4This sort of weather pattern does not happen very often. Late spring is normally pleasantly warm, and the weather gets progressively warmer through summer, which typically includes a few unpleasantly warm days. It rarely gets too hot here, and when it does, it does not last for more than a few days, and tends to cool off at least somewhat at night. The air is normally arid. Humidity is uncommon in a chaparral climate.
While so many in the Northern Hemisphere were experiencing unseasonable warmth, the weather here was unusually mild. When the weather became warm, it did so suddenly. There was nothing unusual about the warmth. It was well withing the normal range for this time of year. The suddenness of the change was what made it unusual.
Humidity complicated matters. Again there is nothing too strange about humidity. Although rare, it does sometimes happen. The problem was that it happened at the same time that the weather suddenly changed from pleasantly mild to somewhat warm.
This combination of the weather changing so suddenly from mild and arid to warm and humid caused an outbreak of spontaneous limb failure. It was very evident in Felton Covered Bridge Park, where several trees that experienced it could be observed in the same place.5
The most recent victim was the biggest old California sycamore in the area. Half of the top of the canopy broke away and got hung up on an adjacent trunk, but started a cascade of other limbs that broke off more major limbs all the way to the ground. A large cavity that contained a very established beehive was exposed. A car parked below was clobbered (but somehow sustained only minimal damage!). The remaining trunks and limbs of the old sycamore are now even more scarred and disfigured than they were before this happened. The biggest gash is about fifteen feet long! What a mess!
Spontaneous limb failure is technically very damaging to the trees who experience it, but not all of them see it that way. Many of the riparian trees that are so inordinately susceptible to it might use it to their advantage. Fractured limbs that remain attached to the original tree while they sag onto the ground can develop roots where they touch the soil, and develop into new trees. These new trees are more stable at first, but eventually develop structural inadequacies like their parents did, and repeat the process. Willows excel at this technique. Cottonwoods and box elders do it too. Sycamore do it only rarely, but sometimes destabilize and fall over so that some of their limbs can grow into new trees as the original trunks decay. It may not be the sort of behavior that we want in our home gardens or parks, but as far as the trees are concerned, it works.6

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14 thoughts on “Nature Is Messy

  1. Most of our trees are terribly stressed after several years of drought and bug infestations — that can’t help the heavy limbs! What a shame to see so much of a tree fall — I hope it does produce new roots and a new tree!

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    1. Drought stressed trees are less susceptible to spontaneous limb failure than those that are healthy and very vascularly active. It is the availability of water that makes them heavier than their limbs can support. Although it is saddening to see such a admirable tree is such sad condition, the process is quite natural. The tree has plenty of roots, and should have no problem regenerating new limbs, although structural integrity will continue to deteriorate as the tree ages.

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      1. Thanks for this response — I’m glad that the tree will survive, even as it ages!
        Interestingly, in last night’s news there was a story about a local urban tree (oak, I think) “exploding.” The explanation was much the same as you have written above.

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  2. Yes, we’re getting a lot more unusual weather events too – much of the South Island has a natural föhn wind but this seems to be occurring out of season and often much harsher in season. We don’t have much info on weather hanges here – the last govt denied climate change so the science grew very sparse across the last decade. I have seen such winds literally open up bush as the leaves are shed (i have seen it called leaf firing).

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    1. Those who complain about climate change within our region have only been here for a few years. My great grandparents who were old enough to remember the Great Earthquake of 1906, and how weather behaved since that time, knew better. They remember the floods of 1982 as being the worst in recent history, but they also know that there were even worse floods in 1955 and 1958, and that floods have been occurring longer than anyone could remember. It is natural. In the early 1970s, we were worried about the impending Ice Age! Fears were justified when it snowed very lightly in San Jose in 1976. Climate has been changing since the beginning of time, but is doubtful that anyone really knows which direction it is going in, or that any of us will live long enough to see the changes.

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      1. I think the one thing that will change things most visually is the rate the CO2 is rising – it’s increased 18% in my lifetime and I know a lot of plants are responding to that in lots of weird ways – and none of them good, weediness and flammability are two of the big ones.

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      2. Combustibility can be attributed to the lack of fire within ecosystems that depend on it. That was the main problem with the Monterey pines on the Monterey peninsula in the 1980s. Disease and insect infestation were proliferating, not because of climate change, but because the trees were not burning and being replaced by fresh replacements. The geriatric elderly trees were naturally very susceptible to disease and insect infestation. The healthiest remedy would have been to burn the entire forest. However, that can not be done because it is a suburban region now. The proliferation of the Eastern red cedar and the associated combustibility in the Midwest is another consequence of the lack of fire. It is not the result of increasing carbon dioxide. It is the result of necessary fire suppression. Prior to the past two centuries, wildfires were huge, and prevented the forests of North America from getting so overgrown and combustible. The fires were not as voracious as they are now because they were more frequent. They were a normal part of the ecology throughout North America and on other continents as well. The native people of the Northwest documented a single fire that started on the Olympic Peninsula in Washington and burned for a few years, right through winter, and eventually reached Wyoming.

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      3. Yes I agree with you re flawed ideas leading to misguided burn control rules but I design landscapes and consider combustibility of plants in some designs – there is some recent recent research looking at changed lignin contents in plants leading to increased flammability e.g. “Combustion properties of Bromus tectorum L.: influence of ecotype and growth under four CO2 concentrations” – Blank, White and Ziska. 2006.
        http://www.fpl.fs.fed.us/documnts/pdf2006/fpl_2006_blank001.pdf – this has gone onto being an active area of research especially in the US mid-West, although the currently political climate in the us can make researching reality quite difficult.

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      4. Such changes in combustibility are likely a natural response to changes in the environment, perhaps as an attempt to correct the damage, or at least exploit the changes.

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