The radiata pine tree NZ 55
Dag Lindgren 1995, edited 2000
The radiata pine tree named NZ 55 is one of the most important trees in the world. It is alive (1999), impressive and accessible. It is one of the reproductively most successful individuals on Earth; its offspring has a considerable economical and ecological impact. NZ55 is probably the world’s most successful known ancestor in use in operational conifer plantings. It can be seen as a symbol for forest tree breeding. It is interesting also for its special characteristics, and it will be much used in future research, because it is so widespread and known.
It may be of general interest to make numerical estimates of the impact of NZ 55, so I have tried to calculate some figures based on discussions and reading at NZ 1995 (when I spent half a year as a visiting scientist at the center of the radiata breeding effort in NZ). These considerations are presented below in Appendix 1. Tentative conclusions were:
Virtually every seed orchard
planted in New Zealand and Australia since 1957 has included clonally propagated
copies of NZ 55 or its progeny.
NZ 55 has currently around 50
million living children and may be one of the reproductively most successful
trees in the world at present.
The progeny of this single tree
will produce about 40 million m3 wood, thus enough to supply all
wood based industry in NZ 1993 for about three years.
The grandchildren of NZ 55 are likely to beat these figures. Probably the use of the offspring of the tree itself has peaked now and will be replaced by its grandchildren. Much of the information below comes from an information pamphlet compiled by Fred Burger latest updated 1999.
NZ 55 grows on a reserve put aside by Carter Holt Harvey a few hundred m uphill east of Rd 1 around 20 km south-east of Tokoroa. Tree NZ 55 was planted 1927 and recognized as a plus tree 1950. The tree is in an old plot, which since 1934 can be regarded as a permanent sample plots, and thus there are measurements before it became a plus tree. It was only slightly above average at age 7, but at age 17 it was the biggest tree in the stand. This is a remainder of the inaccuracy of early decisions. However, a retrospective study showed that among the 10 biggest trees 1988, 7 would have been selected at age 7. The progeny ranks consistently high in all series (among top 20), but from this point of view it is not unique compared with other later selections. Families of tree 55 need considerable less energy for mechanical pulping, while still producing excellent newsprint paper. In a paper (NZ Journal of Forest Science 22(1): 96-110 (1992) the wood and pulping properties of NZ55 were analyzed. They were found that remarkable that the authors use the expression "a genetic misfit". At this point in time NZ 55 is unique in this respect, however it should be remembered that these are expensive recordings which are taken only for a few genotypes. There is now some doubt about the lower energy requirement for mechanical pulping connected to difficulties repeating the pulping trial getting the same results. NZ 55 is regarded as the absolute pits for density and, given the relationship between density and strength, is rapidly going out of favor where focus is on desirable wood-properties.
As NZ 55 is so popular it is always a good question what percentage of the genes in that or that population originates from NZ 55. There are agricultural and animal parallels to an intensive use of a small share of the genetic variation. It is, however, adequate to point out that even if there are many offspring to NZ 55 they still only constitute a small share of all radiata trees on New Zealand, and in most radiata stands the share of genes which originates from NZ 55 is rather limited. It's ability to support the NZ industry will decline as this industry grows, and the statement about the industry may get people to forget that all NZ 55 progeny is not in NZ.
One contender may be Pinus taeda 7-56 from southeastern US, which may have had a similar impact. However, no statistics has been presented. It is possible there are individuals that get as much progeny in Sweden, e.g. the pine W4009, which is in at least 10 seed orchards. However, most Swedish trees get smaller so it may anyway be inferior in cubic meters.
I wrote a note about NZ55 on FORESTGEN (the email discussion club for forest geneticists) asking if there were some similarly reproductive trees around the world. The note initiated a small debate on the net including a comment from Jeffrey Burley. No one challenged the champion NZ 55 in spite of being provoked to do so, so I nominate it to the reproductively most successful tree in the world.
Appendix 1.
Calculations and considerations:
There are around 1.5 million ha of radiata pine plantations planted between 1970 and 1994 in Australia and NZ, assume that each year there were 40000 ha planted in NZ and 20000 ha in Australia and all these remain. Let us disregard Chile and other countries, which also use some NZ 55 progeny. Most of the plantations originate from seed orchards established since 1957. However, in 1970 collections from climbing select and felling select were important seed sources, and first around 1985 non-orchard material become marginal (although still used in Australia). NZ 55 is one of several clones in the orchards. There is an important large seed orchard in Kaingaroa forest with a lot of clones, and NZ 55 has only a small share of the ramets. This single seed orchard keeps a considerable share of NZ seed orchard seeds. Other orchards have typically around 20 clones. From cone collection data the impression is that NZ 55 have a larger share among harvested cones than its share of the clones. It is likely some extra emphasis has been put on NZ 55 by selective harvests, genetic thinning and pollen collection. Thus probably on an average 5 % of the seed orchard cones had NZ 55 as mother. Grandchildren are starting to become important as parents of full sib families, which sometimes are multiplied by cloning. As there are two parents, and NZ 55 functions also as pollen parent, it may be assumed the parent to 8% of the orchard trees. (Paternal contributions can be expected to be lower than maternal because there are pollen sources outside seed orchards, nowadays it is likely to be almost 50 % outside pollen in many open-pollinated orchards). NZ 55 got heavy seeds and its contribution may be overestimated if based on cone or seed weights, but on the other hand it ought to be competitive in the competition after sowing in NZ nurseries, and thus its impact somewhat magnified. I assume there are 800 trees/ha in plantations between 0 and 15 years, and 250 in older plantations. (The assumed age of thinning is likely to be too high for NZ conditions and thus the estimate of living progenies somewhat high). NZ 55 progeny ought to get more frequent after thinning, but this is not considered.
Plantations between 1970 and 1979
10 years
60000 ha per year
0.3 share of seeds from orchards with NZ 55 as a component
0.08 share of plants with NZ 55 as a parent
250 trees per ha
180 thousand ha where NZ 55 occurs as parent, 3.6 million plants with NZ 55 as a parent
Plantations between 1980 and 1989
10 years
60000 ha per year
0.8 share of seeds from orchards with NZ 55 as a component
0.08 share of plants with NZ 55 as a parent
800 trees per ha
480 thousand ha where NZ 55 occurs as parent, 30.7 million plants with NZ 55 as a parent
Plantations between 1990 and 1994
5 years
60000 ha per year
0.8 share of seeds from orchards with NZ 55 as a component
(increasing amounts with NZ as a grand parent disregarded)
0.08 share of plants with NZ 55 as a parent
800 trees per ha
240 thousand ha where NZ 55 occurs as parent, 15.4 million plants with NZ 55 as a parent
Plantations between 1970 and 1994
900 thousand ha where NZ 55 occurs as a parent, 49.7 million trees with NZ 55 as a parent
The total wood production in a radiata stand is 600 m3/ha over a rotation. Thus the production of 900 thousand ha will be 540 million m3, and the 8 % share of NZ 55 kids will be 43 million m3. The current annual cut of NZ is 15 million m3/y.
In total NZ 55 will have almost 50 million living kids in planted forests, and besides that an increasing number of grandchildren. The number will increase the next years, so it may be justified to use a somewhat "high" estimate.
These calculations are rough ones, and could be refined. I have discussed the matter with Shelbourne, Vincent, Burley and Jefferson, and I think the most important factors are listed. More accurate estimates can be made, but at a rather large effort in time. There is also the possibility that efforts to increase resolution would not increase accuracy because of disagreement on details.
Dag Lindgren