China’s forests are growing. It has nothing to do with a natural process, but with a meticulously followed strategy to contain the expansion of deserts and reforest the country with billions of trees. The consequence of this reforestation is not limited to having more trees and two studies have just shown the counterpart of massive ecological engineering.
This is not good news: the continental hydrological cycle is being altered.
The Green Wall. Of China’s deserts, the Gobi may be the best known, but the Taklamakan is one of the most problematic. 85% of this 337,600 km² desert are dunes, which at certain times of the year generates sand storms that leave the surrounding towns without crops. And countries like the two Koreas and Japan also suffered the effects of the storms. In addition, it was growing, so in 1978, the country launched the Refugio Tres Norte Forestry Program.
The strategy: a series of tree belts to contain the expansion of its largest deserts. The objective: to go from forest cover in the country of 5.05% in 1997 to almost 15%, and the idea is to complete that belt by 2050 with a total of 4,500 kilometers long. Currently, the Great Green Wall has completed the shield around Taklamakan with a belt of about 3,000 km, observing a decrease in sandstorms.
Consequences in water. Apart from that desert, in others such as Ulanbuh, Korqin, Hunshandake, Maowusu and Kubuqi, tens of thousands of square kilometers of forest and pasture have been built. And, although the storms have decreased, different investigations are noticing a secondary effect: an alteration of the water cycle throughout the continent. Published in Earth’s Future, a study carried out by Chinese researchers shows how new vegetation has increased evapotranspiration in the region.
Simply put: more water is being pumped from the ground into the atmosphere, meaning that winds are transporting water to regions like the Tibetan Plateau as rain while the northwestern and eastern monsoon regions are experiencing a decline in their net water availability.
Non-uniform redistribution. This greater green cover causes restored forests and grasslands to transpire more water than bare soil or traditional crops. This extra moisture enters the atmosphere, which falls on other regions as rain. According to the study, the consequences at the national level were the following:
- Evapotranspiration increased by 1.71 mm/year.
- Precipitation also increased by 1.24 mm/year.
- Water availability (from aquifers and springs, for example) decreased by 0.46 mm/year.
And, as we say, the process is not uniform because the water is moving from one area to another.
Greening/conserving water. It is not the only study published on the subject, but it is one that coincides in time with another published in August of this year in which, after analyzing 1,046 hydrological stations and their data from the last 60 years, they discovered that the flow of the rivers decreased by more than 70%.
Their conclusion is that it is not an effect of climate change, but of changes in the landscape caused by human intervention. It makes perfect sense: trees need water to grow, and that amount of new trees makes them act like a giant pump, reducing the amount of water that feeds the rivers.
Thus, there is a tension between greening China and conserving its water, since once in the clouds, it precipitates air currents wherever you go.
Implications. In the end, the researchers conclude that the strategy when managing water must be changed and that hydrographic plans must take into account both the land basins and the “air basin”, anticipating where the water evaporated by the forests will travel. Because the ambitious reforestation plan has 24 years left and the country has invested a lot in it directly – by planting trees – but also with policies that prohibit the felling of forests or with incentives for farmers to convert their croplands into pastures.
And, well, the consequences not only have to do with water. That the Natural Forest Protection Program prohibited logging in primary forests caused Chinese loggers to ‘loot’ Burmese forests. Something that adds to the conflict between both nations.
Imágenes | Siggy nowak, Janwillemvanaalst, gastarori
In WorldOfSoftware | In China they already have room for the first city with a vertical forest: a million plants and trees
