Biomes in Ecology: Boreal Forests, Tundra, Tropical Rain Forests, and Tropical Savannas, Slides of Ecology and Environment

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Lecture 5: Biome Concept in Ecology

5. 5 Boreal and polar climate zones have

average temperatures below 5 oC

Boreal forest biome (Climate zone VIII)

Tundra biome (Climate zone IX)

Arctic Tundra

Tundra is treeless plain

Arctic tundra is a frozen plain, clothed in sedges, heaths, and willows, dotted

with lakes, and crossed by streams

Cold Temperature and low precipitation

Two types:

tundra: up to 100% plant coverage, wet to moist soil

polar desert: dry soil, less than 5% plant cover

Unique conditions:

permafrost: isolate and protect soil OM

vegetation: simple form, slow growth, allocate more to roots.

5. 6 Climate zones with tropical latitudes have

average temperatures exceeding 20 oC

Tropical rain forest biomes (Climate zone I)

Tropical seasonal forest/savanna biome

(Climate zone II)

Tropic rain forests in Amazon (a), Malaysia (b), and Northeast Australia (c)

High net primary productivity (NPP)

High diversity of plant and animal life

7% land surface, >50% plant and animal species

10-km2 contain 1500 species of flowing plants and 750 tree species.

Richest area in Malaysia, 7900 species

90% of all primate species live in the tropical rain forest

orangutan (an arboreal ape)

Gibbons, langurs, macaques

(Malaysian)

Gorillas, and chimpanzees

(Africa)

Lemurs

Beetles, butterflies

Tropical Savannas

Savanna: means the treeless areas of South America

Grassland with scattered trees.

Characteristics

Occur on land surfaces of little relief, often on old plateaus, dissected by

rivers

Poor in nutrients, especially P

Dominant species are fire-adapted, subjected to recurrent fires.

Grass cover with or without wood vegetation is always present

Woody component is short-lived (less than a few decades).

Two-layer vertical structure (ground level grass + shrubs or trees)

Support a large and varies assemblage of herbivores, invertebrate and

vertebrate, grazing and browsing.