Abstract: Forests can regulate climate to some extent, which is an aspect of the ecological services of forests. Studies on forest microclimates can help us understand the regulations and mechanism of how the forests affect climate and provide theoretical guides to agricultural and forest production managements. We conducted tenyear parallel measurements of temperature and watervapor pressure both outside and inside a coniferous plantation in subtropical China from 2005 to 2014. To examine the effects of the coniferous plantation on microclimate, air temperature, soil temperature and water vapor pressure inside the forest were compared with those outside of the forest. The results showed that forest can significantly affect temperature and humidity in the forest. At annual scale, the multiyear mean air temperature inside the forest was 0.5 ℃ lower than that outside the forest. The multi year mean monthly maximum air temperature inside the forest was 2.0 ℃ lower than that outside the forest. Moreover, the multiyear mean monthly minimum air temperature inside the forest was 0.4 ℃ higher than that outside the forest. As the age of the forest increased from 20 years to 30 years, the cooling effects of the forest in summer significantly increased. In addition, the regulating effects on maximum and minimum air temperature were enhanced. The water vapor pressure inside the forest was generally higher than that outside the forest, which indicated a humidifying effect of forest. From 2005 to 2014, accompanying with the growth of the forest, water vapor pressure inside the forest significantly increased. The regulating effects of forest on soil temperature were greater than that on air temperature. The multiyear mean annual soil temperature at 5 cm depth inside the forest was 3.6 ℃ lower than that outside the forest. The forest showed significant cooling effects in the hot summers, while it showed heat preservation effects in winter. These effects did not show obvious increase or decrease trends with increasing forest age, but might be affected by soil water contents.

Key words: morphological trait, absorptive root, root-order-based approach, transport root, anatomical trait