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

0

10

20

30

40

50

60

0,00 0,20 0,40 0,60

C-Co

nten

t [%

]

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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