Ecosystems, Sustainability and Global Change Study Notes

Current Fluxes (2006-2015):
  - Fossil fuels & industry: $34.1 ext{ Gt CO}_2/ ext{yr} ext{ (Carbon dioxide emitted from burning fossil fuels and related industrial processes)}$
  - Land-use change: $3.5 ext{ Gt CO}_2/ ext{yr} ext{ (Emissions resulting from deforestation, the conversion of forests to agriculture, and other land-use changes)}$
  - Atmospheric growth: $16.4 ext{ Gt CO}_2/ ext{yr} ext{ (Net increase of CO}_2 ext{ in the atmosphere)}$
  - Land sink: $11.5 ext{ Gt CO}_2/ ext{yr} ext{ (Carbon absorbed by terrestrial ecosystems, such as forests and soils)}$
  - Ocean sink: $9.7 ext{ Gt CO}_2/ ext{yr} ext{ (Carbon dioxide absorbed by the oceans)}$

Anthropogenic Trends (2020 projection):
  - Fossil fuel combustion source: $9.6 imes 10^{15} ext{ gCyr}^{-1} ext{ (Carbon emissions from fossil fuel use)}$
  - Deforestation/land use source: $1.3 imes 10^{15} ext{ gCyr}^{-1} ext{ (Carbon emissions due to deforestation)}$
  - Net balance (sources-uptake): $-3.1 imes 10^{15} ext{ gCyr}^{-1} ext{ (Net carbon uptake by ecosystems, indicating a sink despite significant emissions)}$

Photosynthetic Pathways and Adaptive Values:
  - C3 Photosynthesis:
    - Incorporates $CO_2$ into a 3-carbon compound, primarily using the enzyme RUBISCO (ribulose biphosphate carboxylase/oxygenase).
    - Most efficient under cool, moist conditions ( < 30^ ext{C}), as high temperatures can promote photorespiration, reducing efficiency.   - C4 Photosynthesis:     - Incorporates $CO_2$ into a 4-carbon compound via the enzyme PEP Carboxylase (phosphoenol pyruvate), allowing plants to thrive in high-temperature environments.     - Kranz Anatomy: Features specialized bundle sheath cells where Calvin cycle takes place, enhancing efficiency.     - Adaptive Value: Higher water-use efficiency and faster rates under high light/temperature ( > 30^ ext{C}) by minimizing photorespiration.
    - Disadvantage: More energetically costly due to additional ATP required to regenerate PEP.
  - CAM (Crassulacean Acid Metabolism):
    - Stomata open at night to store $CO_2$ as an acid, conserving water by closing during the day.
    - CAM-idling: In extreme aridity, plants may close stomata all day and night, relying on internal stores of oxygen from photosynthesis for respiration and vice versa.

Stomatal Density and Transpiration:
  - Stomatal Function: Essential for balancing $CO_2$ assimilation with water loss via evapotranspiration. Notably, 99 ext{%} of absorbed water is lost through transpiration.
  - Woodward (1987): Significant research indicating an inverse correlation between atmospheric $CO_2$ concentration and stomatal frequency, suggesting plants adjust stomatal opening to varying environmental CO_2 levels.
  - Historical Evidence: Comparisons of modern and fossil Ginkgo biloba demonstrate significant stomatal shifts corresponding to $CO_2$ levels from the Upper Triassic to the present. Changes in stomatal density provide insights into past climate conditions and plant responses to atmospheric changes.

Climate Change Impacts on Distributions and Biomes:
  - Biome Shifts: Changes in mean annual temperature and precipitation patterns driven by climate change can significantly alter biomes. Doubling atmospheric $CO_2$ levels are expected to shift Canadian ecozones (e.g., Tundra transforming into Boreal forest areas).
  - Cyclamen Case Study: Projections for 2050 suggest a total habitat loss of 53 ext{%} for various Cyclamen species (e.g., C. colchicum, C. creticum, C. cyprium), which may face 100 ext{%} range loss due to habitat incompatibility with shifting climates.
  - Direct Impacts: Changes in distributions, typically moving toward higher latitudes or altitudes, alongside phenological shifts such as earlier flowering, resulting from warming temperatures.
  - Indirect Impacts: Altered ecological interactions, including invasive species spreading into new regions, changes in fire frequency and intensity, and modified interactions between herbivores and pathogens with their hosts due to altered environments.

Biological Responses and Species Interactions:
  - Phenology Mismatches:
    - Visser and Hollemann (2001): Documented timing differences between the winter moth (Operophtera brumata) hatching and the synchronization with host plant bud burst, impacting their survival and reproductive success.
    - Butterfly species (e.g., Euchloe tagis) could lose suitable habitat if their migration routes don't coincide with host plants in shifting climates, leading to population declines.
  - Range Shifts:
    - Parmesan et al. (1999): Approximately 63 ext{%} of 35 studied non-migratory European butterflies have exhibited northward shifts in range as they respond to changing temperatures.
    - Significant range expansion of Thaumetopoea pityocampa (Pine Processionary) correlates with increased mean night temperatures, affecting forest ecosystems where they thrive.
  - Atmospheric Interactions: Moderate levels of $O_3$ (Ozone) can counteract some of the elevated $CO_2$ responses observed in various ecosystems, suggesting potential overestimations in carbon sequestration capabilities when only observing $CO_2$ levels.
  - Insect Development: Temperature remains the primary abiotic factor influencing development rates in invertebrates. Higher temperatures typically accelerate development and survival; however, populations may decline if critical temperature thresholds are surpassed, as observed in species such as Arctia caja.