Evaluation of biogeochemical soil parameters as a ... · The Maputaland Coastal Plain in between...
Transcript of Evaluation of biogeochemical soil parameters as a ... · The Maputaland Coastal Plain in between...
Marvin Gabriel, Franziska Faul, Niko Roßkopf, Jutta Zeitz Humboldt-Universität zu Berlin Division of Soil Science and Site Science
Evaluation of biogeochemical soil parameters as a requirement for restoration of peatlands on the Maputaland Coastal Plain, South Africa
Structure 1. Background and Study Area 2. Approach and Objectives 3. Intermediate Results: Soil Properties 4. Conclusions and Prospect
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1. Background and Study Area
based on National Geographic World Map
Average Temperature 22,2 °C Average annual precipitation 947mm Transition between tropics and subtropics
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1. Background and Study Area
after Lacher 1983
Climate
The Maputaland Coastal Plain in between the Lebombo Mountains (left) and the Indian Ocean (right) Surface is covered by dune sands
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1. Background and Study Area
changed after A. Grundling 2014
Landscape
Distorted relief map of the Maputaland Coastal Plain
Indian Ocean
Lebombo Mountains
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1. Background and Study Area
Peatlands on the Maputaland Coastal Plain
AllWet-RES (Alliance for Wetlands, Research and Restoration)
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1. Background and Study Area
Stakeholder opinion
and land-user needs
Soil properties
and restorability
Wetland ecology
and hydrology
AllWet
Impact of
land use
Studies on and demonstration of alternative
land use options
Website: http://www.allwet.hu-bodenkunde.de/ after: Kollmann et al. 2013
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2. Approach and Objectives
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2. Approach and Objectives
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Peat properties as proxies for degradation
2. Approach and Objectives
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2. Approach and Objectives
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Objective 1: Determine typcial peat substrates for hydrogeo-morphologic peatland types (Poster P12)
Objektive 2: Attribute properties to substrates (of differ-ent stages of decomposition) as proxies for degradation
- Secondary soil formation - Degree of decomposition - Bulk density - C-Content - Saturated hydraulic conductivity - Hydrophobicity
Objective 3: Evaluate and anticipate the impact of degradation on each hydrogeomorphic peatland type
2. Approach and Objectives
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Based on a google earth image
So far:
-3 hydrogeomorphic peatland types
-7 sites
-14 transects
-128 profiles
F. Faul
F. Faul
Fieldwork: Transect based peatland exploration
2. Approach and Objectives
3. Intermediate Results: Soil Properties
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Secondary soil formation Method: Field survey Observations: -Earthification -Murshic tendencies (WRB 2014) -No fully developed murshic horizons M. Gabriel
3. Intermediate Results: Soil Properties
Bulk density vs. degree of decomposition Tendency of higher bulk density with higher decom- position
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N. Guerrero-Moreno
Method: Squeezing test after von Post
3. Intermediate Results: Soil Properties
C-Content vs. Bulk density Method: Lab determination with element analyser
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R² = 0,614
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0,00 0,20 0,40 0,60
C-Co
nten
t [%
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bulk density [g/cm³]
3. Intermediate Results: Soil Properties
Negative correlation between bulk density and total carbon content
(Saturated) Hydraulic conductivity
Methods
Lab: falling-head
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F. Faul
F. Faul
On site: Hooghout-Ernst F. Faul
F. Faul
3. Intermediate Results: Soil Properties
(Saturated) Hydraulic conductivity
Attempt to find relations with the degree of decom- position
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3. Intermediate Results: Soil Properties
Arrangement according to substrates reveals huge dif-ferences
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F. Faul
Hydrophobicity Method: water drop penetration time
-Wood peat extremely hydrophobic -Radicel and Raphia peat severely hydrophobic -Amorphous peat less hydrophobic than expected -Sandy substrates hydrophillic
Classification (according to Bisdom et al. 1993)
3. Intermediate Results: Soil Properties
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4. Conclusions and Prospect
4. Conclusions and Prospect
To summarise: - Secondary soil formation as a result of drainage could be
observed - Different peat substrates vary in their properties - Wood peat has outstanding high hydrophobicity and hydraulic
conductivity - Degraded peat substrates have a higher bulk density, and lower
hydraulic conductivity So far the data basis allows merely a timid conclusion: - Bulk density, C-content and hydraulic conductivity seem applicable as proxies for degradation - BUT: The impact of gyttja content on substrate qualities hard to assess
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4. Conclusions and Prospect
Prospect
The way ahead:
- Enlarged sample size needed to assure a good data quality, for both pristine and degraded sites - Typical values for substrates in different stages of degradation need to be derived - These values should be related to hydrogeomorphic peatland types - The outcomes shall serves as pedological contribution to a tool for assessing vulnerability, health and restorability of the Maputaland peatlands
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Thank you for your interest!
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