Organisation

September

PhD Defence Ms Fangyuan Yu

Department of Natural Resources

4_Portrait _Fangyuan

Title of defence

Conservation biogeography of rhododendrons in China

Summary

Global biodiversity continues to be lost, especially in face of rapid climate and land use change. Rhododendrons form a major biodiversity component of the montane ecosystem in the Himalayan subalpine and alpine zone. However, the Rhododendron genus is one of the most neglected groups of plants in terms of scientific inquiry. The Rhododendrons of China exhibit great diversity, however, knowledge of their spatial distribution at the national level are still poor, especially about narrow-ranging species which are usually endemic and tend to be threatened. Rhododendrons display a great variation in range size, some Rhododendron species occur throughout most of the northern hemisphere, while others are highly restricted to small regions. Therefore, examining and understanding determining factors of spatial distribution, diversity patterns, and potential response to environmental change of Rhododendrons can provide a sound base for the comprehensive conservation strategy for Rhododendrons which required to maintain the sustainable alpine and subalpine ecosystem, as well as expand our knowledge of biogeography for plant conservation.
The main goal is to investigate the biogeographical patterns and the underlying mechanisms of distribution and diversity of Rhododendrons for their conservation in a changing world. The research in this thesis firstly examined the correlations between eight topographic complexity indices and Rhododendron species richness in China at seven spatial scales, the results showed that topographic complexity has positive correlation with Rhododendrons species richness. Secondly, this thesis examined the relationship between geographical and elevational range sizes for 80 endemic Rhododendron species in China, and investigates the importance of basic factors (i.e. climate, topography, and soil) in shaping the distribution of Rhododendrons with various geographical and elevational range sizes. The results showed that climatic niche breadth, especially the range of seasonal temperature variability relative to diurnal temperature variability, can explain variation in geographical range size of Rhododendrons. Thirdly, this thesis predicted Rhododendron diversity patterns, and identified hotspots and priority areas for Rhododendrons in China. Based on a combination of species richness, β-diversity, and weighted endemism, 12 general hotspots and five endangered species hotspots were detected. Lastly, this thesis predicted distribution of geographically narrow- and wide-ranging Rhododendron species under climate and land use change, which demonstrated Rhododendron species generally will be negatively affected by the climatic and land use change, narrow-ranging and threatened Rhododendron species are facing a high risk of extinction in the near future, but some geographically narrow-ranging species may be positively influenced.

This thesis demonstrates one of the Essential Biodiversity Variables (EBVs) - species occurrence, used to build distribution maps and calculate diversity information - provides fundamental data for biodiversity indicators that measure the progress of halting biodiversity loss which is the aim of Convention on Biological Diversity( CBD). Meanwhile, this thesis highlights that elevational range size should be taken into account for assessing the distribution shift of alpine and subalpine plant species. Species richness, β-diversity, and weighted endemism are complementary metrics of diversity, which can represent biodiversity and facilitate the optimal spatial arrangement of conservation areas. Balancing of the selected diversity metrics, the level of spatial congruence of diversity metrics, and spatial scale (both extent and grain) are critical as it may lead to diverging results of hotspots detection and protected areas design when used in isolation.

Biography

Fangyuan Yu was born on 18 October, 1985 in Xinjiang, China. She received the BSc degree in Geographic Information System from Northwest A&F University in 2007. She worked as a research assistant from July of 2007 to August of 2008 at Institute of soil and water conservation, Northwest A&F University. She started her Msc in Land Resources and Spatial Information Technology at Northwest A&F University from September of 2008, and got the MSc degree in June of 2011. In the same year, she was awarded a four-year doctorial scholarship from the China Scholarship Council (CSC), and started to pursue her PhD at the Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente. Her research interest lies in spatial ecology, biogeography, and biodiversity conservation.


 

Timesheet
Event starts: Thursday 21 September 2017 at 12:30
Venue: UT, Waaier 4
City where event takes place: Enschede

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