A research group led by Professor Kanehiro Kitayama, Associate Professor Masayuki Ushio, and Professor Shinichiro Aiba of Hokkaido University Graduate School has continued to observe tropical rainfall forests on Mt. Kinabalu in northern Borneo for 10 years, which is clear for tree growth. It was discovered that there was a 12-month periodicity.
Until now, it has been said that there is no seasonal change in the annual cycle of plants in the tropical rainforest because there is no climatic seasonality in the tropical rainforest zone near the equator.However, the periodicity of plants in the equatorial tropics has not been sufficiently recorded, and the causal relationship has been unclear due to the difficulty of forest observation.
The research group has set up nine forest observation sites on the slopes of Mount Kinabalu in northern Borneo (Malaysia) to observe the weather and the plant seasons of tropical rainfall forests.Mount Kinabalu is covered with virgin forest up to the top of the mountain, and there are various soil types.It is suitable for studying the relationship between plant season and weather in each altitude zone and observing the interaction between weather and soil.
Analysis of the 10-year time-series data obtained at each site revealed a clear 12-month periodicity in leaf loss (leaf litter) in most forests, regardless of altitude or soil type.This suggests that meteorology on a large regional scale, rather than local meteorological, soil and biological conditions, is the driving factor for periodicity.Furthermore, by a statistical method developed independently, it was found that the subtle intra-year fluctuation of the daily average temperature accompanying the movement of the intertropical convergence zone was a factor of the periodicity.
From this result, trees respond to slight changes in temperature and cause leaf expansion and fall in a synchronous and periodic manner, which affects phytophagous insects that depend on new leaves and soil microorganisms that decompose fallen leaves. Is possible.It also suggests that global warming may cause disturbances in tropical rainforests by affecting the year-to-year fluctuations in average daily temperature.
Paper information:[Journal of Ecology] Temperature is a dominant driver of distinct annual seasonality of leaf litter production of equaltorial tropical rain forests
