Terrestrial Ecosystems and Their Relationship to Cultivating Plants

What is an ecosystem?

A community of organisms in a physical environment

What are 3 characteristics of an ecosystem?

Populations of species (plants, animals, fungi, bacteria), depends on carbon fixation from photosynthesis, and all molecules are recycled

What type of organisms are the base of all terrestrial ecosystems?

Plants

Why are plants the base of all terrestrial ecosystems?

Plants capture energy (photosynthesis), store it in carbon based organic materials (biomass)

Natural ecosystems operate with inputs of….

Carbon, energy, + water

In natural ecosystems, organisms are in a…

Stable balance

Symbiosis

Beneficial relationship between 2 organisms

2 examples of symbiosis

1. Mycorrhiza roots

2. Rhizobium bacteria

What happens to energy from the sun that plants harvest?

It is converted to carbon-based molecules through photosynthesis including carbs, amino acids, + lipids

What do herbivores feed on?

Plants

What do predators rely on?

Herbivores for protein, lipids, etc

Where do parasites live?

Live in, or on, other organisms

What are 4 examples of parasites?

1. Bacteria

2. Fungi

3. Viruses

4. Some plants

What do parasites rely on other organisms for?

Essential amino acids, lipids, carbs, + even reproduction

Example of a parasitic plant

Miseltoe

What are some parasites useful as?

Biological control agents for plant pests

Saprophytes

Microorganisms that digest dead plants and animals

Detritivores

Breakdown large pieces of organic matter

Example of a detritivore

Earthworms

3 weaknesses of agricultural ecosystems

1. Too short term to develop stable relationships

2. Crops + animals may not be suited to biome

3. External inputs required to sustain crops

Crop ecosystem

Single species of crop interacting w/ many other organisms (weeds, animals, fungi, bacteria)

Microflora + microfauna are…

Very small organisms

2 ways to make ag ecosystems for sustainable

1. Reduce inputs

2. Maximize natural ecosystem processes

Ecosystem competition occurs when…

Resources are in short supply

Niche

The place an organism has in the ecosystem

A species is less likely to outcompete another species if…

They occupy different niches

In natural ecosystems, most niches are…

Filled

Crop ecosystems have several empty…

Niches

What can fill empty niches in crop ecosystems?

Weeds

Biome

A collection of ecosystems w/ similar climate, soil + plant composition

What enviro factors most impact a biome?

1. Soil

2. Climate

3. Temperature

4. Precipitation

Temperature decreases with an increase in…

Latitude

Seasonal variation increases with an increase in…

Latitude

Avg annual temp decreases w/ increasing…

Elevation

Moisture @ equator

Tropical rainforests

Moisture at 30* north and south

Deserts

Moisture between 40* + 50*

More rainfall, temperate forests

Moisture @ 60* north and south

Boreal coniferous forests

Moisture @ greater than 60* north and south

Tundra

6 biomes

1. Tropical rainforest

2. Deserts

3. Savannahs + grasslands

4. Temperate deciduous forests

5. Boreal coniferous forests

6. Tundra

Carbon dioxide concentration

Ecosystems influence atmospheric CO2 concentration

Human impact on the enviro is evaluated by measuring…

1. Energy requirements

2. Land use

Human footprint

1. Amount of space required to produce what we use

2. Amount of space required to absorb waste that we produce

Tropical rainforest

High ag potential initially for a few years but declines rapidly as nutrients are depleted

Desert

Low potential for ag: will require irrigation + management to reduce salt accumulation

Savannah + grasslands

High if soil is healthy + has sample nutrients

Temperate deciduous forest

High ag potential initially; will require management of nutrient to sustain crop production

Boreal coniferous forest

Low ag potential for large scale production; can be suitable for small operations

Tundra

Very low ag potential; temps are too cold + seasons too short for most crops

Evolution of a biome

Pioneer plants + natural events + niches develop + human activity

Climax community

Last + most stable group of plants

Lake + rock + bare ground lead to…

Pioneer plants