DYNAMIC STUDIES OF VEGETATION 45 



It is interesting to note that according to the old inhabitants 

 the vegetation of the Hempstead Plains used to grow taller than 

 it does now. If some one had only thought of measuring the 

 yield of hay from the Plains fifty or a hundred years ago and 

 placing the results on record we could now tell approximately 

 how fast the apparent retrograde succession is progressing, 

 if at all. 



This investigation of marsh vegetation throws some light on 

 a question raised some months ago^, namely, whether or not the 

 rate of growth increases with the progress of succession. In 

 the brackish marsh near College Point Phragmites is much more 

 abundant now than formerly, according to Mr. Edward N. E. 

 Klein, a botanist and pharmacist who has always lived there 

 (and to whom I am indebted also fdr considerable assistance in 

 \Veighing and burning the vegetation samples), presumably on 

 account of some of the salt water having been excluded by a tide 

 gate. Where a patch of it adjoins one of Spartina patens, as 

 in figure 2, the outposts of the Phragmites look like trees on the 

 edge of a forest invading a prairie^ on a small scale. The great 

 difference in the bulk of the two plants per unit area, and es- 

 pecially in the amount of mineral matter taken from the soil, 

 is brought out in the foregoing table. But as this is not a gen- 

 uine case of natural succession it may not be safe to deduce 

 any general principles from it. 



In most of the cases above mentioned the yield of dry vege- 

 table tissue is less than that produced by the average cultivated 

 crop in average soils, even without fertihzation; and the most 

 likely explanation is that plowing, by aerating the soil, makes 

 the plant food available more rapidly that it is under natural 

 conditions. 



None of the previous investigators cited seem to have made 

 any attempt to determine the inorganic matter in their hay, 

 which is probably as important as the dry weight, if not more 

 so, for it indicates just what the vegetation is taking from the 

 soil. (Of course in a state of nature most of it soon gets back 

 into the soil to be used over again, but a not inconsiderable por- 



^Torreya, 16: 139. June, 1916. 



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