rEBBUAET 12, 1915] 



SCIENCE 



227 



many thousands of acres and property 

 values up into millions of dollars. 



As an ecologist it was my duty to deter- 

 mine from present indications the nature 

 of these so-called lakes in 1847. The work 

 was ridiculously easy, since it was found 

 that these "Lake beds" were covered with 

 upland timber of great age. The attor- 

 neys for the lumber interests endeavored 

 somewhat half-heartedly to show the inac- 

 curacy of the method of determining the 

 age of the trees by a count of the annual 

 rings, but in the face of the hundreds of 

 years of age shown by many of the ring 

 counts, this contention had short shrift. 



Somewhat greater efforts were put forth 

 in support of their claim that trees can 

 grow in lakes, much being made of the 

 well-known fact that the bald cypress, 

 Taxodiiim distichum, occurs in well-de- 

 fined bodies of water. It was here that the 

 ecological argument had its greatest force. 

 Having visited the country of the lower 

 Mississippi on two previous occasions and 

 having made four trips to the territory in 

 question during the course of my work for 

 the government, I was in a position to 

 know the main facts in the ecological suc- 

 cession on the Mississippi bottoms. 



Employing the happy terminology of 

 W. S. Cooper, there are two types of hy- 

 drarch succession in the area in question, 

 that from the river and that from the lakes 

 which generally are back of the levee or in 

 old cut-offs due to a shifted course of the 

 river. On the river front, as the alluvium 

 is built up, there is frequently seen a sand- 

 bar vegetation of ephemeral annuals as- 

 sociated with low summer levels of the 

 river. Back of this there appears the first 

 ligneous vegetation, dominated usually by 

 willows, such as Salix longifolia and 8. 

 nigra. Further back there appear more or 

 less definite stages of vegetation, each 

 stage associated with a water table of a 



given depth, culminating in the great river- 

 bottom forests of Quercus texana, Q. lyrata, 

 Acer rubrum, Liquidambar, Celtis, various 

 hickories, Populus deltoides, Ulmus, Pla- 

 tanus, Fraxinus americana, and the like. 

 It is probable that this forest type is not 

 the permanent climax of the region, but 

 rather a very long-enduring temporary 

 climax. 



In the lakes, whether formed by the ele- 

 vation of natural or artificial levees or 

 through the shifting of the river channel, 

 the course of vegetational development is 

 somewhat different. At first there is a 

 pond vegetation with Nelumbo and other 

 pond aquatics. Following this one finds at 

 times a flag grass prairie or again a willow 

 belt, much like that of the river front. The 

 most striking feature of these lake succes- 

 sions, however, is the stage dominated by the 

 tupelo, bald cypress and water locust, which 

 usually follows the willow or prairie stage. 

 As shown by the great age of the trees 

 (tupelos of 200 years, and cypress of 700 

 years having been observed), this stage 

 may last for a long time. 



It is particularly important to note that 

 many tupelo and cypress trees were seen 

 to have been killed by submergence dur- 

 ing periods of high water, thus showing 

 that these trees are properly trees of the 

 land rather than of the water. If they oc- 

 cur in lakes, as they do, this fact would seem 

 to indicate that the lakes are but tempo- 

 rary, or at least that there were only short 

 periods of particularly high water during 

 their early life. After these trees there 

 comes a forest of red maple, sweet gum, 

 pumpkin ash, planer, pecan, etc., and then 

 again after a lapse of many more years 

 there comes the characteristic forest of the 

 so-called lakes, the temporary climax for- 

 est above noted, with its gigantic oaks, 

 haekberries and other trees of the dry 

 ground; therefore, when one cuts an over- 



