Global warming response


It is now a safe prognosis that the climate gets warmer. Other components of climatic change and variations within Sweden are less certain predictions. Man adds a large contribution to natural changes, thus the future gets more uncertain than the past. How should the forest tree breeding system react to these circumstances? The reaction should not overshoot and risk thereby risk to make things worse, but moderate the effect of predicted change. Earlier it was to unpredictable what would happen locally and the change predicted was to small to bother, but now I suggest it is time to make a change The general reaction should be simple.


I suggest that we decide to now react as average temperature will raise 0.02 centigrade annually (a low estimate according to most Swedish scenario writers) from 1990 to 2100, and assume that change in whole Sweden is the same and that everything else is unchanged. The temperature before 1990 is assumed to be constant and quantitatively as it was 1961-1990 (reference temperature), thus by definition 1990 is here considered the starting year of rising temperature.


Figures on global warming e.g. at (for Europe)


For Swedish counties
and Swedish “similar areas”


Transfer knowledge and performance of “natural provenances” and Tsum calculations is still mainly obtained from the reference period. Knowledge from later periods will have to be adjusted to the temperature rise, but that can wait. 


Altitudinal effects

If the altitude is not the same as that of the tabulated stations a correction for altitude may be made. According to Ångström (1974, Table 5), the month averages in Sweden change with altitude according to the following adjustment factors (degree C per 100 m change in altitude):

Jan                 Feb                Mar               Apr                May               Jun                 Jul                  Aug                Sep                      Oct                Nov               Dec

.36                 .43                 .48                 .56                 .58                 .61                 .60                 .60                 .53                      .46                 .20                 .25

A change in temperature can be considered equivalent with a change in altitude, the higher up the cooler. I suggest the temperature is assumed to change 0.006 centigrade each m of altitude changes the temperature degrees, thus 100 m elevation rise decreases the temperature 0.6 centigrade. Thus the temperature climate 2090 will be as it was 1990 at start of temperature rise on a 350 m lower altitude.


I suggest Swedish forest geneticists respond to the global rise in temperature by making decisions and recommendations from now to 2020 as if it was 1990 but all elevations were 100 meter lower. That corresponds to the temperature around 2020. This is not optimal, but it is almost certain that it is better than no reaction to global warming, and it is a simple heuristic rule, while better and more sophisticated algorithms are developed. To accept a quantified change is a new thought,.


It can be argued that the temperature change has many effects. The average temperature changes, but the winter temperature will rise more than the summer temperature. The vegetation period will be longer. The climate can be said to be more maritime.  The springs will come earlier and the autumns later. The spring and autumn months are warmer. The latest spring frost will occur earlier and the earliest autumn frost later. The exact prognoses are uncertain and I cannot find the information I would like to make exact prognoses. During the vegetation period the main change between temperature change by elevation and temperature change by global warming is probably that change by elevation has rather small effect in late autumn while global warming has rather large. It can be thought more over the details and someone ought to do that at some time.


The forest tree breeding system comprises three components: recommendation for foresters what to plant; recommendations for seed orchards establishers what material to use; and decisions for the long term breeding.


For foresters in cool Sweden the critical is how the trees thrive during the establishment phase. We do not want to risk recommending a seed source which is too mild. We have several instances of conceived too southern materials in Sweden (too southern pines (both Scots and lodgepole) on harsh sites in northern Sweden and Rumanian spruce in south Sweden), and we do not want to do such mistakes again. A seed source is recommended which is adapted to the climate of planting and some years after. Thus “planters guide” could “sink” elevation 50 m compared to the real when recommending material (and recalculate predicted temp sum for the locality). Thus forest regeneration material is “most” recommended compared to earlier recommendations as if the elevation of the plantation site was 50 m lower 1990. Foresters should still feel that they make their own decisions and have an own responsibility and what is the wisest choice may change locally, thus the change could, besides verbal explanation, just be that the default in “Planters guide” is to sink the elevation 50 m, foresters who think themselves may make own adjustments.


For seed orchard establishment it can be argued that the recommended use can be decided when the production comes. The “mistakes” introduced now by not considering global warming at establishment is that the projected areas for different intressents not will be optimal, and that forest tree breeders are likely to select material which is adapted to cooler climates forcing changes in recommended areas for the seed orchard to higher and more northern ones when the seed orchard was designed for. Seed orchards are long lived objects and (in contrast to plantations) the main crop will occur maybe 25 years after the selection of the clones. Thus it could be argued that a rise of 100 m would be justified instead. But it is simpler with a single rule and the first step is to consider the issue at all. A seed orchard comprises material from several breeding populations, typically targeted for areas close to the main target of the seed orchard. Today these neighbouring breeding populations get the same weight but now practically the seed orchard target can be modified for the future by choosing more selections from breeding populations heading for lower elevation that the target and fewer selections for breeding populations designed for areas above the target. Again 50 m is not firm but it is rather a recommendation to whoever appears as adviser to insist on at least that, if the seed orchard owner does not consider the issue.


For long term breeding decision the time span is also longer than establishment. Evaluation of the trial may be done 15 years after decision of what the site and the material choice. Again it is simpler with one thumb rule while more sophisticated are worked out, and that is to place the trials in the breeding populations at 50 meter higher elevation at and average that was foreseen when the breeding populations were constructed. It is possible to keep the geographic targets of the breeding populations, but I do not think that is the most efficient solution, because when some of the selection effort goes to change adaptation instead of being available to artificial selection. Also I think it is recommendable only to change elevation, not latitude, as if latitude changes it interacts with the light climate and the signals for growth cessation. Currently the breeding populations have wider variation than would be motivated from the land distribution just to be able to respond to the climate change which now happens so we can cash in some of the flexibility it gave to arrange breeding populations like this!  However, to replace test plantations most coastal and at low elevations at a later stage I think it will be needed to move breeding material northwards. Here I suggest to let the breeding populations move only as much as the plantation populations, thus so it is right at the plantation of the test. It could be motivated to move them somewhat more as they are meant for the future, but when it is difficult to argue how much more. Breeding populations adapt to the change not forced on by moving them, the idea here is to reduce the needed adaptation, if we try to eliminate it, we can cause a reverse problem. Testing of breeding populations will also be done over a range, the most important is that future change is within that range when they are measured, the likelihood of that increases if we move the centre somewhat in elevation now.


There is some uncertainty about the influence on the spring frost problem of southern Sweden, but is seems spring frost incidents have been less common the last decade, might be that also is an effect of green house gases which may make a clear sky warmer, but more cloudy weather may reduce the spring frost risk. Warmer winters may lead to accumulation of a certain heat sum needed for bud development at a lower average temperature and thus raise spring frost risk. But the guess is that those effects will be very marginal and have little practical importance. 


Trees are plastic and tree populations flexible. Tree populations can evolve and adapt. A hundred meter change in elevation is not a big problem and the change in heat sum is smaller than annual variations. even 100 m change for origin is marginal and makes not much, thus what I suggest is rather risk free, almost cosmetic if nothing big happens. However, global warming may have the same effect as a change of elevation 250 m some half century after planting and in a bad scenario and if local conditions interacts and that may make a considerable change. This change can be moderated to a considerable more benign effect if the change is reduced by 100 m by the change. Thus the change suggested is more for reducing the effect of a larger real change than that it matters if the real change is not larger than the suggested modification. 


Do we overshoot with 100 m change in elevation? The temperature in the summer is predicted to change somewhat more than 1 centigrade per 100 m. The change is suggested to happen as fast as implementable but the effect is predicted first 2015. There are scenarios when the local rise will be smaller that the response. First 50 m is not drastic; the effect of an overshoot will be benign. Second we had some global warming already before 1990. Third, most scenarios predict a larger effect and when the consequences of not implementing the action will be worse. Fourth, by actually reacting we get a principle of reacting established, and once that is done the sophistication degree can be increased till next change, if we just discussed how probably a reaction will be too delayed, fifth, for political reasons it is desirable that a reaction is made.


Seed orchard material can be assumed to be better suited to a changing unpredictable environment than stand seeds. First, it is tested material and test means test on many sites. Natural evolution knows only now and here, multi-site testing can be assumed to produce more stable material. Second, seed orchards comprise selections made over a region where the origin of the trees differ by hundreds of kms and selected based on different trials with a different history. Thus the seed orchard crop can be assumed to be more variable than stand seeds, where the parents often grow near each other. Under different conditions different trees can take over most of the production. Seed orchard crops have a buffering on the populations level. Seed orchards are rather predictable and reproducible and well defined, while stand seeds are likely to become more different and unpredictable in a situation with a drastic climatic change, where different stands will react differently.


Climatic change makes the future more unpredictable, thus it is an ambition to make each tree more plastic and more able to adapt to a variable range of environments than natural populations. Tree breeding in itself is expected to make trees more flexible as testing is made over a range of sites and decisions are made for the average. Still, as a response to an uncertain climatic change, the testing range of genetic materials could be somewhat wider than used historically.


An effect of breeding, seed orchards, intensified forests and climate change is that they constitute a strong incitement to decrease rotation age, and initially that means increase the harvesting. It is difficult to understand that so many factories close down in spite of that they are profitable, when for a layman like me it seems room for increasing the harvest instead. Anyway this is an aspect which does not seem sufficient discussed when the future role of the forest is discussed.





Test sites, zone sizes, breeding population targets


Target sites and site diversity

The current Swedish Tree Breeding tests the breeding material on 4-5 testing sites. This is considered giving sufficient precision considering G*E interactions and risk of loss of site by calamities. Spreading the test sites over the central targets of adjacent zones and if possible also to similar sites in adjacent countries, selections based on the combined data will probably result in more stable and flexible genotypes which are well adapted over a wider range of sites than “natural” genotypes and provenances.  Testing the breeding stock of one breeding subpopulation closer to the target for other subpopulations makes it possible to draw future seed orchards from several (typically 4) breeding populations, increasing selection intensity and thus gain in new seed orchards and in the same time making the crop adapted over a wider area, compared to if all tests were close together in the same target area. It helps to get connectedness among test sites testing different set of genotypes on the same site, which increases the genetic gain when material is drawn from different test series.  In the annual documentation of Swedish breeding subpopulations, insufficient detail of the main target of testing and its variation is given. Details are insufficient for follow up on the national level, which the documentation is intended to serve. A possibility would be to calculate an average test TSUM and its standard deviation, thus documentation in “the annual breeding status report” may look like: “Tested over TSUM 1000±100”. But it may actually be better to leave TSUM as a description of a local as it changes over time and instead express the variation in another way, lat and alt, but I suggested once eq lat to get a single measure. Having this statistics describing the test site variability in hand, it would be easier to see if it looks too narrow or right, and to think on what would be right.

It might be a good idea to include “the local adaptation” to the test site diversity, whenever possible and practical.  Some people and interests have always claimed that the local provenance is best, and this opinion is not likely to vanish in the foreseeable future, and as there is some logic in it, and as it often is rather correct, it will be desirable to have materials, which make a general comparison possible. Current Finnish recommendations are more similar to the local provenance than current Swedish. When experiments grow older they may hint more for the local than when they are young.


Environmental change

Note that this is a preliminary discussion early 2007, it is replaced by other discussions early 2008.

Till now my attitude has been that activities of Man causes drastic environmental changes, which undoubtly will have importance for Future conditions, but these have been too unpredictable to affect decisions by Swedish conifer breeders based on a prognosis of the change. A global change in one direction may cause a change in the opposite direction locally. A change triggers other changes and the end result may not be what was initially expected. There are different changes, which may act in different directions (e.g. global dimming is competing with green house gases). Tree breeding has a perspective which should consider centuries and trees lives for a century, ten-year fluctuations should not receive much attention but more than century long trends should.  “Nothing is as unpredictable as the future”, and Man has made the future more unpredictable than it was. “The future is more unpredictable now than it ever has been”. Climate change is recognised by Swedish Tree Breeding. Tree breeding has prepared on a change in ways not relying on an exact prognosis in different ways (more attention on high and low altitudes in targets than if only the current forest area would be a concern; some spread of testing environments; and no strong differences in resources invested to different targets based on current species use. Sweden uses for a breeding meta-population, which for pine and spruce is structured in about 20 subpopulations aiming at different targets. Testing the same genotype in different environments makes the material more robust and stable than Evolution. That is a desirable side-effect of tree breeding. Evolution knows only here and now. Man can beat Evolution with “Intelligent Design”, thus e.g. base decisions on tests with materials over an area and a range of environments! The individual future trees will be more adaptable. I suggest that shorter rotation time should be expressed as a direct target for breeding and one reason is to increase the flexibility of forestry to changing environments.


But at the publishing of the UN report early February 2007 I changed opinion on an essential point. From now on I think the documentation that Sweden will be warmer is so convincing, so I now suggest adapting Swedish breeding considerations to a warmer Sweden. We will not go back to the situation 1950 for several hundred years ahead compared to the time to the epoch till around 1950. I do understand that others do not feel that the time has not come yet, I did not a month ago. But we only know that it will be warmer, so we restrict ourselves to a moderate change in temperature. We want to be rather certain we do not overshoot, and make the future situation worse. Some conservatism to react to doomsday profetia may be motivated when we are not the cause. I mean that it is very little risk and realistic doomsday scenarios in reduction of e.g. carbon dioxide releases to the atmosphere, and actually it stimulates continued undesirable releases if we pretend that we can manage the problem by reacting too much. Reacting much may also mean that we create other problems. The effect of warming is not too bad for trees; they will generally survive and grow better, so the punishment of under reacting in adaptation of forest materials is not extremely risky. The proper response on climate change may rather be in changing species than adapting existing species, thus the main strategy should not be to adapt breeding and seed delivery. Thus I suggest that we decide to react as average temperature will raise 0.02 degrees per year from 1990 to 2100, and assume that change in whole Sweden and that everything else is unchanged, fine structure of the change is still unpredictable.


Exactly how much warmer and what effect that has and what time perspective which is most important is and what other associated changes will occur are difficult matters. There are many other things which affects and it is very difficult to predict how. Predictions and predicted scenarios should be made, and these indicate the directions of modifications, but modifications should usually be much smaller that if predictions were taken for granted because of the large uncertainty. But my opinion is now that we know enough to react instead of claiming that it is too uncertain. A consequence of the widened uncertainty and increased unpredictability is an incitement to test materials over a wider range than earlier. It is an added reason for attention on minor species (in particular to replace spruce in southern Sweden). I suggest that is mentioned in Swedish breeding strategy. Provenance transfer rules should be revised. They are based on experiments usually established 50 years ago. A consequence could be that the target areas of the breeding populations are moved upwards and to the north.  That could mean that the testing sites should be half a latitude more north than has been planned till now for the material which has now been moved to the south (thus Scots pine in harsh areas could be closer to the local provenance). It could be considered desirable setting up a new breeding population in the far south. It has annoyed me that some southern ones seems a little too extended latitude-wise, that could be solved at that time. For the lowest altitudes there seems no need of new zones (there is no material to be found on the bottom of the Baltic), but in the same time as the timberline raises, the altitude of the highest test sites of the north western breeding populations could be increased. Breeders could state that the breeding population is very useful as gene conservation as it will respond slower to global warming than the forests and ex situ conservation.


The Swedish (and Finnish) breeding zones (targets) are based on heat-sums. Once we accept a temperature raising trend, which I suggest, heat sums for a place increases over time. It will be conceptionally impossible to couple heat sum to a geographic area or place and in the same time treat it as a variable. Maybe we have to go back to latitudes and altitudes (which I have preferred) instead of warmth and light climate. The breeding population targets will move by itself in the geography when meteorologists calculate new heat sums for more recent periods unless the definitions of breeding population targets change. Thus the rule work of the Swedish breeding just has to change in some way and sometime. Such a change could specify how breeding targets fits to geography rather than TEMPSUM (such a change has already taken place for seed orchard zones). The production populations should also be affected by the predicted change and to a higher degree than the long-term breeding populations, as the time perspective concerns only one century for the production populations and nothing beyond that. 


Maybe we just should anchor the breeding targets in the geography and think of heat sum as something variable. Or fix heat sum 1990 permanently and only refer to that when we describe an area with heat sum.


If targets are changed, it is a question when. As a background for a change one would need new temperature sums for a more recent date to compare with, and as this has not done and it was not so long ago the previous calculations were done, it may not be a good idea to tackle this problem of redefining the target areas as a part of this years revision, but wait some years, but still revise the average site choice so TSUM (current calculation) often becomes a little lower on average than the area was initially targeted for. It might be enough to instruct to avoid that TSUM is higher and to see that it is somewhat lower only for pine at high latitudes. 


One aspect of global warming is that probably it does not just make the future more unforeseeable generally, but it does not seem unlikely that it will also be more variable from time to time on a specific spot, thus more robust and flexible materials will be needed even if the average change is correctly predicted and adjusted to.



Seed orchards

The philosophy of constructing production populations has a shorter time perspective, which motivates a stronger link to prognosis. For the matching of existing production populations to localities, the link should be still stronger, thus currently established seed orchards would probably get their targets slightly modified because of global warming predictions. One thing is easy to Skogforsk that is to write something about global warming in Valskog, and suggest forester’s ways of reacting when choosing material by “sinking” the altitude of the plantation site to consider global warming! Or Valskog could be modified to consider global warming (enter year of plantation).

I guess the target for a seed orchard will be different when it starts seed production than when it ends seed production two decades later.

Our seed orchard zones used for TreO are based on the temperature sums 1961-1990. But the seeds will be used 2030. At that time the average temperature has changed 0.8 centigrade. That means that the area of use of the seeds should change compared what was thought when the seed orchard was established. The next prognosis of need of new seed orchards should be based on a dynamic model with a changing temperature. The work for doing that should probably be started now.



The subject is dealt with on Tree Breeding Tools


Thoughts about documentation and use of G*E are found at ..\SkogForsk04\GEtankar.doc


Last edit Mar09