here and there, 

 often as stragglers from the next zone. 

 'Rare" is meant to indicate that only a 

 few specimens occurred on the whole length 



