Biology - Environment

Return to: Biology of Horticulture

Environment - Ecosystems

Do the terms population, community, ecosystem, and biome only apply to "natural" areas or do they apply in agri / horticulture?

All except biome certainly apply to "natural" and artificial situations.

What are two examples of mutualism between lower organisms and angiosperms?

N-fixing bacteria
mycorrhizae

For what environmental resources do plants compete?

firstly light, then water and nutrients

What is allelopathy?

production of chemicals by one plant to inhibit growth of other plants

How do plants cope with attacks by herbivores and pathogens?

mechanical defenses: spines, hairs, stickiness, toughness

chemical defenses: phytoalexins, digestive inhibitors, bitter compounds defenses

How do natural and artificial ecosystems often differ in terms of cycling?

natural systems are conservative with little input or output and most nutrients "tied up"

artificial require more input (fertilizers) and output (crops and crop residues); losses result through leaching and run-off

What are the two main types of organism in food chains and which type do most plants represent?

producers: (plants in terrestrial ecosystems)
consumers (the rest of us)

Why are large, fierce animals rare?

They are secondary or tertiary consumers and at this level little of the primary productivity is left .

What is our position in the food chain and what are the implications for world food supply?

In the West, we are secondary consumers. Tthe carrying capacity of the earth does not permit everyone to live this way

What kinds of events occur to initiate a succession?

emergence of new land surface

clearance of existing land (glaciation, flood, fire, storm, earthquake, agriculture)

What kinds of plants are "pioneers"?

In primary succession special plants:

rock surface - lichens

shallow lake - submerged, aquatic plants

other situations - weeds

What do we mean by a "climax community" - how stable is it?

The community of organisms that tends to develop in a particular physical environment; aging, storms, accidents and long-term climate cause changes.

What are some arguments for and against allowing fires to take their course in natural systems?

it is part of the natural cycle in many ecosystems
people often don't like it.

Return to: Biology of Horticulture

	Do the terms population, community, ecosystem, and biome only apply to "natural" areas or do they apply in agri / horticulture?
	All except biome certainly apply to "natural" and artificial situations.

	For what environmental resources do plants compete?
	firstly light, then water and nutrients

	What is allelopathy?
	production of chemicals by one plant to inhibit growth of other plants

	How do plants cope with attacks by herbivores and pathogens?
	mechanical defenses: spines, hairs, stickiness, toughness chemical defenses: phytoalexins, digestive inhibitors, bitter compounds defenses

	How do natural and artificial ecosystems often differ in terms of cycling?
	natural systems are conservative with little input or output and most nutrients "tied up" artificial require more input (fertilizers) and output (crops and crop residues); losses result through leaching and run-off

	Why are large, fierce animals rare?
	They are secondary or tertiary consumers and at this level little of the primary productivity is left .

	What is our position in the food chain and what are the implications for world food supply?
	In the West, we are secondary consumers. Tthe carrying capacity of the earth does not permit everyone to live this way

	What kinds of events occur to initiate a succession?
	emergence of new land surface clearance of existing land (glaciation, flood, fire, storm, earthquake, agriculture)

	What do we mean by a "climax community" - how stable is it?
	The community of organisms that tends to develop in a particular physical environment; aging, storms, accidents and long-term climate cause changes.