Biomes and Ecosystems

Ecosystem – A community of organisms interacting with their physical environment.
Terrestrial – Land-based ecosystems.
Aquatic – Water-based ecosystems.
Ecotone – A transitional area between two ecosystems; more biodiverse and resilient.
Ecological niche – The role of an organism in an ecosystem (food web, habitat, breeding, etc.).
Resource partitioning – When species divide resources to reduce competition.
Exotic species – Non-native species that may disrupt an ecosystem.
Biome – A large-scale ecosystem defined by climate, vegetation, and organisms.

Tundra – Cold, dry biome with permafrost, low biodiversity.
Taiga – Boreal forest, cold winters, coniferous trees.
Temperate deciduous forest – Moderate climate, broadleaf trees that shed leaves in fall.
Grassland – Dominated by grasses, few trees, moderate precipitation.
Muskeg – A type of boggy wetland found in cold climates.
Deciduous forest – Forest with trees that shed leaves seasonally.

Biotic potential – The maximum population growth rate under ideal conditions.
Carrying capacity – The maximum population an environment can support sustainably.
Law of the Minimum – The most limited resource determines an organism’s success.
Law of Tolerance – Species survival depends on environmental conditions staying within a certain range.
Density-dependent factor – A factor affected by population size (e.g., disease, competition).
Density-independent factor – A factor unrelated to population size (e.g., natural disasters).
Sustainability – The ability of an ecosystem to maintain balance over time.

Permafrost – Permanently frozen soil found in tundras.
Muskeg – Waterlogged soil in cold climates, often acidic.
Understorey – The vegetation layer below the forest canopy.
Littoral zone – Shallow, well-lit area near the shore of a lake.
Limnetic zone – Open water in a lake, where sunlight penetrates.
Profundal zone – Deep, dark area of a lake, low oxygen.
Plankton – Microscopic organisms that float in aquatic environments.
Litter – The top layer of soil, composed of decomposing leaves and organic material.
Topsoil – The nutrient-rich upper soil layer.
Humus – Dark, organic material in soil from decomposed matter.
Subsoil – The layer beneath topsoil, contains minerals but little organic material.
Bedrock – The solid rock layer beneath soil layers.

Ecotones are transition zones between ecosystems.
They are less fragile due to high biodiversity.
More species = more food sources for predators, reducing dependence on a single species.

Natural ecosystems: Self-sustaining, high biodiversity, no human interference.
Artificial ecosystems: Human-made, simplified, require external input.
Artificial ecosystems often have lower biodiversity due to human selection and maintenance.

A species' ecological niche defines its role in the ecosystem.
Different species reduce competition by resource partitioning:
- Using different food sources.
- Living in separate areas.
- Being active at different times.

Littoral Zone – Nearshore, shallow, sunlight reaches the bottom, supports plants and animals.
Limnetic Zone – Open water, enough sunlight for photosynthesis, supports fish and plankton.
Profundal Zone – Deep, dark, low oxygen, inhabited by decomposers and bottom-dwelling fish.

Chemical environment – pH, oxygen levels, and nutrient availability affect life.
Temperature & sunlight – Affects organism distribution and productivity.
Water pressure – Increases with depth, limiting certain species.
Seasonal variation – Temperature and mixing of water layers change with seasons.

Four factors controlling population growth:

A resource in short supply (e.g., water, sunlight, food) can limit population size.
Example: In a desert, water is the limiting factor for plant and animal life.

Point source pollution – Comes from a single, identifiable source (e.g., factory waste).
Nonpoint source pollution – Comes from multiple, diffused sources (e.g., runoff from farms).