TAIGAUNIT 4.4: BIOMES AND THEIR DISTRIBUTION

TAIGA• CONIFEROUS OR BOREAL FORESTS OCCUR IN COLD NORTHERN REGIONS

CHARACTERIZED BY LONG COLD WINTERS AND SHORT SUMMERS. ALTHOUGH THERE IS A LOT OF PRECIPITATION, MOST OF IT FALLS AS SNOW.• THIS BIOME IS FOUND BETWEEN 50° AND 60° NORTH OF THE EQUATOR AND

IS CHARACTERIZED BY EVERGREEN CONIFEROUS TREES WITH NEEDLES INSTEAD OF LEAVES. IT IS ALSO KNOWN AS TAIGA.

LOCATION

CLIMATE• AT THE MOST NORTHERN EXTENT, SUMMER TEMPERATURES RARELY RISE

ABOVE 10°C. AS YOU MOVE FURTHER NORTH, TREES ARE SHORTER AND LESS DENSE BECAUSE OF THE SHORTER GROWING SEASON. WINTER TEMPERATURES CAN FALL AS LOW AS MINUS 30°C. AT ITS SOUTHERN MARGINS, THE TREES BECOME TALLER AND DENSER AND MERGE WITH DECIDUOUS TREES (THOSE THAT LOSE THEIR LEAVES). TEMPERATURES HERE CAN RISE AS HIGH AS 20°C IN THE SUMMER AND CAN FALL TO MINUS 15°C IN WINTER. PRECIPITATION IS 300–900 MM, AND MOST FALLS AS SNOW IN WINTER.

CLIMOGRAPH

VEGETATION- CHARACTERISTICS• CONIFEROUS TREES HAVE THICK BARK TO PROTECT AGAINST THE COLD.

THEY ARE CONE-SHAPED, WITH FLEXIBLE BRANCHES WHICH HELP THEM TO COPE WITH HEAVY SNOW FALL.• PINE CONES PROTECT THE SEEDS DURING THE HARSH WINTER.• THE THIN WAXY NEEDLES REDUCE WATER LOSS.• THEIR EVERGREEN NATURE MEANS THAT THE NEEDLES CAN

PHOTOSYNTHESIZE WHENEVER THERE IS SUFFICIENT SUNLIGHT.• THE DENSE FOREST CREATES WARMTH DURING THE HARSH WINTER.

CONIFEROUS SPECIES

WINTERS

SUMMERS

TAIGA SOIL• SOILS ARE SHALLOW DUE TO LACK OF DECOMPOSITION AND WEATHERING CAUSED BY

THE COLD. THEY ARE ACIDIC DUE TO LEACHING FROM RAINFALL AND THEY ARE ALSO POOR IN NUTRIENTS.• THE LITTER LAYER IS THICK WITH NEEDLES DUE TO SLOW DECOMPOSITION.• THE HUMUS (DECOMPOSED) LAYER IS THIN.• THERE ARE CLEAR BOUNDARIES BETWEEN THE LAYERS IN THE SOIL AS THERE ARE FEW

WORMS TO MIX IT IN THE COLD CONDITIONS.• TREES HAVE SHALLOW ROOTS.• THE TYPICAL SOIL IS A PODSOL, WHICH HAS A DISTINCTIVE ASH GREY LAYER (OR

HORIZON) ABOVE A RED LAYER, WHICH IS RICH IN IRON.

REFERENCES• ENVIRONMENTAL MANAGEMENT BY JOHN PALLISTER• ENVIRONMENTAL SCIENCE BY KAREN ARMS• BBC.CO.UK• PICTORIAL AIDS: FROM GOOGLE IMAGES

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