Under current fallow scenarios, we found no evidence for any yield advantage of fire exclusion over farmer practice, nor detectable effects on soil fertility parameters.
Furthermore, S. orbiculatus has been characterized as a major invader of unburned prairie but the role of fire exclusion and the application of fire with livestock grazing are not well understood for this species (Bragg and Hulbert [1974]; Stubbendieck et al. [2003]).
While we did not estimate labor inputs for these scenarios, requirements are likely to be higher for the fire exclusion practice.
For all plantain fields with fire exclusion, we found positive effects on the growth of remnant trees, and the proportion of tree seedlings remaining in fallow, suggesting that fallow recovery rates would be enhanced (Fig. 5).
While we could not distinguish between impacts of standard farmer burning practice and fire exclusion treatments for the current fallow scenario, we concluded that fire exclusion would lead to higher yields, higher ecosystem carbon stocks as well as potentially faster fallow recovery under the reduced fallow scenario.
From 2011 to 2013, we measured how S. orbiculatus basal resprouting and layering stems were affected by patchy fires on grazed pastures, complete pasture fires on grazed pastures or fire exclusion without grazing for more than three years.
For the reduced fallow scenario, we found that fire exclusion led to an approximately 50%% increase in labor requirements for planting, weeding, and harvesting both in the maize and plantain systems, compared with the farmer practice of burning.
If fire exclusion scenarios were followed for the two field types here, the number of fire events would be greatly reduced.
Therefore, fire exclusion might compensate, to some extent, for reduced fallow lengths by allowing recovery within a shorter period and avoiding further degradation.
Mean fire return intervals prior to fire exclusion (1700 1900) ranged from 1 to 29 years for fires scarring >25% of the fire-scar samples.
