GCFF – What have we learnt to date

Presentation: GCFF Summary_2018 _- GCFF TEAM


Growing Confidence in Forestry’s Future: Where are we adding value?

The Growing Confidence in Forestry’s Future (GCFF) programme is Scion’s flagship radiata pine research programme.

Key goals of the GCFF are to:

  • increase returns from existing forests through mid-rotation interventions
  • improve returns from existing forests through better knowledge of wood quality
  • increase the productivity and consistency of future forests.


The programme has benefited greatly from having access to the long-term nationwide radiata pine trial network established from 1978 onwards. A new series of trials, the Accelerator trials, has been established as part of the GCFF programme.


  1. Where to plant

Conference presenter: Loretta Garrett, Scion    Start time on video: 4:16

Research outcomes: improving value, from putting planted forests in the right place, and understanding what to plan for.

The ‘Forest Investment Framework’ model has been developed to evaluate the multiple benefits of forests – economic, environmental and social.  It includes values for elements such as soil conservation (avoided erosion), carbon storage, and biodiversity benefits. Forest owners or those planning forests can compare values of forests anywhere in New Zealand. The tool is already being used for policy decisions by, for example, regional councils and iwi. It is being developed further to incorporate additional environmental and social benefits of trees, including nutrient mitigation, water filtration and recreation benefits.

The NuBalM model

Other research has investigated site productivity, and the potential to use a nutrient balance model (NuBalM) to improve forest growth. Nutrient cycling throughout a forest rotation is becoming better understood, and when ‘where to plant’ questions are being considered, NuBalM can provide site-specific predictions of fertiliser requirements to meet target productivity.


  1. What to plant

Conference presenter: Mike Watt, Scion    Start time on video: 11:15

Research outcomes: advances in phenotyping (ways of looking at trees and recording what can be seen) will enhance forest productivity through better matching of genotype to site.

Overall, research has greatly improved the understanding of how site and genetics influence radiata pine growth and quality characteristics.

Different remote sensing technologies have captured information about trees at both area level and individual tree level.  Multiple sources of forest and environment information have been combined to produce models which analyse and quantify interactions between all the factors affecting tree growth.

The key conclusion has been that ‘genetics x environment’ interactions are critical in determining tree growth and quality: therefore matching seedlot (tree genetics) to site is an essential key to productive forest management.

New remote sensing techniques now enable scientists to identify and measure individual trees. One immediate benefit is that exceptional trees within a forest can now be pin-pointed, with the potential to use these trees for future breeding programmes.


  1. How to raise trees

Conference presenter: Simeon Smaill, Scion    Start time on video: 23:46

Research outcomes: production of better planting stock, and options to help maintain nursery sector viability.

Major gains have been made in developing alternatives to standard nursery practices. Standard practices involve regular applications of both fungicides and nitrogen fertiliser, often at high dose rates. Research as shown that these chemicals can negatively affect root mycorrhizae, meaning seedlings are likely to be less robust when they go out into the forest and growth is affected.

Commercial-scale trials have proven that seedlings can consistently be raised in the nursery with lower fungicide inputs, without affecting seedling health or viability, and indeed sometimes enhancing these traits. Similarly, Scion’s research has shown that reducing nursery nitrogen fertiliser use is possible.  A novel source of low-nitrogen fertiliser, biuret, has been trialled. Results show that this fertiliser can be added at much lower rates of nitrogen and stimulate the same or greater seedling growth and nutrient uptake as conventional nursery fertiliser regimes.

Growth gains made in the nursery continue once the low-input seedlings are planted out in the forest.

Overall, the research has provided the nursery sector with options to save costs, produce better quality planting stock, and reduce risks to the environment associated with high chemical use.

In future researchers believe that nurseries will be able to adjust their regimes and raise ‘designer seedlings’ for specific planting conditions.



  1. How to monitor and manage forests

Conference presenters: Mike Watt and Simeon Smaill, Scion     Start time on video: 35:14

Research outcomes: step change in the ability to monitor almost all aspects of forests, and many new options for efficient interventions.

Over the course of the GCFF, significant advances have been made in the use of technology and in developing models for measuring and monitoring forests.

Major research effort has gone into investigating ways of using data captured by LiDAR for forest management: the recent announcement that the whole of New Zealand is to be flown for LiDAR should greatly increase opportunities for forest managers to benefit from Scion’s research. Examples of outputs developed from LiDAR data include accurate tree height and growth models, and site productivity models.

Research into the use of satellite imagery for forest inventory has also yielded good outcomes. Satellite data is generally much cheaper than LiDAR, and has been shown to have potential for inventory where large areas of forest are involved.

In addition, techniques and applications for combining imagery from different sensors have been developed.  Identifying and monitoring changes in canopy colour and density, which may indicate a needle disease, is one example where combing LiDAR and UAV images could prove to be a highly cost-effective approach to disease monitoring and management.

Optimal final crop stocking

Forest stocking is generally measured in terms of the number of stems per hectare. Forest stocking at harvest is an important determinant of crop volume and value. Therefore, forest managers need to know what final crop stocking to aim for. They also need guidance on the cost-benefit of pruning radiata pine.

Using long-term trial and economic data, researchers have developed nationwide models predicting the likely optimal final crop stocking for both pruned and unpruned stands. The models indicate that stockings somewhat higher than the current averages are likely to be most profitable, and estimate net gains of $1.7 billion to the NZ plantation estate if the optimal higher density stockings are adopted.

Enhancing microbial activity: precision application of nutrients

Soil microbes are known to play critical roles in forest growth and health. Techniques to better monitor microbial activity have been developed as part of the GCFF, and as a result, understanding of how forest practices affect soil microbes has greatly increased.

For example, one experiment showed that nitrogen fertiliser enhanced microbial activity, and drought tolerance increased as a result.

Ultimately, understanding the role of nutrients in the total forest system will be highly beneficial in helping decisions around when, where, how and how much fertiliser to apply. Precision applications of fertiliser to different parts of the forest is predicted to become the norm in future forest management.

  1. How to protect forest value

Conference presenter: Loretta Garrett, Scion       Start time on video:  56:21

Research outcomes: enhanced capability to maximise stand value and support sustainable practices

Research into protecting forest value within the GCFF programme has included work on:

  • erosion monitoring, the development of the ErodeNZ app, and national erosion and debris flows databases
  • tools to assist decisions on steep land harvesting and site management
  • better understanding long-term nutrient flows in forests over multiple rotations.

“The GCFF program has extended our capability to maximise stand value, particularly through the use of long-term trials, and support sustainable practice during harvest.”


  1. Summary: The Accelerator trials

Conference presenter: Simeon Smaill, Scion    Start time on video:  1:05

A series of six new radiata pine trials has been established since 2016, in part to replace older trials which have now been harvested. These trials are already being used to test and develop some of the most promising research findings from the GCFF. For example, new research into microbial activity under different fertiliser regimes is underway, as is the use of UAVs for new types of image capture and inventory.

Overall, the GCFF has made significant advances and is driving the shift towards precision forest management.  The programme has created a valuable legacy:

  • fundamental advances in monitoring capability
  • new understanding of critical biological interactions
  • better options for precise and sustainable tree management
  • new systems to quantify wood quality and value
  • new trials that will provide value for many years to come.