I am aware that a tree is oxgen / carbon neutral on balance, it is the turnaround of water which I understand to influence weather patterns beond an immediate locality. Were the western Amazonian area to reduce its rainfall, the total amount of vegetation would reduce. Surely the effects of reduced moisture and of reduced cloud would change the weather systems of the area, convection currents, temperature gradients, fresh w\ater on salt and so on, with knock on effects on a wider scale?