What Are Abiotic Variables?
Definition
Abiotic factors
Abiotic factors are non-living components like temperature, water availability, salinity, and soil type.
Think of abiotic variables as environmental "filters" that determine which species can pass through and inhabit a particular area.
Definition
Range of Tolerance
- Each species has an optimal range of abiotic factors within which it can thrive.
- Conditions outside this range lead to stress or intolerance, making survival or reproduction impossible.
Abiotic Factors Affecting Plant Distribution
- Temperature
- Tropical Plants (e.g., banana trees) cannot withstand frost.
- Alpine Species like Ranunculus glacialis have “antifreeze” compounds for high-altitude, coldenvironments.
- $Ranunculus\ glacialis$ grows in high-altitude areas with intense sunlight and short growing seasons.
- Its adaptations, such as tolerance to frost and acidic soils, allow it to survive where few other plants can.
Can you think of another plant species adapted to extreme temperatures? What are its key adaptations?
- Water Availability
- Cacti store water in stems and use spines instead of leaves to reduce water loss in deserts.
- Mangroves tolerate waterlogging and salinity by excreting excess salt via specialized glands.
Water availability often interacts with other abiotic factors, such as temperature, to create unique challenges for plant survival.
- Light Intensity
- Rainforest Trees (e.g., yellow meranti) grow tall to reach canopy light.
- Shade-Tolerant Plants (e.g., mosses) thrive on the forest floor, where light is scarce.
- Many students think that all plants need high light intensity to grow.
- However, shade-tolerant plants are adapted to low light conditions and may even be harmed by excessive sunlight.
- Soil pH and Nutrients
- Acidic Soils: Support species like blueberries, adapted to low pH.
- Alkaline Soils: Favor plants like lavender, which require high pH conditions.
- Think of soil pH as a recipe for plant growth.
- Just as certain ingredients are needed for specific dishes, plants require specific pH levels to access the nutrients they need.
Abiotic Factors Affecting Animal Distribution
- Temperature
