Microclimate beneath pine plantation, semi-mature pine plantation and mixed broadleaved-pine forest

To study the dynamics of pine plantations, three stands were selected, which had matured from a pure pine plantation to a mixed broadleaved-pine forest. Microclimatic conditions inside the stands were monitored: air temperature, soil temperature, air relative humidity and global radiation. A reference station was installed in an open area nearby. Forest cover has a weak effect on temperatures: air and soil temperatures are warmer in the mixed broadleaved-pine stand and the coldest under the pine plantation. No difference in relative humidity (h, %) or vapour pressure deficit (D, Pa) was observed across the forest maturing stages, but a strong effect of forest cover in general was observed. Radiation was highly attenuated beneath the canopy and was the most heterogeneous variable between and within stands. These variations were significantly and negatively related to the local basal area or canopy cover; the exact shape of the relationship could not be assessed because of too few spatial data.