Biomass refers to the total mass of living or recently living biological material within a defined area or volume, typically expressed as a weight per unit area, per unit volume, or as a total quantity within a system. In stormwater management and aquatic science, biomass commonly includes plants, algae, microorganisms, and animals present in soils, sediments, and waterbodies.
In the context of stormwater systems, biomass is most often discussed in relation to vegetation and microbial communities that influence water quality and treatment processes. For example, in practices such as bioswales, rain gardens, and wetlands, plant biomass plays a key role in stabilizing soils, slowing runoff, promoting infiltration, and taking up nutrients such as nitrogen and phosphorus. Similarly, microbial biomass in soils and sediments is essential for processes like decomposition, nutrient cycling, and pollutant transformation.
Biomass can be beneficial or problematic depending on its quantity and location. Healthy levels of plant and microbial biomass are critical for effective stormwater treatment and ecological function. However, excessive biomass, particularly in the form of algal growth in receiving waters, can indicate nutrient enrichment and may lead to water quality impairments. Large accumulations of algae or aquatic plants can contribute to oxygen depletion when they die and decompose, potentially leading to hypoxic or anoxic conditions.
Biomass is also an important metric used to assess ecosystem productivity and the effectiveness of stormwater best management practices. It reflects how much biological material is present and, by extension, how actively biological processes are occurring within a system.
Biomass is the total quantity of living or recently living organic matter in a given environment, and in stormwater management it is a key indicator of both ecological health and the performance of natural treatment processes.