Towards Commercialising Cypress as a High-Value Plantation Forest Species
Report Date: March 2017
Author: Dean Satchell, Sustainable Forest Solutions, R.D. 1 Kerikeri, Northland 0294
+64 21 2357554
In memory of Allan Levett, cypress enthusiast and advocate for undertaking this research.
Special thanks and acknowledgement go to:
- MPI Sustainable Farming Fund
- Cypress Development Group (NZFFA)
- Marika Fritzsche
- Brian & Barbara Gibson
- Ben McNeil & family
- Andy & Tinks Pottinger
- Vaughan & Jude Kearns
- Angus Gordon
- Jeremy Thomson & Sashil Dayal
- Glenn Crickett & Catherine van Paassen
- Allan & Gail Laurie
- Neil & Pam Cullen
- John and Robyn Fairweather
- John Moore
- Charlie Low
- David Henley
Clonal cypress trials were established by the Forest Research Institute (now Scion) between 1994 and 1998 across a range of different regions and locations in New Zealand. Clonal cypress forestry was being evaluated as potentially the best option to rapidly deploy improved cultivars, offering breakthroughs in terms of canker resistance, good growth rates, improved form and resilience across a range of sites.
Clones were measured during November and December 2016 and rated using four performance criteria. These trees were considered to be mature in terms of a performance assessment for selection.
Performance of most clones was poor and these were found to not be suitable for deployment. However, some clones did perform very well across a range of challenging sites, suggesting that clonal cypress forestry may have considerable potential for plantation forestry in New Zealand.
The purpose of this study was to evaluate performance of the clones using a rating method for four performance criteria: tree size (as diameter), tree form, stem quality and foliar (crown) health.
Because the same clones were planted in multiple locations, the most important opportunity identified for this research was to assess and compare the importance of site or region on relative performance of individual clones and all clones.
Both growth/form and stem/foliar disease were found to be influenced by site. Clone by site interaction is large. Relative performance differs by site.
Climate data was integrated into the analysis for any influence rainfall or warmth could have on levels of disease and growth rates. Dry conditions or cool conditions alone were insufficient to significantly reduce disease levels, but cool dry conditions consistently produced low disease levels. However, growth rates in the one site with cool and dry conditions was poor. It is not known whether this was influenced more by nutrient deficiency or climatic factors, but the trees appeared to have a nutrient deficiency that limited growth. Further work could look at what nutrients may be limiting growth in that site (Canterbury High Country) with a view to exploring the opportunity for growing cypress commercially in cool dry areas of New Zealand not suitable for radiata pine (because of excessive snowfall or establishment issues).
Although most of the selections put into these trials have performed very poorly, this presented as an opportunity for comparing relative performance between sites. Different clones responses to climatic influence was variable, with some clones proving to be more resilient than others. The Ovensii clone proved to be healthy at all sites but growth & form was variable, especially in South Island sites. Ferndown, on the other hand, had variable health on all sites and on average was healthy in the Bay of Plenty but not Northland, while growth & form scores were more variable than Ovensii, suggesting a lower "resilience" score.
Some clones did perform well throughout all locations present at, illustrating the commercial potential of the species if high quality clones were deployed to production forestry. A key outcome from this research is that selection criteria needs to be dramatically improved from what was used for selection of clones for these historical trials. Additional selection criteria recommended for clonal selection programmes include low levels of fluting, high heartwood content, wood density and strength, low incidence of stem breakage, toppling and canker disease over fifteen years of tree growth. Longer term selection work is recommended for confident deployment of improved material, to give industry sufficient confidence in performance of cypress clones that are released to growers.