Consistently, soil moisture during 2009-2010 and 2015-2016 were 6.23+2.61 and 6.02+1.93% WFPS. These were lower than normal years which were 9.15+3.84 and 9.85+4.12% WFPS, respectively. The soil temperature was significantly higher during El Niño; 29.6+3.36 and 29.00+2.99oC than during the normal years; 26.54+1.84 and 26.41 +2.92oC (p<0.01 and 0.02 for soil moisture and soil temperature, respectively). According to the climate conditions, the study of El Niño impacts on responses of litter fall and carbon exchange in dry season was divided into 4 periods; the extreme period during 2009-2010 (1st El Niño) and 2015-2016 (2nd El Niño), the normal period during 2010- 2011 and 2014-2015. For the dry season during 2014-2015, although El Niño started on February 2015 8 but there was a lot of rainfall in April 2015, so a drought was not found. B. Shift of litter fall timing In this secondary forest, the litter fall during the study period ranged from 0.43 to 0.60 kg m-2. We found that the litter fall occurred about one month earlier and the peaks were higher during El Niño years than during the normal years. Without El Niño in 2010-2011 and 2014-2015, the litter fall peaked during February to March. Meanwhile, during the El Niño years in 2009-2010 and 2015-2016, the litter fall occurred mainly in January. The highest normalized litter fall were 0.58 and 0.47 during El Niño years while these were 0.39 and 0.41 in the normal years (Fig.2). Casco et. al., (2015) reported that several droughts led to high litter fall production 21. The declined soil moisture during high soil temperature affected litter fall production more than rising air temperature and there was a time lag for a month. A previous study Fig.2 Timing of litter fall production in dry season during the period without El Niño a) 2010- 2011 b) 2014-2015 and during with El Niño c) 2009-2010 d) 2015-2016, different letters indicate significant differences by Tukey’s HSD test at p=0.05; n=11 Proceedings of the International Conference on Climate Change, Biodiversity and Ecosystem Services for the 307 Sustainable Development Goals (SDGs): Policy and Practice 27-29 June 2016, Cha-am, Phetchaburi, Thailand
Proceedings of International Conference on Climate Change, Biodiversity and Ecosystem Services for the Sustainable Development Goals : Policy and Practice 27-29 June 2016 at the Sirindhorn International Environmental Park, Cha-am, Phetchaburi, Thailand
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