2.3 flows of energy and matter

productivity

the conversion of energy into biomass over a given period of time, rate of growth or biomass increase in plants and animals, measured per unit area per unit time, per meter squared per year (m-2 yr-1)

gross

the total amount of something made as a result of an activity

net

the amount left after deductions are made, what you have left and is always lower than the gross amount

primary

in ecology, means to do with plants

secondary

in ecology, means to do with animals

biomass

the living mass of an organism or organisms but sometimes refers to dry mass

gross productivity (GP)

the total gain in energy or biomass per unit area per unit time, the biomass that could be gained by an organism before any deductions

net productivity (NP)

the gain in energy or biomass per unit area per unit time that remains after deductions due to respiration

gross primary productivity (GPP)

the total gain in energy or biomass per unit area per unit time by green plants, the energy fixed (or converted from light to chemical energy) by green plants by photosynthesis but some of this is used in respiration

net primary productivity (NPP)

the total gain in energy or biomass per unit area per unit time by green plants after allowing for losses to respiration, increase in biomass of the plant, how much it grows, is the biomass that is potentially available to consumers (animals) that eat the plant: [NPP = GPP - R, R = respiratory loss]

gross secondary productivity (GSP)

the total energy / biomass assimilated by consumers, calculated by subtracting the mass of fecal loss from the mass of food eaten: [GSP = food eaten - fecal loss]

net secondary productivity (NSP)

the total gain in energy or biomass per unit area per unit time by consumers after allowing for losses to respiration, other losses in animals but respiration is the main one, calculated by subtracting respiratory losses (R) from GSP

maximum sustainable yield (MSY)

the largest crop or catch that can be taken from the stock of a species: [ex. a forest, a shoal of fish)]without depleting the stock, taken away is the increase in production of the stock while leaving the stock to reproduce again, often used in managing fisheries, MSY is equivalent to the net primary or net secondary productivity of a system

carbon fixation

occurs in photosynthesis when plants recapture carbon and lock it up in their bodies for a time as glucose or other large molecules

nitrogen fixation

when atmospheric nitrogen (N2) is made available to plants through the fixation of atmospheric nitrogen

nitrification

the process of conversion of ammonia or reduced nitrogen compounds into the easily absorbable form of nitrogen that is nitrates and nitrites

denitrification

the microbial process of reducing nitrate and nitrite to gaseous forms of nitrogen, principally nitrous oxide (N2O) and nitrogen (N2)

assimilation

the absorption and digestion of food or nutrients by the body or any biological system

energy budget

the quantities of energy entering, staying within and leaving the animal or population

anthropogenic

a process, effect or activity derived from humans

energy subsidy

the additional energy that we have to put into the system above that which comes from the Sun’s energy