Ecosystems and Energy Flow

Terms:
biogeochemical cycling, residence time, net primary productivity, gross primary productivity, standing crop biomass, detritus, watershed, weir, vernal dam

biogeochemical cycling: Cycling of nutrients from abiotic to biotic sources through biological, geological, and chemical processes.

detritus: Dead organic matter.

gross primary productivity:   Total energy gained by a plant from the sun through photosynthesis, before any is used in respiration. 

net primary productivity:  Total energy gained by a plant from the sun through photosynthesis that is used for growth of new tissue, or energy left after respiration and cellular metabolism. 

residence time:   The average amount of time that a nutrient spends in a given source or pool. 

shifting baseline syndrome: When ecosystems that are degrading are viewed as 'pristine' by each human generation that is exposed to that ecosystem when they are young.

standing crop biomass:  The weight or mass of above-ground, dry plant material in a defined area at a given point in time.

trophic cascade: when indirect effects from species interactions originate from top predators and spread downward in a food web

vernal dam:  When the first plants to grow in the spring in a deciduous forest act to stop the loss of nutrients in the soil that are washing out from spring runoff and snowmelt. 

watershed: An area above one source of outflow for water draining out of that area.

weir: A structure in a stream at the base of a watershed where stream volume, outflow, and water chemistry can be measured.