soil carbon dynamics: a catchment based approach c. martinez, g. hancock, j.d. kalma & t. wells...
Post on 23-Dec-2015
214 Views
Preview:
TRANSCRIPT
Soil Carbon Dynamics: A Catchment Based
Approach
C. Martinez, G. Hancock, J.D. Kalma & T. Wells
NAFE’06 WorkshopFebruary 13-14, 2006
Introduction
• Significance of terrestrial C fluxes within global C budget• Lack of understanding of C dynamics at hillslope, catchment
& regional scales– particularly lack of studies within Australia– Northern Hemisphere (US, Canada) studies dominate (different
environments/conditions)
• What’s driving catchment soil C dynamics?– textural properties?– soil moisture/temperature?– vegetation?– hillslope/catchment hydrology/ geomorphology?
Introduction cont…
• Traditional methods of soil sampling for estimation of SOC
– attempts to reduce/remove the need for soil sampling
– using remotely sensed data
Project Aims
• Investigate the spatial & temporal patterns of soil C dynamics at hillslope & catchment scales
• Model & predict distribution (temporal & spatial) of soil C within Goulburn River catchment using ground based & remotely sensed data
Data Requirements
• Existing SASMAS network of ground based weather, soil moisture/temperature & stream gauges
• Complement with ground based soil & vegetation sampling & additional water quality instrumentation for quantification of DOC at Stanley
• Data collected at 4 scales:– Hillslope (Stanley transects)– Small catchment (Stanley)– Large catchment (Krui)– Regional (SASMAS & NAFE’05)
Data Requirements cont…
• Remotely sensed data (NDVI)– Use to extrapolate ground based hillslope & sub-catchment
scale data to larger catchment & regional scales
– Satellite vs aircraft vs ground based
• Digital elevation models (DEMs)– 25m LPI DEM
– High resolution 5m DEM (DGPS) for Stanley
– LIDAR (1m)???
Current Study
• Soil C dynamics at hillslope (Stanley) & catchment scales (Stanley = small; Krui = large)– Stanley micro-catchment (C, N & 137Cs)
• 7 SASMAS stations (1 = weather station)• 1 flume• 5m DEM (DGPS)• water quality instrumentation (DOC)
– Krui River catchment (C & N)• 13 SASMAS stations (including Stanley)• NAFE’05 (soil moisture, vegetation, soil C & N)
• Regional SOC dynamics– SASMAS network & NAFE’05
Current Study cont…
• Land use management effects on SOC (C & N)
• Remotely sensed data – Landsat (NDVI) > ground (above-ground biomass [AGB]), aircraft &
satellite• SOC dynamics modelling (RothC, CENTURY)
NAFE’05 Regional Data
• AMSR regional scale sampling (Mondays)
– Week 3 (14/11) & Week 4 (21/11)
– teams collected additional soil samples for C & N determination
– total of 88 soil samples (5cm core depth) collected over Krui & Merriwa River catchments by the 4 teams over 2 days
Catchment Scale• Stanley catchment 1ha grid sampling strategy (Week 4 of NAFE’05)
– 175ha Stanley catchment sampled on a 1ha grid (i.e. sample pt every 100m)
– 133 points sampled (see Figure)
– at each sample point, data collected:• soil core (max. depth 22cm)• AGB sample (0.5m x 0.5m quadrat)• soil moisture via thetaprobe (mV)
Stanley Catchment
Sample Processing• Regional scale samples
– wet & dry weights recorded for all samples (determination of volumetric moisture content)
– oven dried at 400C (Uni of Newcastle)– samples disaggregated using mortar & pestle and passed
through 2mm sieve– 50g acidified samples for C & N analysis (LECO – UWA)– particle size analysis (Malvern); pH; EC; CEC
• Stanley catchment samples (same as above)– *** IN ADDITION remaining <2mm fraction analysed for
137Cs (Uni of Newcastle)• Relationships between SOC & soil redistribution
processes (i.e. erosion & deposition)
Initial ResultsAbove-ground Biomass (t/ha) Volumetric Soil Moisture (%)
Soil Depth Sampled (cm)Vegetation Water Content (kg/m2)
Initial Results cont…• DATA TO COME:
– Process soil samples & analyse for C & N (LECO)
– NAFE’05 aircraft data (NDVI & LIDAR?)
– Landsat OR SPOT NDVI data for sampling period (Nov’05)
– 137Cs analysis
– PSA (Malvern)
– pH
– EC
– CEC
NDVI (Landsat, May’05)
Conclusions
• SOC = key element in global C cycle
• Lack of understanding of SOC dynamics at hillslope and catchment scales
• What’s driving catchment SOC dynamics?
• Need for better & faster (BUT still reliable) methods for quantifying SOC dynamics
Conclusions• NAFE’05
– Regional scale data• Soil moisture/temperature
• Vegetation (NDVI)
• Soil C & N
• LIDAR???
• Stanley catchment scale data– SOC
– 137Cs
– Soil moisture
– Above-ground biomass
Ground-based & remotely sensed (aircraft platform)
top related