2.2 Ecosystem Services

• human activity leads to disruptions of natural processes, having economic and ecological consequences

• environmental worldviews: anthropocentric or ecocentric (balance is biocentric)

• sustainable development: using resources in a way that fulfills human needs but does not deplete their quantity for future generations (profitable)

Types of Ecosystem Services

• Provisional: resources directly derived from sources in nature

  • most basic of all ecosystem services

    • ex. water, food, plants, fuels, timber, herbal medicine

• Regulating: processes that maintain natural phenomena to be clean, functional, and resilient

  • essential for human survival; costly to replace

    • ex. air/soil quality, pollination, water flow, carbon sequestration

• Cultural: abstract concepts/ideas that contribute to the cultural/theoretical development of human society

  • not a necessity for basic human survival

    • ex. knowledge, sports, sense of place, aesthetics, art

• Supporting: basic natural processes that sustain life on Earth

  • the foundation of all other processes

    • ex. photosynthesis, water cycle, nutrient cycle

Human Impact on Biodiversity

• burning fossil fuels → acid deposition = pH/climate disruption

• deforestation → habitat/species loss

• industrial agriculture → monocropping

• overfishing & pesticide use → species loss

• genetically modified crops → loss of genetic variation

• water pollution → loss of aquatic habitat diversity

2.3 Island Biogeography

• study of ecological relationships and distributions of organisms on islands + their community structure

  • created by Caral Linnaeus (1707 - 1778) Charles Darwin (1809 - 1822), Alfred Russel Wallace (1823 - 1913)

• species richness: # of species in an area

• species evenness: comparison of pop. of species

• Robert McArthur & EO Wilson (1967)

  • Highest species richness: large islands near the mainland

  • lowest species richness: small islands far from the mainland

Habitat Fragmentation

• physical and geographical disruption of various environments caused by human activity

  • → loss of apex predators (ie. wolves, bears, etc.) and more specialist feeders

  • → increase in # of organisms of generalist feeder species (can easily adapt to changes in food sources and other resources)

  • limits migration for isolated species in different biomes

  • human activity (agriculture and societal development) → increase in habitat fragmentation → separation of species

• solution: habitat corridors (connecting fragmented habitats through animal-friendly tunnels or bridges = easier migration & greater diversity)

2.4 Ecological Tolerance

• range of abiotic conditions (temperature, sunlight, salinity, etc.) that an organism can endure

  • measured on a bell curve

  • > range (below avg range of ecological tolerance) = reduced fitness; inability to thrive/reproduce

2.5 Natural Disruptions to Ecosystems

• ecological impact of natural disruptions >= ecological impact of human disruptions

• natural processes: quick vs short-term

  • periodic: one event → long-term effect/event

  • episodic: sudden event → greater effects/events over time

  • random: sudden, w/o leading cause

Climate Change

• has changed over time thru geological shifts, including:

  • amount of solar radiation reaching the Earth

  • changes in atmospheric composition (ie. greenhouse gases, ozone layer depletion)

  • rising sea levels due to melting glacial ice

Migration

• seasonal movement of animals from one habitat → another habitat

  • adaptative response for better opportunities for resources and mating

  • varies greatly by the organism

    • ex. birds migrate from the Northern Hemisphere → Southern Hemisphere annually

2.6 Adaptations

• organisms adapt to their environment over time (short & long-term scales) through incremental genetic changes, leading to:

  • physical changes in appearance

    • ex. peppered moths (lighter body tones → darker body tones)

  • biochemical changes

    • ex. pesticide resistance (mutations in the genes of pests cause pesticides to become ineffective), natural selection

• adaptations persist in an organism species if it is advantageous to their survival in the environment → reproduction to pass similar genes to offspring

• gene must be present BEFORE the environmental change

Natural Selection

• sudden or gradual environmental changes → endangering lives of different species in habitat:

  • changes in behavior (adaptation)

  • migration

  • extinction

    • ex. climate change → extinction of dinosaurs, deforestation → dislocation of species

• organisms with a selective advantage will be better at adapting and surviving in a new environment

2.7 Ecological Succession

• a gradual process where community structure changes (typically replacement of community)

  • affects the total biomass, species richness, and net productivity

    • ex. changes in predominant plant community → habitat/wildlife change

  • biomass: larger plant species have more biomass than smaller plant species (material & weight)

  • richness: greater in previously distributed species; less in recently distributed species

  • productivity: more biomass → higher rates of photosynthesis (a measure of productivity)

• primary succession: a new area is dominated by pioneer species (lichens)

  • rock → soil formation & initiating plant growth

  • caused by human or natural disruptions

  • primary succession + adaptation over time = origin of new species

• pioneer species: broad range of ecological tolerance to survive ecological disturbances

  • adaptable; can quickly pass on genetic traits; supports the emergence of new species

• secondary succession: new species take over old land (still filled with soil)

  • also caused by human or natural disruptions

• keystone species: plays a significant role in determining community structure

  • ex. otter, sea urchin, kelp

• ecosystem engineers: organisms that alter habitat beneficially

  • ex. beavers

• mutualists: two organisms interact for mutual benefit

• indicator species: represents aspect or quality of an ecosystem is present

  • has a narrow range of ecological tolerance

    • ex. amphibians