I have heard that there is no limit on the growth of trees, but then why do some trees, such as boxelders and poplars, tend to live shorter than redwoods, for example? Some advertisements for improved lombardy poplars state that their trees have an extended life span, up to 75 years? The trees with shorter life spans seem to weaken at a certain age, and then contract diseases more easily.
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$\begingroup$ do clones count as part of the lifespan? If so, many trees have an infinite lifespan. (I'm not hunting for technicalities, I'm just guessing that most trees die as a result of macroscopic effects like rotting out, infections, etc) $\endgroup$– ShepMay 2, 2012 at 12:23
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$\begingroup$ No. clones, once established and detached from the parent plants, become essentially new plants, and have a whole life ahead of them. $\endgroup$– J. MusserMay 3, 2012 at 1:16
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2$\begingroup$ The answer to (this question) may be relevant to you. I didn't see your question until now, and it is very similar to a recent question I answered! $\endgroup$– LukeSep 30, 2013 at 10:51
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$\begingroup$ The answer that @Luke gave seems to apply very well to this question. $\endgroup$– OreotrephesJul 12, 2014 at 20:06
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3 Answers
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The answer to this could be that there are many factors contributing to the length of the life of tree species.
Climate: You can see that trees that have a reputation of becoming really old live in environments that have low moisture levels and much sunlight over the course of the year.
For example, you can see that the most long-lived trees in America are located in California, where the temperatures are relatively high, while moisture levels are low. If you have one without the other trees don't tend to live that long. Cold climates make growth harder for each individual, yet hot and moist climates tend to help trees grow easier, but also die easier. Think of the amazon. It is one of the richest forests in the world, yet the growth of bacteria and high competition in the areas of the equator make life a lot harder for the longest living and slowest growing species.
As you can see, the vast majority of the longest-living trees are located in California, or other regions of the same latitude! http://en.wikipedia.org/wiki/List_of_oldest_trees
Other species and the life around it/Its Ecosystem: Individual trees tend to be less likely to be destroyed by a fire, as they are less likely to catch fire. At some instances, forest trees or dried-out grass can catch fire and pass it on to other individuals. Microbes and bugs found in some parts of the world are known to their abilities to destroy trees!
Current size of the tree: Larger trees are generally less likely to die of causes like drought or damage to their trunks, as they have greatly extensive nets of roots and thick trunks and thus are able to, even partly, recover these incidences.
If a rockfall for example causes damage to one side of the tree, some of the brunches will probably die, but the rest of them, that have their own network to the roots, will probably survive.
This means that luck is involved and if the tree is lucky enough to avoid dying for a certain amount of time, regular fluctuations in the environment do not kill it as they would kill a younger, less robust tree.
Biology of tree species: Debate is held as to whether tree cells have telomeres working the same way as they do in animals. Research published in 2001 suggests that telomeres don't work the same way, as plants developed without telomeres after six generations continue living and growing without problems. But even if they do use telomeres, they may use them in a different way. This is an area where research is still being conducted, though, and you may find controversies in the bibliography! For example in the paper "Analysis of telomere length and telomerase activity in tree species of various life-spans, and with age in the bristlecone pine Pinus longaeva" Barry E. Flanary & Gunther Kletetschka which can be found in the rep
we can see that sometimes, short lived trees have longer telomeres than long lived ones! (Look in the second paragraph of the section "Results"). This means that actually, nobody really knows!! It may be the telomeres, it may be something else, it may be a combination of factors.
http://www.madsci.org/posts/archives/2002-04/1019349924.Bt.r.html (notice that this post has links to pages that are no longer available).
Distillation and the most important point: The way that the tree is adapted to its environment determines its longevity in it. Planting an olive tree in the amazon is a great way of making sure it will not survive! Some trees are better at surviving in a certain climate (even if it is at your own garden) simply because they have evolved to live there.
That means that the trees probably don't have a defined lifetime in general, but the life expectancy is defined in each environment, depending on the circumstances!
This means that species we currently think of as short-lived can reach get really old: http://www.ncbi.nlm.nih.gov/pubmed/11295506
What some companies may have done is try to combine characteristics of individuals through selective breeding - and yes, it works for trees as well!- to match the climate and terrain characteristics found in the certain country or region! Or they may have selected for resistance against the most common pests in your area!
I hope I answered you question adequately!
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$\begingroup$ Why do individual trees with no competition undergo a growth decline at a certain age, which lead to catching a disease, and the death of the tree? Some trees always do this. What is going on inside these trees? $\endgroup$ Jul 13, 2014 at 0:31
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$\begingroup$ Read the new section "Biology" in my answer! $\endgroup$ Jul 13, 2014 at 7:59
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$\begingroup$ Please change the !-. But looks pretty good. $\endgroup$ Jul 14, 2014 at 22:11
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Everything has a life span. When it comes to trees, there are significant variations between species (see here some examples).
Apart from the external factors, these variations seem to be related to telomeres length and telomerase activity [1]:
The results from this study support the hypothesis that both increased telomere length and telomerase activity may directly/indirectly contribute to the increased life-span and longevity evident in long-lived pine trees (2000-5000 year life-spans) compared to medium-lived (400-500 year life-span) and short-lived (100-200 year life-span) pine trees, as well as in P. longaeva with age.
Also, the lower metabolic rate of some trees increases life span [2]:
... the extremely high longevity of trees may be explained by the lower metabolism displayed by the stems. These results clearly reflect different energy allocation and energy expenditure rate strategies between leaves and stems, which may result in different senescence rates (and life spans) in these organs. They also suggest that, in contrast to animals, the ROL (rate of living ) theory of aging may apply to woody plants at the organ level, thereby opening a promising new line of research to guide future studies on plant senescence.
Leaf longevity is also correlated to shoot growth [3]:
These results suggest that leaf longevity is greater on shoots with low annual growth potential. Thus, a slow-growing tree at high elevation (low annual shoot growth potential) can have the same amount of foliage per shoot as a fast-growing tree at lower elevation.
References:
- Flanary BE, Kletetschka G. Analysis of telomere length and telomerase activity in tree species of various life-spans, and with age in the bristlecone pine Pinus longaeva. Biogerontology. 2005;6(2):101-11. doi: 10.1007/s10522-005-3484-4. PubMed PMID: 16034678.
- Issartel J, Coiffard C. Extreme longevity in trees: live slow, die old? Oecologia. 2011 Jan;165(1):1-5. doi: 10.1007/s00442-010-1807-x. PubMed PMID: 20963610.
- Schoettle AW. The interaction between leaf longevity and shoot growth and foliar biomass per shoot in Pinus contorta at two elevations. Tree Physiol. 1990 Dec;7(1_2_3_4):209-214. PubMed PMID: 14972918.
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$\begingroup$ On 'long-lived pine trees (2000-5000 year life-spans)', I haven't seen any evidence that there are trees older than about 4600 years old, but there are several trees of that age. I'm guessing there was an event at about that time that affected the trees. Those old specimens haven't been declining, so I think they might have a longer life span than people have thought. What are your thoughts on that? $\endgroup$ Jul 14, 2014 at 22:17
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Although most plants can potentially reproduce sexually, there are some plants that effectively always reproduce by shedding off branches which, when they fall in the right conditions, grow into new 'clones' of the same tree, which the exact genetic material. In these cases, it is advantageous for the tree to be able to survive as long as possible. Plants that reproduce sexually by the cross of two different individuals have a recombined genetic material in every generation, and the survival of that plant with that new genome is usually shorter.
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$\begingroup$ why do you think that recombination of genetic material leads to shorter life span? $\endgroup$ Jun 14, 2012 at 12:15
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2$\begingroup$ Because recombination is a mechanism to adapt to environmental changes. Then it is more important that nutrients, light and water are available for the "improved" next generation than for feeding yet unadapted elder individuals that might not survive long under new conditions. $\endgroup$ Aug 27, 2013 at 6:14