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Western University
Environmental Science
Environmental Science 1021F/G
Geoff Stewart

CHAPTER 11: FORESTS -less than 2% of the Gonaives forest in Haiti remains – 6% of the land has no soil at all -DEFORESTATION: net loss of trees in a forested area THE LOCATION AND CHARACTERISTICS OF FOREST BIOMES ARE INFLUENCED BY TEMPERATURE AND PRECIPITATION -forests are biomes dominated by trees – they cover 30% of Earth’s landmass – home to more than 50% of Earth’s terrestrial life and more than 60% of its green photosynthesizing leaves -many types of forests – each are characterized by the temperature and amount of precipitation -BOREAL FORESTS: characterized by evergreen species like spruce and dir, cover vast tracts of land in the higher latitudes and altitudes and are characterized by low temperatures and precipitation levels – represent some of the last expansive forests left on Earth (Canada) -TEMPERATE FORESTS: contains deciduous trees that lose their leaves in the winter like oak, hickory, and maple – found in mid-latitudes – found in areas with high populations – found in areas with four seasons and a moderate climate – receive 750-1500 millimetres of rain per year – may include confers and/or hardwood deciduous trees -Canada is the largest timber exporter – 45% of our land area is forested, but we have lost 6% of original cover mostly from temperate forests -TROPICAL FORESTS: contain a diverse mix of tree and undergrowth species and are found in tropical latitudes where temperatures do no vary much throughout the year – found in equatorial areas with warm temperatures year round and high rainfall – some have distinct wet and dry seasons but none has a winter season -most forests consist of four distinct layers: canopy, emergent, understory, and forest floor -CANOPY: upper layer of the forest formed where the crowns (tops) of the majority of the tallest trees meet -EMERGENT: the region where a tree that is taller than the canopy trees rises above the canopy layer -UNDERSTORY: the smaller trees, shrubs, and saplings that live in the shade of the forest canopy; beneath the canopy where shade-tolerant shrubs, smaller trees, or the saplings of larger trees grow – sometimes these trees are dense enough to form a lower canopy -FOREST FLOOR: the lowest level of the forest, containing herbaceous plants, fungi, leaf litter, and soil – decomposes over time -within each forest layer is a range of species uniquely suited to the temperature, humidity, and amount of sunlight that layer receives, and well-adapted to its particular neighbours -in a temperate deciduous forest, wildflowers on the forest floor will blood early in the spring before the bigger trees “leaf out” and block the sun -sunlight is a precious commodity on the forest floor and wildflowers compete for it -disruption is one part of the forest that can have a trickle-down effect that impacts each subsequent layer -charcoal is a partially burned wood that ignites more easily and burns hotter than the original wood itself – its used it may developing countries that lack other reliable fuel sources – produced by a slow, low temperature roasting of the wood in a low-oxygen environment – this releases CO2 and particulates (soot) into the atmosphere and causes pollution FORESTS PROVIDE A RANGE OF GOODS/SERVICES AND FACE A NUMBER OF THREATS -soil – which the forest itself helps to form and maintain: leaves and branches die, fall to the ground, and decay, forming a thick layer of nutrients in which all future generatio
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