Methodologies Objective and question of the study Context: Perennial crop and biodiversity: a debate Conclusions Results

Methodologies

Objective and question of the study

Context: Perennial crop and biodiversity: a debate

Brauman  Alain1_{,  Perawatchara  Monrawee}2_{,  Lafaye  De  Micheaux  Marin}1_{,  Robain  H}1_{,  Alonso  Pascal}1_{,  Nopmanee  Suvannang}2  _{,  Choosai  ChuEnan}3_{,  Sebag  David}4_{,  Chevallier}  

Tiphaine5_{,  Trap  Jean}5_{,  Gay  Frederic}6  

•  Tree  plantaEons  are  oOen  denigrated  for  their  negaEve  impact  on  natural  resources  parEcularly  loss  of  biodiversity.  

•  Rubber  plantaEons  represent  the  second  world  perennial  crop  and  most  of  natural  rubber  is    produced  in  Asia  (94%  of  world   producEon).  

•  Rubber  plantaEon  impact  on  biodiversity  is  undeniable  when  tree  plantaEon  encroached  natural  forests.    

•  However  in  Thailand  (first  world  natural  rubber  producer),  rubber  plantaEon  oOen  replaced  intensively  managed  annual  crops  

such  as  cassava.  

•  The  impact  of  this    land  use  change  on  soil  biodiversity  remains  unknown.  

u 

 Land  management  (pineapple  intercropping)  rather  than  land  use  changes    (cassava  to  rubber)  affects  the  density  and  acEvity  of  the  soil  fauna.  

u 

 PlantaEon  age  and  soil  type  are  the  main  drivers  of  soil  fauna  diversity  in  rubber  plantaEons.    

u 

 Old  rubber  plantaEons  represent  a  specific  environment  in  terms  of  soil  biodiversity  characterized  by  the  dominance  of  earthworms  and    Firmicutes.    

1  _{IRD,  UMR  ECO&SOLS,  Thailand,}  2  _{Land  Development  Department,  Thailand,}  3  _{Khon  Kaen  University,  Thailand,}  4  _{IRD,  UMR  M2C,  France,}  5  _{IRD–  UMR  ECO&SOLS,  France,}  6  _{CIRAD,  UMR}  

ECO&SOLS,  Kasetsart  University,  Thailand,  

This  research  was  funded  by  the  TICA  project,  the  LMI  LUSES  and  the  French  Ins?tute  for  Natural  Rubber  (IFC)  and  the  companies  SIPH,  SOCFIN  and  MICHELIN  

Results

5%   5%   64%   1%   4%   3%   9%   1%   1%   7%   11%   2%   57%   7%   5%   18%   4%   59%   18%   5%   14%   49%   35%   9%   1%  4%   2%   56%   13%   19%   3%  3%   1%   5%   Tot al de ns ity (ind/m ²) Cassava 1-3 y 4-6 y 8-12 y 23-25 y 35 55 75 Dermapt. Lepidopt. Diplo. Earthworms Isopt. Form. Arach. Dipt. Coleopt. Hemipt. Legend Biomass (g/m²)

 intercropping     Canopy  closure   Young  planta,ons:  High  

decrease  of  density  but   slight  structural  change  

Old  planta,ons:  increase  of  

fauna’s  biomass  and  change   of  soil  fauna  structure  at  

the  canopy  closure  

Biplot  of  redondancy  analysis   (RDA)  

Variance  parEEoning  (Venn  Diagram  )  by   soil  properEes  and  age  of  plantaEon  

Soil  proper,es  and  age  of   planta,on  are  the  main  

driver  of  soil  fauna   diversity  

III-­‐  Microbial  biomass  dynamic  

Cass 1-3 4-6 8-12 >23 Cass 1-3 4-6 8-12 >23 Cass 1-3 4-6 8-12 >23

               35.4  

10.8   60.2  

Soil  Parameters  PlantaEon  age  

Soil  engineers    

Young  planta,ons  

dominated  by  ants    

Old  planta,ons  

dominated  by  termites   and    earthworms   Fungi   Bacteria   µ g C -C o 2 g -1 So il h -1 ab a b b ab b b _b a 20-­‐25   perturbation Resilience ?

In  vivo  measurements  (substrate  induce  respira?on  )   Fields  measurements  

So il C O 2 e ffl u x ( µ m o l. m -2 .s -1 )   a a a a b 0,0   0,5   1,0   1,5   2,0  cellulose   eau   ferr  acid   glucosamine   glucose   glutamine   glycine   malic  acid   oxalic  acid   urea   vanil  acid  

Cassava   1-­‐3  y    23-­‐25  y  

23y  

10y   5-­‐6y  

1-­‐3y   _Cass  

Only  old  rubber  plantaEons  differs  significantly  from  cassava  fields  In  terms   of  microbial  parameters  (density,  acEvity,  structure  and  diversity)  

d = 1 R20-25y R8-12y R20-25y R8-12y C R1-3y R4-6y 18 %   58  %  

     

49  %   11 %   PCA  analysis   R1-3y C R4-6y PCA  analysis   Re laE ve  ab un dan ce  o f  p hy la   %     0" 20" 40" 60" 80" 100"

"""Proteobacteria" """Firmicutes" """Ac6nobacteria" """Acidobacteria"Cassava" 1;3y" 4;6y" 8;12y" 20;25y"

0   1   2   3   4   5   6   7   Cassava   RP  1-­‐3  

years   RP  4-­‐6  years   RP  8-­‐12  years   RP  23-­‐25  years  

Cassava 1-3 y 4-6 y 8-12 y 23-25 y

Cassava 1-3 y 4-6 y 8-12 y 23-25 y

IV-­‐Microbial  metabolic  profiles  

Biomass

Objec,ve  

Impact  of  land  use  change  (cassava-­‐>rubber  trees)  on  soil  biodiversity  

Ques,on  of  the  study:  What  is  the  most  important  driver  of  soil  biodiversity  

Land  use  changes  

PlantaEon  age     Soil  type    

Conclusions

V-­‐Bacterial  diversity  

I-­‐Soil  fauna  dynamic  

II-­‐What  are  the  main  driver  of  soil  fauna  diversity  

•  A   chronosequence   containing   four   classes   of   plantaEon   ages   and   cassava   field  

(the  previous  crop)  have  been  selected.    

•  Sampling   and   field   measurements   were   realised   at   the   same   Eme   in   3   blocks  

contains  a  full  sequence  of  four  age-­‐classes  of  rubber.    

Group  I 1-­‐3  y.  old   Cassava   field cassava   Group  II 4-­‐6  y.  old   Group  III 6-­‐10  y.  old   Group  IV >  23  y.  old  

•  Research   site:   Thailand,   Rubber   Research   Center   (CRRC)   Chachoengsao   Province.   Tropical   climate,  

1200  mm  annual  rainfall,  4  months  dry  seasons,  T°=28°C,  sandy  clay  type  soil.  

•  Parameters   measured:   soils   physico-­‐chemical   parameters,   soil   fauna   diversity   using   TSBF  

methodology   (Anderson   &   Ingham   (1993);   soil   microbial   physiological   profiles   (15   substrats)   using  

MicrorespTM   _{techniques   (Campbell   et   al.,   2003),   microbial   diversity   using   barcoded   pyrosequencing}  

analysis   (454)   using   universal   primer   27F   and   518R   for   bacterial   ,   and   ITS   1F   and   ITS2   for   fungal   diversity.  

AcEvity  (µresp)  

Soil  analysis   Soil  fauna  diversity   Soil  microbial  diversity