Rubber plantapon impact on biodiversity is undeniable when tree plantapon ... The impact of this land use change on soil biodiversity remains unknown.
Brauman Alain1, Perawatchara Monrawee2, Lafaye De Micheaux Marin1, Robain H1, Alonso Pascal1, Nopmanee Suvannang2 , Choosai ChuEnan3, Sebag David4, Chevallier Tiphaine5, Trap Jean5, Gay Frederic6 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,
Context: Perennial crop and biodiversity: a debate • 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.
Objective and question of the study Ques,on of the study: What is the most important driver of soil biodiversity
Objec,ve Impact of land use change (cassava-‐>rubber trees) on soil biodiversity
PlantaEon age
Land use changes
Soil type
Methodologies 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.
• •
Cassava field
cassava
•
Group IV
Group III
4-‐6 y. old
1-‐3 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.
•
Group II
Group I
> 23 y. old
6-‐10 y. old
AcEvity (µresp) Diversity (454) Soil analysis
Soil fauna diversity
Soil microbial diversity
Results 7% 5% 5%
9% 4%
3%
11%
18%
1% 4%
2%
2% 3%
5%
1%
Canopy closure
14%
4%
64%
57%
49%
18%
59%
5%
9%
5%
7%
3% 1%
19% 56%
35%
13%
Biomass
Cassava Legend
1-3 y
Biomass (g/m²)
35
55
75
4-6 y
8-12 y
23-25 y
Earthworms
Dipt.
Dermapt.
Isopt.
Coleopt.
Lepidopt.
Form.
Hemipt.
Diplo.
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
Fungi
b
Cassava
PlantaEon age
Cass
60.2
10.8 35.4
1-3 y
Soil proper,es and age of planta,on are the main driver of soil fauna diversity
23y
cellulose 2,0 1,5
b
b
4-6 y
8-12 y
eau
0,5 0,0
Cassava
7
b
6 5
a
4
a
a
a
3 2 1 0
Cassava RP 1-‐3 Cassava 1-3 y years
23-2520-‐25 y
RP 4-‐6 4-6 y years
RP 8-‐12 RP 23-‐25 8-12 y 23-25 years years y
PCA analysis R20-25y
ferr acid
glucosamine
R8-12y R4-6y
C R1-3y
glucose
glycine
glutamine
1-‐3 y
23-‐25 y
49 %
V-‐Bacterial diversity
PCA analysis
100"
d=1
18%
80"
R20-25y
C R1-3y
60"
R8-12y 40" R4-6y
20"
0"
58 % Cassava"
1;3y"
4;6y"
8;12y"
20;25y"
"""Proteobacteria" """Firmicutes" """Ac6nobacteria" """Acidobacteria"
10y
Biplot of redondancy analysis (RDA)
b
malic acid
RelaEve abundance of phyla %
Old planta,ons dominated by termites and earthworms
II-‐What are the main driver of soil fauna diversity
1-‐3y
b
1,0
oxalic acid
Young planta,ons dominated by ants
Soil Parameters
a
IV-‐Microbial metabolic profiles
Soil engineers
5-‐6y
a
ab
urea
Cass 1-3 4-6 8-12 >23
Resilience ?
ab
vanil acid
Cass 1-3 4-6 8-12 >23
Bacteria
perturbation
Arach.
Cass 1-3 4-6 8-12 >23
Fields measurements
In vivo measurements (substrate induce respira?on ) Soil CO2 efflux (µmol.m-2.s-1)
intercropping
11%
1% 1%
III-‐ Microbial biomass dynamic µg C-Co2 g-1 Soil h-1
Total density (ind/m²)
I-‐Soil fauna dynamic
Only old rubber plantaEons differs significantly from cassava fields In terms of microbial parameters (density, acEvity, structure and diversity)
Variance parEEoning (Venn Diagram ) by soil properEes and age of plantaEon
Conclusions
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. u
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
