Inter-annual variation in growing season length of a tropical seasonal forest in northern Thailand

Tropical seasonal forests play an important role in global cycling of carbon, water and energy in terms of inter-annual variation in the growing season. We investigated year-to-year variations in the canopy duration and transpiration period as measures of growing season length using time series data of radiative transmittance and sap flux in a teak plantation in Thailand over a 3-year period. In 2001, leaf-out and tree transpiration commenced earlier than in 2002 and 2003 following exceptionally heavy rainfall in the late dry season, strongly suggesting that enhanced soil moisture advanced the timing of leaf unfolding and commencement of tree transpiration. The commencement of leaf-fall and decline in tree transpiration at the beginning of 2003 were late in coming in correlation with a prolonged rainy season. Declines in tree transpiration were directly controlled by soil moisture conditions at the beginning of the dry season, with time lags between the timing of leaf-fall and decline in tree transpiration. These results revealed that soil moisture conditions are a major determinant of large inter-annual variation in the growing season at this site. The variation in canopy duration and transpiration period in this study, from 2001 to 2004, spanned about 40 and 60 days, respectively. This was much larger than the inter-annual variations previously reported in temperate deciduous forests, implying a profound potential impact on surface energy balance and canopy-atmosphere water and carbon exchange on an annual time scale. # 2006 Elsevier B.V. All rights reserved.

[1]  T. Black,et al.  Inter-annual variability in the leaf area index of a boreal aspen-hazelnut forest in relation to net ecosystem production , 2004 .

[2]  Derek Eamus,et al.  Does irrigation affect leaf phenology in deciduous and evergreen trees of the savannas of northern Australia , 1998 .

[3]  S. Running,et al.  The impact of growing-season length variability on carbon assimilation and evapotranspiration over 88 years in the eastern US deciduous forest , 1999, International journal of biometeorology.

[4]  James M. Vose,et al.  Seasonal changes of leaf area index (LAI) in a tropical deciduous forest in west Mexico , 1995 .

[5]  R. Borchert,et al.  Modification of Vegetative Phenology in a Tropical Semi-deciduous Forest by Abnormal Drought and Rain1 , 2002 .

[6]  R. Borchert.  Climatic Periodicity, Phenology, and Cambium Activity in Tropical Dry Forest Trees , 1999 .

[7]  Dennis D. Baldocchi,et al.  Seasonal and interannual variability of energy fluxes over a broadleaved temperate deciduous forest in North America , 2000 .

[8]  N. Jensen,et al.  Similar net ecosystem exchange of beech stands located in France and Denmark , 2002 .

[9]  S. Allen,et al.  Measurement of sap flow in plant stems , 1996 .

[10]  S. Kanae,et al.  Impact of Deforestation on Regional Precipitation over the Indochina Peninsula , 2001 .

[11]  Yoshinobu Sato,et al.  Water cycling in a Bornean tropical rain forest under current and projected precipitation scenarios , 2004 .

[12]  Ramakrishna R. Nemani,et al.  Canopy duration has little influence on annual carbon storage in the deciduous broad leaf forest , 2003 .

[13]  Wenjun Chen,et al.  Increased carbon sequestration by a boreal deciduous forest in years with a warm spring , 2000 .

[14]  J. Tenhunen,et al.  Long-term variations in leaf area index and light extinction in a Fagus sylvatica stand as estimated from global radiation profiles , 2004 .

[15]  R. Closs.  The heat pulse method for measuring rate of sap flow in a plant stem. , 1958 .

[16]  K. E. Moore,et al.  Detecting leaf area and surface resistance during transition seasons , 1997 .

[17]  Nobuko Saigusa,et al.  Gross primary production and net ecosystem exchange of a cool-temperate deciduous forest estimated by the eddy covariance method , 2002 .

[18]  Katsunori Tanaka,et al.  Transpiration peak over a hill evergreen forest in northern Thailand in the late dry season: Assessing the seasonal changes in evapotranspiration using a multilayer model , 2003 .

[19]  J. William Munger,et al.  Exchange of Carbon Dioxide by a Deciduous Forest: Response to Interannual Climate Variability , 1996, Science.

[20]  Dennis D. Baldocchi,et al.  Solar radiation within an oak—hickory forest: an evaluation of the extinction coefficients for several radiation components during fully-leafed and leafless periods , 1984 .

[21]  R. Borchert,et al.  Soil and Stem Water Storage Determine Phenology and Distribution of Tropical Dry Forest Trees , 1994 .

[22]  S. Running,et al.  A continental phenology model for monitoring vegetation responses to interannual climatic variability , 1997 .

[23]  J. Lean,et al.  Simulation of the regional climatic impact of Amazon deforestation , 1989, Nature.

[24]  R. Borchert,et al.  Water status and development of tropical trees during seasonal drought , 1994, Trees.

[25]  H. Mayer,et al.  Measuring and modelling plant area index in beech stands , 2004, International journal of biometeorology.

[26]  A. McGuire,et al.  Global climate change and terrestrial net primary production , 1993, Nature.

[27]  Y. Malhi,et al.  Tropical forests and atmospheric carbon dioxide. , 2000, Trends in ecology & evolution.

[28]  K. E. Moore,et al.  Seasonal Variation in Radiative and Turbulent Exchange at a Deciduous Forest in Central Massachusetts , 1996 .

[29]  Peter B. Reich,et al.  PHENOLOGY OF TROPICAL FORESTS : PATTERNS, CAUSES, AND CONSEQUENCES , 1995 .

[30]  Hans Peter Schmid,et al.  Measurements of CO2 and energy fluxes over a mixed hardwood forest in the mid-western United States , 2000 .