Tag: Drought

Trees and drought.

The scientific findings of how the height of trees affects their ability to cope with drought.

I subscribe to the online Physics World website and a recent article tickled my fancy. Because it was supported by what we see here at home.

That is that shorter and taller trees do not handle drought conditions as well as medium-height trees.

First the article and then some supporting evidence from home.



Medium-height trees survive drought best

04 Sep 2018

Courtesy iStock_MilosJokic.jpg

Forests with canopy heights of around 18 metres are more resistant to the effects of severe drought than those with shorter and taller trees, according to researchers in China and the US.

In the past, studies have disagreed on whether forests with lower or higher canopies will be more likely to make it through prolonged spells of hot, dry weather. The discrepancy has made it difficult for forest managers, who need to know which tree heights to encourage to ensure the highest growth and survival rates during extreme drought.

Study leader Peipei Xu at Beijing Normal University in China and her colleagues believe the issue is increasingly pressing. “Climate data indicate that warm areas of land are increasing, and the warmed areas are also drying,” says Chuixiang Yi at the City University of New York, US. “Hot-dry-induced forest mortality poses a significant global concern for the future as carbon dioxide continues to rise and the climate continues to warm.”

Xu, Yi and the rest of the team aimed to quantify the relationships between canopy height, growth and survival rates during drought accurately for the first time. They analysed data gathered during a severe drought in the southwestern US in 2002 that showed the effect on the ring widths of tree trunks, a useful indicator of their yearly growth. In addition, satellite data revealed how the density of vegetation changed over the course of the drought; the team used this to calculate both leaf growth and tree mortality rates.

The results revealed that trunk and leaf growth under drought conditions increased with canopy height for trees shorter than 18 metres but decreased with height for trees taller than 18 metres. “Our results indicate that both high and small trees have relatively low drought resistance,” says Yi.

After establishing these relationships, the researchers could determine the biological mechanisms governing tree growth and survival during drought.

“All organic matter in a tree is formed on the leaves at the top of the tree by photosynthesis,” Yi explains. “Tall trees have a longer water transport path from roots to leaves and [it’s] more difficult to overcome tissue resistance and … gravity, particularly under dry conditions. The roots of small trees are short, and their abilities to access water and nutrient supplies unavailable to the surface soil layer are extremely limited.”

The researchers believe that using their results to inform the active management of canopy structure could safeguard vulnerable forests. As climate models predict hotter, drier droughts becoming more commonplace, this could be essential to combat forest dieback – a phenomenon that will also drive climate change.

“Our findings provide insights into how to manage forests or plant what trees to increase forest drought resistance in facing hot-dry climate conditions to mitigate climate change,” says Yi.

The team reported the findings in Environmental Research Letters (ERL).


So turning to home.

Here are a couple of photographs of tall trees to the Northern side of the house that are clearly showing some stress.

A tall fir tree that is due for removal because it is clearly dead.


Another tall tree, this time a pine, showing signs of stress.


Now in stark contrast look at the trees in the photo below. (Oh, that’s the smoky summit of Mount Sexton, elevation 3,829 ft., in the distance.)

Medium-height trees that border the Northern side of our driveway from the road to the house.

As our taller trees are felled each year we are planting new young trees, two for every tree felled, in one of our grass fields.

Because it is not just Jeannie and me, and all the wild birds, who love our trees!

Do you know, I feel the need to pee!


This seems to have a good smell about it!


Ah! That’s so much better!

Will close with another photo with a tree in it taken a few nights ago.

We must never, ever lose our trees!

Cities and forests; the outlook

Just a couple of items that came through my ‘in-box’ in recent times.

From the Payson Roundup newspaper of the 9th October, last.

Southwest forests are already in the early stages of a mega drought brought on by climate change.

Southwest forests are already in the early stages of a mega drought brought on by climate change that will result in massive tree die-offs and sweeping changes in Rim Country forests, according to an analysis published in the scientific journal Climate Change.

Severe drought will dominate much of this century, creating stresses on forests not seen for more than 1,000 years, according to the research that used tree ring samples from 13,000 trees, historical rainfall records and computer projections of future climate change.

The shifts will likely dramatically shrink the world’s largest ponderosa pine forest in northern Arizona, replacing pines with junipers at elevations like Payson and replacing junipers with chaparral and cactus at lower elevations.

The article concludes,

Unfortunately, the team’s climate prediction models suggest that within the next 40 years the region will fall deep into mega drought conditions. The models predict that even the wettest, coolest years in the late 21st century will exceed mega drought levels. In that case, the drought conditions of the past decade will prove the new normal rather than a bad stretch.

Williams noted that while winters in the past decade haven’t been exceptionally dry, summer temperatures have soared. As a result, the stress on the trees in the past 13 years has exceeded mega drought levels about 30 percent of the time — conditions not matched for the previous 1,000 years.

Now to a more positive message, this one from Climate Denial Crock of the Week for 10th October, 2012.

One of the clean little secrets about dealing with climate change, is that if we make our cities more efficient, and reduce their carbon footprint, we will also make them more resilient, quieter, more comfortable, more human scaled, more inviting,  and more fun.

For more on this story go to http://www.pbs.org/newshour/topic/climate-change/

As global temperatures rise, urban areas are facing challenges in keeping their infrastructure and their residents cool. Chicago is tackling that problem with a green design makeover. This report is part of our Coping with Climate Change series.

Changing the person: Me!

It is better to light a candle than curse the darkness. – Chinese Proverb

Yesterday, in a post that picked up on the deep implications of Bill McKibben’s chilling essay on where the world is heading if we don’t change, I set out my understanding of what holds us back from that change.  I wrote, “ … the process of change cannot start until we  truly want to change; a total emotional commitment.  And the formation of those emotions, that realisation, requires a new understanding of the world around us, who we are and who we want to be.”

Previously on Learning from Dogs I have quoted Jon Lavin, “The best way to save the world is to work on our selves.”  I remember decades ago when working as a humble office-products salesman for IBM UK the well-worn saying, “Selling is 90% me and 10% the customer.”  Sort of reminds me of Woody Allen’s: “Eighty percent of success in life is showing up.”

OK, enough of these mental perambulations.  Let’s get on with the task of looking at change.  Because make no bones about it, if we rely on ‘them’, on others, to turn mankind back from where we are heading then it’s all over!  It comes down to each and every one of us deciding to change.

Think this is all melodramatic nonsense?  Go and read the first paragraph of Bill McKibben’s article where he states, “June broke or tied 3,215 high-temperature records across the United States. That followed the warmest May on record for the Northern Hemisphere – the 327th consecutive month in which the temperature of the entire globe exceeded the 20th-century average..

Want more reason to change?  Try this from a recent article on The Daily Impact:

From American Drought to “Global Catastrophe”

Some poet  invented the name “Arab Spring” as a label for the tsunami of public desperation that last year took down the governments of Tunisia, Egypt and Libya. Poets and Pollyannas saw the events as an upwelling of love for democracy. Realists related them to the spike in world food prices that threatened the survival of whole populations and made them desperate for change — any change.  Now, thanks in large part to events unfolding in the American heartland, get ready for another, worse, spike.

We are running out of superlatives with which to describe the Mid- and Southwestern drought and its effect on this year’s corn and soybean crops. According to this week’s USDA crop update the situation during the previous seven days went from “critical” to, um, worse than that. The drought is the worst in half a century. Of the largest US acreage ever planted in corn (industrial agriculture was crowing about that just a couple of months ago), only one-quarter is still in good condition. (Modest rainfall in drought-stricken areas early this week provided mostly emotional relief; the drought is forecast to continue unabated through October.)

Change really does seem like a ‘no-brainer’!

Here’s a lovely cartoon that summarises the steps of change, the process of transition, for you and me.

That diagram is from John Fisher’s model of personal change, full details of which are here.  It includes a link to the process of transition diagram, show above, here.

The most important thing to note, and this is why so many ‘change’ ambitions fail, is that change is deeply unsettling at first.  When change happens for the majority of us, often ‘forced’ on us as a result of unplanned life events, we are left deeply unsettled; a strong feeling of being lost, of being in unfamiliar surroundings.  Think divorce or, worse, the death of a partner or child, reflect on how many sign up for bereavement counselling in such circumstances.  Big-time change is big-time tough (apologies for the grammar!).

Stay with me for a short while while I reinforce this from my own experiences.

My previous ex-wife announced in December, 2006 that she was leaving me for a younger model!  It came as a complete surprise.  Subsequently, I was invited to spend Christmas 2007 out in San Carlos, Mexico with Suzann and her husband, Don.  Suzann is the sister of my dear, close friend of many years, Dan Gomez, hence the connection.  There I met Jean, a long-term friend of Suzann living in San Carlos and, coincidentally as I am, another Londoner by birth.  Jean and I fell deeply in love with each other and a year later I moved out from SW England with Pharaoh to Mexico.

Throughout 2008 I suffered from what was eventually diagnosed as vestibular migraine.  It involved partial loss of vision, vertigo, headaches and significant short-term memory disturbances; let me tell you it was pretty frightening!

Eventually, in 2012 well after we moved from San Carlos up to Payson, Arizona, I got so worried that I went to see a neurologist, convinced that I was heading down the road of dementia.  Dr. Goodell examined me thoroughly and said that there were no signs of dementia or early-onset Alzheimer’s disease.  His conclusion: I was showing the normal signs of forgetfulness that any person of my age (now 67) would show having been through similar life changes.  Dr. Goodell went on to explain that back in England 98% of my life was constant and familiar and therefore adjusting to a 2% change was unremarkable.  However, on moving my life out to Mexico and then on to Arizona, it was all reversed: 2% of my life was constant and 98% was change and that was a huge psychological hill to climb with all the associated mental stresses that I had been experiencing.

Interestingly, that diagnosis rapidly set me on the path of feeling so much better!

So, apologies for that personal diversion but I hope it underlined that life-change is a big deal!

In my trawl across the Web looking for change references, I came across a software engineer by the name of Dave Cheong.  Dave writes a blog.  In Dave’s blog was a piece about change.  Change as a result of a merger of his employer.  This is what Dave wrote:

As a result of the merger, lots of change is happening. Some folks are questioning where things are headed, what management have planned, how their lives will change, etc. Most certainly, there will be job losses as the two companies consolidate things, in particular administrative positions.

With the chaos that’s been unfolding, I’ve thought a bit about “change” in general. What is it? Why do people resist it? Is it always a good thing? What should I do?

And later he writes after referring to the Satir Change Process model, named after Virginia Satir, an American author and psychotherapist:

The diagram depicts several stages of accepting change. The first stage is known as Status Quo (Gray Zone), a state where everyone is generally comfortable with the way things are. The second stage is a point in time a Foreign Element, trigger or change agent is introduced. What follows is a period of Resistance and Chaos (Red Zone), personified as a result of people being scared of the uncertainties the change has brought about and how their lives will be impacted.

The level of performance generally drops off and fluctuates more greatly between the Gray and Red Zones. There are various reasons for this – people may reject the change to protect the status quo; are confused with the change and are unsure of what to do; or simply become less competent with the new tools and processes introduced.

This describes why people by nature resist change. They don’t want to become less useful than they already are.

Just reflect on that.  Dave calls it being ‘less useful’ but that downplays the emotional significance of partially losing one’s self-image, one’s self-identity, the undermining of who we think we are.  As I wrote earlier, life-change is a big deal!

Here’s my final example of how dealing with change is all about the self.  It’s from the Best Self Help website, and opens,

Self help, personal development and self-improvement are topics of considerable interest to pretty much everyone on the planet.

In 1975 my life was a total mess. I was depressed, unemployed and my 5 year marriage was ending.

I’m not going to quote it all but it really is worth a read.  However, I do want to quote the conclusion,

Finally, I Got It!!!

In the Western world, we are educated to look outside ourselves for validation. We want more money to acquire “things” with the mistaken belief this is the source of happiness.

The true source of love, health, happiness and financial success cannot be found outside of ourselves – each of these is already within us. The key is learning how to access and activate that which we already possess.

 “True wisdom comes to each of us when we realize how little we understand about life, ourselves, and the world around us.” ~Socrates~

So that’s enough for today. If you haven’t got the message about change coming from within, then not sure what else I can offer!  However, if you do want to explore changing the way you impact this beautiful planet (and it applies equally to me) then drop in tomorrow.


The way the world is – now!

There has been a wealth of information going past my ‘desk’ in the last couple of days that gives plenty of cause to worry.  But I’m going to spend a few days mulling it all over rather than react in some ‘knee-jerk’ fashion.

However, a couple of stories caught my eye a few days ago on the BBC News website and seemed worthy of sharing with you.

The first was,

Mild drought caused Maya collapse in Mexico, Guatemala

Relatively mild drought conditions may have been enough to cause the collapse of the Classic Maya civilisation, which flourished until about AD950 in what is now southern Mexico and Guatemala.

Scientists have long thought that severe drought caused its collapse.

But Mexican and British researchers now think that a sustained drop in rainfall of only 25-40% was enough to exhaust seasonal water supplies in the region.

The findings were published in the journal Science.

The research was conducted by the Yucatan Centre for Scientific Research in southern Mexico and the University of Southampton in the UK.

Mayan pyramids of Tikal

Read the full news piece here.

The second piece published by the BBC within 24 hours went as follows,

Drought conditions in England ‘set to widen’

Ongoing dry weather over the spring and summer threatens to place more areas of England in a state of drought, the Environment Agency (EA) has warned.

It singled out parts of western, central and south western England and parts of south east Yorkshire.

The agency said time was running out for rain to restore groundwater levels before the new growing season begins.

Earlier this week the South East joined most of East Anglia in a state of official drought.

In parts of south-east England groundwater levels are lower than in the infamously dry summer of 1976.

Again, read the full article on the BBC website here.

And closer to home?

The historical (30-year average) precipitation for Payson up here in the Rim Country is 2.30 inches for January, and 2.41 inches for February.  Today, February 29th 2012, we have had less than 0.5 inches for the whole of 2012 so far!  Interesting times!

The Granite Dells Wilderness