🌾World Biogeography Unit 3 – Climate and biomes

Key Climate Concepts

• Climate encompasses long-term weather patterns and average conditions of a specific area
• Factors influencing climate include latitude, altitude, ocean currents, and atmospheric circulation patterns
• Temperature and precipitation are the two main variables used to characterize climate
• Köppen climate classification system categorizes climates based on temperature and precipitation patterns
  • Five main climate groups: tropical, dry, temperate, continental, and polar
• Microclimate refers to local variations in climate within a small area due to factors like topography or vegetation
• Seasonality describes the regular changes in temperature, precipitation, and other climate variables throughout the year
• Climate diagrams visually represent the annual temperature and precipitation patterns of a location

Major Biome Types

• Biomes are large, distinct ecological communities characterized by similar climate, vegetation, and wildlife
• Terrestrial biomes include tundra, boreal forest, temperate forest, tropical rainforest, grassland, desert, and savanna
  • Tundra: cold, treeless biome with low-growing plants adapted to harsh conditions (Arctic tundra)
  • Boreal forest: coniferous forest biome with long, cold winters and short, cool summers (taiga)
• Aquatic biomes include freshwater (rivers, lakes, wetlands) and marine (oceans, coral reefs, estuaries) ecosystems
• Ecoregions are smaller, more specific geographic areas within biomes that share similar ecological characteristics
• Biomes are determined by a combination of climate factors, such as temperature, precipitation, and seasonality
• Ecotones are transitional areas between two adjacent biomes, often exhibiting characteristics of both

Climate-Biome Relationships

• Temperature and precipitation patterns are the primary factors determining the distribution of biomes worldwide
• Biomes are arranged in latitudinal bands that correspond to global climate zones
  • Tropical rainforests are found near the equator, where temperatures are high and rainfall is abundant year-round
  • Deserts occur in areas with low precipitation and high evaporation rates, often in the rain shadow of mountain ranges
• Elevation gradients create similar biome patterns to latitudinal gradients due to changes in temperature and precipitation with altitude
• Soil type and nutrient availability also influence biome distribution and characteristics
• Biomes shift and adapt over time in response to long-term climate changes, such as glacial cycles
• Climate-biome relationships are not always straightforward, as local factors like topography and ocean currents can create regional variations

Adaptations and Biodiversity

• Organisms within biomes exhibit adaptations that enable them to survive and thrive in specific environmental conditions
  • Cacti have thick, waxy cuticles and specialized photosynthetic pathways to conserve water in desert environments
  • Coniferous trees have needle-like leaves to minimize water loss and withstand cold temperatures in boreal forests
• Biodiversity refers to the variety of life within a given area, including genetic diversity, species diversity, and ecosystem diversity
• Biomes with more stable and productive climates, such as tropical rainforests, tend to have higher levels of biodiversity
• Endemism describes species that are unique to a particular geographic location or biome, often due to isolation or specialized adaptations
• Keystone species play a disproportionately important role in maintaining the structure and function of their ecosystem (sea otters in kelp forests)
• Biodiversity supports ecosystem stability, resilience, and the provision of essential services like nutrient cycling and carbon sequestration

Human Impacts on Biomes

• Human activities have significantly altered and degraded many biomes worldwide
• Deforestation, particularly in tropical rainforests, leads to habitat loss, fragmentation, and reduced biodiversity
  • Agricultural expansion, logging, and urbanization are major drivers of deforestation
• Overgrazing and conversion of grasslands to cropland can lead to soil erosion, desertification, and loss of native species
• Wetland drainage and filling for development or agriculture destroys critical habitats and alters hydrological cycles
• Pollution, such as agricultural runoff and industrial waste, can degrade aquatic biomes and harm wildlife
• Invasive species introduced by human activities can disrupt ecosystems and outcompete native species
• Climate change, largely driven by human greenhouse gas emissions, is shifting biome boundaries and altering species distributions

Climate Change Effects

• Rising global temperatures are causing shifts in the distribution and composition of biomes
• Warmer temperatures are leading to the poleward and upslope migration of species and biomes
  • Tundra and alpine ecosystems are particularly vulnerable to warming, as they have limited room to shift to higher latitudes or elevations
• Changes in precipitation patterns, such as increased droughts or floods, can alter biome structure and function
• Melting permafrost in tundra regions releases stored carbon, contributing to further climate change through a positive feedback loop
• Ocean acidification, caused by increased absorption of atmospheric carbon dioxide, threatens marine biomes like coral reefs
• Phenological mismatches can occur when the timing of species' life cycles (e.g., migration, reproduction) becomes out of sync with seasonal climate cues
• Climate change interacts with other human impacts, such as habitat fragmentation, to exacerbate threats to biomes and biodiversity

Conservation Strategies

• Protected areas, such as national parks and wildlife reserves, aim to safeguard biomes and their associated species
• Habitat restoration involves actively rehabilitating degraded ecosystems to improve biodiversity and ecosystem function
  • Reforestation and afforestation can help mitigate climate change by sequestering carbon and restoring forest biomes
• Sustainable land management practices, like agroforestry and rotational grazing, can balance human use with biome conservation
• Corridors and connectivity between protected areas allow species to move and adapt to changing conditions
• International agreements, such as the Convention on Biological Diversity, promote global cooperation in biome and biodiversity conservation
• Community-based conservation engages local communities in the sustainable management and protection of their surrounding biomes
• Climate change mitigation, through reducing greenhouse gas emissions and enhancing carbon sinks, is crucial for long-term biome conservation

Case Studies and Examples

• The Amazon rainforest, the world's largest tropical biome, is facing rapid deforestation due to agricultural expansion, logging, and infrastructure development
• The Sahel region of Africa has experienced desertification and loss of grassland biomes due to overgrazing, drought, and climate change
• The Arctic tundra is warming at twice the global average rate, leading to permafrost thaw, altered vegetation, and impacts on wildlife like polar bears
• The Great Barrier Reef, a diverse marine biome, has suffered extensive coral bleaching and mortality due to rising ocean temperatures and acidification
• The Yellowstone to Yukon Conservation Initiative aims to protect and connect the temperate forest biome across western North America
• The Serengeti-Mara ecosystem in East Africa is a iconic savanna biome, known for its large mammal migrations and high biodiversity
• The Sundarbans, the world's largest mangrove forest, is a unique biome that provides critical habitat and coastal protection but is threatened by sea-level rise and human activities