Date of Award

December 2015

Degree Type

Thesis

Degree Name

Master of Science

Department

Biological Sciences

First Advisor

Stefan A. Schnitzer

Second Advisor

Filipe Alberto

Committee Members

Stefan A. Schnitzer, Filipe Alberto, Rafael L. Rodriguez-Sevilla

Keywords

Competition, Ground Based Lidar, Lianas, Panama, Plant Area Index (pai), Secondary Tropical Forest

Abstract

Lianas are an important component of tropical forests, where they reduce tree growth, fecundity and survival. Competition for light among plants may be intense; however the amount of light that lianas intercept is poorly understood. We used a large-scale liana removal experiment to quantify light interception by lianas in a Panamanian secondary forest. We measured the change in plant area index (PAI) and forest structure six weeks after cutting lianas in eight 80x80 m plots and in eight control plots, and then annually for four years. We used ground-based LiDAR to measure the 3-dimensional canopy structure before cutting lianas and annually for two years afterwards. Six weeks after cutting lianas, mean plot PAI was 20% higher in control versus liana removal plots. One year after cutting lianas, mean plot PAI was ~17% higher in control plots. The differences among treatments diminished significantly two years after liana cutting and, after four years, trees had fully compensated for the removal of lianas. Ground-based LiDAR revealed that lianas were distributed in the upper and middle parts of the canopy, and not just the upper canopy as previously suspected. Therefore, lianas attenuated ~20% of the light in the upper- and mid-canopy of the forest.

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