Analyzing soil charcoals to assess the naturalness of tropical - - PowerPoint PPT Presentation

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Analyzing soil charcoals to assess the naturalness of tropical forest Julie Morin-Rivat 1, 2 Anas Gorel 1 , Kasso Danou 1 , Jean-Franois Gillet 1 , Nils Bourland 1 , Achille Biwol 1 , Adeline Fayolle 1 , Olivier Hardy 3 , Alexandre

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ATBC – OTS 50th Anniversary Meeting 26th of June 2013

Julie Morin-Rivat 1, 2 Anaïs Gorel1, Kasso Daïnou 1, Jean-François Gillet 1, Nils Bourland 1, Achille Biwolé 1, Adeline Fayolle 1, Olivier Hardy 3, Alexandre Livingstone Smith 2, Jason Vleminckx, Jean-Louis Doucet 1, Hans Beeckman2

1 University of Liège, Gembloux Agro-Bio Tech, Belgium 2 Royal Museum for Central Africa, Belgium 3 Free University of Brussels (ULB), Belgium

Analyzing soil charcoals to assess the naturalness of tropical forest

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Prologue: On what forest conceals

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Chapter 1: On the history that soil reveals

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Chapter 1: On the history that soil reveals

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Cameroon

Chapter 2: On why, when and where it happened

FRFC project (FRS/FNRS, Belgium): “Population dynamics of light- demanding trees and herbs in the dense forests of Central Africa in relationship with climatic and anthropogenic disturbances”

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Chapter 2: On why, when and where it happened To find evidence for and to characterize past human presence

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Chapter 2: On why, when and where it happened

Forest company SFID-Mbang (concession) Alongside the transect, 3 sites of 4,8 km each A each site, up to 20 plots of botanical inventory Soil sampling by layers of 10 cm

Plot of botanical inventory Central pits for anthracology (50 x 50 x 60 cm in depth) Soil samples (auger) Central transect

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Chapter 3: On why soil charcoal is an ideal archive

Time Space

Botanical inventories Short term evaluation Local signal

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Chapter 3: On why soil charcoal is an ideal archive

Time Space

Palaeoecological proxies Long term processes Regional signal

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Chapter 3: On why soil charcoal is an ideal archive

Time Space

Long term processes Local signal Soil charcoals

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Chapter 3: On why soil charcoal is an ideal archive

Time Space

Long term processes Local signal

Pedoanthracology

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Chapter 3: On why soil charcoal is an ideal archive

  • Ubiquitous
  • Well preserved
  • Easily extractable
  • Quantitative
  • Carbonization conserves wood anatomy
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Chapter 4: On the extent to which anthracologists are crazy

53 pits

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Chapter 4: On the extent to which anthracologists are crazy

  • ca. 2500 kg

(+ ca. 5200 kg from other pedological pits)

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Chapter 4: On the extent to which anthracologists are crazy

318 samples

(+ ca. 405 from other pedological pits)

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Chapter 4: On the extent to which anthracologists are crazy

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Chapter 4: On the extent to which anthracologists are crazy

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Chapter 4: On the extent to which anthracologists are crazy

823 samples

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Chapter 4: On the extent to which anthracologists are crazy

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Chapter 4: On the extent to which anthracologists are crazy

10 14C dates

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Chapter 4: On the extent to which anthracologists are crazy

Excavating Transporting Sieving Sorting Selecting Dating Weighing Counting Analyzing Mapping

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Chapter 4: On what soil charcoals taught us

Charcoals (g) Other seeds (g) (non identified yet) Oil palm endocarps (g)

Charred botanical remains are not correlated

  • seeds ~ charcoals (R=0.020, p>0,05)
  • oil palm ~ charcoals (R=-0.012, p>0,05)
  • seeds ~ oil palm (R=0.027, p>0,05)
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Chapter 4: On what soil charcoals taught us

Charcoals (g) Other seeds (g) (non identified yet) Oil palm endocarps (g)

Charred botanical remains are not correlated

  • seeds ~ charcoals (R=0.020, p>0,05)
  • oil palm ~ charcoals (R=-0.012, p>0,05)
  • seeds ~ oil palm (R=0.027, p>0,05)

Represent different signals

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Chapter 4: On what soil charcoals taught us

Charcoals by site and by depth Site 1 Site 2 Site 3

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Chapter 4: On what soil charcoals taught us

Charcoals by site and by depth Site 1 Site 2 Site 3

Fields

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Chapter 4: On what soil charcoals taught us

Oil palm endocarps by site and by depth Site 1 Site 2 Site 3

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Chapter 4: On what soil charcoals taught us

Oil palm endocarps by site and by depth Site 1 Site 2 Site 3

Villages

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Chapter 4: On what soil charcoals taught us

Orbs of influence of ancient villages (4th c. BC – 3th c. AD) Slash-and-burn agriculture

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Chapter 5: On the implications for conservation

Systematic sampling with simple tools The forest investigated is not natural

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Chapter 5: On the implications for conservation

Systematic sampling with simple tools The forest investigated is not natural

The biggest pedoanthracological sampling for tropical Africa

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Chapter 5: On the implications for conservation

Human was present long time ago (Bantu initial spread ca. 2000 yr ago) Other results on more recent human activities (last centuries):

(Oslisly et al. & Morin-Rivat et al. in press)

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Chapter 5: On the implications for conservation

Human was present long time ago (Bantu initial spread ca. 2000 yr ago) Other results on more recent human activities (last centuries):

(Oslisly et al. & Morin-Rivat et al. in press)

Secondary forest is

  • nly about 2

centuries old

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Chapter 5: On the implications for conservation

Study on Pericopsis elata (N. Bourland) Gregarious, endangered species (IUCN) Gaussian structure of population > Problems of regeneration Weak correlation with soil nutrients

Strong correlation with charcoal abundance Need of larger gaps to regenerate

e.g. slash-and-burn agriculture

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Chapter 5: On the implications for conservation

Study on Pericopsis elata (N. Bourland) Gregarious, endangered species (IUCN) Gaussian structure of population > Problems of regeneration Weak correlation with soil nutrients

Strong correlation with charcoal abundance Need of larger gaps to regenerate

e.g. slash-and-burn agriculture

Light-demanding spp. are closely related to disturbances

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Epilogue: On what will be done next

New 14C dates

(evidence for more recent human settlements)

Relationship with traits

(assemblages of traits during the past)

Environmental reconstruction

(age of the trees, charcoal taxonomical identification)

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Epilogue: On what will be done next

New 14C dates

(evidence for more recent human settlements)

Relationship with traits

(assemblages of traits during the past)

Environmental reconstruction

(age of the trees, charcoal taxonomical identification)

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CoForChange project (ERANet BiodivERsA – NERC/UK – ANR/Fr) www.coforchange.eu Nature+ asbl. (Belgium) FRIA (F.R.S./FNRS, Belgium) The forest companies SFID Mbang (Rougier Group) and Pallisco

Analyzing soil charcoals to assess the naturalness of tropical forest

Julie Morin-Rivat et al. jmorin@doct.ulg.ac.be

ATBC – OTS 50th Anniversary Meeting 26th of June 2013

Acknowledgements

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