Tundra Study Notes

Tundra Overview

• Definition: Biome characterized by bare ground, absence of trees, and growth of mosses, lichens, sedges, and low shrubs.

Types of Tundra

• Arctic Tundra: Circumpolar region, low elevation.

• Alpine Tundra: High mountain region, higher elevation.

Environmental Characteristics

• Cold, moist conditions with low precipitation.

• Short growing season (50-160 days depending on type).

• High P/E ratio (>1) with limited soil nutrients due to slow decomposition.

Permafrost

• Definition: Perennially frozen subsurface.

• Impedes drainage, root growth, and decomposer activity.

• Thaw depth ranges from a few centimeters to half a meter.

Tundra Structure

• Vegetation: Dominated by few long-lived species (20-100 years), mostly under 10 cm tall.

• Patchy vegetation patterns due to microrelief and environmental conditions.

• Includes types such as cottongrass, dwarf willows, heaths, and mosses.

Arctic vs. Alpine Tundra Differences

• Area Covered: Extensive (Arctic) vs. Small patches (Alpine).

• Precipitation: 100-500 mm (Arctic) vs. 1000-2000 mm (Alpine).

• Adaptation and growth: Vegetative (Arctic) vs. Seed-based (Alpine); length of growing season varies significantly.

Biogeochemical Factors

• Temperature Stress: Cold climate affects metabolic processes; adaptations include antifreeze proteins.

• UV Radiation: High at altitude; adaptations include thick cuticles and UV-absorbing pigments.

• Nutrient Stress: Limited nitrogen and phosphorus; adaptations include symbiosis with mycorrhizal fungi.

Ecosystem Functionality

• Primary production is low, influenced by short growing season.

• Belowground biomass typically exceeds aboveground.

• Production primarily supports the detrital food chain involving bacteria and fungi.

Human Impacts

• Arctic: Oil exploitation and pollution; Indigenous communities affected.

• Alpine: Overgrazing by livestock; recreational activities leading to ecological changes.