Canopy level of temperate rainforest
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Temperate rainforest definition
Temperate rainforests are coniferous or broadleaf forests that occur in the temperate zone and receive high rainfall. For temperate rain forests of North America, Alaback's definition is widely recognized: 1. Annual precipitation 200–400 cm 2. Mean annual temperature between 4oC and 12oC. (39o and 54o Fahrenheit) However, required annual precipitation depends on factors such as distribution of rainfall over the year, temperatures over the year and fog presence, and definitions in other countries differ considerably. For example, Australian definitions are ecological-structural rather than climatic: 1. Closed canopy of trees excludes at least 70% of the sky 2. Forest is composed mainly of tree species which do not require fire for regeneration, but with seedlings able to regenerate under shade and in natural openings The latter would, for example, exclude a part of the temperate rain forests of western North America, as Coast Douglas-fir, one of its dominant tree species, requires stand-destroying disturbance to initiate a new cohort of seedlings. The North American definition would in turn exclude a part of temperate rain forests in other countries.
Canopy level definition
For forests, canopy also refers to the upper layer or habitat zone, formed by mature tree crowns and including other biological organisms (neophytes, lanais, arboreal animals, etc.). The canopy level is the third level of the temperate rainforest. The trees forming the canopy, conifers, can stand as tall as 91.44 meters (300 feet). A variety of species survive in the canopy. The tops of these trees collect most of the rain, moisture, and photosynthesis that the rainforest takes in. They form a canopy over the forest, covering about 95% of the floor during the summer.
There are five different types of conifers occupying the forest; Coastal Redwood, Douglas Fir, Sitka Spruce, the Western Red Cedar, and the Western Hemlock. Airplants live on the conifers in the canopy. Epiphytes are a common plant that grows on the trees in the canopy level. Ferns, lichens, and mosses inhabit the conifers.
The canopy’s coverage affects the shade tolerance levels of forest floor plants. When the canopy is in full bloom, covering about 95% of the floor, plant survival decreases. Some plant species have become shade tolerant in order to survive. The treetops take in the heavy amount of rain and keep the lower levels of the forest damp.
The canopy survives through photosynthesis. The leaves provide energy and nutrients for the trees, which provide homes and food for the forest. Through satellite data, the radiation use efficiency(RUE) calculates the annual amount of photosynthesis that occurs in temperate rainforests. A diverse amount of photosynthesis occurs based on the location and microclimates of the forest.
- Choudhury, B. J. Estimating Gross Photosynthesis Using Satellite and Ancillary Data: Approach and Preliminary Results. Remote Sensing of Environment 75:1-21.
- Lusk, C. H. 2002. Leaf area accumulation helps juvenile evergreen trees tolerate shade in a temperate rainforest. Oecologia 132:188-196.
- Weir, R. Temperate Rainforest Ecosystems.