Biomes: Global Patterns of Life

1. Biomes: Global Patterns of Life

2. Outline • Terrestrial Biomes • Marine Ecosystems • Open Ocean • Shallow Coasts • Freshwater Ecosystems • Lakes • Wetlands • Human Disturbance

3. TERRESTRIAL BIOMES • Biomes - Areas sharing similar climate, topographic and soil conditions, and roughly comparable communities. • Temperature and precipitation are among the most important determinants in biome distribution. • Most terrestrial biomes are identified by the dominant plants of their communities.

4. Biomes

7. Tropical Moist Forests • Humid tropical regions support one of most complex and biologically rich biomes. • Ample rainfall and uniform temperatures. • Cloud Forests - High mountains where fog and mist keep vegetation continually wet.

8. Tropical Moist Forests • Tropical Rainforests - More than 200 cm annual rainfall with warm-hot temperatures year-round. • 90% nutrients tied up in living organisms. • Rapid decomposition and nutrient cycling. • Thin soil cannot support continued cropping, and cannot resist erosion.

9. Tropical Rainforests

10. Tropical Seasonal Forests • Semi-evergreen and partly deciduous forests tending toward open woodlands and grassy savannas. • Characterized by distinct wet and dry seasons with hot temperatures year-round

11. Tropical Savannas or Grasslands • Too little rainfall to support forests • Dry season prone to fire • Plants with deep, long-lived roots • Many migratory grazers

12. Tropical Savannas or Grasslands

13. Deserts • Characterized by low moisture levels and precipitation that is infrequent and unpredictable from year to year. • Wide daily and seasonal temperature fluctuations. • Soils are easily disturbed by human activities, and slow to recover. • Plants exhibit water conservation characteristics.

14. Deserts

15. Temperate Grasslands • Communities of grasses and seasonal herbaceous flowering plants (scattered trees in savannas.) • Few trees due to inadequate rainfall. • Large daily and seasonal temperature fluctuations. • Thick organic soils. • Historic grazing by roaming herds of large ungulates. • Much converted to farmland.

16. Grasslands

17. Mediterranean • Characterized by warm, dry summers and cool, moist winters. • Fires are a major factor in plant succession. • Referred to as chaparral in California. • Biodiversity hotspot. • Referred to as thorn scrub in Africa. • Landscape dominated by acacias and other spiny plants.

18. Broad-Leaved Deciduous Forest • Temperate regions support lush summer plant growth when water is plentiful. • Deciduous leaves an adaptation to freezing temperatures. • Eastern half of US was covered with broad leaf deciduous forest when European settlers arrived. Much of that was harvested a century ago for timber. • Now large areas have re-grown and are again approaching old-growth status.

19. Temperate Deciduous Forests

20. Temperate Conifer Forests • Cone-Bearing • Plants reduce water loss by evolving thin, needle-like evergreen leaves with thick waxy coating. • Can survive harsh winters or extended droughts and accomplish photosynthesis even under poor conditions. • Fire often plays role in maintenance.

21. Conifer Forests • Boreal Forest -Northern Conifer Forest • Broad band of mixed coniferous and deciduous trees between 45° and 60° N latitude. • Moist and cool climate with abundant streams and wetlands. • Taiga - Northernmost edge of boreal forest • Species-poor. Harsh climate limits productivity and resilience. • Produce large peat bogs.

22. Boreal Forest

23. Conifer Forests • Temperate Rainforest • Wettest portion of coniferous forests of Pacific Northwest. • Mild temperatures, and very abundant precipitation. (>250 cm) • Canopy condensation is major form of precipitation.

24. Temperate Rainforests

25. Tundra • Treeless • Very short growing season, with cold harsh winters. • Damage slow to heal. • Arctic Tundra exhibits low productivity, diversity and resilience. • Alpine Tundra receives intense solar radiation, hot daytime summer ground temperatures, and potential droughts.

26. Tundra

27. MARINE ECOSYSTEMS • Saltwater ecosystems cover vastly more total area and contain much greater volume of water than all freshwater bodies combined. • Oceans hold bulk of world’s water. • Aquatic ecosystems are influenced by local characteristics of climate, soil, and resident communities, and also by adjacent terrestrial ecosystems.

28. Critical Characteristics • Dissolved Substances • Suspended Matter • Depth • Temperature • Flow Rate • Bottom Characteristics • Internal Convective Currents • Connectivity to Other Aquatic Ecosystems

29. Marine Ecosystems • Vertical stratification is an important aspect of many aquatic ecosystems. • Organisms tend to form distinctive vertical sub-communities. • Benthic - Bottom sub-community. • Low oxygen levels. • Pelagic - Water column

30. Light Penetration

31. Shallow Coasts • Coral Reefs - Accumulated calcareous skeletons of colonial organisms (coral). • Depth limited by light penetration. • Among most endangered communities. • Mangrove trees grow in salt water. • Occur along calm, shallow, tropical coastlines.

32. Tidal Environments • Estuaries - Bays or semi-enclosed bodies of brackish water that form where rivers enter the ocean. • Usually carry rich sediments. • Fan-shaped sediment deposit (delta) formed on shallow continental shelves.

33. Barrier Islands • Barrier Islands - Low, narrow, sandy islands that form offshore from a coastline. • Protect inland shores from surf. • Prized for human development. • Loss of vegetation triggers erosion.

34. FRESHWATER ECOSYSTEMS • Lakes • Freshwater lakes have distinct vertical zones. • Epilimnion • Hypolimnion • Benthos • Thermocline - Distinctive temperature transition zone that separates warm upper layer and deeper cold layer.

36. Wetlands • Land surface is saturated or covered with water at least part of the year. • Swamps - Wetlands with trees. • Marshes - Wetlands without trees. • Bogs and Fens - Waterlogged soils that tend to accumulate peat. • Water usually shallow enough to allow full sunlight penetration. • Trap and filter water, and store runoff.

37. Wetlands

38. HUMAN DISTURBANCE • By some estimates, humans preempt about 40% of net terrestrial primary productivity. • Temperate broad-leaved deciduous forests are the most completely human-dominated biome. Tundra and Arctic Deserts are the least disturbed. • About half of all original wetlands in the US have been degraded over the past 250 years.

39. Human Disturbance

40. Summary • Terrestrial Biomes • Marine Ecosystems • Open Ocean • Shallow Coasts • Freshwater Ecosystems • Lakes • Wetlands • Human Disturbance