Tropical forest dynamics: drought, fire and degradation

Transcription

1 Tropical forest dynamics: drought, fire and degradation Ted R. Feldpausch main Univ Exeter collaborators: L. Aragão, C. Belcher, L. Carvalho, T. Hill, L. Rowland, L. Mercado, S. Sitch, R. Betts

2 Group Themes/projects T1: Old-growth forest dynamics How do droughts affect Amazonian forests and savannas? Approach: Analysis of long-term growth and mortality census data (UNEMAT, RAINFOR) T2: Contemporary forest degradation and recovery: How do nutrient limitations affect tropical forest regrowth? Approach: nutrient addition experiment (INPA) Contemporary fire effects on forest dynamics, structure, and composition? Approach: Permanent forest plots and airborne LIDAR, RS (SilvaCarbon Fund, CAPES, Met Office)

3 Group Themes/projects T3: Long term (centennial-scale) changes in tropical forests Forest advance into savanna along the Amazon Arc of deforestation over the last 10k years? Approach: Soil delta 13 C analysis along a 1000 km forestsavanna transect (CNPq, PPBio, NERC) Historical fire effects on forest dynamics, structure, and composition? Basin-wide soil charcoal, radiocarbon dating, forest plots, climate, LIDAR RS (NERC; CAPES) Drivers and contribution of charcoal to Amazon Basin-wide soils? Approach: Study of pyroc to 2 m depth across Amazonia (NERC)

4 T1: intact forests dynamics Drivers of biodiversity and C Long- term changes Role of changing climate

5 intact forests dynamics Long- term C sink Amazon Pg C yr - 1, around 25% of the residual terrestrial carbon sink Rate of C gain is declining N JAS PNY Kilometres ACL PTN MIN ALP MNU BAC LOR DOI CUZ CLA SCR RET LCA BEE RIO FMH ROM BDF HCC PTB ALF TAP VCR NOU AGB biomass change (Mg ha-1 yr-1) CAX MRB CPP 1 to 2 0 to 1 0 to -1-1 to Brienen, Phillips, Feldpausch et al Nature

6 Thirty years Drought a sink effects B net change anomaly drought shut down C sink Mg ha -1 yr -1 (-1.11, 0.19) impact driven by increase in biomass mortality 1.45 Mg ha -1 yr -1, p < and decline in biomass productivity Mg ha -1 yr -1, p < Latitude 10 N 5 N 0 5 S 10 S 15 S 70 W 60 W 50 W Longitude Feldpausch et al GBC

7 Droughts 2005, 2007, 2010 Good news? No interaction between multiple droughts However, El Nino 2015

8 T2: Forest management, degradation, and recovery Forest degradation by fire and logging in Brazilian Amazon equivalent in area to deforested land (INPE 2016 DEGRAD; Aragao et al. 2010) World s tropical forests net C source, ± 92.0 Tg C yr 1 Losses of ± 80.2 Tg C yr 1 and gains of ± 31.0 Tg C yr 1. Losses from degradation account for ~70% of overall losses (Baccini et al. 2017)

9 Biomass resilience of neotropical secondary forests Above ground biomass (Mg/ha) Age (years) Poorter et al Nature

10 T2: Forest management, degradation, and recovery >half of the world s tropical forests not old- growth, but naturally regenerating forests (FAO 2010) Studying: Process of degradation and recovery e.g., C, nutrients, burning, management, logging Recuperation of processes Fertilizer experiment; natural regeneration Time for recovery? Resilience and climate

11 No fire Burned 1999 Fire Studying: Tree mortality Carbon (veg. and soils) Changes in species composition Functional traits Burned 2010 Burned 3x Richness recovers 2 decades after fire Diff. in composition most pronounced for small trees (<2.5 cm D) Prestes, Feldpausch et al Species richness Number of individuals Morton et al. 2013

12 T3: Long term changes (centennial- scale) changes in tropical forests Drivers of C uptake When is a secondary forest an old- growth? Feldpausch et al. unpublished data

13 Determining drivers Old- growth - CO 2 Disturbance Biomass [CO 2 ] effect ~400 kg C ha - 1 yr - 1 Biomass Disturbance effect Overestimate [CO 2 ] effect Studying: Time Centennial- scale fires Effects on vegetation and soil C storage, biodiversity, dynamics Drivers and contribution of pyrogenic C to Amazon Basin- wide soils Time since last fire Kills 50-90% of small stems Trees <20 cm D: 500 to 900 yrs Fire reduces carbon accumulation rates by 50% (Zarin et al. 2005; Feldpausch et al. 2007) Photo credit: J. Barlow

14 Conclusions Drivers of C uptake Intact tropical forests a long- term C sink (but declining) C response to drought Range of rates of C recovery (exploring drivers) Fire important driver of change affecting forest structure/composition and soil (exploring long- term effects)

15 Projects 'Do past fires explain current carbon dynamics of Amazonian forests? (NE/N011570/1): Feldpausch, T.R. (PI); Co- I: L. Aragão, C. Belcher, O. Phillips; Project Partners: M. Bird, C. Quesada, K. Macario 'Fire and pyrogenic carbon in tropical forests CAPES: Feldpausch, T.R. (PI); Project Partners : B.H. Marimon Junior, B. Marimon, C. Quesada, M. Bird, K. Macario 'Effects of El Niño and fire on Colombian forests', T. Feldpausch (PI), L.C.S Carvalho (co- I), E. Alvarez- Dávila (project partner, Colombia) 'Biomass and fire in degraded forests: Evaluation using airborne LIDAR remote sensing' SilvaCarbon Fund: Keller, M. (PI); Feldpausch, T.R. (Co- I) 'Cerrado- Amazonia Transition: ecological and socio- environmental basis for conservation' - Long- Term Ecological Research Network, CNPq- Brazil: B.S. Marimon (PI), Project partners: B.H. Marimon, O. Phillips, R. Brienen, T.R. Feldpausch Forest Network (ReFlor): biodiversity, climate change, and biotechnology in the 'Arc of Deforestation', Brazil, FAPEMAT: PI B.H. Marimon, Rafael Soares de Arruda (co- I), Project partners: B.S. Marimon, O. Phillips, E. Gloor, T.R. Feldpausch 'Lightning: An invisible driver of tree mortality in the tropics?' NERC (NE/P001564/1): Hill, T. (PI); Co- I: T.R. Feldpausch, E. Mitchard, M. Haddad; Project Partners: G. Chuyong, H. Chapman, J. Elworthy, L. Rowland, D. Mitchard 'Phytogeography and paleovegetation of the Amazon/Cerrado transition in Mato Grosso, Brazil' FAPEMAT: Marimon, B.H. (PI);Feldpausch, T.R. (Project Partner) 'Phytogeographic characterization, species distribution, and woody vegetation determinants in the Cerrado / Amazonia transition CNPq: Marimon Junior, B.H. (PI); Feldpausch, T.R. (Project Partner)