UNIVERSITY OF BASEL
No year since weather records began was as hot and dry as 2018. A first comprehensive analysis of the consequences of this drought and heat event shows that central European forests sustained long-term damage. Even tree species considered drought-resistant, such as beech, pine and silver fir, suffered. The international study was directed by the University of Basel, which is conducting a forest experiment unique in Europe.
Until now, 2003 has been the driest and hottest year since regular weather records began. That record has now been broken. A comparison of climate data from Germany, Austria and Switzerland shows that 2018 was significantly warmer. The average temperature during the vegetation period was 1.2°C above the 2003 value and as high as 3.3°C above the average of the years from 1961 to 1990.
Part of the analysis, which has now been published, includes measurements taken at the Swiss Canopy Crane II research site in Basel, where extensive physiological investigations were carried out in tree canopies. The goal of these investigations is to better understand how and when trees are affected by a lack of water in order to counter the consequences of climate change through targeted management measures.When trees die of thirst
Trees lose a lot of water through their surfaces. If the soil also dries out, the tree cannot replace this water, which is shown by the negative suction tension in the wood’s vascular tissue. It’s true that trees can reduce their water consumption, but if the soil water reservoir is used up, it’s ultimately only a matter of time until cell dehydration causes the death of a tree.
Physiological measurements at the Basel research site have shown the researchers that the negative suction tension and water shortage in trees occurred earlier than usual. In particular, this shortage was more severe throughout all of Germany, Austria and Switzerland than ever measured before. Over the course of the summer, severe drought-related stress symptoms therefore appeared in many tree species important to forestry. Leaves wilted, aged and were shed prematurely.Spruce, pine and beech most heavily affected
The true extent of the summer heatwave became evident in 2019: many trees no longer formed new shoots – they were partially or wholly dead. Others had survived the stress of the drought and heat of the previous year, but were increasingly vulnerable to bark beetle infestation or fungus. Trees with partially dead canopies, which reduced the ability to recover from the damage, were particularly affected.
“Spruce was most heavily affected. But it was a surprise for us that beech, silver fir and pine were also damaged to this extent,” says lead researcher Professor Ansgar Kahmen. Beech in particular had until then been classified as the “tree of the future”, although its supposed drought resistance has been subject to contentious discussion since the 2003 heatwave.Future scenarios to combat heat and drought
According to the latest projections, precipitation in Europe will decline by up to a fifth by 2085, and drought and heat events will become more frequent. Redesigning forests is therefore essential. “Mixed woodland is often propagated,” explains plant ecologist Kahmen, “and it certainly has many ecological and economic advantages. But whether mixed woodland is also more drought-resistant has not yet been clearly proven. We still need to study which tree species are good in which combinations, including from a forestry perspective. That will take a long time.”
Another finding of the study is that it is only possible to record the impacts of extreme climate events on European forests to a limited extent using conventional methods, and thus new analytical approaches are needed. “The damage is obvious. More difficult is precisely quantifying it and drawing the right conclusions for the future,” says Kahmen. Earth observation data from satellites could help track tree mortality on a smaller scale. Spatial patterns that contain important ecological and forestry-related information can be derived from such data: which tree species were heavily impacted, when and at which locations, and which survived without damage? “A system like this already exists in some regions in the US, but central Europe still lacks one.”
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I suggest that they import some Bluegum seedlings and put them in.
I have seen them grow in the highest towns in the World such as Pune in Peru at lake Titicaca and in Sri Lanka, Saudi Arabia, Brazil and anywhere else you care to name.
And they love the heat also.
Philip
“import some Bluegum seedlings”
Please say you’re joking. Eucalyptus are a fire climax species.
You want more forest fires? Plant Bluegum.
Trees under stress, let’s convert from the only known economic system that works to one that has killed 100,000,000 people in the name of the various leaders greed. Yes makes sense (sarc)
And yet there’s a place in Spain called La Pineda.
Guess what types of trees thrive in La Pineda?
Especially in Germany this summer is cold and rainy. I don’t know where people got this data from.
Heat stress. According to BBC news yesterday it’s affecting humans too. They interviewed nurses who have discovered that working in hospitals without AC, dressed head to toe in plastic PPE makes them sweat. And of course, it’s only going to get worse.
https://www.bbc.co.uk/news/science-environment-53415298
No year since weather records began was as hot and dry as 2018. A first comprehensive analysis of the consequences of this drought and heat event shows that central European forests sustained long-term damage
Utter nonsense. I live there. Yes, we have had several months without rain, usually July, August and september, but that’s just about normal. Recent summers, such as the current, have been significantly cooler than almost every summer upto about 2012 and especially 2003. We have also had flooding rains every spring for the past 7 years. This year my mobile reversible heat pump has remained in the cupboard, so far.
HOWEVER, some trees show signs of suffering although fruit trees have been stunning for years. It may just be that if you look hard enough for what you want to find you will find it.
“Even tree species considered drought-resistant, such as beech”
These are the same beech tree’s I suppose that have been expanding across Europe since the end of the last ice age.
From UNESCO, Ancient and Primeval Beech Forests of the Carpathians and Other Regions of Europe.
Quote:
“Since the end of the last Ice Age, European Beech spread from a few isolated refuge areas in the Alps, Carpathians, Dinarides, Mediterranean and Pyrenees over a short period of a few thousand years in a process that is still ongoing. The successful expansion across a whole continent is related to the tree’s adaptability and tolerance of different climatic, geographical and physical conditions.”
Except of course a couple of years where it got a bit hot in 2018/2019 that stopped them in their tracks, oh please, and the massive heatwaves of the early 1300’s, or the year 1540 when you could cross the Rhine on foot, or the 70 day heatwave of 1911, what happened then?
The world didn’t start when your weather records began, what the hell is happening to history?
Darwin noted this type of struggle in his great tome ‘Origin Of Species’ Chapter 3, ‘The Struggle For Existence’.
Here Darwin details instances where the competition for food or predators will tend to keep populations in check, but more powerful factors can be diseases, or changes in climate with extended times of cold or drought.
Even when the climate varies in such ways which might seem more favorable for survival of a particular species, one individual may have a variation which helps them prosper over the others and in turn crowd out the original for precious resources. And in a contrary way, climatic conditions that should tend to go against a particular variety or species may give rise to a particular (rogue?) variation(s) that survives much better, or even thrives. Such is the complex nature of survival.
Overall Darwin noted when climates are extreme species tend to struggle against the environment, when more hospitable the struggle is between species and their varieties.
A day late and a dollar short, but I was speaking with an old friend, talking about the weather and the start of our summer monsoon here in the Southwest. He was very interested in the study and wanted to contact the authors with a question: “Have you seen any entwives?” -Treebeard.
The dryest summer I recall in the UK was 1976, which followed a dry 1975 and dry winter.
The whole countryside was bleached a fawn colour, crops and grass. Corn harvest mostly finished a month early.
Except for the hedges and trees which remained dark green and alive, although some beech trees suffered where they were on shallow soil.
Much more damage was caused to trees in our neck of the woods by very high winds in 1987 and 1990 where trees and in some cases whole woods were blown down, some in as little as 3 minutes the gusts were so strong. Beech trees were particularly affected and where blown over looked like huge mushrooms on their side with the root ‘plate’ showing the shallow rooting depth of the beech trees.
Where trees had been pollarded regularly they were not affected as the bulk of their mass was in the wide trunk, although a whole avenue of beech trees at Longleat that had been pollarded in the past but not for some years provided more resistance to the winds and were toppled.
Whole hillsides of trees (most often shallow-rooted tuliptrees and white pines) were uprooted by a massive ice-storm in 1994 in mountainous southwest Virginia where I lived. Seems trees near the hilltops fell downhill and acted like dominoes caused uprooting all the way down to the bottom. Deeper-rooted oaks got branches broken, but usually resisted uprooting.
Spruces are shallow root trees.
In our garden, we have groundwater in about 7 m depth, and I measured this year an increased volome of groundwater in comparision to last year. Nevertheless, in our surounding in other gardens, the spruces are all dead.
2018 was just a warm spike during a warm AMO phase, the warm AMO phase dries the region, and the warm AMO phase is normal during each centennial solar minimum. I doubt that it was warmer or drier than 1540, 2003 saw more high temperature records, and moreover, all of these major heatwaves are discretely solar driven, and cause climate change, climate change cannot cause them.
https://www.linkedin.com/pulse/major-heat-cold-waves-driven-key-heliocentric-alignments-ulric-lyons/
No year since weather records began was as hot and dry as 2018. A first comprehensive analysis of the consequences of this drought and heat event shows that central European forests sustained long-term damage.
Local conditions. Few years were as wet in the US central Appalachians as 2018. Forest & crop growth was extraordinary — field corn was 12 ft high.
I hope this this gets posted:-
To establish the next stage of the cycle, how beech replace oak, I studied a mature oak woodland in the New Forest of Hampshire. Here, after a few hundred years of soil improving by the deep-rooted oaks, the beech trees were taking over. Beech species are very shade tolerant, and have a drooping leader in the spring growth season. The ecological advantage of a drooping leader is the beech is able to rapidly penetrate the branches of the overlying oak canopy, quickly straighten up and so avoid wind lash damage to its apex growth point. (Hemlocks – Tsuga species and false cypress have exactly the same growth strategy for the same reason).
Beech grow physically taller than English oak (Quercus robur) and so in Epping Forest the beech will eventually overtop and kill the oaks by shade competition. In the New Forest Durmast Oak (Quercus petraea) co-exists with the beech, (I only found 6 mature durmast specimens in my Epping Forest study area). Durmast oaks are physically taller than Q. robur and so are not overtopped. In Epping Forest the Q. robur naturally co-exist with the much smaller Hornbeam on the damp valley lows where the shade tolerant moisture loving hornbeam (Carpinus) replace the Beech in the species pattern, but do not overtop the English oaks.
To study this process of natural cyclical succession I used a Markovian Matrix with the key parameter of age at death of my three species, Birch, Oak and Beech. The data were obtained by coring dead specimens in the study area. Canopy size is also a feature, in general 3 mature birch equals one oak in a dense woodland setting where upward competition for light is severe and canopy diameter is constrained. The purpose of the Markovian analysis is to establish the stable population age profile of the three dominant species that results in a smooth transition for the woodland as a whole; so that somewhere in the species pattern there are always patches of new replacement regeneration in an endlessly repeating series of growth and decay.
I have not studied coniferous woodland succession but I have observed how in the mature Scots Pine pioneer woodland at Aviemore in Scotland, the woodland is being replaced by saplings of Douglas Fir (improver) and Hemlock (shallow rooted shade tolerant exploiter) growing in the shade of the pine under-story in this ancient mono-species forest.
So, what message do I want to give you? My Markovian Matrix analysis showed that managed forests in which a multi-aged mix of stands of pioneers (birch or pine), improvers (oak or silver fir) and exploiters (beech or spruce) is the most ecologically stable and diverse. This is because with a managed areal pattern and a large age profile there is always somewhere for the herbaceous species to move to, and somewhere were the soil seed bank is being replenished.
End of message.
Yes it makes perfect sense scientifically that temperatures above 20 C are an intolerable stress to plants, unsurpassed with the possible exception of an innocent mushroom being misgendered.
Like all progressive climate science it hangs together so well and consistently with our knowledge of past climate disasters. Climate itself is always a disaster. As we now know. Like Donald Trump and Brexit.
That’s why at the Holocene optimum 9000 years ago with temperatures 2.5C warmer than now, 25 % of all life went extinct. Including polar bears. And at the optimum of the previous Eemian interglacial 110 Kyrs ago that was 5 C warmer than now, 50 % of all life went extinct! Including all insects.
And during the Cretaceous 100 Myra ago with temperatures 10 C warmer than now, 100 % of life -all of it – went extinct!! Since then there had been no life.
Can’t see what problem skeptics have with any of this settled science.