TREE GROWTH IN VICINITY OF GRINNELL, IOWA 105 



On the originally treeless high prairie of this region, on the Marshall 

 silt loam, about lOO species of trees are now flourishing. With some 

 the rate of growth is prodigious. At first cottonwood, box elder, 

 willow, Lombardy poplar, and soft maple were planted. Elm soon came 

 into prominence and hackberry and ash followed. Orchard trees were 

 early introduced. Our data on these are not so precise as could be 

 desired, but they admit of some very striking conclusions. 



Grinnell was settled about 1855. Since that time on a part of the 

 college grounds (Chamberlain Park) a generation of Lombardy poplars 

 has matured and gone ; a generation of soft maples, following the pop- 

 lars, is represented by one large tree 4 feet in diameter, with trunk 

 twisted by the cyclone of 1882. The maples were succeeded at ma- 

 turity by American elms, which are now i to 2 feet in diameter. An 

 elm growing beside an unpaved street and felled in January, 1907, was 

 27^ inches in diameter and 40 years of age. In the last 23 years the 

 tree made a radial growth of 10 inches, or 20 inches increase in diam- 

 eter, nearly an inch per year. The growth from 1875 to 1882 was 

 almost as rapid. A row of ash trees {Fraxinus pennsylvanica) along 

 a country road averaged about 18 inches in diameter, when cut recently, 

 at the age of 40 years. Cottonwoods are frequently as large as 3 or 4 

 feet in diameter and not more than 60 years old. The old maple tree in 

 Chamberlain Park is not over 60 years old at the outside. Fruit trees 

 are short lived. The first apple tree of Grinnell is still standing. Most 

 fruit trees become broken and decadent in 25 to 30 years. Apples, 

 pears, and cherries (Primus cerasus) make extremely rapid growth, 

 with densely bushy tops. They require much pruning and thinning and 

 seem to vegetate so luxuriantly as to have little stimulus to fruiting. 



All these facts show that the trees of the natural timber and many 

 others find the upland prairie soil and climate most congenial ; if any- 

 thing, too stimulating. The conditions are no less favorable for seed- 

 lings. I have counted 27 soft-maple seedlings of second year's growth 

 in a square yard of close blue-grass sod. In hedges and fence rows 

 young box elders, elms, and maples are among our most common weeds. 

 On bare ground elms annually spring up near parent trees so thickly 

 as to obscure the soil when they are only 2 inches tall. We have 

 counted 268 per square foot in the edge of a grove. Maples, box elders, 

 cottonwood, and ash seedlings often appear in great numbers and hack- 

 berries and lindens spring up freely under the street trees. In pastures 

 wild crab-apples and Crataegus spp. spring up wherever the seeds arc 

 dropped undigested by cattle. I have counted 13 seedlings of Cratreg^is 



