Productivity

he measure of energy created into biological substance in any living system is measured as primary productivity.

Productivity

ingredients	process			outcomes
Input	+	Output	=	productivity	+	by-products
Through put			equals	products	and	wastes
Sunlight & Water	plus	carbon dioxide & trace elements	yields	glucose	plus	oxygen

The flow of energy in nature

Ian Tattersal on hominid descent
Ernst Mayr on Evolution
atmospheric carbon accumulation
biological diversity and climate change
Richard Lewontin
James Watson
E. O. Wilson
Human genetics

All living systems are productive organisms or collections of organisms that generate waste.

Four principles of waste in any system

Waste by-products are a sign of life, actually.
One person's or creature's waste may be another person's or organism's treasure.
Without a consistent recycling of waste material, no ecosystem could continue to function.
Whenever a bottleneck or pile up of waste occurs, most systems cease to function effectively.

The dung beatle of Africa, which the ancient Egyptians took as their image for making ornamental scarabs, represents an animal that uses the feces of elephants or other large animals to survive. Animals that fed off of waste material or detritus, are called detritvores. They, like fungi are decomposers who break-down complex products or by-products of other creatures and these decomposers are called saprotrophs.

Lichens are even more instructive of the second priciple above, because they are a composite creature. By a composite, we mean an organism composed of two different creatures, living together. In biology living together is calle symbiosis. Symbiotic lichens are made of creatures that live effectively, efficiently, and successfully utilizing each other's byproducts.

One

The algae, green photosynthetic creature makes food.

Two

The fungi, a form of life that lives by breaking down complex molecules into simpler compounds for other creatures, usually bacteria and plants to utilize in their metabolism.

The fungus is a saprotroph and the algae is a producer and they live together well in the body of the lichens. Lichens are found all over the world and the predominate in the tops of mountains and the polar or frigid zones where they comprise a large portion of the tundra biome. They are a perfect example of how one creatures waste is another organism's food.

All ecological systems need producers, consumers and decomposers. That means that detritovores or saprotrophs are just as necessary as any other component in an ecological system in order to keep sufficient material recycling. This reuse of materials is necessary to feed all of the participants in the ecosystem.

Participants in an ecosystem either, make their own food -- called producers, or eat others --called consumers, or breakdown the byproducts of others -- called decomposers.

level	name	function	economic role
1	autotroph	create its own food	producer
2	heterotroph	digest other creatures	consumer
3	saprotroph	break down complex matter	decomposer

Waste is a measure of productivity, just as inefficiency in production can be estimated through measuring waste.

Net versus gross primary productivity is fundamental in ecology.

Ecological Productivity

	Radiant energy is available sunlight	An explanation
add	gross primary productivity	energy obtained by producer
minus	respiration	energy used by producer
equals	net primary productivity	energy left for consumers

Productivity of different plant associations or biocenose:

Ecosystem type	maximum net primary productivity (gr/m 2/yr)
Tropical rainforest	3,500
Temperate forest	2,500
savannah	2,000
temperate grassland	1,500
desert	250
estuaries	3,500
reef	4,000
swamp & marsh	3,500

Begon, Harper, & Townsend, Ecology, 2d ed., (Cambridge, Ma.: Blackwell Scientific, 1990).

Graph of different plant communities -- called biomes -- with respect to theirrelative productive capacities.

Productivity, trophic levels and available energy

Energy defined

Productivity changes with altered circumstances.


The affect of water on productivity	The influence of heat on productivity

Law of the minimum or limiting factors

So under the above circumstances certain trace elements act as limiting factors in that the nutrients needed in the least amount may pose a confining condition on plant growth causing yields to decline when the following nutrients are unavailable in sufficient quantity and in the appropriate ion quality:

calcium
phosphorus
nitrogen
magnesium
potassium
sodium
selenium
zinc

Too little or too much of theses trace elements have a marked negative influence on plant growth when sufficient carbon dioxide or water availability fluctuates.

Just the correct amount of nutrient to stimulate growth is known as the law of the optimum.

Summary

Some kinds of “alleged waste” may have positive, neutral, or negative affects on productivity in ecological systems.

None is not nearly enough to nourish plants.
A little waste is ok to nourish plants.
A lot is too much and stresses plants.

In order to economic returns the ecological productivity of water, nutrients and plant growth must create surpluses.

principles | partnerships | participants | ecosystems | comparative biomes | graph | conditions | summaation