Lecture 2 – Sept 15th – the biosphere.docx

Lecture 2 – Sept 15th – the biosphere.docx - Lecture 2...

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Lecture 2 – Sept 15 th – the biosphere Parnika Sharma Biosphere : zone of life on Earth. Biomes : large-scale biological communities shaped by the physical environment, particularly climate. categorized by dominant plant forms, not taxonomic relationships. Convergence : Evolution of similar growth forms among distantly related species in response to similar selection pressures. Similar growth forms can be found on different continents, even though the plants are not genetically related. dry/warm = desert, wet/warm = tropical = ends limitation of figure - doesn’t account for seasonality Plants occupy sites for a long time and are good indicators of the physical environment, reflecting climatic conditions and disturbances. Terrestrial biomes are characterized by growth forms of the dominant plants, such as leaf deciduousness or succulence . = adaptations to specific environments evergreen - small herbaceous, not grasses, not woody shrub – tough, leathery leaves Stress Effects + Interactions Temperature directly affects physiological effects on plant growth form Precipitation and temperature act together to influence water availability and water loss by plants. Water availability and soil temperature determine the supply of nutrients in the soil. Human Activities Land use change: Conversion of land to agriculture, logging, resource extraction, urban development. The potential and actual distributions of biomes are markedly different.
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Climate diagrams show the characteristic seasonal patterns of temperature and precipitation at a representative location. blue = temp below freezing = frost stress yellow = water retention (dry szn) *be able to tell biome by graph^^ Tropical Rainforests disappearing bc logging/conversion to pasture and croplands (originally nutrient poor) fish bone pattern shows tropical rainforest loss over time (logging trails) Approx. ½ tropical rainforest biome has been altered.
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