An introduction to mass tree planting schemes

Trees and coastal cities’ defenses

Responding to disaster using trees, as a part of disaster preparedness

Interesting research is being done on tree planting in some of the world’s cities, exploring the many benefits from doing this. In general terms, trees help to ‘clean’ air by removing carbon dioxide and releasing oxygen into the air, they can cool the air through evaporation and can prevent erosion and save water, depending on the careful selection of useful trees. Tree planting can have huge social benefits too.  The coastal city of Miami, Florida, is exploring tree planting because the city’s location at sea level and tendency to experience tropical monsoon, make it vulnerable to the impacts of climate change, such as coastal flooding. Trees help minimize flooding by absorbing the force of  water and acting as a barrier between storm surges and homes near the shoreline.

Satellite image sourced online. The red shows the vast inland lake resulting from flood waters from inland catchments. The inland catchments could be reforested to mitigate against this type of situation of huge water flows.

What was also noticed in Miami, USA, was the limited number of trees in the city’s under-served neighbourhoods, a common occurrence in many cities. Research showed this lack of tree canopy can impact academic performance, crime rates, personal health and even increased illness and death from extreme heat and poor air quality.

The full suite of benefits range from things like raising  quality of life standards, promoting safe, resilient construction, restoring degraded land, training communities on environmental protection and at a higher level  informing green policy and Sustainable Development Goal objectives. However, there are more grim aspects to tree planting, notably to soak up the excess of carbon dioxide and try and avert the full climate change suite of horrors, and to restore degraded forests and scrub lands so that they can once again act to absorb the impact of cyclonic rainfall and prevent the worst floods.

Tree planting and atmospheric carbon

The movement to grow large numbers of trees as a form of environmental remediation has been growing over the last 20 years, notably since the highly public and successful work of Nobel Prize winner, Wangari Maathai in Kenya. Currently, many large corporate agencies (Coca Cola and Timberland ) have been promoting this as a good use of Corporate Social Investment (CSI),  team building, and contributing to useful climate change projects, for example, Timberland’s  goal of planting 50 million trees globally.

‘Green Wall’ tree planting schemes to stem the movement of the deserts

  • In  China, the desert sands have been moving and creating dust pollution many miles away. China’s Great Green Wall has been a work in progress for many years, to stop the advance of the Gobi desert.
  • In the Sahel region of Africa, the Sahara desert sands are moving southward, covering farms and grazing lands. Part of the cause of desertification in the Sahel has been land degradation and removal of trees and shrubs that held back the sand. To remedy this situation, a wall of trees some 4500 miles long is envisaged, and production of seedlings by communities is well under way.  The idea for the Initiative (GGWSSI), was launched in 2007 by the African Union (AU) and plans to reverse the effects of land degradation and desertification. The model for this giant vegetation planting scheme, is the Chinese Great Green Wall, being planted over a vast area.   The Great Green Wall is an African-led movement to grow an 8 000km line of trees across the entire width of Africa to fight climate change, drought, famine, conflict, and migration.
  • Food and Trees for Africa, a South African NGO, has distributed 4.2 million trees over the years, and set up a variety of community tree nurseries in townships around South Africa

The idea is to consider mass tree planting and catchment/flood plain restoration as a key disaster prevention activity, along with other measures like the building of canals, or re-planning the locality of towns and cities, moving them (difficult!) to higher ground.

Sources of information

Timberland Commits to Plant 50 Million Trees Over Next Five Years

Coca-Cola and American Forests to Plant Trees in Miami

Coca-Cola and American Forests to Plant Trees in Miami

Big old trees – a fascinating genetic resource

The Everglades (USA) and re-growing new forests of the world’s oldest trees

An experiment in re-growing forests of the world’s oldest trees led a group of environmentalists in the USA to try some ‘extreme climbing’ to gain good quality cuttings of a nine-storey high 2000 year old Cyprus tree called ‘Lady Liberty’ in the Florida Everglades. They have to climb very high to get ‘new growth’ material from these very old and tall trees. Their aim was to propagate these cuttings and so make available saplings for restoration projects in the Everglades.

Archangel Ancient Tree Archive (AATA) is a quirky but determined NGO that has a plan to collect and preserve the offspring of ancient trees. A big part of the AATA mission is to propagate the world’s most important old growth trees before they are gone. AATA have tissue culture laboratories, nurseries and a ‘super grove’ where they plant and nurture some of the ancient ‘germ lines’ of charismatic large trees and species.

The mission of Archangel Ancient Tree Archive is to:

  • Propagate the world’s most important old growth trees before they are gone.
  • Archive the genetics of ancient trees in living libraries around the world for the future.
  • Reforest the Earth with the offspring of these trees to provide the myriad of beneficial ecosystem services essential for all life forms to thrive including releasing oxygen, sequestering carbon dioxide, providing beneficial aerosols and medicines: essentially a global warming solution.

AATA believe that these very old trees are genetically the ‘best of the best’ trees because they have survived for so long, AATA has developed a micro-propagation system for replicating old growth genetics that can be shared with partner facilities in other countries to produce literally millions of champion trees for reforestation globally. The Copemish, Michigan, warehouse now houses thousands of these cloned trees in vitro and in various stages of development. Each has the exact DNA of the parent ‘champion tree. From micro-propagated rooted cuttings to saplings up to six feet tall, these are rapidly maturing trees and are ready for planting. This stage is completely funded by private gifts. Some of this work was also funded by a grant from the National Tree Trust, some from private donors. Duplicate propagation facilities on the U.S. West Coast and countries around the world, beginning with a facility in the United Kingdom with existing interested partners.

The project also works in Cornwall UK and Ireland, to identify and propagate ‘superior’ ancient tree lines. See more at

One of the Grand Old Ladies of the Everglades, USA. There is an attempt to save these trees through mass propagation.


So, while the USA’s AATA project is charismatic and valuable, it may have flaws. There could be problems with the way that Archangel Ancient Tree Archive distributes their clonal trees, and unless great care is taken, these clonal specimens could ’contaminate’ existing and more modern tree lineages with ‘ancient genes’, noting that clonal trees are all genetically identical. They will not reflect the full ‘library’ of genetic possibilities in a wild forest species. Also, if they are all identical, they will all respond in the same way to a pest or pathogen. They will all be susceptible (or resistant) in the same way, and this may not be a useful situation. Diversity is what creates ecosystem resilience.

We need to avoid making mistakes with mass tree planting schemes by considering that we plant trees with as much natural genetic diversity as possible. This will replicate the genetic legacy of endangered trees, but also allow for evolutionary processes to continue through reflecting the full genetic diversity of the species.

Time travelling trees

Forest restoration and tree planting in Africa

The genetics of trees – important to consider in mass tree planting projects

Because trees are so long lived, their reproduction involves a type of ‘time travel’ – in that trees of great age can still be breeding (and therefore cross-pollinating) with a matrix of their descendants – their great-great-great-great ‘grand-children’ – and creating new saplings. This means a continued reshuffling and refining of genetic selections that originated thousands of years ago in response to very different conditions with genetic responses to current conditions. Very few other organisms are able to do this. See more at

In Africa, there are many reforestation projects

In Africa, there are many reforestation projects underway where saplings are prepared from seeds and cuttings and planted out by communities or NGOS. There isn’t the same focus on preserving ‘ancient germ lines’ but on simply replacing deforested and degraded areas with as many specimens as possible of once-common trees, or with a ‘suitable local trees species’. The way that genetic material is selected for restoration projects can often be contentious as ‘genetic contamination’ can occur when restoration is carried out with trees (or other types of plants) of the correct species, but from distant areas.
The Great Green Wall project in the Sahel is a very charismatic tree planting project, covering many thousands of kilometers, and involving communities along the way. It would be interesting to learn more about this project and how plants are being selected for propagation.

Landscape restoration must not homogenise local tree genetic variety

In selecting trees as ‘mother plants’ for the source of seeds or cuttings, there are often formally designated regional tree sub-species and their populations which need to be considered, rather than the mass planting of a single type of tree. Most plant and tree species have a fluid genetic composition with population diversity and variation existing over the entire range in which they occur, one wants to be able to reflect this diversity in mass tree planting schemes, rather than narrow it down. Great care has to be made to propagate and replant the exact same trees so that regional variants can be preserved. This is to avoid the ‘homogenisation’ of the genetic diversity of a species and the loss of a great variety of characteristics through replanting a tree monoculture. Tree monocultures are typically what one would see in a forestry plantation, and not in a natural ecosystem.

Genetic variation is the true treasure
It is this genetic variation in natural forests that is the true heritage of ‘ancient trees’. It is not the old specimens themselves, locked in the past, that are valuable, but their progeny. More recent offspring have come about through the constant mixing and remixing of genes at each generation. This means that, by chance, progeny trees may have the genetic compliment that enables them to adapt to the current climate and situation. These more modern tree lineages would represent genetic statements about adaptation to more recent conditions, while the older genes may be ‘fossilised’ in time and no longer relevant to today’s conditions. The ancient trees may in fact be ‘out of step’ with modern conditions, for example, climate change, new pests and diseases and new heat/rainfall patterns, and so less valuable than their newer offspring. We need to carefully preserve all that is linked to the ongoing evolution of natural trees and forested ecosystems.

Improving sunflower for both climate change and disease resistance

A discussion with Dr Nicky Creux, Plant Sciences, University of Pretoria.  6th August 2019.

Dr Creux, now working at the University of Pretoria, spent five years at the University of California (UCLA) doing a post-doc on sunflowers and their disease pathology. The main focus of her work was to investigate sunflower physiology and the ways in which sunflower plants respond to various environmental signals, like drought or fungal attack. These studies were so that she could begin to understand how the sunflower plant copes with pathogens, as well how it might respond to altered growing seasons and temperatures linked to a hotter/wetter climate linked  climate change.  She returned to South Africa to take up a research post at the Forestry and Agricultural Biotechnology Institute (FABI) to study the fungal pathogen Sclerotinia sclerotiorum.

Cultivated sunflower (Helianthus annuus L.) is prone to many diseases caused by fungi, bacteria, and viruses, but the most detrimental to crop health are those caused by fungi.  Two of the most important fungal pathogens are Sclerotinia and Phomopsis, but the focus of Dr Creux’ South African studies will be Sclerotinia. Within the genus  Sclerotinia, the species  Sclerotinia sclerotiorum causes a devastating basal stalk rot and subsequent wilt of the sunflower plant, and can destroy an entire field of crop sunflower.  In sunflower,  S. sclerotiorum causes a head rot and mid-stem rot, and this is a major problem when sunflower is grown in wetter conditions  or during wetter years (Ramusi and Flett, 2015 ).  While this fungus is not yet a very serious problem in South Africa, there are concerns that this situation may change due to climate change and climate variability.  In South Africa, sunflower is an important rotation crop with maize, and is also seen as a useful field crop to plant if the rain occurs too late in the year to plant maize. The challenge is to find ways in which the sunflower crop can be protected from the fungus through crop management systems, or be given genetic protection through conventional plant breeding, so that it has the full suite of mechanisms to resist this fungus.


Ramusi M and Flett B., 2015. Sclerotinia disease of sunflower: A devastating pathogen. Agricultural Research Council (ARC) Grain Crops Institute, South Africa.