Assessing the completeness of inventories of vascular epiphytes and climbing plants in Chilean swamp forest remnants

Resumen:
Plant species inventories provide the foundation for more complex analytical studies and are the basis of monitoring programmes; however, if they are to provide reliable information in the long term, their level of completeness needs to be estimated. This work assessed the completeness of inventories of climbing plants and vascular epiphytes in swamp forest remnants of the Araucania region of south-central Chile, which has been severely disturbed by agroforestry expansion. We sampled 30 sites using transects, with observations from ground level to a height of 2.3 m up the trees. To assess the potential existence of unrecorded species we drew rarefaction curves based on sample trees and extrapolated them towards one of the most intensely sampled sites. We then calculated the asymptotic species richness with the Chao 1 estimator. The results showed: (1) a total richness of 16 species of epiphytes and 17 species of climbing plants; (2) the rarefaction curve differentiated only two categories of sampling effort ('rich' and 'poor' sites) as a result of the substantial overlap of the confidence limits at 95%; and (3) the maximum richness estimated by Chao 1 was similar to the richness observed in all the sites. We conclude that greater sampling effort is required to obtain tighter statistical confidence levels in the rarefaction curve; however, from a biological point of view, the sampling effort achieved adequate representation of the species richness at all the sites. Total richness of vascular epiphytes and climbing plants was only slightly below values reported for much larger areas of better-conserved forest in south-central Chile and adjacent areas of Argentina. Finally, we found evidence that forest fragmentation has more severe effects on species richness of vascular epiphytes than on that of climbing plants.

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