This post is also available in: Español (Spanish)
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How Trees Affect Air Quality Directly And Indirectly
This post is also available in: Español (Spanish)Natural forests, along with ornamental urban trees and shrubs, affect air quality directly and indirectly by altering the atmospheric environment. Their effect on the environment is related to the removal of air pollutants and particulate matter from the atmosphere, photosynthetic byproduct output of oxygen and reduction of local air temperatures. Leaves have a primary function in all three cases. Trees remove gaseous air pollutants from the atmosphere by uptake through leaf stomata or absorption through other surfaces. Additionally, gases taken into the leaf defuse into intercellular spaces, combine with water and form acids, or react with internal leaf structures. Carbon dioxide is one of the gases leaves take up, and it represents the major component of photosynthesis; the food-making engine of the tree. Consequently, oxygen is a byproduct of photosynthesis and its release improves air quality. Due to this approximately a single large tree can absorb 10 pounds of air pollutants per year and produce some 260 pounds of oxygen. Also, trees transpire water vapor through the leaf stomata, contributing to the atmospheric water content. Intercepted airborne particles may be absorbed into the tree, or they adhere to plant surfaces and are later washed to the ground by rain. Global Temperature Additionally, with the presence of trees local temperature lowers. Because, not only do they provide shade from direct sunlight; but of transpiration, which takes up almost 80% of the cooling effect. Taking up latent heat from the leaf surface and cools the surrounding air. This is nature’s version of the evaporative coolers used for air conditioning in desert regions. Shading the ground surface from the direct rays of the sun reduces soil temperatures and contributes to the cooler temperatures. Studies in the middle latitudes in summer, have shown that below small groups of trees over grass; mid-day temperatures are about 1 degree cooler than in adjacent open areas. By reducing air temperatures, trees indirectly improve air quality; because the rate of pollutant emission and ozone formation are temperature dependent.Both decreasing with lower air temperatures. Also,Trees impact local atmospheric conditions by reducing wind speed and turbulence. Air Pollution Several factors come into play when considering the local effects of trees on air pollution. In natural forests, and urban settings, tree size and the density of plantings together determine the magnitude of positive impact on air quality. In tropical and subtropical regions, as well as high latitude boreal forests, where evergreen species predominate, trees provide a year around benefit to air quality. However, in middle latitude regions of deciduous forests and ornamental trees, the effect is only present during the in-leaf season. The overall positive effects of tree are significant on a global basis. Maintaining natural forests is the most important strategy to improve overall air quality on a global scale. As a result, ornamental tree growth in urban environments has been shown to improve local air quality. In order to accomplish this goal, policies should be implemented to increase the numbers of large healthy enviroments. Definitely, planting such trees in polluted or heavily populated urban areas will come as a great benefit.
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Street Trees -The Key Issues Facing Street Tree Cultivation
This post is also available in: Español (Spanish)Street trees are a subset of urban trees, representing species with growth forms best suited to cultivation along pedestrian walkways and roads. Most cities and towns of the world are landscaped with street trees and shrubs. The trees enhance the appearance of residential, commercial or industrial property areas; consequently to a small degree, preventing the loss of natural vegetation cleared for construction of buildings, streets and roads. Street tree plantings generally take place on public rights-of-way and are the responsibility of the local government public works department. Tree plantings on private properties abutting streets can be complementary to public landscaping.
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What Are Evergreen Trees? What Does Evergreen Mean?
This post is also available in: Español (Spanish) By definition, evergreen trees are never without leaves, whereas deciduous trees spend part of the year without foliage in response to cooler or dryer climatic conditions. Most broadleaf rainforest trees and shrubs, along with conifers, palms and cycads are evergreen. Some subtropical or tropical trees are difficult to place in either an evergreen or deciduous category, being described as semi-evergreen or semi- deciduous; the two terms being about equivalent, although the latter is more commonly used.
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Exotic And Native Trees & Their Natural Distribution Worldwide
This post is also available in: Español (Spanish) Trees, and all plants, have a natural distribution in the world. We refer to a tree native as when it occurs naturally in a particular place. Natural plant distribution may be considered at different levels on the basis of classification: plant family, genus and species, each level ranging usually from the most extensive to the most restricted. For example, the extraordinarily large and diverse Pea Family, Fabaceae, includes about 700 genera, including among them trees and shrubs which are spread throughout the subtropical and tropical world.
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