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Research: Tree Census Study

Dates Conducted: 1974 - present
Lead Researcher: Dr. Randy Van Dragt, Professor of Biology & Director of Ecosystem Preserve
Student Researchers: Summer Preserve Stewards/Researchers


Prior to the Ecosystem Preserve being formally established, Dr. Alan Gebben (Professor Emeritus, Biology), assisted by Dr. John Ubels, Professor of Biology (Calvin student at the time), conducted the first research project on the preserve's original 10 acre lot. They began a long-term tree census study that now allows us to track the succession of trees, and assess the health of the forest. Very few studies exist of this duration, making this a valuable study that will potentially reveal the impacts of both intrinsic and extrinsic factors on woodlot development. Smaller stands of trees like this one comprise a significant number of urban forests. These small woodlots are subject to many pressures that affect their development over time and, with that, the role they play in the urban environment.

The Study

Tree survey research is conducted every five years on the public 40 acres of the preserve. The property is divided into sections of 400 square meters, staked in each corner, and these squares are divided into four quadrants. For each quadrant, every tree that is 2" or larger in diameter is numbered, identified, mapped using GPS, and measured using a DBH (diameter at breast high) tape. Additionally, for any tree 12" or larger in diameter, a laser range finder is used to determine the height of the tree (using the distance from the tool to the tree base, straight ahead to the tree trunk, and to the top of the tree, resulting triangles are used to calculate height). For saplings less than 2" in diameter and at least 30 cm tall, they are identified, counted and recorded. For the first time, in 2014, a light sensor was used to measure the amount of light in the center of each quadrant, which was then averaged for each square. Researchers hope to ascertain if and how the quantity of light near the forest floor correlates to the forest's growth and development.


The area is classified as a Beech Maple forest in secondary succession. A total of 1850 large trees and 2000 saplings reside in the study area of the preserve. Growth data obtained over the past 40 years will start to be processed to help develop a picture of how the preserve's tree populations have changed. In analyzing the growth and mortality data, we will be taking into account several rounds of disease that have happened in that period, as well as the ongoing changes in climate that accompany global warming.

Measuring the tree diameter.

Measuring the tree height.

Identifying a sapling.

Native Species Growing in Study Area

Red Maple
(Acer rubrum)
Silver Maple
(Acer saccharinum)
Sugar Maple
(Acer saccharum)
(Amelanchier arborea)
Paper Birch
(Betula papyrifera)
(Carpinus caroliniana)
Shagbark Hickory
(Carya ovata)
Flowering Dogwood
(Cornus florida)
Grey-bark Dogwood
(Cornus foemina)
Red-osier Dogwood
(Cornus stolonifera)
(Crataegus sp.)
American Beech
(Fagus grandifolia)
American Ash
(Fraxinus americana)
(Hamamelis virginiana)
(Juglans cinerea)
Back Walnut
(Juglans nigra)
(Lindera benzoin)
Black Gum
(Nyssa sylvatica)
(Ostrya viginiana)
Trembling Aspen
(Populus tremuloides)
Wild Black Cherry
(Prunus serotina)
Choke Cherry
(Prunus virginiana)
White Oak
(Quercus alba)
Swamp White oak
(Quercus bicolor)
Bur Oak
(Quercus macrocarpa)
Red Oak
(Quercus rubra)
(Sassafras albidum)
American Basswood
(Tilia americana)
American Elm
(Ulmus americana)
Mapleleaf Viburnum
(Viburnum acerifolium)
Northern Arrowwood
(Viburnum dentatum)
Cranberry Viburnum
(Viburnum opulus var. americanum)