Trees Are Awesome:  Desertification vs. Afforestation

Trees Are Awesome: Desertification vs. Afforestation

I’ve written this series on the awesomeness of trees and the functions they perform in direct contrast to the pieces I wrote on desertification.  Whereas desertification is a self-replicating, self-reinforcing downward spiral of death, drought, and barrenness, afforestation is an upward spiral leading to greater life, water, and productivity.  Both contain self-reinforcing feedback loops that lead to their expansion.  Most importantly, whichever cycle is underway largely depends, in many cases, on how people are managing the land.

grazing can contribute to desertification or reforestation, depending on human management.

grazing can contribute to desertification or reforestation, depending on human management.

As I wrote in my introductory post, people are the keystone species of the planet, which means our actions have far reaching effects on the environment around us.  In fact, our ability to change our environment increases at a greater rate than our ability to perceive that change.  In short, depending on how we manage the earth, we can kickstart the process of desertification (and we have throughout history, mostly through our use of agriculture), or we can be the catalyst for afforestation.  In this post, I will tie together all the previous posts on desertification, and the awesomeness of trees, and show how afforestation can be used to convert the Arabian Peninsula into a productive, resilient, and bio-diverse land.  If you want more details, follow the links.

First off it should be noted the cycle of desertification had a jumpstart when a national policy unintentionally lead to a collapse of the traditional land management systems, the hima.  Once that desertification is underway, it manifests cycles that inhibit rainfall, increase evaporation, and make it harder for life to become established.  Those cycles involve an increase in temperature, the creation of dust, and the loss of nuclei for water droplets and clouds to form around.    As rainfall and precipitation are inhibited, temperatures increase more, dust increases more, and only the hardiest of plants survive, leading to less and less nuclei.  Soil turns into dust, the nutrient cycle ceases, and the water cycle becomes undependable and erratic, and total evaporation goes up.   In this way, deserts expand.

A huge dust storms swings through the empty quarter from the Arab Gulf, heating the atmosphere past the dew point, so that no clouds may form.  Source:

A huge dust storms swings through the empty quarter from the Arab Gulf, heating the atmosphere past the dew point, so that no clouds may form. Source:

In my last few posts, i’ve written specifically on how trees can counter each aspect of desertification.  They decrease the amount of atmospheric dust, and block winds so less dust gets thrown up there.  They also lower ground temperatures by providing shade and absorbing a tremendous amount of heat from the sun.  Finally, in areas away from coasts, they provide the majority of nuclei and water vapor for clouds to form.  They can care for their own hydrology allowing for soil life to recover and the nutrient cycle to start back up again.  Finally, they increase precipitation, both through generating rainclouds and capturing dew.  Thus, establishing trees can reverse the cycle of desertification, restore a healthy functioning of the water and mineral cycles, and bring life back to the desert.   Of course, in all deserts the question then becomes, “How do we establish trees in a place with no soil and no water?”

The Arab Peninsula

The coastlines where humidity and clouds can form are the edge to start on.

This is where design and understanding nature’s cycles come in.  The key to reversing desertification will depend on the larger macro weather cycles, as well as the geography of whatever desert you’re looking at.  No matter what it is absolutely imperative that you start at the edge of the desert rather than in the middle.  Starting in the middle would be foolish and pointless.  All change happens on the margin.

In the Arabian Peninsula there are 3 margins to focus on–the Hijaz, the Omani Coast, and Yemen.  The hijaz gets lots of humidity and water coming off the red sea, whereas Oman gets typhoons coming off the Indian Ocean.  Finally the SW corner of Yemen hits the tail end of the green belt across Africa.  These are the edges where you could start because this is where you still get some water (albeit not very dependably) that you could use for reforestation.  As those forests encroach on the desert, you can start to beat it back.

Mountains provide an opportunity to reforest desert because of floods & runoff.

Mountains provide an opportunity to reforest desert because of floods & runoff.

In the hijaz, that water shows up as flash floods, with some 90% of the fresh water running into the sea.  That’s enough water to reforest the Hijaz.  Reforesting the hijaz would be a catalyst to increase rainfall over the tihama plain, as well as the western edge of the empty quarter, which in turn would allow more growth to occur in those areas.  Thus forests, just like deserts, contain within themselves  self-perpetuating mechanisms that spur their expansion and provide their resilience.  Whichever one occurs is a question of human management.

This wraps up the first major part of the blog series about greening the Arabian Peninsula.  Up till now I have provided a general overview of the cycles, and the science behind what’s going on environmentally in this part of the world, as well as how we could convert the peninsula into productive landscape.  The principles in this series are applicable in any desert, though some would be much more difficult to tackle than others.  How people will manage the land under their stewardship will dramatically affect the coming generations’ ability to feed themselves, and to drink.  My hope is that these posts will help open peoples’ eyes to the possibilities, and to how much positive change human society can bring to the environment through smart management, good design, and cooperating with nature.




Trees Are More Awesome Than You Thought:  Dew in the Desert

Trees Are More Awesome Than You Thought: Dew in the Desert

There are some desert areas where dew consists of 100% of all the precipitation–particularly in the Atacama of South America as well as in some areas of the Namib desert (the above picture is from the Namib Desert, sourced here).  That dew drop depends entirely on the local foliage–without those plants, the dew would not fall.  This leads to some chicken and egg type questions–if the plants need the dew to live, and if the dew only happens because of those plants, how did they get there in the first place? Regardless, even in temperate climates dew can be a significant source of precipitation–up to 30% in some areas (my source on that is Geoff Lawton, in a personal conversation).

In deforested areas, the dew-catching and creating phenomena ceases, and the affect can be enormous.  Through reforesting these areas, we can increase total precipitation through dew collection alone–not counting the increase in rainfall and cloud creation caused by the trees.

Dew collects on the leaves of an Albizia

Dew collects on the leaves of an Albizia

Here is how that works:

The dew point is the temperature at which water in the air begins condenses on solid surfaces–particularly those that are not connected to the heat of the ground.  Leaves, grass blades, metals, or even stones can play this role.  If there is no surface for the water vapor to condense on (as in much of Al Baydha) then the water in the air will simply stay as vapor.  This is how the Groasis Waterboxx works, how air-wells work, and how many dryland coastal-forests acquire much of their water.  Trees especially, that can have acres of surface area along their leaves, can catch a surprising amount of dew, which then drips underneath the tree into their root zone.  As the trees grow, their shade further reduces ground temperatures and dessication by way of the wind, which raises the dew point, reduces further evaporation, and makes the whole process more likely to happen.

Dew and other types of condensation should not be underestimated as a source of precipitation, especially in coastal deserts, like those along the coasts of the Arabian Peninsula, and could probably provide enough water for the early stages of their reforestation.