Lecture 6: Biosphere

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Lecture 6 Biosphere

• Overview and Definitions
• Life Processes
• Ecosystems
• Biosphere - climate connection

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Definitions

• Life -
• Self-replicating matter that exchanges energy and
  matter with its environment
• Biota - Everything thats alive
• Biosphere
• Earths organic material, living or dead
• Ecosphere - biosphere surroundings
• Species -
• Set of organisms that can reproduce

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Classification of Life

• Several schemes based on relationships between
  organisms
• Evolutionary
• Genetic
• Ecological
• Taxonomic categories
• Kingdom, phylum, , genus, species
• Based on degree of shared characteristics
• No info about numbers-behavior-process
• Ecological considerations are arguably the most
  relevant to climate and environmental change

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Numbers of Living Things

• 1.5 million species? 14 million?
• Many species yet to be found
• 10 to 100 million possible?
• Distribution
• Insects half
• Higher plants sixth (flowering plants rule)
• Other animals sixth (invertebrates rule)

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Life Processes

• Reproduction
• Passes on information (implicitly, information
  about environment)
• Photosynthesis
• fixes carbon, makes carbohydrates using water,
  CO2, solar energy (other elements)
• Respiration
• Burns carbohydrates using oxygen
• Behavior, Evolution

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Photosynthesis
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Lifes Timescales

• Cell
• Less than second to minutes or more
• Organisms
• Minutes to hundreds of years
• Populations, ecosystems
• Seasonal and decadal, to millennial
• Species
• Millennial to millions of years

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Ecosystems Definitions, 1

• Ecology - study of how life and its environment
  interact
• Population - all members of the same species
  living in the same area at the same time
• Community - all organisms that live and interact
  in the same area
• Ecosystem - a biological community and its
  surroundings

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Ecosystems Definitions, 2

• Biome - broad regional types of ecosystems, in
  which physical conditions and biological
  interactions are similar but species are
  different (e.g., deserts)
• (Net) primary productivity - (net) change per
  unit time in the biomass at the lowest level in
  food chain (or web). Plants are the primary
  producers

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Ecosystems Concepts

• Dynamics
• Energy and nutrient flow
• Organization
• Trophic level, food chains and webs
• Biomass varies with level (more low)
• Major biomes largely reflect climate

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Biomes and Climate
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Primary Production

• Gross versus net primary productivity (NPP)
• Gross everything produced (by plants)
• Net whats left for consumers after respiration
  by primary producers
• Fundamental to life!
• Magnitudes of NPP
• As energy 300 x 1019 joules/year
• As power 1011 kW (equivalent to 10x energy
  consumption in developed countries)
• As matter (C) 6 x 1010 metric tons/year

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Earth and Environmental Processes Mediated by Life

• Atmospheric Composition Climate
• O2, CO2
• DMS (dimethyl sulfide) and clouds
• Hydrological cycle
• Evapotranspiration in rainforests
• Primary production
• Carbon cycle in general

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Carbon Cycle Main Reservoirs
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Carbon Cycle Main Fluxes
Just guess which reservoir were messing with
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Atmosphere-Biosphere Linkages
CO2
CH4
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Vegetation-Albedo Feedback
positive or negative?
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Vegetation-Precipitation Feedback
positive or negative?