Chap 24B - Climate Change II

Describe effect of climate change on Organisms

• Temperatures rising beyond tolerance range causes physiological stress -> reduced growth, impaired reproduction and increased mortality

• Migration is not always possible due to geographical barriers, habitat fragmentation or limited dispersal ability

• Extreme weather events can cause sudden population declines by destroying shelter, food sources and breeding grounds

Define phenology

(Def.): timing of seasonal biological events such as flowering, migration, nesting and breeding

Describe effect of climate change on phenology

• Include easily observed events like leaf emergence and flowering 

• Species rely on environmental cues like temperature and rainfall to regulate their life cycles

• Climate change disrupts cues -> shifts in seasonal timing

• Different species respond to climate change at different rates -> mismatches between species that depend on one another -> reduce reproductive success and survival -> affect population stability

Describe impact of climate change on physiology

1. High temperature stress 

• (Def.): Rise in temperature beyond a critical threshold for a period of time sufficient to cause irreversible damage to plant growth and development

2. Low temperature stress 

• Chilling stress results from temperatures cool enough to produce injury without forming ice crystals in plant tissues.

• Freezing stress results in ice formation within plant tissues

• Tropical and subtropical plants sensitive to chilling stress as they lack cold acclimation mechanisms

3. Water stress 

• Caused by transpiration rate too intense, drought 

• 'Physiological drought': Water exists in soil solution but plants cannot take it up

• Drought/water stress lowers plant water potential and turgor to the extent that plants face difficulties in executing normal physiological functions

  • Reduced plant-cell's water potential and turgor -> increase solutes' concentrations in the cytosol and extracellular matrices

  • Alteration in plant cell wall elasticity, disruption of homeostasis and ion distribution in the cell.

  • Negative effects on mineral nutrition (uptake and transport of nutrients) and metabolism

• Cell enlargement decreases -> growth inhibition -> decrease in the leaf area -> reproductive failure

Describe impact of climate change on food chains

• Food chains and webs depend on stable interactions between producers, consumers and decomposers

• When species alter their life cycles due to climate change:

  • Some animals may lay eggs, migrate or emerge from hibernation earlier.

  • Plants or insects as food not available -> and lowers survival rates

• Species that store food for winter may experience spoilage due to warmer winter temperatures -> reduce food availability during periods of scarcity

• Extinction or migration of species from an ecosystem disrupts established food webs + increase competition

Describe effect of drought on habitats

1. Effect of drought 

• Dry up wetlands,

• Reduce freshwater availability

• Kill vegetation that provides food and shelter

Describe Effect of flooding and storms on habitats

2. Effect of flooding and storms 

• Soil erosion

• Sedimentation in rivers

• Reduction in water quality

• Destruction of aquatic habitats

Describe Effect of Rising Sea Level and Ocean Warming on habitats

3. Effect of Rising Sea Level and Ocean Warming

• Affect mangroves and corals 

• Reef collapse causes significant biodiversity loss

• Loss or degradation of habitats reduces carrying capacity (less organisms supported within ecosystem)

Define niche occupation + effect of climate change on it

• (Def.): role an organism plays in its ecosystem, including its habitat, food source, and interactions with other species

• Climate change causes species to migrate or if they cannot adapt/migrate, they go extinct