Stem density refers to the number of individual plants in a specified area; the area is usually standardized to square meters. Stem density can be used as an index of abundance, biomass and system productivity within a certain habitat.
Abundance
Often, ecologists desire a metric for plant abundance that can be comparable between habitats and ecosystems. The total number of plants per unit area allows for this comparison, so long as the same area is used in all locations.
Biomass
Many researchers have developed equations to determine the mass of a plant based on its height. Utilizing these equations in conjunction with stem density allows for estimations of above-ground biomass and subsequent comparisons between habitats.
Productivity
Ecosystem productivity is often described in grams of carbon per squared-meter per year. Researchers can use stem density to estimate how much plant biomass has been produced over a measured amount of time and, therefore, estimate how productive one system is relative to others.
Importance
Using stem density to determine abundance, biomass and productivity are key to ecology. One of the driving forces behind ecology is to understand the interactions between the living (e.g. plants) and the non-living (e.g. nutrients, sunlight) components within and between ecosystems.
Caution
Stem density can be determined by counting the stems of all plants within an area or by counting the number of stems of an individual species. Stem density cannot tell an ecologist everything about an ecosystem. Other metrics such as species richness, the number of different species within an area, should also be used to complement stem density.
Tags: abundance biomass, between habitats, stem density, Stem density, within area
