lunes, 9 de noviembre de 2015

Estimating emissions from shifting cultivation in tropical dry forest

Shifting cultivation is considered to be an important cause of degradation and carbon emissions in tropical dry forests.  Under REDD+, two sets of solutions have been proposed:

 (1) switching to permanent cultivation (sedentarization and intensification of production, to allow ´sparing´ of some forest)  and
 (2) lengthening of the fallow cycles, to allow more time for recuperation of stocks.

In InfoBrief 4, which can be downloaded from the side menu, we calculate the carbon emissions that would result from production of one tonne of maize in shifting cultivation and compare this to emissions in a permanent cultivation system.  We find that emissions from loss of biomass under shifting cultivation are higher than in permanent agriculture, but this does not take into account the much higher inputs of carbon in the form of agro-chemicals and energy in permanent agriculture.

We then calculate the impacts of shortening and lengthening the fallow cycle.  We find that contrary to common perceptions, in many cases shortening of the cycles increases standing carbon stocks across the affected landscape and reduces emissions.

We will be presenting this material in our side events at the Paris CoP, which you are welcome to attend. 

Degradation and deforestation of tropical dry forests in western Mexico

Tropical dry forest is the natural vegetation of 
much of western Mexico

The lower lying, level areas are mostly already  
deforested for permanent agriculture

while the lower slopes are commonly used for 
shifting cultivation and temporary pastures,
resulting in degradation.

There is rapid regrowth of secondary forest  following
shifting cultivation 

but cattle are often allowed to graze freely on 
these slopes, reducing the capacity of 
the forest to regenerate.