Research/Project ResultsTemperate Rainforest BiomePuget Sound, Page 5 |
Biotic Data: AnimalsMany different types of animals were found in this field study. The types of organisms in the forest depend on the types of plants that are found there. This was the 3rd year of a Western Tent Caterpillar outbreak. They particularly like alder trees, and alders were the most important tree here! Tent caterpillar populations tend to rise and fall in cycles. While they can be an unpleasant pest when their numbers are large, and while they may defoliate a tree, they rarely kill trees. Most trees will produce a 2nd set of leaves, after the 1st set has been eaten by caterpillars (and hopefully after they have pupated and turned into adult insects!). In this relationship, there is no benefit to the caterpillar if the trees die! However the trees might die if there are several sequential years of infestation and if other factors (drought, heat, other pests) are attacking it as well. Forests are also home to rodents and birds. Birds in particular will feed off of insects like the Western Tent Caterpillar. This creates a food chain: alder ---> tent caterpillar--->robin Thus, the population of robins will affect the population of tent caterpillars, that will affect the population of alders. As well, the relationship effects will also work in reverse! |
This photo shows alder trees in the background. These trees require light for their seeds to germinate and grow. For this reason, they usually grow in sunny areas like cut over places or where trees have fallen down, where their seeds can receive sufficient light for germination. The alders usually replace woody grasses and shrubs. They end up producing too much shade for their own seeds. In their shade the seeds of conifers usually grow. Thus, eventually the shade produced by the alders cause alders to be replaced by shade loving conifers like the redwood and spruce. Alder are typical trees in areas of early succession; spruce are typical of later succession. Succession is the process of 1 characteristic organism being replaced by another.
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The data that the students collected was the following: Most common arthropod - Western Tent Caterpillar 2nd most common arthropod - Bees 3rd most common arthropod - Spiders
Mammals sighted - Squirrel
Bird calls/sightings - Robins, swallows, pileated woodpeckers, starlings
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