Sample PicturePost Pictures: Green Down of Trees

As autumn sets in and the amount of daylight decreases and the temperature becomes colder, deciduous trees begin their "green down" phase. Below is a sequence of pictures taken generally once a week for a month, starting in early October, 2005.

October 1, 2005

October 22, 2005

October 30, 2005

November 6, 2005

November 12, 2005

Notice the variety of trees in the picture and that each species has its own timing in changing leaf color and dropping of leaves. Although pictures were taken on clear days, the weekly amount of precipitation may be inferred from the changing water levels in the pond (use the large rocks as markers). Rising water levels indicate a week marked with several rain events, falling water levels occur during a week without much precipitation, and unchanging water levels indicate moderate rainfall during the week.

Extension Activities

• Identify the species of trees that are visible in the image and label them on a reference picture that may be used to study green down each year. Upload the labeled picture as a reference for others.
• Take a picture with a visible scale of known length beside trees of interest. You may then use the MVHimage software to measure how the tree grows over years. Since the trees don't physically relocate on their own, one picture with the scale nearby will be the reference for years to come.
• Measure the distance and direction to each tree (or GPS the location if you have access to a handheld GPS tool). This may help community planners use the photographs with Geographic Information Systems (GIS) software. Exploration is underway with City Lab from Worcester Polytechnic Institute (WPI).