Effects of future crop tree flagging and skid trail planning on conventional diameter-limit logging in a Bolivian tropical forest

Abstract

Sustainable natural forest management initiatives in the lowland tropical forests of Bolivia require that cost-effective measures be identified to help maintain timber stand quality and reduce damage to advance regeneration during logging operations. This study considered the potential costs and benefits of including two ‘best’ management practices—the pre-harvest flagging of future crop trees (FCTs) and improved planning of skid trails—in adjacent 45 ha plots, in conjunction with conventional planned diameter-limit logging in a lowland tropical forest in the Department of Santa Cruz, Bolivia. The study also included a general assessment of FCT damage and timber waste associated with standard felling operations. The additional costs of flagging FCTs ≥30 cm DBH were estimated to be US$ 0.38/ha. FCT flagging significantly reduced damage by 20% in felling gaps and by 10% along skid trails that received 2–10 skidder passes. A mean directional error of ±35° per tree felled was observed for felling operations, indicating that damage to FCTs during felling could be reduced through implementation of directional felling techniques. Improved felling techniques could increase mean timber utilization by as much as 0.16 m 3 or US$ 3.20 per tree felled through reduced wood waste associated with stump pull, a common problem observed during felling operations. Pre-harvest skid trail planning increased costs an estimated US$ 1.46/ha, but reduced mean skidder “search times” (min/m 3 harvested) by 23% and unnecessary skid trails by 96%. Compared to normal harvesting operations, overall operational efficiency increased by approximately US$ 3.00/ha. Pre-harvest skid trail planning significantly reduced FCT damage along skid trails that received 2–10 skidder passes. The results of this study indicate that pre-harvest skid trail planning and improved timber felling techniques yield short-term financial gains relative to conventional management as well as potential long-term gains through FCT conservation and, therefore, warrant implementation. Forest certification groups should consider FCT flagging for inclusion in timber certification criteria for the region given its low cost and proven utility for maintaining timber stand quality.