A Mechanistic Explanation for Global Patterns of Liana Abundance and Distribution

Abstract

One of the main goals in ecology is determining the mechanisms that control the abundance and distribution of organisms. Using data from 69 tropical forests worldwide, I demonstrate that liana (woody vine) abundance is correlated negatively with mean annual precipitation and positively with seasonality, a pattern precisely the opposite of most other plant types. I propose a general mechanistic hypothesis integrating both ecological and ecophysiological approaches to explain this pattern. Specifically, the deep root and efficient vascular systems of lianas enable them to suffer less water stress during seasonal droughts while many competitors are dormant, giving lianas a competitive advantage during the dry season. Testing this hypothesis in central Panama, I found that lianas grew approximately seven times more in height than did trees during the dry season but only twice as much during the wet season. Over time, this dry season advantage may allow lianas to increase in abundance in seasonal forests. In aseasonal wet forests, however, lianas gain no such advantage because competing plants are rarely limited by water. I extend this theory to account for the local, within-forest increase in liana abundance in response to disturbance as well as the conspicuous decrease in liana abundance at high latitudes.

Mesoscale assessment of changes in tropical tree species richness across a bioclimatic gradient in Panama using airborne imaging spectroscopy

“…Schnitzer (2005) developed the hypothesis that lianas reach peak species richness at intermediate rainfall. Our results could as such suggest that trees plus canopy lianas reach peak species (top) Map of the total area under the spectral proxy for SACs (i.e.…”

Structure of the understory community in four stretches of Araucaria forest in the state of São Paulo, Brazil

“…Therefore, species with the vine growth habit were more common at the location with a more seasonal climate (Itaberá), which can be attributed to their ecological characteristics. Due to the anatomical, ecological and physiological advantages that vines enjoy, at the expense of tree species in regeneration, the recruitment of vines in the forest understory is directly proportional to the seasonality of the local climate (Benítez-Malvido & Martínez-Ramos 2003;Schnitzer 2005).…”

Hyperspectral discrimination of tropical dry forest lianas and trees: Comparative data reduction approaches at the leaf and canopy levels

“…The deciduous trees have a higher risk of being misclassified because the leaves of the lianas are the only leaves being seen (i.e. the classifier is not separating tree and liana leaves as at the leaf level) since in many cases lianas lose their leaves after the host trees (Kalacska et al, 2005) or may maintain leaves through the dry season (Schnitzer, 2005). A possibility (though not investigated in this study) is that because of intra-species spectral variability, the aggregated spectra from those canopies resembled that of the trees with less than 40% liana coverage (Zhang et al, in press).…”

“…Lianas have been considered a significant fingerprint of the effects of global environmental change in tropical environments (Lewis et at, 2005). Field studies indicate liana coverage is increasing in neotropical forests (Phillips et at 2002;Wright et at, 2004), which may be a biological signal of higher CO2 concentration, increased disturbance or decreased precipitation (Schnitzer, 2005). Lianas have been shown to alter both old-growth and secondary forest structure (Laurance et at, 2001;Perez-Salicrup, 2001;PerezSalicrup & de Meijere, 2005;Putz, 1984;Schnitzer & Bongers, 2002) and because lianas' impact on trees varies according to the tree's phytogeny and ecology, an increase in liana loading could alter tropical forest biodiversity (Phillips et at, 2002).…”