A desert in China. To fight against desertification, the country has been planting trees. Image credit: Gabriel Jorby
Areas frequently referred to as drylands, such as Ordos, Inner Mongolia, China, make up around half the earth, house more than a third of the global population, are renowned for their water scarce environs, extreme variability in rainfall, and are sensitive to change because of the water scarcity.
But while China has successfully executed a number of afforestation programmes that will continue to 2050 and make the drylands more economically viable, planting trees makes the water crisis worse even though more trees will lower discharge. This is because at the bottom of it all, trees need water to grow.
China cultivates enough food for 20 per cent of the global population though they are only hold on to seven per cent of the world’s arable land. As Kai Schwärzel, Academic Officer, Head of Soil and Land-Use Management at the United Nations University wrote for The Conversation, agriculture is concentrated in the dryland region, including the Loess Plateau. Created by wind-blown loess sediment carried by the winds from the Gobi desert for millennia, the soil there is fertile and easy to farm. It is certainly of no surprise that the cradle of Chinese civilisation can be found there.
But because it is sediment, the soils are also prone to water and wind erosion. Centuries of mismanagement have culminated in decaying land and huge loads of sediment in the nearby Yellow River, the third-longest river in Asia. A large chunk of the Loess Plateau Region – two-thirds, in fact – is negatively affected by soil erosion, and in the late 1950s, up to three gigatonnes of sediment was found in the Yellow River a year.
To keep soil erosion in check, a multitude of soil conservation projects, executed by the Chinese government since the 1950s, have come up over the years, consisting of check dams, terracing, vegetation restoration, as well as afforestation.
By setting up forests, the Chinese government were not just minimising soil erosion – they were also fighting against land degradation in northern China, a scourge that had brought down the amount of arable land for farming and threatening the sustainable regional development. While soil erosion has indeed decreased along with sediment in the Yellow River, another issue has risen – the water discharge from the river has lowered a significant amount.
This may have a large negative impact on China’s food security as agriculture is consistently the largest consumer of water in the world, and up to 80 per cent of water withdrawals from the Yellow River Basin can be traced to it. But for the decade between 2000 and 2010, the annual discharge was only 60 per cent of the numbers seen from 1950 to 1999.
Much of it can be linked to afforestation, according to Schwärzel.
As the forest cover in the Loess Plateau stood at six per cent in 1949 and ballooned to 26 per cent in 2010, the decline in water can be contributed to the forest. Forests generally allow more water to evaporate compared to other land covers, and China’s newly established forests are growing more slowly due to the shortage of water, succumb more easily to diseases, and also showcase poor stability.
According to Schwärzel, another, more sustainable way is to install management approaches that can guarantee teamwork and synergies between the economy, environment, and society.
Floods and droughts are going to continue, and are predicted to be more intense and frequent as climate change continues to grip the planet, further threatening food and water security, raising social vulnerability, and driving instability in China.
But now, China also needs to manage their forests, land, and water. Due to the sprawling lands and varying climates in the nation, measures should be adapted to the conditions of the local environs.
Re-vegetation should be considered, according to Schwärzel, as it allows a more stable forest to take shape. Fewer trees also raises forest stability, and reduces water consumption.
Although the Chinese government has plans to invest US$9.5 billion in afforestation in the Loess Plateau by 2050, lessons from past struggles against soil erosion should be taken into account.
Source: The Conversation