Productivity and energy storage

Net annual production of plant communities is traditionally determined by measuring or estimating dry matter accumulation at the end of the growing season. Published records list crop or forest yields, i.e. the bales of hay, tons of silage, bushels of grain or cords of wood harvested. The yield represents only a portion of the organic matter produced. Each year a tree forms leaves, twigs and bark which are not harvested, and each year an entire new corn plant-roots, stalks and leaves-must develop to produce the bushels of grain. Primary production is the entire amount of growth for the year. For many purposes, the accumulation of organic matter (on a dry weight basis) is an adequate measure of production; however, total dry matter production maybe misleading as a measure of the energy actually stored

Productivity of an urban park

We have moderately good knowledge of the yields of crops and of commercial forest land. In contrast, little is known of the productivity of urban park areas. Parks are neither grassland nor forest-in structure they most closely resemble savanna, i.e., grassland spotted with trees bearing large crowns. How much energy is trapped by these communities? How much oxygen is liberated? What are the water requirements and recharge potentials of such areas? How can vegetation be best managed to promote the aesthetic and recreational needs of the urban citizen-and at the same time maintain its vital function as a living filter? To begin examining these questions, we studied the productivity of an open portion of the Downer Woods located on The University of Wisconsin-Milwaukee campus