THE GROWTH OF FOREST TREE ROOTS

Abstract

ROOTSusually necessary to remove the glass when an observation was to be made.(II) The vertical glass-plate method.In order to make observations on roots located somewhat deeper than was possible by using horizontal plates, holes were dug in the earth two and one-half feet wide by five feet long and two feet deep.A glass plate, one foot square, was then placed against the soil and roots at one end of the hole in such a way as to exclude any extensive air spaces between the glass and the soil, and held in place by means of long pins made of number nine wire.A piece of felt roofing was placed against the glass to exclude light and was held in place by board props.The hole was then covered with a board cover hinged to two stakes at one side and locked with a padlock to a third stake at the opposite side.Observations were made by both of the above methods on two individuals of each of the following four species of trees: Acer saccharinum L., Tilia americana L., Carya laciniosa (Michx f.) Loud., and Quercus alba L. The holes were dug and the glass put in place during December, 1913.They were first visited for observation on January 5, 1914, but regular observations did not begin until the twentyeighth of April of that year.The work was continued until September 2, 1915.During the warmer parts of the year observations were made weekly except on two occasions, one in August, 1914, and one in July, 1915, when I was out of town for periods of two weeks.