No. 2, December, 1921] ECOLOGY, PLANT GEOGRAPHY 75 



468. DuDGBON^, WiNFiELD. A Contribution to the ecology of the Upper Gangetic Plain. 

 Jour. Indian Bot. 1: 9-10. 1920. — A study of vegetative types and successions based on ob- 

 servations through several seasons in a region about Allahabad is reported. The climatic 

 factors produce 3 distinct seasons: (1) Rainy season, July-Sept., with high rainfall, low in- 

 solation, high temperature, high humidity; (2) cold season, Oct.-Feb., with low rainfall, high 

 insolation, low temperature, high humidity; (3) hot season. Mar .-June, with low rainfall, 

 high ''nsolation, high temperature, low humidity, and high winds. — The biotic feature influences 

 the vegetation as much as does the climatic. The rural population of the region is 530 per 

 square mile; grazing domestic animals number 470 per square mile. This causes marked and 

 continual retrogression from the climatic climax. Seasonal succession is distinct, the vegeta- 

 tion being luxuriant in the rainy season, moderately luxuriant with different types prevailing 

 in the cold season, and sparse in the hot season. — Hydrarch topographic succession is obscured 

 by the interference of human factors but it presents in general the following stages: (1) aqua- 

 tic, (2) wet meadow, (3) dry meadow, (4) thorn scrub poorly developed. If the retrogressive 

 influence of biotic factors were removed it seems clear that successions would progress through 

 (5) thorn scrub fully developed, (6) pioneer monsoon deciduous forest, (7) climatic climax 

 monsoon deciduous forest. — L. A. Kenoyer. 



469. Harvey, Leroy H. Some phytogeographical observations in Lake County, Michigan. 

 Michigan Acad. Sci. Ann. Rept. 21 : 213-217. 1919.— The author holds that the northern half 

 of the southern peninsula of Michigan represents "a great tension zone in which the northern 

 outposts of the deciduous climax forest formation and the southern relicts of the northeastern 

 evergreen forest formation overlap and intermingle, thus becoming competitors for occupa- 

 tion." A study of soil and atmospheric conditions proves inadequate to explain present 

 distributional conditions, and renders it probable that succession has been abbreviated in 

 most, if not all, of the tree associations. He believes that the original upland forest associa- 

 tions have been more the result of preoccupation and self-perpetuation than of a well-marked 

 successional development. In general he believes that "any region should be classified upon 

 the basis of the highest ecological type which may find expression therein." From these 

 considerations, the presence of numerous areas of hardwood or mixed hardwood formations in 

 this region of conifers would seem to link it up with the deciduous climax formation to the 

 south. — //. T. Darlington. 



470. Hastings, Ghoege T. The vegetation of a cinder field. Torreya 20: 96-100. 1920.— 

 In the summer of 1916 an area of some 3 acres on the west shore of the Hudson River opposite 

 Hastings, New York, was filled in with ashes and rubbish from 1 to 6 feet in depth, and over 

 this a layer of cinders 6 inches to a foot in thickness was placed. In the summer of 1917 the 

 area became well covered with vegetation; the next year, however, the area was covered with 

 a layer of clayey soil, and but few of the original plants reappeared. In 1917, 96 species of 

 flowering plants appeared on the area. This was distinctively a weed flora, only 6 of the spe- 

 cies belonging to the flora of the adj acent hillside. Only 29 per cent of the species were native, 

 and over half were annuals. The grasses and composites made up more than 40 per cent of the 

 species. Many of the plants would have survived for many seasons had not the cinders been 

 covered the following season. A complete list of the species observed is appended. — J. C. 

 Nelson. 



471. Phillips, E. Percy. A preliminary report on the veld-burning experiments at Groen- 

 kloof, Pretoria. South African Jour. Sci. 16: 28.5-299, PL 31-33 and diagrams. 1920.— 

 The burning of the veld tends to encourage the flowering of many plants, particularly hemi- 

 cryptophytes. There appears to be a definite life history in the development of the succes- 

 sion and the formation of vernal aspect societies. Soil protected by vegetation does not 

 exhibit such extremes of heat and cold as bare soil. The water content of soil covered with 

 vegetation does not fluctuate between very high and very low extremes; it is more stable in 

 this respect than bare soil. — E. P. Phillips. 



472. R.YMALEY, Francis. SomeT mountain plant communities on sandy soil. Plant World 

 22 : 313-328. 3 fig. 1919. — An account is given of the vegetation on a sandy area near George- 



