- Authors:
- Tang, K. J.
- Hwang, L. S.
- Liu, C. P.
- Lu, S. Y.
- Source: Taiwan Journal of Forest Science
- Volume: 17
- Issue: 2
- Year: 2002
- Summary: Rapid increases in betel-nut plantations in the 1980s and 1990s have significantly affected the environment and biological conditions of slopeland in Taiwan. Impacts of converting from forested land to betel-nut plantations on the environment are serious enough to have attracted much concern from government and environmental groups. A series of research on this topic has already been carried out. However, most of these researches were focused on problems of soil and water conservation associated with slopeland betel-nut plantations. In order to examine differences in microclimatic conditions between betel-nut plantations and natural hardwood forests, the average air temperature, relative humidity, earth temperature, solar radiation, and rainfall above and below the canopies of these 2 stands were continuously monitored. The available continuous records from January 2000 to January 2001 indicate that there are no differences between these 2 study areas in temperatures above and below the canopy. However, the yearly average earth temperature (at 5-cm depth) of the betel-nut plantation was 2.3degreeC higher than that of natural hardwood forest, which was significant at the 1% level. The multi-layered and denser canopy of natural hardwood forest stands consumes much solar energy by evapotranspiration and photosynthesis than does that of betel-nut stands. Therefore less energy is available for heating the soil which results in lower earth temperatures than found in betel-nut plantations. However, the difference is less significant during rainy days and at night. Relative humidity is strongly influenced by canopy cover. The transportation of moisture can be hindered under a heavy forest canopy which results in higher relative humidity. Statistical results indicate that relative humidity was significantly under-canopy conditions of natural hardwood stands, whereas above the canopy, it was not as high. In addition, the long-term weather records at Lienhuachih meteorological station of Taiwan Forest Research Institute also reveal that the annual average air temperature, especially for summer seasons, shows a tendency of increase after 1980. Further studies are needed to clarify the effects of the rapid increase in betel-nut cultivation on climate changes in the Lienhuachih area.
