Essentials of Ecology

SUPPLEMENT 9 S55

Producer

to primary

consumer

Primary

to secondary

consumer

Secondary to

higher-level

consumer

All producers and

consumers to

decomposers

Moss campionMoss campion

MountainMountain

cranberrycranberry

LemmingLemming

DwarfDwarf

willowwillow

Willow ptarmiganWillow ptarmigan

Horned larkHorned lark

MosquitoMosquito

Grizzly bearGrizzly bear

Snowy owlSnowy owl

Long-tailed jaegerLong-tailed jaeger

CaribouCaribou

ArcticArctic

foxfox

Moss campion

BacteriaBacteria

FungiFungi

Bacteria

Fungi

Mountain

cranberry

Lemming

Dwarf

willow

Willow ptarmigan

Horned lark

Mosquito

Grizzly bear

Snowy owl

Long-tailed jaeger

Caribou

Arctic

fox

Figure 3 Some components and interactions in

an arctic tundra (cold grassland) ecosystem. When

these organisms die, decomposers break down their

organic matter into minerals that plants use. Col-

ored arrows indicate transfers of matter and energy

among producers, primary consumers (herbivores),

secondary or higher-level consumers (carnivores),

and decomposers. Organisms are not drawn to

scale. Question: What species might increase and

what species might decrease in population size if the

arctic fox were eliminated from this ecosystem?