Author : Chye Tee Teoh

Summary : The soil moisture contents of five upland ecosystems, found at the University of the Philippines at Los Ba¤os' (UPLB) Upland Hydroecology Program Main Site at Puting Lupa, Calamba, Laguna, were monitored daily over a 9-month period, covering the wet and dry seasons. Daily records of solar radiation, sunshine duration, rainfall, and air temperature were also monitored. Soil temperature at 5 cm below the soil surface were obtained daily in the same ecosystems for four months, mostly during the dry season. Significant differences in soil moisture contents and in soil temperatures were found to occur among the ecosystems. Soil moisture was negatively correlated with solar radiation and positively correlated with rainfall. Except for the grassland ecosystem, all the other ecosystems showed significant differences in soil moisture contents among different slopes (30 degrees, 50 degrees, and 70 degrees). However, the differences were not consistent from one ecosystem to another. There was highly significant negative correlation between soil moisture content and soil temperature in the grassland, new Kaingin (slash-and-burn), and old kaingin ecosystems, but not in the plantation and secondary forest ecosystems. The leaf stomatal densities and distribution, leaf relative water contents, leaf moisture contents, leaf stomatal diffusion, resistances, and leaf temperatures were studied in seven plant species as they occured in the five ecosystems. Significant positive correlation between soil moisture content and leaf relative water content was found only in Gliricidia sepium. Two species, Carica papaya and Ficus septica, showed significant positive correlation between soil moisture content and leaf moisture content. In Musa paradisiaca, soil moisture contnent was negatively correlated with leaf stomatal diffusion resistance. Psidium guajava showed highly significant negative correlation between leaf temperature and stomatal diffusion resistance.