Division of Layers Emergent Layer: Contains the tallest trees in the rainforest(150~200 feet). Windy, relatively dry, lots of sun. Canopy: The primary layer of the rainforest(15~150 feet). Sun, humidity, water, shelter, leaves, flowers, fruit. Understory: Seldom grow to more than 12 feet.Difficulty with pollinization because of the lack of air movement. Filtered sun, high humidity, lack of air movement. Forest Floor: Almost no plants (because 0-2% light & 100% humidity). Few flowering plants, mosses, herbs, and fungi.
Species Diversity A mature tropical rainforest has incredible diversity. Why? There are a variety of specialized niches in distinct layers (based mostly on their need for sunlight).
Biodiversity Scales of organization genetic -- diversity of genetic information found within species and populations species -- diversity of species community -- diversity of community composition ecosystem -- diversity of assemblages of communities (Fox River watershed) landscape -- diversity of assemblages of ecosystems (Western Great Lakes)
Definitions: Sustainability or stability: Maintained by a constant dynamic change in response to changing environmental conditions. Usually comes with high biodiversity. Persistence or inertia: The ability of a living system to resist being disturbed or altered. Constancy: Ability of a system (population) to keep its numbers within the limits imposed by available resources. Resilience: Ability of a living system to bounce back after an external disturbance that is not too drastic.
Things that Probably Don’t Cause Natural Extinctions Epidemics –Rapid co-evolution of disease and host Evolution of New Competitors in Place –Existing organisms already well-adapted
Human-Caused Extinction Excessive Predation (Food, fur, collecting, pest eradication, etc.) Habitat Destruction Destruction of keystone species Introduction of Exotic Species –Competitors –Predators –Diseases Pollution and Contamination