Cost and efficiency of cutting lianas in a lowland liana forest in Bolivia
Perez-Salicrup D; Claros A; Guzman R; Licona J; Ledezma F
Liana cutting is a commonly suggested silvicultural practice aimed at reducing the negative impacts of lianas on timber production but few experimental studies have been conducted to evaluate the cost and efficiency of this practice. In this study we estimated the cost of cutting lianas in 12 plots of 0.25 ha each in a densely liana-infested forest of lowland Bolivia and evaluated the efficiency of this silvicultural treatment in terms of the proportion of lianas missed the density of resprouting liana stumps and the number of liana-infested trees after two years of an experimental liana treatment. The cost of cutting lianas in this forest by locally hired laborers was 23.6 (SE = 2.48) person-hours/ha. Considering local cost of labor and the U.S.‚ÄìBolivian currency exchange rate at the time of the study this figure translates to ca $15/ha. Liana density decreased from 2471 (SE = 104.3) to 130 (SE = 24.2) liana stems ‚â•2 cm/ha immediately after cutting because 5.5 percent of lianas were left uncut (missed). Slender lianas were missed more often than lianas with large-diameter stems. Liana species that grow 2‚Äì3 m before they start to twine were also frequently missed. Twenty-two percent of liana stumps ‚â•2 cm sprouted after cutting. Liana stumps with larger diameters sprouted more than stumps with smaller diameters. Most liana stumps produced only two sprouts. Two years after cutting 78 percent of trees had no living lianas in their crowns in contrast to only 13 percent liana-free trees in the control plots. Sixty-four percent of trees still had hanging dead lianas two years after cutting but only 23 percent of trees were reinvaded by lianas using dead liana stems as trellises. Liana cutting can efficiently reduce the number of lianas in liana-infested forests and the effects of cutting lianas last for at least two years; however the treatment is expensive. Thus we recommend that it is better to view liana cutting as a preventive activity to avoid liana infestation rather than as a corrective measure after poor management. Liana cutting can be easily conducted along with other reduced-impact logging practices.