plant ecology - chapter 18 biomes. terrestrial biomes defined by the physiognomy of the predominant...
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Plant Ecology - Chapter 18 Biomes Slide 2 Terrestrial biomes Defined by the physiognomy of the predominant vegetation Slide 3 Boundaries? No sharp boundaries between biomes Intergrades Slide 4 Importance of climate Prevailing climate is most important factor in determining what kind of biome will develop Precipitation, temperature are most important Slide 5 Desert biomes Forest biomes >30 inches (>76.2 cm) of rain per year Taiga or coniferous forest Temperate deciduous forest Tropical rain forest Slide 8 Climatograph Slide 9 Temperature, precipitation not sole determiners Overlap among different biomes on plot suggests that other factors also are important Seasonality of precipitation Temperature fluctuations around mean Soil composition (based on geology) Slide 10 Deserts Lands where evaporation exceeds rainfall High evaporation rate 7-50X precipitation Slide 11 Deserts Occur in 2 distinct belts between 15-35 N & S latitude Result primarily from worldwide circulation of air masses (dry over deserts) ~25% of worlds land mass Slide 12 Slide 13 True deserts Tropical rain forest >250 cm of rain per year Perpetual midsummer conditions Uninterrupted plant growth Types of tropical forests Slide 31 Tropical rain forests Contain as many species of plants and animals as all other types of ecosystems combined 4 mi 2 area - 750 species of trees, 1500 species of flowering plants Slide 32 Tropical rain forests Typically stratified into 5 layers Each layer has characteristic plants, animals May reach height of 80 m Slide 33 Tropical rain forest soil Very poor - little or no topsoil Easily weathered Subsoil with iron-based clay - laterite Major problems with slash-and-burn agriculture Slide 34 Tropical rain forests today Deforestation Slide 35 Loss of forests at present rate will mean disappearance within next 15-25 years Major problems will result from climate change, loss of species of medicinal, economic importance Slide 36 Temperate deciduous forest Eastern N. Amer, N. Europe and east Moderate temps., moderate moisture levels 5-6-month growing season Slide 37 Temperate deciduous forest Dominated by broad-leaved deciduous trees Relatively nutrient-rich soil provides for good growth Typically have 4 layers present Ground, shrub, sapling, canopy Rich diversity of plant, animal life Slide 38 Taiga Boreal forest, coniferous forest Harsh winters with lots of snow Slide 39 Taiga Dominated by conifers - spruce, pine, fir, hemlock Best suited for short growing season because they are not deciduous Can carry out photosynthesis whenever temps. rise above freezing Needle shape, waxy cuticle conserve moisture Slide 40 Thin, acidic, develop slowly Pine needles break down slowly in cool climate Taiga soils Slide 41 Taiga animals Primarily seed, insect eaters, or those that feed on plants in or near water Squirrels, birds, elk, moose, deer, beaver, porcupine, grizzlies, wolves