Understanding Vegetation Stress and Summer Fire Activity in Portugal

1. Vegetation stress Vegetation stress and summer fire and summer fire activity in activity in Portugal Portugal Sílvia A. Nunes, Carlos C. DaCamara, Teresa J. Calado (sanunes, cdcamara, mtcalado) @fc.ul.pt CGUL/IDL, University of Lisbon, Lisbon, Portugal March 2013

2. Motivation  Wildfires are a major problem in Portugal; the cumulated burned area since 1980 is equivalent to 3/5 of the forested surface.  Like in other regions of Mediterranean Europe, fire activity in Portugal is linked to several atmospheric mechanisms working at different temporal and spatial scales, namely the climatological background and associated weather conditions.  For instance, rainy and mild winters followed by warm and dry summers lead to high levels of vegetation stress.  The aim of this study is to assess the added-value of remote sensed information to monitor vegetation stress during the pre-fire season in Portugal and help building up scenarios of the following fire season. 2

3. Goals  Characterize the annual cycles of vegetation and temperature in Portugal and link those cycles with water and thermal vegetation stress  Relate the inter-annual variability of vegetation and temperature cycles with the inter-annual variability of fire activity in Portugal  Build up a simple model that allows anticipating the level of severity of the summer fire season in Portugal 3

4. Data  Total annual burned area in July and August, as derived from the official database supplied by Instituto de Conservação da Natureza e das Florestas (ICNF)  15-day composites of the Leaf Area Index (LAI) as derived from the GIMMS LAI3g database, with 1 km spatial resolution, covering the period from August 1981 to November 2011  Daily values of 2-m temperature as derived from ECMWF ERA-Interim reanalyzes 4

5. Severe and mild years 5

6. Severe and mild years 6

7. LAI cycle 7

8. LAI cycle 8

9. Temperature cycle 9

10. Temperature cycle 10

11. Forest cover and burnt areas 11

12. Vegetation Anomalies 12

13. Temperature Anomalies 13

14. Temperature versus LAI 14

15. Temperature versus LAI MORE BIOMASS MORE STRESS 15

16. Temperature versus LAI LESS BIOMASS LESS STRESS 16

17. LAI versus Temperature 17

18. Sugeno Model year centroid LAI=2.1 T=26.5 °C LAI=2 T=25.5 °C LAI=1.7 T=24.5 °C verbal description LAI high and temperature high LAI high and temperature moderate LAI low and Temperature low severe medium mild 18

19. Result of Sugeno model observed mild medium severe mild 7 4 0 modelled medium 0 9 0 19 severe 0 3 7

20. Conclusions S e v e r e y e a r s o f f i r e a c t i v i t y a r e a s s o c i a t e d t o S e v e r e p o s i t i v e a n o m a l i e s o f L A I i n s p r i n g ( b i o m a s s a va i l a b i l i t y ) f o l l o w e d b y p o s i t i v e a n o m a l i e s o f t e m p e r a t u r e i n s u m m e r ( f a v o ra b l e c o n d i t i o n s f o r i g n i t i o n )  M i l d y e a r s o f f i r e a c t i v i t y a r e a s s o c i a t e d t o n e g a t i v e a n o m a l i e s o f L A I i n s p r i n g ( l a c k o f b i o m a s s ) f o l l o w e d b y n e g a t i v e a n o m a l i e s o f t e m p e r a t u r e i n s u m m e r ( u n f a v o ra b l e c o n d i t i o n s f o r i g n i t i o n )  A s i m p l e v e r b a l m o d e l , u s i n g s p r i n g L A I a n d s u m m e r t e m p e r a t u r e a s p r e d i c t o r s i s a b l e t o p r e d i c t t h e l e v e l o f s e v e r i t y o f t h e s u m m e r s e a s o n  T h i s m o d e l m a y b e u s e d b y f o r e s t f i r e m a n a g e r s t o a n t i c i p a t e t h e d e g r e e o f s e v e r i t y o f t h e s u m m e r f i r e s e a s o n i n Po r t u g a l  20