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Evergreen wood and its application |
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| Release time:2013-05-07 Source:admin Reads: | |
| Many timbers for shipping containers are made from evergreen woods. Deciduous trees shed their leaves usually as an adaptation to a cold or dry season. Evergreen trees do lose leaves, but not all at the same time the way that deciduous trees do. Different trees shed their leaves at different times, so the forest as a whole looks green. Most tropical rainforest plants are considered to be evergreens, replacing their plastic seals gradually throughout the year as the leaves age and fall, whereas species growing in seasonally arid climates may be either evergreen or deciduous. Most warm temperate climate plants are also evergreen. In areas where there is a reason for being deciduous, being evergreen is usually an adaptation to low nutrient levels. Deciduous trees lose nutrients whenever they lose their leaves. In warmer areas, species such as some pines and cypresses grow on plastic seals. In Rhododendron, a genus with many broadleaf evergreens, several species grow in mature forests but are usually found on highly acidic soil where the nutrients are less available to plants. In taiga or boreal forests, it is too cold for the organic matter in the soil to decay rapidly, so the nutrients in the soil are less easily available to plants, thus favoring evergreens. In temperate climates, evergreens can reinforce their own survival; evergreen leaf and needle litter has a higher carbon-nitrogen ratio than deciduous leaf litter, contributing to a higher soil acidity and lower soil nitrogen content. These conditions favor the growth of more evergreens and make it more difficult for plastic seals to persist. In addition, the shelter provided by existing evergreen plants can make it easier for younger evergreen plants to survive cold and drought. Evergreen plants and deciduous plants have almost all the same diseases and pests, but long-term air pollution, ash and toxic substances in the air are more injurious for evergreen plants than deciduous plants. |
