Climates and Nutrient Cycles

Energy and Nutrients

• Energy from the Sun   - Feeds the ecosystem through plants and other photosynthetic organisms.   - Energy flows through food chains as a one-way trip where it dissipates due to:     - Metabolic heat loss     - Waste     - Growth.   - Additionally, solar energy powers weather, climate, and nutrient cycles.

Weather vs. Climate

Weather

• Defined as what is happening outside at any given time, including:   - Precipitation (e.g., rain, snow)   - Cloud cover   - Temperature

Climate

• Refers to the weather conditions in a particular region over extended periods.   - Influenced by:     - Temperature and precipitation patterns.     - Variations in solar radiation due to Earth's axial tilt during its orbit around the sun.     - Topography and proximity to water bodies.

Effects of Solar Radiation

• Solar radiation distribution is uneven:   - Direct rays at the equator vs. spread-out rays near the poles.   - Tropical regions are warmer than temperate regions due to higher solar intensity.   - Differences in air temperature and pressure result in varying precipitation and wind patterns.

Effect of Precipitation

• There are significant differences in temperature and precipitation from the equator to the poles.   - Influenced by wind patterns.   - Climate zones arise at different latitudes:     - At the equator, intense sunlight causes high evaporation.     - Warm, moist air rises, losing moisture as rain, resulting in high rainfall.

Major Biomes Distribution

• Major Biomes Include:   - Rain forest   - Temperate rain forest   - Deciduous forest   - Savanna   - Shrubland   - Desert   - Taiga   - Tundra

Seasons

• Include summer/winter and rainy/dry seasons.

Water Bodies

• Influence climate significantly:   - Water has a high heat capacity, warming and cooling slowly, moderating local temperatures.   - Ocean currents can alter climate; warm currents create warm winds, and cold currents create cool winds.

Case Study: Niagara Fruit Growing Region

• Breezes from Great Lakes maintain stable temperatures   - Support growth of delicate fruits (grapes, peaches).   - In contrast, KW experiences less moderating effect due to absence of significant water bodies.

Lake Effect Snow

• In winter, cold winds warm up and gain moisture over the warmer Great Lakes.   - The resulting wind carries moisture that condenses and falls as snow, contributing to significant snowfall in regions like Ontario’s cottage country and Buffalo, NY.

Nutrient Cycles

• Major cycles include:   - Water   - Carbon   - Phosphorus   - Nitrogen.

Global Biogeochemical Cycles

• Pathways of chemical cycling involving both biotic and geological components.

• Key Terms:   - Reservoir: Source unavailable to producers (e.g., fossilized remains, rocks).   - Exchange pool: Source from which organisms draw chemicals (e.g., atmosphere, soil).   - Biotic community: Pathway through which chemicals move along food chains.

Types of Biogeochemical Cycles

• Gaseous cycles: Chemicals drawn from and returned to the atmosphere (e.g., carbon, nitrogen cycles).

• Sedimentary cycles: Chemicals drawn from soil by plant roots, consumed by animals, and returned to soil by decomposers (e.g., phosphorus cycle).

• Water is unique as it exists in all three states (gas, liquid, solid).

Water Cycle

Evaporation

• Water changes from liquid to vapor using solar energy or heat sources.   - Evaporation distills and purifies water (dissolved salts remain).   - Evaporated water can travel globally with winds, leading to precipitation in distant areas.   - Vital for sustaining inland rivers, lakes, and wetlands.   - Rain replenishes inland water bodies.

Transpiration (from plants)

• Plants take in soil water via osmosis.   - Evaporation from leaves creates a tension that pulls other water molecules up the plant, assisting nutrient transport.   - This process contributes to microclimates in forests and helps mitigate flooding.

Precipitation

• During condensation, gas turns to liquid, leading to various forms of precipitation (rain, sleet, snow).

Groundwater

• Aquifers are critical for communities; around 80% of drinking water in KW comes from groundwater.   - Groundwater is hard due to minerals leached from soil.   - Overuse of aquifers leads to depletion faster than natural replenishment.

Freshwater Scarcity

• Freshwater constitutes only 3% of Earth's water; Canada holds around 7%.   - Freshwater is renewable but can be overconsumed or polluted.

Phosphorus Cycle

Key Characteristics

• Essential for life; involves DNA, RNA, ATP, and phospholipids.

• Mainly found in sedimentary rocks, leading to issues like algal blooms and eutrophication.

Process Overview

• Phosphorus moves from land rocks to oceans, back through geological upheaval.   - Weathering makes phosphate ions available to plants;   - Animals consume plants and redistribute phosphorus.   - Essential for the formation of biological molecules.

Human Impact

• Runoff containing phosphates from fertilizers can lead to eutrophication, resulting in nutrient overload in water bodies.

Dead Zones Example: Gulf of Mexico

• Mississippi basin collects nutrient-rich runoff leading to blooms of algae that, upon decomposing, deplete oxygen in the water, causing dead zones.

Nitrogen Cycle

Key Characteristics

• Predominantly nitrogen gas (N2), making up 78% of atmosphere.

• Essential for proteins and nucleic acids but unusable in its gaseous form by most organisms.

Steps of the Nitrogen Cycle

1. Nitrogen Fixation: Conversion of N2 to usable ammonium ions (NH4+) by bacteria, making nitrogen accessible to plants.

2. Nitrification: Conversion of ammonium to nitrates (NO3-) via:    - Atmospheric events (lightning)    - Nitrifying bacteria in soil.    - Steps involve converting ammonium to nitrites (NO2-) and then to nitrates (NO3-).

3. Denitrification: Conversion of nitrates back to nitrogen gas (N2) by denitrifying bacteria, thus returning nitrogen to the atmosphere.

Human Activities Impact

• Human-induced nitrogen fixation through fertilizers increases nitrogen compounds in the environment contributing to eutrophication.

• Burning fossil fuels emits nitrous oxide (N2O), impacting global warming and air quality.

Carbon Cycle

Overview

• Carbon is fundamental to all living organisms, forming the basis of biological structures.

Key Processes

1. Photosynthesis:    - Equation: $6CO_2 + 6H_2O + ext{light energy} ightarrow C_6H_{12}O_6 + 6O_2$

2. Cellular Respiration:    - Equation: $C_6H_{12}O_6 + 6O_2 ightarrow 6CO_2 + 6H_2O + ext{energy}$

Reservoirs of Carbon

• Carbon is stored in living organisms, fossil fuels, and decaying organic matter.

• Deforestation releases stored carbon, increasing atmospheric CO2 levels.

Greenhouse Effect

• Plays a critical role in maintaining Earth's temperature by trapping heat.

• Balance is disrupted by excess greenhouse gases, leading to climate change.

Other Greenhouse Gases

• Include methane, nitrous oxide, chlorofluorocarbons (CFCs), and water vapor, all of which contribute to heat retention and global warming.

Climate Change

• Historical natural climate changes are now outpaced by human-induced changes due to industrial activities.

• Rapidwarming presents challenges for many species to adapt.

Consequences of Climate Change

• Ocean warming, sea level rise (approximately 8 inches since the 1880s), and increased flooding risks for coastal cities.

• Effects on biodiversity include coral bleaching and alteration of species distributions.

Actions to Mitigate Climate Change

• Suggestions include:   - Reducing fertilizer use (opt for organic compost).   - Planting native species to enhance carbon storage.   - Minimizing idle vehicle time to reduce carbon emissions.   - Conserving water by fully loading appliances before use.

Upcoming Class Agenda

• Ecology Lab in outdoor settings.

• Reminders regarding textbook readings and upcoming assignments due in week 13.