Abundance and Distribution of SpeciesLiebig's law of the minimum: The single factor closest to these survival limits is the critical limiting factor that determines where a particular organism can live. The major factor is one in the minimum. or:single environmental factor in shortest supply relative to demand is the critical determinant in species distribution Shelford added to Liebig's work: Single environmental factor closest to tolerance limits determines where a particular organism can live Shelford's principle of tolerance limits: Each environmental factor has both minimum and maximum levels called Tolerance limits, beyond, which a particular species cannot survive or is unable to reproduce. For terrestrial organisms: temperature, moisture, and nutrient availability. For aquatic organisms: salinity, gradient (water current). Sometimes the requirements and tolerances of species are useful indicators of specific environmental characteristics - environmental indicators (trout, lichens etc.).
Limiting factors include ABIOTIC (physical) factors and BIOTIC factors Abiotic Factors:Light availability/day length, seasonality; moisture/water availability; temperature, diurnal temperature range; height or depth, pressure; salinity; wind; pH, CO2, O2, availability of N, P, K, Ca, etc. Biotic Factors:Competition; predation; parasitism; disease; pollinators, dispersal agents; food availability; species density /distance to nearest neighbour).
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