Les feuilles tropicales
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Soil degradation and solutions

Deforestation.jpeg

After logging, rains wash-out the top soil, leaving degraded soils directly exposed to sun light. Forest trees fail to find nutrients, or the shade protection required to grow

 

The solution is to first plant a selection of tree spe-cies that:

  • tolerate poor soils

  • fix atmospheric nitrogen in the soil, acting as a natural fertiliser

  • grow fast and withstand harsh environment

  • are strong light demander

  • tolerate drought

 

These “pioneer trees" are planted with high density (1,000 trees per acre / 2m  separation). After 3 years, they start to join their branches, providing protective shade. Their roots continuously release nitrogen into the soil while allowing  rainwater to permeate. Their falling leaves create a layer, providing humidity for fungi to develop.

In ACRE program, pioneer trees are harvested 20% each year from year 6 to year 10. The timber is sold on the market. With the galloping deforestation, the ensuing rarefaction of ordinary timber, for cons-truction, plywood or pulpwood, has  caused timber price soaring. The retail market price is currently  (2021) around 5 lakhs (US$380) per ton.

Nitrogen fixing chart.jpg
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