Climate and plant productivity
Overview
Rates of biomass growth and decomposition, and associated carbon stock changes in forests and soil, are strongly affected by the prevailing climate. Climate data are used to derive estimates across Australia for soil moisture and plant productivity. These are incorporated into the FullCAM model to estimate biomass and soil carbon.
Implementation
Weather station data are accessed on rainfall, minimum, maximum and average temperatures, evaporation and frost days for the period from 1968. These are used in combination with the ANUCLIM software package to generate monthly climate maps for each attribute. The interpolation takes account of influences on micro-climate such as elevation and aspect, using a national 9 second (approximately 250 m resolution) Digital Elevation Model.
The monthly climate maps are derived at variable resolutions (grid sizes), providing climate mapping which is both temporally and spatially relevant to the carbon accounting model (FullCAM). The accuracy of the climate maps is tested by comparison between predicted values and actual weather station data.
Soil moisture is mapped using weather data. Long term plant productivity is mapped using a variant of the 3PG - Physiological Processes Predicting Growth - model, and a combination of data on:
- climate/weather - from ~2,500 weather stations
- solar radiation - derived from weather data in combination with a digital elevation model
- leaf area index - derived from satellite data.
The resulting productivity index is then converted to an index of biomass potential, and submitted to the FullCAM carbon accounting model. FullCAM adjusts for factors which may reduce biomass potential, such as site disturbance, low nutrient status or water/temperature deficits.
The following table shows the spatial and temporal resolution of climate and productivity maps used in estimating emissions from land use change.
| Name | Description |
|---|---|
| Rainfall | 1km, monthly 1968-2002 250m, long-term average |
| Temperature min/max/average |
1km, monthly 1968-2002 250m, long-term average |
| Evaporation | 1km, monthly 1968-2002 |
| Frost days | 1km, monthly 1968-2002 250 m long-term average |
| Solar radiation | 1km, monthly long-term averages 1952-2002 250m, monthly long-term averages, slope and aspect corrected |
| Leaf area index | 1km, fortnightly 1992-2002, derived from NOAA AVHRR NDVI data |
| Forest productivity index | 250m long term average (1921-1995) 1km, annual and monthly 1970-2002 |
Analysis and integration
Climate data are used within the FullCAM modelling framework to provide a 30-year dynamic perspective on the nature and extent of change in land systems across the continent over the period since 1970.
- Analytical methods and supplement (these link directly to bookmarks within a pdf document)
- FullCAM model
- Latest results
Technical reports
Specific climate related work commissioned by the NCAS is documented in the following technical report.
- Developing a National Forest Productivity Model - TR23, 2004
