Afforestation - a viable solution to the deforestation crisis?

In the majority of previous posts within this blog the word "afforestation" has been thrown around as a potential solution to deforestation. It has crept up in the comments section time after time and in this latest blog post I plan to explore what afforestation actually is, does it work and its impact on the deforestation discourse.

Afforestation  - the planting of trees on non-tree land. It is different from reforestation which refers to the planting of trees on land that previously contained trees. The difference between afforestation and reforestation varies between definition but general concerns the amount of time that has undergone before a portion of land is considered "non-tree" (IPCC).

The Next Generation (CFS)

Afforestation and Global Climate Change
It is well known that the mighty oaks and little saplings act as a major carbon sink for planet Earth removing 3 billion tonnes of carbon each year (Canadell and Raupuch 2008). Therefore, it is vital deforested trees are replaced. Carbon dioxide released through the burning of fossil fuels worldwide is taken up by plants through the process of photosynthesis.

Whilst Canadell and Raupuch praise afforestation/reforestation processes as a solution to the global climate crisis, Bonan (2008) notes a major limit of boreal forest afforestation techniques.They have a positive feedback mechanism due to a low albedo and therefore create a warming process.

Limitations of Afforestation Practices
The main issue that is thrown around in the media is that managed reforestation and afforestation techniques will not restore the same biodiversity of the original forest. In an incredibly dated account by Stirling-Maxwell (1917) he describes the detrimental effects afforestation practices have on the environment. A devote critic of afforestation it appears, he talks about how different types of forest distinguish different regions of the world and that afforestation makes the environment more homogeneous (this opens up a whole new bag of worms surrounding "a flat world" and "the end of geography" - see the works of David Harvey and Doreen Massey). Whilst this may be true to some extent because the land is never fully returned to its original state, the same limitation of homogeneity can be applied to deforestation and Stirling-Maxwell (1917) offers no opinion on that. Wallace and Good's (1995) research into the North East of England supports Stirling-Maxwell's account of afforestation in that afforestation leads to a single more dominant species with other co-existing vegetation not being replaced.
However, Day et al. (2010) looked into afforestation on agriculture in Eastern America and noted that vegetation complementary to the dominant species (in this case oak) was grown as well to increase biodiversity. The research showed that because the seedlings and trees required consistent management for survival and growth that it was only realistic on a small scale.
The effects of afforestation vary between locations and are dependent on the techniques employed.

The Green Wall of China
Most of China's trees have been destroyed, devoured by the imperial juggernaut of urbanization, pollution and babies. The Chinese government set targets for the next 80 years but as of 2008 had made no progress in meeting them. With the help of Shanghai Roots and Shoots, a division of the Jane Goodall Institute, a total of 1 million trees have been planted to date to stop the expansion of the Gobi Desert.
China's problems do not stop there, however, as the detrimental impacts of non-native species is starting to have an effect with the non-native species removing excessive amounts of the water from groundwater causing the water table to be reduced (Window of China News)
Lets put this in perspective though - the Trees for the Future foundation has planted 35 million trees worldwide whilst the Green Belt Movement in Kenya has planted 47 million trees.

The Green Wall of China - a pipe dream? (Youtube)

Is Afforestation a viable solution to our deforestation problems?
This blog post is clearly summative in its analysis of the major limitations and benefits of afforestation/reforestation with whole books dedicated to just the biodviersity impacts of these techniques. Afforestation, like most solutions, is not without its limitations. Taking away productive land from other sectors such as food production and housing for trees is clearly an issue with much debate surrounding it as we constantly fight for space. Other than reducing deforestation (a post about deforestation, policy and politics is on the horizon) afforestation and reforestation is one of the most viable and popular solutions to deforestation. Furthermore, significant afforestation could have a noticeable impact on our climate system that may have beneficial impacts on climate change - although research into this is vague and poorly understood. I see afforestation and reforestation techniques as a policy that most governments should implement on some level - Brazil's afforestation policies is shocking! - because the benefits outweigh its limitations.

Amazon Deforestation and Climate Change

In last week's post we explored the relationship between humans and deforestation in the African continent. Now we are flying a few thousand miles across the Atlantic to explore the relationship between deforestation and global (and local) climate change in the Amazon.

The Amazon Rainforest is one of the most beautiful and captivating locations on our planet and hosts roughly half of the world's species and covers an area of 5.4 million km2 (62% of Brazil).

Outstanding Natural Beauty - the Amazon is at risk (source)

How does deforestation alter the landscape and effect local climate?
The removal of lowland tropical rainforests in the southern and eastern parts of the Amazon jungle for cattle ranches and soybean production means that trees are being replaced by grass.
Shukla et al. (1990) undertook numerical modelling to evaluate the effects of deforestation on local and global climate. They found that there would be an rise in surface temperature and a reduction in evapotranspiration and precipitation would cause an increase the duration of the dry season (supported by Malhi et al. 2008). This was also modeled in the 2007 IPCC report which showed a decrease in dry season rainfall but an increase in rainfall in the western Amazon during the wet season. Shukla et al's work is convincing yet dated and the recent work by Malhi et al. (2008) explores the climatic effects of deforestation one step further.

Evaporation and condensation over the Amazon  are the locomotives driving global atmospheric circulation. Furthermore, 25-50% of rainfall is recycled from forests which is important in places, such as the Amazon, where precipitation is a consequence of regional convection (Shukla et al. 1990). Removing the trees reduces rainfall, decreases cloudiness and increases insolation. It also alters the surface roughness increasing wind speed and therefore desertification and soil erosion. The changes to local scale climate are extensive.

% Change in Rainfall due to deforestation. Red shows the areas that will experience large decreases in rainfall. This are often the areas where the greatest deforestation occurs (NOAA)

How does deforestation alter global climate?
An incredibly recent study by Exbrayat and Williams (2015) showed that Amazon deforestation had a net contribution of 1.8ppm of atmospheric CO2 or 1.5% of historical growth which reflects the significance of the Amazon in the global system. It reinforces the argument that deforestation directly contributes to climate change (much in the same way as burning fossil fuels).
Malhi et al's (2008) work also touched upon the global carbon cycle and climate change talking about the release of stored carbon from trees and within the soil following deforestation. Soil carbon is released when the tree roots that hold rainforest detritus together are no longer present and the soil is eroded through aeolian and fluvial processes.

Significance and Future
As these articles and pieces of research demonstrate, the Amazon rainforest is an important component in the Earth system. It is vital for so many species including our own (Feeley and Rehm 2012). However, if nothing is done the Amazon rainforest could be completely gone within 50-100 years (Shukla et al. 1990). An increased rate of deforestation is chronicled in an interesting article by the Guardian written last year.Huge amounts of research continues to be conducted in the Amazon because it is a site of outstanding scientific interest.

Picking up the pace - rates of deforestation in the Amazon are increasing (The Guardian)