Climate-related Changes in Tropical-fruit Flowering Phases in Songkhla Province, Southern Thailand

Abstract

Changes in the timing of plant phenological phases in response to anomalous climate variability and the ongoing anthropogenic climate change have recently been studied in southern Thailand. In this study, we showed the evidence of climate-related changes in flowering phases of 2 tropical-fruit species: mangosteen (<em>Garcinia mangostana</em> L.) and longkong (<em>Lansium domesticum</em> Corr.) during 2003-2012. The flowering dates of these tropical fruits recorded at Hat Yai district, Songkhla province and daily climate data were used to assess phenophase response to variations in rainfall and evaporation. With the observed changes in local climate conditions which are defining factors for phenological development of tropical fruits particularly in southern Thailand, the flowering dates of both tropical fruits during 2003-2012 have significantly delayed comparing with the regular pattern in the past. Paradoxically, below-than-normal rainfall was also found in the El Niño years, while La Niña years were found in opposite. In summary, rainfall variations in Hat Yai district, Songkhla province are associated with ENSO. It was evident that the flowering period of tropical fruits tended to shift to the second-half of the year instead of the first- half of the year as usual. The results revealed that, during 33 years (1980-2012), annual rainfall totals, the annual number of rainy days, relative humidity, maximum and minimum temperatures from the Thai Meteorological Department significantly increased by 29.5 mm/year, 0.83 day/year, 0.116 %/year, 0.033 and 0.035°C/year, respectively. These findings suggest that anthropogenically warm climate and its associated inter-annual variations in local weather patterns may to the great extent influence on tropical-fruit phenology and their responses to recent climate change seem to be complex and nonlinear. Therefore, further study is needed to shed more light on such causal-effect linkages and plausible underlying mechanisms.