Chapter 1: Moisture and Sunlight

Ecosystem productivity is fundamentally constrained by non-living environmental inputs that drive biological processes.
Distinguishing between abiotic and biotic factors is essential for evaluating environmental controls on primary production.

Abiotic Factors: Non-living chemical and physical components of an environment that affect living organisms and ecosystem functioning.
Moisture and Sunlight as Limiting Factors:
- Moisture: Regulates cellular metabolic functions, nutrient transport, and photosynthetic efficiency in producers.
- Sunlight: Functions as the primary energy input required to drive photosynthetic chemical reactions, directly constraining energy capture in autotrophs.
- Both moisture and sunlight act as key abiotic constraints that limit overall biomass production and photosynthetic rate within ecosystems.

Evaluation of ecological factor pairs by abiotic versus biotic classification:
- Moisture and Sunlight: Exclusively non-living physical inputs (abiotic factors) that limit ecosystem productivity.
- Trace Elements and Molds: A mixed combination containing an abiotic chemical input (trace elements) and a living biological entity (molds, which are biotic).
- Parasites and Fungi: Exclusively living organismal factors (biotic factors).
- Diseases and Herbivores: Exclusively biological processes, living pathogens, and organismal interactions (biotic factors).