Geographic analysis of Red List Rhododendron (Ericaceae) taxa by country of origin identifies priorities for ex situ conservation

S E Gardiner,M B Mackay

doi:10.3767/blumea.2017.62.02.05

Abstract

A Red List assessment is insufficient to determine priorities for ex situ conservation in large genera such as Rhododendron, where there may be hundreds of taxa in any one Red List category. We have utilised an analysis of the geographic origins of 1?215 taxa of Rhododendron (Ericaceae) as a method to prioritise Red List taxa for ex situ conservation. This analysis includes descriptions of distribution and endemism by country of origin, analysis of the incidence of the 715 Red List taxa by country of origin, and determination of the extent to which taxa from each country of origin are in cultivation. We determined that of 30 countries of origin and a ‘Europe’ aggregate, 24 origins contain Red List taxa. Of those 24 origins, 17 origins and ‘Europe’ have greater than 75 % of Red List taxa ‘in cultivation’, as defined in this study, so that Target 8 of the Global Strategy for Plant Conservation has theoretically been met. However, for some of these origins the number of each taxon held ‘in cultivation’ is very low and genetic diversity is likely to be poor. The remaining six countries of origin have less than 75 % of Red List Rhododendron taxa recorded ‘in cultivation’ (Indonesia (28 %), Papua New Guinea (29 %), Malaysia (59 %), China (60 %), Japan (62 %) and Solomon Islands (0 %)). Analysis of a set of Red List factors and ‘not in cultivation’ factors reveals that Red List taxa from Indonesia, China and Papua New Guinea should take priority for ex situ conservation.

Highlights

Determination of priorities is one of the key challenges of conservation decision making and underpins successful development of both in situ and ex situ conservation strategies (Oldfield 2010, Ma et al 2013)
Under the Global Strategy for Plant Conservation (GSPC) (Sharrock et al 2014) priorities are initially driven by the Red List process, conducted as part of Target 2 of the Strategy, whereby taxa under threat are identified and prioritised ahead of remaining taxa
Plant conservation involves a range of initiatives, in this study we focus on ex situ conservation where taxa are held in living collections in botanic gardens

Summary

Introduction

Determination of priorities is one of the key challenges of conservation decision making and underpins successful development of both in situ and ex situ conservation strategies (Oldfield 2010, Ma et al 2013). Target 2 drives Target 8, which requires 75 % of Red List taxa to be in cultivation by 2020 (Sharrock 2012) This process appears to be sufficient for small genera comprised of similar life forms, but does not have a fine enough resolution for large genera of wide distribution and multiple life forms, where there may be hundreds of taxa in any one Red List category. In these genera additional factors such as taxonomic groupings, geographic re presentation, endemism and centres of diversity (Farnsworth et al 2006, Castaneda-Alvarez et al 2015, Cavendar et al 2015), can be used to identify key groups of taxa. We examine a series of factors that can be used to identify taxa from geographic origins that should be prioritised for ex situ conservation

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