Final presentation of Bachelor internship

1. Physico-chemical properties and litter decomposition
in forested ponds in the forest of Chinon
TRAN Ngoc Bich
USTHBI3-010
Supervisors: Assoc. Prof. Dr. Séraphine GRELLIER
Assoc. Prof. Dr. Francis ISSELIN
CItés, TERritoires, Environnement, Sociétés (CITERES), UMR 7324 CNRS.
Université François Rabelais de Tours, France
1

2. Outline
• Introduction
• Methods and materials
• Results and Discussion
• Conclusion
Outlines
2

3. Introduction Methods and Materials Results and Discussion Conclusion
Forested ponds
Tran N.B.
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Late winter
Spring
Natural ephemeral/temporary
wetland: Seasonal hydrological cycle
Tran N.B.
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Source: ONF
Source: ONF
Molinia caerulea
Sphagnum palustre
Triturus marmoratus
Triturus cristatus
Species-rich
vegetation belts
Breeding habitat for
many endemic species
Must be maintained and restored !
Forested
ponds3

4. Restoration of forested ponds in Chinon
Forest plantation in 1970s
- Drainage
- Filling of forested ponds
 Destruction &degradation
National Biodiversity Strategy
- Reshaping
- Canopy clearance
- Scraping of filled ponds
 Restore ecological continuity
GEREZOH – Ecological Engineering
for Wetland Restoration
Studies of ecological and
hydrological characteristics of the
forested ponds
Benefits of restoration work?
Source: Google maps
Source: Geoportail
Introduction Methods and Materials Results and Discussion Conclusion
Restoration of forested ponds in Chinon
4

5. Objectives
Objectives
Introduction Methods and Materials Results and Discussion Conclusion
Monitoring 6 parameters (pH, DO, ORP, EC, …)
over three years after restoration and comparing
to reference ponds
Assessing the decomposition rate of leaf litter in
restored ponds, comparing to reference ponds
Physico-chemical properties Litter decomposition
Assessing the benefits of restoration work
5

6. Study Site
Forested ponds
Map: IGN Paris
Ponds: CNRS - F.Isselin
Introduction Methods and Materials Results and Discussion Conclusion
Study site
6
Map: IGN Paris
Ponds: CNRS - F.Isselin
9 Reference ponds
- Favorable condition
- Non-restored
5 Ponds outside network
- Forest fire limitation
- Distantly isolated
>30 Restored ponds
- Degraded
- Restored in 2012

7. Physico-chemical properties monitoring
Hydro
coefficient
Relative water level of
the pond
0 Dry
1 Humid soil
2 1/8 of maximum volume
3 1/4 of maximum volume
4 1/2 of maximum volume
5 3/4 of maximum volume
6 Maximum volume
7 Overflow
Hydro coefficient grading system Physico-chemical parameters measurement
In-situ multi-parameter probes
Dissolved Oxygen
Conductivity
Redox potential (ORP)
pH
Average
temperature
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Source: HACH
• Measurement every two weeks
• No measurement when too little water (Hydro coefficient <3)
Repeated-
measurement
ANOVAs
Responses
Hydro coefficient,
Conductivity, DO, ORP,
pH, Temperature
Factors
-Types of ponds: restored,
reference, outside network
- Week of measurement
2013, 2014,
and 2015
data
Introduction Methods and Materials Results and Discussion Conclusion
Physico-chemical properties monitoring 7

8. Litter decomposition experiment
1 Restored pond 1 Reference pond
Tran N.B. Tran N.B.
Spatially replicated transects
Litterbag
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- Size: 11×11×2 cm
- Mesh-size: 3mm
- Decomposing material:
3.0±0.2 g of air-dried oak
tree leaves
(Q. Penduculata )
3 Habitat zones
Introduction Methods and Materials Results and Discussion Conclusion
Litter decomposition experiment
8
Forest soil
Transition
Center
Highest
water
level

9. Litter decomposition experiment
After 1 month
Litterbag recovery
Mass loss
determination
Cleaning
Oven-drying
Weighing
Litter elemental
analysis
Grinding to fine powder
CHNS-O analyzer
Retrieved litterbags
Mass loss (%) = [Final weight – Initial weight]/100
Change in total C,N, or H = (final weight × final %) – (initial weight × average initial %)
%C
%N
%H
Data
analyses
2-way ANOVAs
Responses:
Mass loss,
%C, %H, %N
Change in total
C, H, N
Factors:
- Types of ponds
- Habitat zone
Introduction Methods and Materials Results and Discussion Conclusion
Tran N.B.
Tran N.B.
Tran N.B.
Tran N.B.
Tran N.B.
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Source: Thermo Fisher
Litter analyses 9

10. Physico-chemical properties
3
3.5
4
4.5
5
5.5
6
6.5
7
pH
10
30
50
70
90
110
2-Apr 30-Apr 28-May 25-Jun 23-Jul
Conductivity(µS/cm)
28-Apr 26-May 23-Jun 27-
Apr
11-
May
2013 2014 2015
Introduction Methods and Materials Results and Discussion Conclusion
Higher pH
Outside network: Different trend
pH and conductivity
Reference : Higher conductivity than Restored
10

11. Physico-chemical properties
0
5
10
15
20
25
30
Temperature(°C)
0
1
2
3
4
5
6
7
2-Apr 30-Apr 28-May 25-Jun 23-Jul
Hydrocoefficient
2013
28-Apr 26-May 23-Jun
2014
27-
Apr
11-
May
2015
Introduction Methods and Materials Results and Discussion Conclusion
Temperature and Hydro
coefficient
Higher temperature
Higher water level
Restored: wide variance range
11

12. Physico-chemical properties
0
2
4
6
8
10
12
DO(mg/L)
50
150
250
350
450
2-Apr 30-Apr 28-May 25-Jun 23-Jul
ORP(mV)
2013
27-Apr
11-May
2015
Introduction Methods and Materials Results and Discussion Conclusion
DO and ORP
Restored: Higher DO than Reference
Outside network: Different trend
 The ponds
outside network
showed 5 out of 6
properties different
from restored and
reference ponds
12
 Restored and
reference ponds had
5 out of 6 properties
similar (except
conductivity)

13. Litter decomposition
12.67 11.4412.08 12.339.25 9.56
8.00
9.00
10.00
11.00
12.00
13.00
14.00
Reference Restored
Massloss(%)
Ponds
Center Transition Forest soil
Introduction Methods and Materials Results and Discussion Conclusion
-145.4 -141.3-135.0 -156.5-105.3 -124.1
-190.0
-170.0
-150.0
-130.0
-110.0
-90.0
ChangeinTC(mg)
Mass loss and change in TC
46.0 45.546.2 45.445.9 45.2
44.0
44.5
45.0
45.5
46.0
46.5
Reference Restored
Ccontent(%)
Lower decomposition rate
%N, %H, C:N, Change in Total N
and Total H were not significantly
different among zones and ponds
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14. Conclusion
 Restored and reference ponds had similar properties and
decomposition rate during study period
 Positive result for the ecological continuity and restoration
 Decomposition rate is higher in forested ponds than in forest soil
 Forested ponds help enhance litter decomposition in the forest
 Forested ponds outside network showed different properties
from the ponds in the network
 Forested ponds were potentially linked when located in the
same area
Introduction Methods and Materials Results and Discussion Conclusion
conclusion 15

15. Acknowledgements
Séraphine Grellier Francis Isselin Pauline Hervé
Aurélie Thaureau
The end
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