Sustainable timber harvesting in Venezuela: a modelling approach

Summary Reliable data on the growth and yield of logged‐over forest, to determine sustainable cutting cycles, are widely missing for the tropics. We used the process‐based model formind 2.0 to analyse the growth and yield of logged‐over forest in Venezuela under different logging scenarios over a period of 240 years, and compared results with unlogged stands. The performance of the model was evaluated with a detailed stability and sensitivity analysis. In the absence of further logging, the logged‐over stand approached the stand structure of mature forest in terms of bole volume and basal area after about 50–100 years. Thirty‐year cutting cycles with conventional logging methods and net extraction volumes of 45 and 60 m 3 ha −1 cycle −1 did not provide sustainable yields under either of two minimum felling diameters (35 and 50 cm) that were applied. Only the 60‐year cutting cycle provided sustainable yields under conventional and reduced‐impact logging, with the different minimum felling diameters and a range of net volumes extracted (30–60 m 3 ha −1 cycle −1 ). With the longest cutting cycle (60 years), bole volume recovered to levels similar to the mature unlogged stand, but the species composition was very different. Scenarios with reduced‐impact logging provided a significantly higher timber volume than under conventional logging. The conservation of forest resources will only be possible with long cutting cycles (at least 60 years) in combination with reduced‐impact logging.