Hi all, I'm trying to figure out what I make of the Great Green Wall of China. I love their emphasis on reversing desertification, but I'm not sure about the way they are going about it. The wiki reports that there are concerns about planting such vast quantities of trees without the water infrastructure to support them, eating into underground water aquifers which may be disastrous for some of the remaining desert farmers. Artificial desalination without a high local population just isn’t practical or economic. (Most of China's population is in the East Coast of China, not the North West desert regions). They need to plan to trap the naturally occurring rainfall as best they can, maybe using a Tal-Ya water box every few trees or bushes to help collect morning dew where appropriate. At least such a plastic box is passive, and not energy intensive. The wiki also says mono-culture forests are not as good for ecosystem biodiversity and birds and other species are not as attracted to them as they would be to more natural forest plantings, which of course are more expensive and difficult to arrange. https://en.wikipedia.org/wiki/Three-North_Shelter_Forest_Program What does everyone make of it? What species of plants can survive in such low rainfall areas? Is there an economic rationale to pump water up there, or divert it from the Yellow river to green these deserts? Are there areas that could host a "Las Vegas" of North West China for eco-tourism, resorts, golf, or other activities in a re-greened desert? For instance, Time Magazine reports Kubuqi, for one, boasts China’s largest single-stage solar farm, boasting 650,000 fixed and sun-tracking panels, which together channel 1,000 megawatts of electricity into the national grid — about half the power-generating capacity of the Hoover Dam. A team of 47 households are employed to maintain the panels. “Everyday each household can clean more than 3,000 panels using high pressure water jets,” says chief engineer Tian Junting. “And the run-off water feeds the crops that grow underneath.” But the Kubuqi desert only has 740,000 people trying to rejuvenate 18,600 sq km of desert!
you may not start with a diverse forest, but if there are any other remnants around like seeds in the ground or nearby trees that can still reproduce they can gradually turn it into a more diverse forest. the most important thing is to get a wind-break in place which holds the soil, nutrients and water and keeps any detritus from blowing away. once you get a windbreak and some stability then the plants can form a community and eventually... i'm not familiar with arid species, but they do exist and they can survive if there is enough stability. if you can find any way to introduce a crust that holds up to some wind then that can be enough until the plants are established.
Hi Eclipse, I think that there are a few things missing from the Chinese approach to their "great green wall", first and foremost being the ongoing management of plant succession. It appears that their mono-species plantings of fast growing trees (i.e., pioneer species) is expected to be the complete solution to expanding desertification, when we know it to be only a starting point. Getting an initial windbreak and shade planting begins to protect the soil from evaporation and starts the process of soil building by leaf fall, but I'm not reading anywhere that they follow-up with adding diversity as the pioneer species take hold. The biggest concern in arid and semi-arid climates is keeping moisture in the soil (preventing evaporation) and the biggest contributors to evaporation are direct sunlight, wind, and lack of organic material/topsoil. Planting pioneer species begins to address evaporation and creates a micro-environment within which less hardy productive trees & shrubs can be inter-planted. Slowing and sinking any surface water flows using swales is a great foundation for successional plantings, especially useful at the base of the desert's surrounding mountains/hills.
in an emergency a first step is important. perhaps there are enough native seeds that can grow once the windbreak and some shade are in place? it's hard to say for sure what happens next without followup studies and pictures. i usually don't see them though. just to keep the sand from shifting and blowing is a good step and much needed there to improve the downwind air quality and to protect those downwind areas from being engulfed. plus if you can stop the sand from moving long enough for a few rains to happen and then perhaps a bit of a crust and microbial community can work. maybe even spraying with some kind of organic glue like substance would also help as that could provide some substrate for bacteria, fungi, mosses, etc. that can form a crust too. it could all be a part of something to get started. that's the key i think, just to hold something in place long enough it can be tied down a bit more until some rains come and that gives any stray seeds in there a chance to grow and tie more of the sand together. once those plants can grow then you get the organic matter and moisture holding and shade and ... it _can_ work, but it does take time... often in the desert it's a longer term thing too (as compared to here where empty land gets rapidly recolonized) measured perhaps in decades.
A few of the biologist and ecologist that are working on the green wall project are also involved in the Loess project so I suspect they are running back and forth. That could lead to it looking like they are only planning pioneer species (which could be the case in this instance) or it could be that the government has sliced funding. I know they are doing great things in loess, so I would expect similar succession planting and perhaps even some earth works once they have the wind barrier in place. However it is China, one of the few still Communist countries, regardless of what they want to appear to the west, they are sill very much in line with Mao's design. If the green wall project isn't near the top of their priority list, it has the probability of being shorted the funds needed to do the job correctly. I hope that isn't the case, it would be a very good thing for them to succeed so other areas would have a good example to use for their own designs of restoration,.
