Sunlight is the major limiting factor. Only the hardiest plants can survive on the dimly lit forest floor. Another major limiting factor for rain forests is habitat loss or deforestation. Once humans convert forestland into homes or agricultural land, organisms that have very specific niches, specialized habitats or localized populations can decline or even disappear.
Limiting factors are factors that determine the population of a particular species in a specific biome or ecosystem. For instance, water is a major limiting factor in deserts. These factors are either biotic or abiotic. Biotic limiting factors include disease and predation. Abiotic limiting factors deal with environment and climate and include light intensity, temperature range and water availability. Hope this helps ;)
