Impacts of lianas on tree growth and mortality in secondary seasonally tropical dry forest: a twelve-year record

Lianas have been implicated in the mortality and growth reduction of tropical trees. But the details of these impacts of lianas on trees remains poorly documented. This is particularly true in secondary forest and seasonally dry tropical forests where recent work suggested that lianas have little effect on trees. We report on twelve years of tree growth observations in secondary tropical dry forest in northwest Costa Rica. We measured the growth of over 1500 tree stems with band dendrometers. In addition to measuring annual growth, we made observations of liana presence and the degree to which a trees crown was obscured by the lianas using an ordinal scale. Lianas were present on 55% of the trees we followed, but only obscured the crowns of 35% of trees. Averaged over the length of our study, trees where lianas obscured more than 50% of the trees crown appear to have lower growth rates. But these effects varied with species, tree size, and annual rainfall. We also investigate the influence of stand-level environmental factors on liana prevalence and how the liana-growth or liana-mortality relationship changed over the course of twelve years, which included a major drought.