Biosphere Contents

1. Organic Matter

Standing crop, biomass and productivity are important ecological concepts

Standing crop. The standing crop is the amount of an organism present at a point in time. A field may have a grass crop. If a square metre of that crop were removed and weighed that would be the standing crop per m2. We could measure a hectare, a km2 or, in water, a cubic metre, and in every case (with appropriate units) the result would be the standing crop. The 'crop' could be plants, trees, fish, mammals, birds, or other biological materials.

Biomass. Biomass, the biological mass, is the amount of organic material contained in living organisms per unit area. This includes both above- and below-ground material, and normally includes dead matter (such as wood or hair) that is connected to living organisms, but excludes dead matter that has been shed (such as leaf litter). Biomass is often measured as mass of dry organic matter per unit area, or as energy per unit area.

Examples and uses of plant biomass

Productivity. This is the rate at which biomass is produced. Productivity is measured as the energy or dry mass produced over a specified area during a specified time period (e.g. tonnes per ha per year). We must be careful to include the growth of material that has been grazed or harvested or has grown then subsequently died over the course of the year in our estimate of productivity. In the case of, say, a pasture, the biomass will be small relative to productivity but in the case of a forest containing trees that may be hundreds of years old, production per year will be much lower than the biomass.

What do the terms standing crop, biomass and productivity refer to?