Wednesday, April 7, 2010
Billions of dollars and billons of hours of labor have gone into reforestation in poor countries - most has been wasted and the results are very limited. Trees by themselves do not stop erosion. Once a forest is established after 20 or 30 years the forest stops erosion and retains rainfall and assures that water is released slowly so that generally flooding does not occur. Creating a forest is the difficult part. We know that if vetiver hedgerows are planted across denuded slopes in the first instance, then the microclimate changes (better soil moisture conditions) that allows for trees to be planted between the rows (in the second or third year). these trees grow well and the first steps to creating the forest will have been achieved, whilst all along the vetiver hedges are protecting the land and doing waht a mature forest is able to do later. A good example of this is Don Miller's catchment conservation in Vanuatu, South Pacific. Another example is the rehabilitation of the "red desert" in Guangdong Province, China. In this case some 500 ha of completely eroded hillside (only "C" horizon remained - top image) was first treated with vetiver hedgerows. Two years later Eucalyptus sp were planted between the hedgerows. After 5 years the area was looking like a forest again.
Another case was in HongKong, very badly denuded granite hillside was first protected with vetiver and then successfully planted with Acacia mangium. We recommend that our forestry friends take note of this, and by the way if they want to grow better quality tree seedlings they would be well advised to read some of Norman Jones' (one of the great foresters that I had the privilege to know) notes that can be found on TVNI website. They are short, sweet, and very applicable.
You May Also Like To Read:
Useful gallery of all blog images (with captions) posted on Picassa