|MadSci Network: Zoology|
Symbiotic, broadly defined, means living together, so that there are literally thousands of relationships that would fall into that category. Among the TYPES of relationships that could be considered symbiotic are predator-prey, host-parasite, (including host-disease), mutualism, commensalism and others. A more restricted definition of symbiosis often includes only those relationships in which both participating species benefit (called mutualism) and those in which one species benefits and the partner species is unaffected (called commensalism)
Specific examples of these in a deciduos forest are:
MUTUALISM mycorrhizae - In this relationship a particular fungal species has an intimate relationship with the roots of a particular speicies of higher plant. The fungus provides the plant with increased ability to absorb nutrients (particularly phosphorus) and water and often offers some disease resistance. In return the plant offers the fungus energy in the form of carbohydrates in the root sap. Many of these relationships are obligatory.
COMMENSALISM - there are many examples of this type of symbiosis. Many species of moss or algae may live on the bark of a tree. The tree is completely unaffected and the moss or algae has a place to live above the clutter of leaf litter on the ground that would suffocate (eliminate light) to the moss or algal plant. Many animals make homes in trees without damaging the trees. Of course some animals do damage trees when they make their homes.
PARASITISM - One of my favorite parasitic relationships in the deciduous forests here in Ohio is between the American beech tree and a plant called beech drops. Beech drops are only found growing under beech trees. Although they are flowering plants, they have no chlorophyll(they are cream colored) and live entirely on sap absorbed (stolen) from the beech tree. The beech drops have a special root structure called a haustorium which connects them to the host plant.
I have only touched the surface of this subject. Symbioitic relationships are the rule and you could not find an organisms in a deciduous forest that does not have at least one sybiotic relationship with another organism. Even you have symbiotic relationships with beneficial bacteria that live in your intestine and others that live on your skin!
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