ECOLOGY/EVOLUTION

Not Just a Hanger-On

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Science  10 Jun 2005:
Vol. 308, Issue 5728, pp. 1521
DOI: 10.1126/science.308.5728.1521c

Among the many characteristic features of tropical forests are large lianas (woody vines) that loop through the canopy and the understory. Unlike trees, they defy easy quantification and so have tended to receive less attention in ecological studies of forest structure and dynamics.

Phillips et al. have redressed the balance in a study of liana dynamics in western Amazonian forests, using (i) time series of data on the turnover (defined as death and replacement) of liana and tree stems collected over periods of one to two decades at a number of forest sites, and (ii) a structural inventory of all lianas in an intensively sampled 1-ha plot in southern Peru. The long-term turnover rates of large lianas (with stems >10 cm in diameter) were rapid—about three times those of trees—with annual recruitment and mortality rates exceeding 6%. Infestation with large lianas was associated with higher death rates in canopy trees, though it is difficult to disentangle cause and effect: Liana infestation may hasten death, yet older trees will have been hosts to lianas for longer. Forest primary productivity was also positively associated with liana turnover rates. Although the biomass of lianas is small relative to that of trees, lianas appear to play a disproportionately active role in forest dynamics.— AMS

Ecology 86, 1250 (2005).

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