Forest edge influence on species richness and functional characteristics of epiphytic orchids in oil palm plantations

Project Number 189 Back to projects

Start date

2018-02-12

End date

2018-06-06

Research areas

Biodiversity

Data use

Masters Project

Rationale

This project seeks to examine the differences in orchid presence, diversity and functional traits between forest canopy and oil palm plantation. Borneo is reportedly home to 2,500 to 3,000 species of orchids: one of the highest diversities in the world. Conversion of forest to oil palm threatens the diversity of these species. Orchids have been observed to be present in oil palm plantations, but the extent and diversity present has never been studied in Borneo. Increasing the scientific body of knowledge about the extent and characteristics of orchids in oil palm plantation presents an opportunity to increase plantation biodiversity and to conserve a charismatic group of species. My hypotheses are as follows:
(1) Species richness will be higher in canopy height trees than in oil palm plantations.
(2) Species richness and abundance in oil palm plantation will decrease with distance from the forest edge.
(3) Orchids in oil palm will have characteristics suggesting greater drought tolerance than that of orchids found in forest canopy; this pattern will increase within the plantation with distance from forest edge.

Methods

Field Collection
Oil palms will be surveyed for orchids in plantation land that directly borders forest. The oil palm plantation is laid out in a grid pattern, with roughly 10 m between palms in each direction. Five palms per row will be sampled between 10m and 50m into the plantation from the forest (n=25). On each palm, all orchids between one to two meters below the crown will be surveyed. Eight plots along the forest edge will be sampled (Total n=200). Each plot will be separated by 25 m, mirroring a Conservation International (CI) epiphyte survey protocol (Gradstein et al. 2003).
Canopy height trees of suitable safety for climbing will be selected in forest habitat near SAFE project and accessed via single rope technique (SRT) (Maher 2006). Canopy branches will then be surveyed for species richness following the CI protocol, which involves surveying eight canopy height trees and their surrounding 20 m2 plots (Gradstein et al. 2003)
Orchids will be classified to the genus level using Chan et al. (1994) and then classified either to the species level using genus-specific keys or sorted into morphospecies.
Drought Resistance
Live specimens (n= 24 per habitat) will be identified, tagged and collected from both the oil palm and forest canopy based on species abundance (Yang et al 2016). Individuals will be randomly assigned to the control or experimental group. Once removed, orchids will be placed in the drought resistance experiment within 24 hours. Each will be weighed daily during the trial, which will last 400 hours, following Yang et al. (2016). Desiccation chambers will be constructed from clear plastic bins; each will be sealed with the exception of a small airflow tube. The experimental chamber will have silica gel beads, including beads in the airflow tube to reduce influx of humidity, to simulate drought. The control chamber will not have silica gel.
Leaf Functional Traits
Two leaves will be collected per species per distance treatment within the oil palm and two per species per canopy height tree in the forest. Leaves will be selected and measured for Specific Leaf Area (SLA) following the protocol of Garnier et al 2001. Portions of each leaf will then be prepared for a stomatal peel and cross sectioned for closer examination of layer traits, such as cuticle thickness (Zhang et al 2016). Slides will be photographed for later analysis using ImageJ, an open source image analysis software (Abramoff et al 2004).
Statistical Analysis
Each palm and tree plot will be treated as an independent sample for purposes of statistical analysis (Prescott et al. 2015). Species accumulation curves will be calculated to ensure minimum sample size is met for species richness (Gradstein et al. 2003). Independent t¬-tests will be used to evaluate differences in image-assessed leaf functional traits between groups following a similar protocol to that described by Zhang et al (2016). Differences within species before and after drought stress will be tested using a one-way ANOVA following the data analysis protocol of the same group.

Project members
ResearcherProject roleProject contact
Ashley StumvollLead Researcher