All in all just another tree in the wall?

Establishing tree cover in drought stricken areas is a challenge facing many countries facing problems with desertification. A new planting technique to improve drought resistance in which planting holes are lined with biodegradable plastic to reduce drainage and evaporation was tested in an arid, erosion-prone, hilly area of the Chinese Loess Plateau between 1997 and 2006, during a period of lower-than-normal precipitation. 15 types of tree were grown with and without the bag. The new tree-planting technique promoted root growth in the topsoil by keeping the soil moisture than the surrounding soil evident during the first 4 months after planting.

Tree survival rates, branch growth increment per year, tenth-year canopy area, and tenth-year canopy density in trees planted using the new method increased by an average of 41.4%, 29.0%, 16.9%, and 65.3%, respectively, compared with the values for the conventional planting technique. This suggests that the new planting technique is more suitable than the conventional method for arid areas such as the Loess plateau and may prove useful elsewhere in the globe. The results of this study offer much hope for the survival of China’s ‘Green Wall’ and long term prospects concerning the countries prevention of desertification.

Cao, S., Chen, L., Liu, Z. and Wang, G. (2007). A new tree-planting technique to improve tree survival and growth on steep and arid land in the Loess Plateau of China. Journal of Arid Environments, In Press.

Characteristics of Chinese Desertification

Source: Fullen & Mitchell 1994


The figure above shows the distribution of sandy deserts (1-8) and lands (9-12) with respect to climatic zones in China. Sandy deserts and lands are differentiated as the latter is formed out of human activity. Historically many parts of China have been susceptible to desertification, all of them located in the north-west, north and north-east dryland area. The Mu Us sandy land (see figure) has existed throughout the Quaternary but its extent has fluctuated through time with moisture availability. More recently it has been subject to encroachment by a sandy desert since the Tang Dynasty (AD 618-906). There is evidence for widespread desertification in the semi-arid steppe dating back to the Han Dynasty (202 BC-AD 220). Historically the control of the aridity has been linked to the effect of the ITCZ on the East-Asia monsoon, and its failure has been linked to the collapse of the Tang dynasty.

Source: Yong Zha and Jay Gao (2000)

China's Desertification Policy

In 2001 China adopted new legislation intended to control and ultimately reverse the worsening trend of desertification in the country, which has an estimated annual direct economic cost of $6.5 billion.

The new law:

-States that land occupants have a duty not only to prevent desertification but also to restore areas that have already become desert;

-Promises unspecified preferential policies, tax breaks, subsidies and technical support to offset the cost of this unfunded mandate;

-Creates a new class of protected areas off-limits to development and calls for farmers and herders to be removed from those areas; and

-Authorizes local governments to grant land-use rights of up to 70 years to desertified areas if the landholder promises to undertake restoration efforts.

Source:
http://www.usembassy-china.org.cn

Urbanising Tibetan Nomads

The houses seen above are being built high up on the Quinghai plateau in an attempt to urbanize nomad Tibetans, whose Yak herding the Chinese government believes is causing desertification. These houses are a 3 day walk from the nearest town and employment opportunities are limited high up on the Tibetan plateau. Not only does this policy cause a multitude of problems for the displaced Tibetan Nomads, but the causes of Chinese desertification are far greater than nomadic Yak herding.

Each family receives 8,000 Yuan (1,060 dollars) for moving and 100,000 people are expected to move by 2010, resulting in a massive cultural shift in the area.





Tibetan nomadic herding

Sources:
http://environmentdebate.wordpress.com/2008/01/22/chinas-desertification-policy-and-urbanization-of-tibetan-nomads/

http://www.sinodaily.com/reports/100000_Tibetan_nomads_ordered_to_settle_in_towns_999.html

http://afp.google.com/article/ALeqM5guapJRda-NSrCy_q7Qn3W4ONf0yg


Image: jim mcgill photography

Moving Deserts

The image above shows the encroaching sanddunes engulfing the village of Langtougou. The village is just 160 km north of Beijing and its inhabitants survive on subsistence crops and raising horses, goats and pigs. In 2000 violent sandstorms dumped entire dunes into the once-fertile Fengning county valley, now most of the grass is gone and the Chaobai River stands dry. Sand from the distant Gobi desert threatens even Beijing, which some scientists say could be silted over within a few years. Dunes forming just 70 km from the capital may be drifting south at 20-25 km a year, although conservative estimates say 3 km a year.

Firewood collection (32.4%), excessive grazing (30%) and over-cultivation (23.3%) are the main factors in causing the desertification in northern China, according to a study by Chinese researcher Ning Datong. In order to combat these problems, new regulations have banned the collection of firewood and the agricultural practices on which the village relies; now villages rely on manure as their primary fuel source and promises of rice and money from the government. Others suggest that increasing drought in the region is to blame.

In the northwest, where the biggest problems lie, desertification has escalated from 1,560 sq km annually in the 1970s to 2,100-2,400 sq km in the 1990s. A Ministry of Science and Technology task force says desertification costs China about $2-3 billion annually, while 800 km of railway and thousands of kilometres of roads are blocked by sedimentation. An estimated 110 million people suffer from the impacts of desertification. Following current trends, another 2,500 sq km will turn to desert each year.

So far nothing the government has done has come close to stopping the advance of the deserts across China's vast landscape. In 2006 there were a number of unusually strong sandstorms in northern China, which some meteorologists say is, in part, a result desertification. Cities such as Beijing have days in which sand fills the air, blocking the sun and creating long-lasting health hazards, maybe this will be enough to spur the government to the necessary action.

Sources:
http://www.gluckman.com/ChinaDesert.html

http://www.voanews.com/english/archive/2006-07/2006-07-31-voa30.cfm?CFID=30040281&CFTOKEN=70783329

Image:
Ricky Wong