PhD Defense Seminar cum Oral Examination
Conservation of epiphytic orchids in urbanised tropical environments
Speaker: Muhammad Izuddin Bin Mohamad Rafee (Graduate Student Dept. of Biological Sciences, NUS)
Date: 13 April 2018, Friday
Venue: DBS Conference Room (S3 LEVEL 5, #05-01)
Supervisor: Assoc Prof Edward L. Webb
“As urban expansion persists, preserving biodiversity becomes progressively difficult. Yet, ex situ methods can facilitate biodiversity conservation in urban spaces. However, species-specific niche requirements—particularly in urbanised environments—remain largely unknown, making ex situ conservation programmes ineffectual. Using native epiphytic orchids as a study system, I assessed two primary ecological barriers to orchid regeneration in urban habitats, namely availability of orchid mycorrhizal fungus / fungi (OMF) as well as the niche requirements of OMF and native orchids.
First, I assessed the availability of OMF on urban trees and the orchid-site suitability of various orchid species by conducting metabarcoding and next-generation sequencing on tree bark and orchid samples. I also identified biophysical factors that influenced OMF presence and richness on urban sites.
Second, I investigated the germination niches—i.e. compatible OMF and suitable biophysical conditions—of four orchid species by conducting orchid mycorrhizal fungal baiting and seed sowing experiments. I then assessed the potential for aboveground orchid seed banks (seed longevity) using seed viability tests on post-experimental, non-germinated seeds.
Third, I evaluated the effectiveness of managed relocation of multiple native orchid species in various urban habitats via long-term planting experiments, as well as identified species post-germination niche requirements that influenced the long-term survival and growth of translocated orchids.
My results indicated that OMF are present on urban trees. However, presence, diversity, and distribution of OMF were primarily constrained by biophysical factors. Urban trees can support germination niches for native epiphytic orchids as well. I also found evidence of seed bank formation on epiphytic microsites. Based on the long-term study, majority of the species showed survival and positive growth. Overall, this thesis demonstrates how species-specific niche requirements can be evaluated / quantified and how the information gained can benefit ex situ, as well as in situ, orchid conservation.”
All are welcome