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Bioproductivity, efficiency, and related terms

Bioproductivity, efficiency, and related terms

The concept may apply to a single organism, a population, or entire communities and ecosystems. In aquatic systems, productivity is often measured in volume instead of area.
The quantity of organic matter or its equivalent in dry matter, carbon, or energy content which is accumulated per area during a given period of time.
Bioproductivity is the coordinated manifestation of the efficiency with which biological processes operate at various organization scales, from molecular/cellular to the whole organism and population.

Efficiency :

the capacity of a system to meet all requirements. In biology, the ratio of productivity of an organism to its supply of energy. For the biosystem, efficiency thus means the ability of the planet or ecosystem to effectively maintain life and be resilient, through adaptations and optimizations according to available resources and their phasing at various organization levels.

Bioproductivity

The bioproductivity is the amount and rate of production which occur in a given ecosystem over a given time period.
The rate of primary production as biomass with reference to space and time. The amount of biological material useful to humans that is generated in a given area. In agriculture, productivity is called yield (biomass x land area). Expressed in amount per hectare [1-2].
Higher yield implies the use of less land to reach the same productivity [3].

Biological productivity (or primary productivity), expressed as the harvestable yield in tons per hectare at a specific location for a complete growing season is based on the use of a computerised model combining rainfall, evaporation, vegetation and soil characteristics, including space imaging, spectrometry and biochemical methods
(Ronald E. Schulze, Department of Agricultural Engineering at the University of Natal).
Ecologists distinguish between primary productivity (by autotrophs) and secondary productivity (by heterotrophs). Plants have the ability to use the energy from sunlight to convert CO2 and water into glucose and oxygen, producing biomass through photosynthesis. Primary productivity of a community is the rate at which biomass is produced per unit area and time by plants, expressed in either units of energy [joules/(m-2)(day)] or dry organic matter [kg/(m2)(year)].
The following definitions are useful in calculating production :

Gross primary production

Gross primary production (GPP) is the total energy fixed by photosynthesis per unit time. (gross production = respiration + heat losses + net production).

Net primary production

Net primary production (NPP) is the gross production minus losses due to plant respiration and heat losses per unit time, and it represents the actual new biomass that is available for consumption by heterotrophic organisms.
Secondary production is the rate of production of biomass by heterotrophs (animals, microorganisms), which feed on plant products or other heterotrophs [4].

Productivity (soil) :

the capacity of soils to support biomass production (quality, quantity) according to inherent qualities (such as depth, nutrient status and pH, organic matter and biological activity, porous status and air and water movement), weather and management. (adapted from [5]).
Referenced soil and climate data are based on FAO’s Digital Soil Map of the World and associated soil characteristics (e.g., slope, depth, and salinity), global land-cover data generated from satellite imagery (U.S. Geological Survey, resolution of 1 kilometer with cropland identified according to the International Geosphere-Biosphere Programme land-cover classification scheme). These are combined with spatially referenced long-run average temperature and precipitation data to establish land quality classes distinguished by their suitability for agricultural production [6].

1. Global Footprint Network - Glossary [http://www.footprintnetwork.org/en/index.php/GFN/page/glossary/#biocapacity]

2. WWF - 2010 Living Planet Report [http://wwf.panda.org/about_our_earth/all_publications/living_planet_report/2010_lpr/]
3. Yield Booster - Yield Glossary [http://www.yieldbooster.org/intrinsic-yield/yield-glossary]

4. Biological productivity [http://encyclopedia2.thefreedictionary.com/Biological+Productivity]

5. What is Soil Health ? [http://vro.dpi.vic.gov.au/dpi/vro/vrosite.nsf/pages/soilhealth_what_is]

6. Wiebe K : Linking land quality, agricultural productivity, and food security. USDA-ERS Agricultural Economic Report No 823 2003:19-27.

Publié ou mis à jour le 14 juin 2012