The green wall of China

Afforestation is a controversial topic in terms of it's success.  Since 1978 Northern China has been undergoing the hugest afforestation/reforestation effort ever (Cao et al 2010), and we'll see if they're succeeding.

Historically China has destroyed most of its forests; but in recent decades steps have been taken to replant trees and reverse the damage done by deforestation.  The largest project underway is the 'Green Wall of China' - this involves artificially planting strips of forest to not only restore trees but to stop the expansion of the Gobi desert.

Fig 1: Map of the Green Wall scheme (Wang et al 2010)
 

Due for completion in 2050, the trees will stretch 4500km.  China achieves it's afforestation goals in several ways, including aerial seeding, providing incentives to farmers to grow trees on their land, and the requirement for every citizen aged 11+ to plant one tree a year.  

Fig 2: Graph showing afforestation in China 1952-2005 (Cao 2008)

 
Because of this China has the highest rate of afforestation in the world, and saw a 31.6% increase in forest cover between 1990-2010 (UN stats 2010).

However, I've looked at several papers regarding the scheme and most seem to conclude that it is either unsuccessful or the outcome is unmeasurable, for many reasons.

• Cao (2008) concluded afforestation caused more environmental degradation than before the project started, as amount of degraded land is expanding.
• Only 15% of the trees planted actually survived (Cao 2008), (Cao et al 2010).
• The remaining trees were predominantly dwarf trees, which are less effective at capturing carbon
• The trees soak up the groundwater and cause groundwater problems and water stress upon themselves, especially in N China which has an arid climate (Cao et al 2010).
• Pollution has weakened the soil and made many places unsuitable for planting.
• Loss of biodiversity.
• Unsuitability of planted trees to China's climate (Cao 2008).  Natural vegetation in this area was actually desert steppe or dryland shrubs.
• Proper evaluation or assessment of the program's efforts and effects cease to exist (Wang 2010).

Cao (2008) concluded the best strategy would be for the government to reduce funding for afforestation as a result of the reasons aforementioned, and spend more money and effort on alternative strategies to combat desertification.  Wang et al (2010) challenges the Chinese governments evaluation of the project - although they claim it is a success and has provided environmental improvement, other evidence proves otherwise.  They conclude more evidence is required into both proving or disproving the success of the project; as a basis for important future decision making with regards to improving the environment.  Cao et al (2010) suggest that the project will be more successful if more research and thought is put into selecting the type of vegetation, as well as taking other measures into consideration such as stopping deforestation or changing agricultural practices.

From what I read, it's obvious a huge amount of money has been invested in afforestation in China, not only in the green belt project but 5 other major projects also (Cao et al 2010).  Such huge afforestation efforts are commendable but it worries me that they just plant any old trees as opposed to taking into account factors such as hydrology and climate to determine the right type of vegetation to plant.  Surely this would save money and enhance survival rate?  Obviously choosing fast-growing trees might be a priority but if only 15% of them survive then why bother... I disagree with Cao (2008) in reducing the government funding to afforestation schemes, they just need to invest in the correct type of vegetation to yield better results, and understand that you can't plant a forest anywhere!
Also, I didn't come across any papers on evaluating how afforestation in China was capturing carbon, they seem more concerned with planting forests in order to combat desertification and stop soil erosion and water depletion.  This also worries me because China is the worst offender for emitting GHGs.. although planting trees will always eventually capture carbon, this can take centuries.  Nevertheless billions of hectares have been planted on and it would be interesting to know exactly how much more is required to offset their emissions.

Cao, S. (2008) 'Why large-scale afforestation efforts in China have failed to solve the desertification problem', Environmental Science Technology, 42, 6, 1826-1831.



Cao, S., L. Chen, D. Shankman, C. Wang, X. Wang and H. Zhang (2010) 'Excessive reliance on afforestation in China's arid and semi-arid regions: Lessons in ecological restoration', Earth-Science reviews, 104, 4, 240-245.

Wang, X., C. Zhang, E. Hasi and Z. Dong (2010) 'Has the Three Norths Forest Shelterbelt Program solved the desertification and dust storm problems in arid and semiarid China?', Journal of Arid Environments, 71, 1, 13-22.