A team of researchers has developed a prototype system combining the technique of process-based modelling and remote sensing data with the traditionally used method of empirical modelling. The goal is to equip forest managers with improved planning and forecasting to inform the maintenance and development of their plantations for maximum forest growth and yield.
Industry recommendations have also been put forward to enable companies to easily access, adopt and operationalise this new hybrid approach to modelling within the next five years.
Traditional empirical modelling tends to lose reliability where forecasts are required to consider future conditions. While the underlying physiological relationships between CO2, temperature and rainfall might remain the same, predictions under changed conditions can be uncertain. As climate variables change, therefore, so too must our forecasting methods.
Remote sensing and process-based modelling
There are many opportunities (and complexities) associated with using new data sources for the prediction of current and future characteristics of plantations. This data, which will help guide the most effective forest management practices, can be sourced using the likes of satellite, airborne or ground-based sensors, as well as what’s known as process-based modelling.
Remote sensing options can offer additional useful sources of data, by scanning stand metrics for direct input into the overall modelling.
Process-based modelling uses specific mathematical representation of ecosystem processes that support wood production, including the use of light, water, and nitrogen to forecast plantation characteristics. This approach considers future conditions, and therefore offers a more reliable yield prediction under a changing climate.
“Often, taking full advantages of new opportunities such as process-based modelling and remote sensing technologies requires specialist skills not always available within companies,” said research leader Dr Philip Smethurst, a soil and water scientist, and plant nutritionist at CSIRO Land and Water.
“As a result, many companies rely on legacy technologies and systems, alongside various modern additions, limiting the potential of their capabilities.”
The research
In 2020, the two-year FWPA-supported project Next Generation Resource Assessment and Forecasting for Australian Plantation Forestry began to help address these concerns.
This work explored industry needs and evaluated, investigated, and developed these new technologies to create a prototype system. The idea is for the prototype to enhance, rather than replace, existing growth and yield forecasting systems by incorporating new data sources alongside traditional empirical modelling.
“This research set out to offer the potential for growers to design and experience elements of a modern system akin to those available and successfully applied by grain growers and in other agricultural sectors,” Smethurst said.
The tool was developed and tested predominantly in pine plantations in south-east Queensland and the Green Triangle region of South Australia and Victoria.
The Agricultural Production Systems sIMulator (APSIM) modelling framework – well-established in the agricultural sector nationally and internationally for research and commercial uses – was chosen as the process-based modelling framework for this project.
APSIM simulates plant growth and before this project had been calibrated for Eucalyptus grandis plantations and related tropical and sub-tropical genotypes.
Other genotypes required for temperate eucalypt plantations in Australia (E. globulus and E. nitens) and pines in tropical-to-temperate regions (Pinus radiata, P. elliottii, P. caribaea and hybrids) were then added.
These models not only use climate variables as inputs, but also management variables, including initial stocking, thinning, mortality, weeds, nitrogen fertilisation and irrigation. New genotypes can also be calibrated.
A collaborative approach for easy and affordable industry access
While in-house expertise or consultancy services are theoretically the best options for the adoption of advanced technical services, results of an industry survey indicated an overwhelming belief that individual companies do not have the range of technical expertise required, and consulting services can be expensive and lack technical flexibility.
Tree Breeding Australia was profiled as an example of a long-standing model for delivering advanced technical services to the forestry sector. The main elements of this business model were explored with a view to creating a similar approach to providing process-based modelling and remote sensing services to industry.
“The project explored opportunities for an industry cooperative model that could potentially provide such services with more technical flexibility, and at a reasonable cost,” Smethurst said.
For those interested, a more detailed look at this project can be found in the forthcoming R&DWorks edition. Sign up here!
