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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

Jonsson  and  Eklundh  in  TIMESATsoftware  packagewas  used  to  fit  the  curve  of  time  series data  following  second  order  polynomial  and  to extract  the  following  phenological  metrics  19,  20,  21,  22.  - Start  of  growing  season  (SOS):  This  is  defined  as  the  dates  of  leaf  unfolding, this  study  considered  SOS  as  a  date  when  NDVI  increases  to  5%  of  the  amplitude  during  the  beginning  period  of  the  NDVI  time  series.  For  the  series  of  NDVI  in  a  given  NDVImax  year,  is  the  maximum  of  NDVI  and  NDVImin  is  minimum  of  NDVI  in  the  first  half  of  the  year.  NDVIstart  was  calculated  as  follows;  - End  of  the  season  (EOS):  This  is  defined  as  the  dates  leaf  discoloration  and  leaf  fall  at  the  end  of  season.  This  study  considered  EOS  as  a  date  when  NDVI  decreases  to  5%  of  the  amplitude  during  the  ending  period  of  the  NDVI  time  series.  NDVIend  was  calculated  as  follows; -   Length  of  the  growing  season  (LOS)  is   the  number  of  days  of  growth  from  the start  to  the  end  of  this  season.  The  results  of  5%  changing  in  NDVI  value  from  minimum  for  SOS  and  EOS  agreed to  the  transition  date  of  LAI  index  and  NLR,  therefore  this  threshold  has  been  applied  for  extracting  seasonality  data  such  as  start,  end  of the  season  and  the  length  of  the  season  in  this  study. 2)  Relationship  between  NDVI  and  Climate  Factors:  Daily  data  at  the  meteorological station  in  Lampang  Province  were  aggregated  to  an  8  day  period  by  calculating  average  for  temperature  and  accumulated  precipitation.  Base  on  the  distribution  of  data,  the  non- parametric  Spearman  was  applied  to  check  the  correlation  coefficient  between  NDVI  and  climate  factors  23. III.  RESULTS  AND  DISCUSSION A.  NDVI  Time  Series  of  Teak  Plantation The  variation  of  NDVI,  precipitation,  minimum  and  maximum  temperature  at  Teak  plantation  are  shown  in  Fig.2,  3  and  4  respectively.Rainy  season  starts  between  March to  May,  the  same  time  as  the  teak  leaf  starts  to bud  reflecting  the  gradual  increase  of  NDVI  values.  Rainy  season  ends  between  October  and  November,  corresponding  to  the  decrease  of  NDVI  values  in  this  period  of  time  (Fig.2). During  April  which  is  the  hottest  month,  NDVI  value  was  lowest,  indicating  the  leafless  period  of  teak  plantation.  NDVI  values increased  from  0.35-0.40  to  0.75-0.80  during  May  to  October,  and  then  it  decreased  in  November  and  December  (Fig.3,  4).  Growing  season  ended  in  January,  February  or  March  in different  areas. The  linear  correlation  between  NDVI  with  LAI  and  NLR  was  found,  confirming  the  cloud  free  data  set.  It  was  found  that  NDVI  was  significantly  correlated  with  LAI  (r=0.81,  p<0.0001),  and  NLR  (r=0.77,  p<0.0001)  (Fig.6).  This  correlation  is  consistent  with  other  previous  reports.  For  example,  the  relationship  between  NDVI  and  field  measured LAI  in  deciduous  forests  were  reported  by  Madugundu  et  al.  24.  In  their  study,  NDVI  was  strongly  correlated  with  LAI  (r2=0.68,  p≤ 0.05)  but  showed  evidence  of  saturation  above  a  biomass  of  100  g/m2  and  an  LAI  of  2  m2/m2 25.  Potithep  et.  al.  23  has  also  found  that  NDVI  changes  in  relation  to  the  seasonal  variations  of  LAI  26.  These  results  indicate  that  the  preprocessing  NDVI  derived  from  satellite  is  sufficient  to  capture  the  teak  forest  phenology. Proceedings  of  the  International  Conference  on  Climate  Change,  Biodiversity  and  Ecosystem  Services  for  the 277 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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