Seed zones for trees: helpful or hindrance?

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ccpike
Posts: 8
Joined: Fri Jan 22, 2016 9:49 am

Seed zones for trees: helpful or hindrance?

Postby ccpike » Fri Jan 22, 2016 2:28 pm

Trees have large, genetically diverse genomes and are capable of disseminating pollen long-distances. Seed zones have been used for decades to guide the transfer of genotypes within their home range to ensure optimal survival and growth rate, but today they are not used widely across the US. One commonly cited justification is that tree species have been moved across the globe successfully (lodgepole pine in Europe, radiate pine in NZ for example), so why worry about moving sources widely within their natural range? Implementation of seed zones requires that a nursery separate seed sources of a species by their zone (instead of having one source or zone for each species), adding costs and inconvenience to growers. In the long run, do you think separating seed by zone is a cost-effective practice for growers and landowners?

treenerd
Posts: 6
Joined: Tue Feb 09, 2016 8:16 pm

Re: Seed zones for trees: helpful or hindrance?

Postby treenerd » Mon Feb 22, 2016 2:51 pm

We only grow seedlings based on their zones as well as elevations within those zones and we would never move seed outside of those ranges with the exception of fringe areas near that zone or a common drainage. Some orchard stock has been tested on a wider geographic scale and can be moved within a larger range but wild pick seed I wouldn't move far at all.

I have been to a couple of sites up in the cascades where seedlings were purposefully moved outside of their zone and elevation bands and it reinforced those zones. All of the seedlings were Douglas fir in this trial. Seedlings from lower elevations planted at higher elevations had broken tops right around 15' off the ground. These stands were 40 years old and the lower elevation and more coastal stock all experienced the same problem. None of those trees were more than 15' tall and the ground was riddled with broken tops from years past.

ccpike
Posts: 8
Joined: Fri Jan 22, 2016 9:49 am

Re: Seed zones for trees: helpful or hindrance?

Postby ccpike » Tue Feb 23, 2016 2:03 pm

The topic of seed zones is being discussed for eastern forests where topographical relief is less extreme, and seeds can be moved greater distances with fewer consequences than the west. For many nurseries, maintaining seeds and seedlings by zone is cost-prohibitive and some vehemently argue that it is not necessary. In the east, losses of growth that result from unguided and distant transfer many not be realized for years when trees fail to meet growth expectations. Your example from the west is interesting- we need good data for the east!


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