Phytoncides in forest atmosphere

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The major phytoncides found in coniferous and broad-leaved forests are α-pinene and isoprene, respectively. The amounts of these phytoncides vary between seasons, increasing from June to September for the summer, and decreasing for the winter. The patterns of diurnal variation differ between the different substances; the amounts of monoterpenes, such as α-pinene, are higher during the night than during the day whereas the amounts of isoprene are the opposite. In a forest, the horizontal distribution of phytoncides during the day tends to be more concentrated near the center of the forest than its edges and their vertical distribution tends to be more concentrated closer to the ground.

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