This is a response to an earlier conservation (see below). I argued that reproductive output of genotypes could be a consideration for seed production. Michael Frankis objected that in the forest we want wood and not reproductive output. This is a very interesting and relevant argument and there is much to say about it. I have listed some arguments.

There are often very large differences between trees in a stand and between clones in a seed orchard for reproductive output. There are cases then the low seed yield from seed orchards and consequently high price of seed orchard seeds is an argument against investing to get more genetically improved seed orchard seeds. That leads to a lower fraction of plantations with genetically improved seeds and thus lower returns from forestry. For a fraction of those seed orchards the seed orchard economy would be sufficiently improved if only the "better half" of the clones considering reproductive output was used, leading to a higher use of seed orchard seeds.

The trees or clones without reproductive output do not transmit their genes, so even if foresters want to decrease reproductive output of the productive forest, it does not help to let unfertile trees remain in a seed production area. To convert a stand into a seed production area means to make actions and investments which benefits seed production on the cost of other values. It does not seem logic to involve trees, which do not benefit seed production in that action. If pollen migration is a problem it will improve the genetic quality of the seeds if the pollen production of the stand is higher, and it will be higher if trees which does not produce pollen are cut than if trees which produce pollen are cut. The initial question concerned an exot. Adaptation is a problem to be considered for an exot. Reproductive success can be regarded as a sign of adaptation (almost by definition). Trees, which get offspring, are probably better adapted for the environment than those, which do not. Thus, removing infertile trees probably increases the genetic adaptedness of the trees in the seed production area. It is true that stress may induce flowering in some badly adapted trees, but those trees would probably anyway be thinned away for bad health. With my remark to consider seed production and pollen production I mainly thought of removing trees, which anyway do not contribute much to the offspring. However, it may be difficult to make forecasts based on observations on young trees, especially as larch can be an irregular flowering species with large annual variations.

While choosing among reasonable fertile trees, it could be debated if and to what degree reproductive output should be a premium. Pollen production may be sufficient, an increased pollen production beyond a certain level may not increase the genetic quality (although I doubt that this is often the case). If we select trees for seed production it means that we can not select with the same intensity for other characters, so the genetic quality for production characters of the trees chosen to the seed production area and thus seeds produced will be lower.

An argument that reproductive success should not be a heritable trait can be made. If so, fertility of the parents would not influence the fertility of the offspring. On average each individual in a stable population has two offspring. Individual parents may however have more or less than two offspring. Look at a population with four parents (A, B, C and D). A*B get the offspring E, F and G and C*D get the offspring H. Thus three offspring (EFG) get parents who have three offspring (AB) and one offspring (H) parents with one offspring (CD). Two of the parents get three offspring and two get one offspring. If we assume that heritability of reproductive success is 1, reproductive success raises from 2 to (3*3+1*1)/4 =2.5 in one generation. The offspring originates mostly from the parents with the highest reproductive success. Thus reproductive success should increase each generation and the world would soon be overpopulated. This argument can be raised for any positive heritability. It is generally so that the current population mostly origins from parents with reproductive success above average. Can there be another explanation than that heritability of reproductive success is zero in the long ran? Well, there are several problems with this argument and it is oversimplified. E.g. reproductive success is not the same thing as number of seeds and pollen. But still it is a remainder that seed and pollen production in the offspring is not the same as in the parents, and the heritability may not be that high.

If seed production areas are established from seeds (which I suggest should be considered), heavy overrepresentation of some parents can be avoided. A few stands could be established in such a way that they are suitable to convert to seed production areas, and for that purpose I suggest restricting the number of seeds from the most fertile trees to reduce problems with decrease in gene diversity and later inbreeding. This should also have the effect to decrease the average fertility and thus compensate for a possible increase in fertility when selecting the particular trees, which will remain in the seed production area.

Breeding and domestication is likely to shorten the time span to sexual maturity. Early flowering will get a premium among second generation selections even if it is not intentional (we cannot use trees with no flowers in the breeding population). The character "early maturity" may be inherited and that means that a larger share of resources go into reproductive structures at an earlier stage and thus for a longer accumulated period than in a "natural" population.

Seed production areas are low-cost and low-tech options. The argument that we should make trees, which produce wood instead of offspring, should get less room where, than in a high-tech program. In high-tech programs there are some possibilities to think about. Vegetative propagation techniques open options to select genotypes, which do not waste resources on seed and pollen. For long term breeding genotypes with those sterility characters could be forced to flower by artificial means. Now the genetic engineering technology has opened the option to introduce a gene (gene package) for early and prolific sexuality. This gene could be introduced into sterile "races"; run for a number of very short breeding generations; and when removed. (The "gene" is usually dominant and can thus easily be "removed" by selection among segregating zygotes at the end of the program, so the resulting forest would not be genetically engineered...).... But, honestly, there are psychological factors, which probably are more important than the biological considerations. The more often scientists' present visionary thoughts about the benefits to human to genetically manipulate the forest so it becomes sterile, the less forest tree improvement the public opinion will tolerate. The opposite argument, to discuss about the possibility that forest tree breeding might be accompanied by a slightly increased fertility, will probably not turn the public against forest tree improvement.

Some of these arguments are not my own, we have had a less official debate about this problem, I thank the participants.

Regards

Dag Lindgren

Dag Lindgren wrote:

<snip>

> When thinning to create a seed production area, it seems motivated to give
> some consideration to pollen production and seed set of the trees if
> possible.

<snip>
Michael Frankis wrote

Beware of this one - trees which invest heavily in seed production may be
diverting most of their resources to this, and less to wood production. Fine
for creating a new generation of seed orchards, but less good if the purpose is
to produce seed for forest planting.

Reminds me of the Lulu Islands fiasco - Britain imported huge amounts of Pinus
contorta seed from Lulu I., B.C., only to discover they were from trees which
produced massive seed crops and just about nothing else. Totally worthless as
timber trees, but very cheap to harvest the seeds.

Best just select for the trees which show the best characteristics of what you
want the seed for - even if you do get lower seed volume, you should be able to
get a better price for the seeds in the long run.

Michael
Newcastle, UK

Reactions to my plee for an internal discussion

From Seppo

God morgon!

Det är kanske inte så mycket kommenter till just det som du ville, utan av
mera allmänna slag. Egentligen hittils har jag inte brytt mig så mycket om
variation i fröproduktionsförmåga, utan har tänkt att den egenskapen som
man förädlar för är den enda som har betydelse. Men nu när jag har arbetat
men granfröplantagematerial med Teijo har jag blivit till litet annorlunda
tankar. T.ex. i fröskördet på ett år hade den minst fröproducerande
tredjedelen av kloner så liten betydelse för hela fröskördet att om man helt
utesluter dem, sjunker Ns bara från 28 (Nr 42%) till 25 (ursäkta Teijo, att jag
avslöjade sådan ny forskningsrön utan att först diskutera med dig). Så det är
verkligen också en kostnadsfråga att ha en stor massa oproduktiva kloner på
en fröplantage.

Man får nog inte dra sina slutsatser av för korttidiga observationer. Och
kanske man måste också ta hänsyn till frögroning och plantornas utveckling
och överlevnad.

> offspring. If we assume that heritability of fertility (number of offspring) is
> 1, fertility raises from 2 to (3*3+1*1)/4 =2.5 in one generation. The offspring
> originates mostly from the parents with the highest fertility. Thus fertility

På sikt skulle det väl leda till att heritabilitet sjunker. Man kan även
spekulera att det är kanske mera det speciella kombinationsförmågan som
är viktigt i fertilitet.

Seppo

From Yongqi

>In our early caribbean pine breeding program, we set up seed orchards with
>selection on seed productivity of trees and ignored the growth traits. The
>outcome was that the genetic gains obtained for growth traits were actually
>negative.
>If you do not select for growth traits you do not expect any gain and
>stochastic variation can make it non-significantly negative. Can that be the
>explanation?

Sexual growth is generally negatively correlated with vegetative growth, it seems true with plants. Individuals good in regeneration may not good in growth. So it needs balance in selection.

I mean that at an early stage of the seed orchard, we can only consider growth, but at later stage (sexually matured), the seed productivity of trees will be taken into account.I am not sure whether the heritability of fertility is easy to evaluate and workable.

Yongqi

Tim

Hej Dag!

I see you've been quite excited that your comments on this FORESTGEN thread have elicited a response. I had read some of it on the list, and have read quickly through the off-list communications you attached. Many issues are touched on and there is no way I can comment on everything within your timeframe. It is also difficult (at least with my current skills) to make highlighted revisions to an html file. I will focus just on the following paragraph.

At 15:36 28/03/00 +0200, Dag Lindgren wrote:

What is the long-term effect of selection for reproductive success? Let us
be a bit speculative. On average each individual has two offspring. But
todays individuals are on an average offspring of parents which had more
than two offspring. Look at a population with four parents (A, B, C and D).
A*B get the offspring E, F and G and C*D get the offspring H. Thus three
offspring (EFG) get parents who have three offspring (AB) and one offspring
(H) parents with one offspring (CD) Two of the parents get three offspring
and two get one offspring. If we assume that heritability of fertility
(number of offspring) is 1, fertility raises from 2 to (3*3+1*1)/4 =2.5 in
one generation. The offspring originates mostly from the parents with the
highest fertility. Thus fertility should raise each generation and we will
soon be overpopulated. This has not happened in spite of that evolution has
been active for millions of year. Can there be another explanation that
heritability of fertility is zero in the long ran? Anyway, I am not too
worried cone-set will immediatly sky-rocket in the offspring just because it
is not completely neglected at selection among the parents.

I feel you've got rather carried away with your speculation. You demonstrate that if fertility had an h2 =1, that population growth would be uncontrollable. So, it's no big surprise that fertility is also affected by environment, and that genetic expression of fertility differs in different environments. Population growth leads to increased competition and it is well-known that genotypes respond differently to competition and other environmental variables with respect to reproductive output.
Remember, if you will, that while the organism under discussion will, on average under zero population growth, produce two reproductively active off-spring, it will probably produce millions of viable seeds during its lifetime. Selection acts on these millions of offspring, not on their parents. The fact that one parent produces twice as many million zygotes as another would increase it's chances of higher representation if all other things are equal -- but the fitness of these millions of seeds are NOT equal. There is a huge role for environmental controls of reproductive output and for stochastic factors of population growth. To ignore these aspects is rather simplistic.
You suggest in your html text that higher reproductive output is a sign of adaptedness. Many would suggest the opposite, at least for many temperate tree species, where it is well known that reproductive output of a genotype increases when it is in a stressful environment. Under conditions to which it is well adapted, seed production may fall off. When a tree is grown in a favourable environment, the number of buds usually increases. An unfavourable change in that environment will often illicit a response leading to a greater proportion of these buds differentiating as reproductive structures. (Trees growing slowly in marginal populations under stressful conditions may be small, but we often see a disproportionately large percentage of the initiated buds differentiating into reproductive structures -- sort of a desperate attempt to increase the likelihood of reproduction, despite the personal energy cost to the parent.) When an area is managed for seed production, environmental changes are brought about in the hope of increasing seed output. While treatments are known to increase seed production "on average", individual tree responses vary tremendously.

Perhaps that stirs up a few more ideas in your brain.

Regards, Tim

Comments below did not appear on FORESTGEN

Hi, Dag,

This is my opinion in short:

First I should say that don't forget the aim and limitation of seed production area. This kind of area is to meet the demand of immediately/or very soon use of seeds. And the improvement you can expect from seed production is relatively lower than from seed orchard. I don't think you should emphasize too much on characteristics for end-product of future plantations.

First of all, I don't want to deal with this as a serious debate.

I think that the main purpose of seed production area is to produce and supply immediately. If the person that made the question first is a nursery man, he doesn't want to establish the seed production area, he will buy seeds with as cheap as possible. But, he may be a sort of tree breeder, so he wants to get some progress or to give genetic results in his research work.

The gain from the seed production area is in general less than 10%, and the gene diversity may also be much less than that from seed orchards. We already knew that. By definition, therefore, it is good enough for seed production areas to produce a little improved seeds as soon and many as possible. But still gain and diversity are not the main matters. If you know genetic information (e.g., heritability), it also means that there has been much research work. However, there is usually not much studying when we need to have seed production areas. I mean that genetic testing is in general coupled to establishment of seed orchards. Of course, it is not easy to select trees with high quality and high flower production in seed production areas. Anyway, we can do using check list or some other methods.

In my experience with Larix spp. in seed orchards, the flowering variation of Larix leptolepis is very large among clones and between years. Most serious problem is that the flowering period is quite irregular and long like Norway spruce in Scandinavian countries. Once the flowering is good, then we have to wait for next good flowering at least 6 or 7 years. So, in Korea, most of Larix seed orchards have been systematically thinned with intensity of 75%. So, a number of trees are 100 per hectare (initially 400 trees/ha). After thinning, the flowering variation was improved, and the seed production was also increased a bit. And combination of fertilizer and physical treatments (e.g., girdling, root cutting) or hormones could also increase the amount of flowering

Dear Dr. Lindgren,

Here is an extract from an article (unpublished) that I wrote a few years
ago. Since then, I haven't had time to return to this theme, but this
general approach still seems to be the way forward for tree improvement
programmes with fluctuating budgets.

JOnathan

(on tree improvement for smallholders).............
By contrast, the socioeconomic environment affecting smallholders
threatens the very existence of programmes. It seems reasonable to
conclude, therefore, that whereas differences in biological-technical
factors may require differences of degree or emphasis, differences in the
socioeconomic background affecting smallholders and companies would seem to
require a difference in approach. The lack of and instability of funding
is the most serious and fundamental of the problems noted, and requires a
reconsideration of smallholder tree improvement and tree breeders’ role in
it. In particular, approaches to smallholder tree improvement need to be
designed that are sustainable, particularly under worst-case budget
conditions, that allow for expansion should external funding become
available, and that ensure that the benefits of such periods of expanded
activity continue to be felt if and when the external funding is removed.
Some characteristics of such approaches are considered below.

APPROACHES TO SMALLHOLDER TREE IMPROVEMENT
Long-term, realistic objectives
Most tree breeders would agree that their principal goal is the development
of germplasm that matches user needs as closely as possible. As long-term
programmes in pursuit of this goal are possible in low-budget situations,
it seems reasonable to suggest that the one of the reasons for the lack of
long-term perspective and planning in smallholder tree improvement is a
lack of awareness of such possibilities.
The precondition for some progress at the simplest level is nothing more
than restriction of seed movement combined with continued tree planting,
the product of which will be the slow domestication of plantation varieties
(Libby, 1973), of both native and exotic species. The role of the tree
breeder - or forest manager - at this simplest level would be simply to
ensure that this essentially passive process is allowed to function, by
avoiding the indiscriminate use of 'outside' seed or, at the regional
(within country) level, to avoid the centralized collection and
indiscriminate redistribution of seed, as practised by some national seed
banks. At a slightly higher level, such facilitation of passive processes
could be reinforced by actively encouraging the integration of genetic
principles into silviculture. Tree breeders would promote the use of seed
collected locally in each environmental zone from phenotypically superior
trees (in thinned stands, where applicable), would aid farmers' groups in
defining ideotypes in order to inform seed collection; would promote
nursery culling based on nursery performance of seedlots sown by family,
etc. In short, tree improvement, rather than being the object of research
projects, would become simply a good silvicultural habit.
In both these cases, instead of managing skeletal and perhaps ineffective
tree improvement programmes, the tree breeder would fulfil a catalytic and
facilitative role in the process of 'pushing nature into a higher gear and
in a particular direction' (Palmer 1994). The budgetary requirements of
the first option are virtually nil, and of the second would run little
beyond the salary and operating costs of a forest geneticist or
'para-geneticist'. Both options might appear to be more similar to a
guided and somewhat accelerated development of land races than to
traditional tree breeding. However, land races and intensively-bred seed
are merely two extremes of a continuum of types of local varieties selected
for certain sites and management regimes, rather than products of
qualitatively distinct activities. For higher budget situations, Namkoong
et al. (1980) have described minimal investment programmes which more
closely resemble traditional tree improvement programmes.
The availability of such options means that organizations with low budgets
need not be dependent on external funding in order to implement long-term
tree improvement programmes. The formulation and assiduous pursuit of
realistic long-term objectives, including such details as ideotype
specifications, probable breeding zones, breeding population size and
structure, etc. is likely to be a major factor in the success and
continuity of such programmes, very much as in the industrial case.
The foregoing should not be taken to imply that smallholder tree
improvement programmes should aim no higher than the low-intensity
programmes mentioned. Rather, an important feature of such programmes
should be the capacity to expand and intensify when external funding
becomes available or is increased, but without losing their identity and
independence. This aspect is further explored below.

Independence and incorporation of projects
Long-term objectives are much more than a planning and management tool.
Without long-term objectives, then a programme, as distinct from a series
of ad hoc projects, cannot really be said to exist, and the issue of its
independence does not arise. Only when long-term objectives and,
therefore, independent programmes, do exist, can the projects suggested by
external funding agencies be evaluated in terms of the degree to which they
contribute to and are consistent with long-term objectives, whilst both
internally and externally prepared projects can be designed with the same
criterion in mind. The periods of increased funding associated with
projects consistent with long-term objectives can then be used to reinforce
and accelerate the domestication process, without being allowed to take it
over completely. After withdrawal of funds, then the domestication process
might return to its previous intensity, but would not cease completely, and
would continue to advance due to the incorporation into the base population
(sensu White, 1987) of the gains made during the period of increased
funding. Such an approach can only exist if long-term objectives that are
realizable in worst-case situations are in place.



Jonathan Cornelius
Investigador / Researcher
Forest Fragmentation (Genetic Effects) Project
Area de Manejo y Conservacion de Bosques y Biodiversidad
CATIE
Turrialba 7170
Costa Rica
Tel. +506 558 2528
Fax: +506 556 1533

Dear Dr. Lindgren,

Just a note to thank for sending the two publications. They arrived today
(in record time!) and look very interesting.

JOnathan

Thank you very much.
I will write an application (to our developing aid agency) for theoretical
development of three "low intensity" plans.
The scenarios will be from an in cooperation with Vietnam, Mozambique and
China.
A part of the China plan is probably secured for by my new Chinese (who
links to several activities in China).
For China it will be a more central approach towards industrial forestry
(but still low intensity).
For Mozambique it will be directed towards small landholders (farm
villages).
For Vietnam to (centrally) create an option for one among many potentially
interesting trees.

The philosophy behind includes thoughts similar to yours. Your document is
helpful, it phrases some things clearer than I have been able to. I
appreciate very much that you shared it with me. It is a good document
focusing on important issues. Of course all tree breeding project are
exposed to very fluctuating funding during the centuries they operate, so
just in the fluctuations in funding, those will be important even in rich
circumstances also.

My plan is to make more substance. To specify and optimise number and
techniques into very concrete plans. To make a clearer documentation of the
arguments for real case studies. To confront theoretical ideas with
practical circumstances. Lets see where it leads, but at least for China it
seems to lead to something independent of if the the current funding effort
succeeds.

I get SO excited that there is SOME interested person somethere out in the
world, they are not many!

I do have a single reprint, and it would be possible to send a copy of that.

But actually we got more and better developed papers on the subject. I
choose to cite the mentioned because of its provocative title (successfully
provocative evidently).

Instead I send you Eriks (Erik is "Andersson") PhD thesis, which makes the
same point and includes a similar paper and give you some extra bed time
reading. And a proceedings paper.

I send them to you by snail mail. If you are impatient you may find parts of
Eriks thesis on my web site. I send Erik a copy of this to boost his mood,
because I have in my mind that I may visit him sometime in the not too
distant future :-) This gives you the option to communicate directly to him.

When I have a proceedings paper "in press".

Where I expand on the idea of "cheap breeding". I enclose it in word format.

I would very much appreciate comments on the "cheap breeding paper", because
the next weeks I will write an application based on that and in the autumn I
get a fresh postgraduated student from China to work on that (these are
reasons which triggered me to make the comment to FORESTGEN).

Dear Dr. Lindgren,

I've been interested in cheap breeding for some time, or, more
specifically, the idea of breeding strategies that can respond to budget
reductions (e.g. withdrawal of donor agencies, as in Central America) maybe
by contracting to successive seed stands for one or two generations until
funding becomes available, rather than collapsing entirely. I await with
interest the material you've sent.

Jonathan

Dear Dr, Lindgren,

I read your interesting reply to the seed stand inquiry.

I'd like to get a copy of the following article that you mentioned:

Andersson EW, Spanos KA, MullinTJ & Lindgren D 1998, Phenotypic selection
can be better than selection for breeding value. Scand. J. For. Res.
13:7-11.

Would it be possible to s end me a copy, or else forward my request to the
senior author?

Thanks,

Jonathan

Comments below appeared on FORESTGEN in later half of March 2000
Dag Lindgren wrote:

<snip>

> When thinning to create a seed production area, it seems motivated to give
> some consideration to pollen production and seed set of the trees if
> possible.

<snip>

Beware of this one - trees which invest heavily in seed production may be
diverting most of their resources to this, and less to wood production. Fine
for creating a new generation of seed orchards, but less good if the purpose is
to produce seed for forest planting.

Reminds me of the Lulu Islands fiasco - Britain imported huge amounts of Pinus
contorta seed from Lulu I., B.C., only to discover they were from trees which
produced massive seed crops and just about nothing else. Totally worthless as
timber trees, but very cheap to harvest the seeds.

Best just select for the trees which show the best characteristics of what you
want the seed for - even if you do get lower seed volume, you should be able to
get a better price for the seeds in the long run.

Michael
Newcastle, UK

There is probably a place for low cost options to get (slightly) improved
seeds in many situations.

In such low cost tree improvement options phenotypic selection in
non-pedigreed population probably have an important place. Phenotypic
selection has actually been shown to be of interest compared to combined
index selection (e.g. Andersson et al. 1998). If the family structure of a
population is known, it may be limited advantage in considering this
pedigree information when selecting a breeding population. As we all know
combined index selection will maximise gain in a short time perspective, but
in terms of breeding progress per consumption of gene diversity unit, and
also gain after some generations, phenotypic selection can be quite
compatible.

For starting to develop a land race from a stand, the first step seems to be
to consider if the stand has a suitable origin.

If the question arises to convert stands to seed collection areas, it may be
a good idea to add the question what could be done now to establish stands,
which could serve as genetically improved seed collection areas in some
decades. Some considerations could be done already at collecting seeds and
planting a stand.

In a system there the future forest is created from harvest in seed
production areas, the harvest should comprise a sufficient number of parent
trees to avoid the build up of coancestry and inbreeding. This was studied
by Bila et al. (1999) for a stand with 154 trees hypothetically regenerated
over generations. The current suggestion for a seed collection area is
around 300 trees. This is sufficient and allows room to focus on the better
trees at seed collection. Some considerations could be given to the likely
effective number of parents to the present stand.

A question is if the local climate and conditions support seed production,
probably this can be checked, as flowering has started (there may be
problems with seed set). There may be several alternative plantations to
check and select among. It may generally be a good idea to create more than
one potential seed collection area to be able to choose among them later.

When thinning to create a seed production area, it seems motivated to give
some consideration to pollen production and seed set of the trees if
possible.

Perhaps the area is too small for sufficient pollen production? For Scots
pine it seemed that the central part of a seed production area would get
improved pollination if surrounded by 100 m pollen producing trees (Yazdani
and Lindgren 1991). This is especially relevant if native Larch pollen is
considered a problem.

Andersson EW, Spanos KA, MullinTJ & Lindgren D 1998, Phenotypic selection
can be better than selection for breeding value. Scand. J. For. Res.
13:7-11.

Bila AD, Lindgren D & Mullin TJ 1999. Fertility variation and its effect on
diversity over generations in Teak plantation (Tectona grandis L.f.). Silvae
Genetica 48:109-114.

Yazdani R & Lindgren D 1991. Variation in pollen contamination in a seed
orchard of Scots pine. Silvae Genetica. 40:243-246.

Sincerely

Dag Lindgren

This should be a very good, low cost option for obtaining an adapted seed
source for what is in your area, an exotic species. You would be developing
a land race. Focusing on the best trees in the stand with regard to growth
rate and form is fine. You would obviously discriminate against any trees
exhibiting susceptibility to insects or disease. Since seed production is
your main goal, you can't afford to be too strict on selection, unless the
area is big. The main thing is to give the crop trees plenty of light.
This will encourage better flowering, and perhaps even more frequent
flowering.

Regards,

Larry

Andrew,

A word of warning - hybridisation with L. laricina is not difficult, and can be
expected to occur - the hybrid (L. x pendula) occurred very soon after the
first introduction of L. decidua into N America, so long ago that the hybrid
was introduced back to Britain as a presumed new 'wild' species in 1789.

Michael Frankis
Newcastle, UK

Hello,

I am considering turning a small (5-6 acre) operational planting of Larix
decidua into a seed production area. Dominant and codominant trees have
already begun to flower, in some cases quite extensively. I understand
that each tree should be evaluated on vigor, stem form, branch angle and be
free of insects and diseases. I am aiming for 50 trees/acre (roughly
125/hectare). Natural hybridization with the native Larix laricina is
difficult at best so I dont think I will need a large pollen dilution zone.

Are there different schools of thought on how to select the trees?

Is there anything else I am forgetting?

Sincerely,


Andy
___________________________________________

Andrew David
Assistant Professor
University of Minnesota
North Central Research and Outreach Center
1861 Highway 169 East
Grand Rapids, MN 55744

218.327.4521 office
218.327.4126 fax