Conservation of threatened relict trees through living ex situ collections: lessons from the global survey of the genus Zelkova (Ulmaceae)

Maintaining living ex situ collections is one of the key conservation methods in botanic gardens worldwide. Despite of the existence of many other conservation approaches used nowadays, it offers for many endangered plants an important insurance policy for the future, especially for rare and threatened relict trees. The aim of this research was to investigate the global extent of living ex situ collections, to assess and discuss their viability and inform the development of conservation approaches that respond to latest global conservation challenges. We used as a model taxon the tree genus Zelkova (Ulmaceae). The genus includes six prominent Tertiary relict trees which survived the last glaciation in disjunct and isolated refugial regions. Our comprehensive worldwide survey shows that the majority of botanic institutions with Zelkova collections are in countries with a strong horticultural tradition and not in locations of their origin. More importantly, the acutely threatened Zelkova species are not the most represented in collections, and thus safeguarded through ex situ conservation. Less than 20% of the ex situ collections surveyed contain plant material of known wild provenance while the majority (90%) of collections are generally very small (1-10 trees). Botanic gardens and arboreta particularly in regions where iconic relict trees naturally occur should play a vital role in the conservation of these species. The coordination of conservation efforts between gardens has to be enhanced to prioritise action for the most threatened relict trees. Large scale genetic studies should be undertaken, ideally at genus level, in order to verify or clarify the provenance of ex situ collections of relict trees in cultivation. For the most threatened relict tree genera, well-coordinated specialist groups should be create

The Tertiary relict tree Zelkova abelicea (Ulmaceae): distribution, population structure and conservation status on Crete

Relict species provide a unique opportunity to understand past and recent biogeographical and evolutionary processes. Zelkova abelicea (Ulmaceae), which is endemic to the island of Crete (Greece), is one of the most prominent Tertiary relict trees of the Mediterranean region. We collected distribution, threat and population structure data by reviewing literature and herbaria and through field surveys at 14 study plots throughout the range of the species. The present distribution of Z. abelicea is extremely fragmented. Although the total estimated number of individuals is relatively high, the populations are dominated by dwarf, severely browsed, non-flowering individuals. The population structure is asymmetric. At most, 5% of a plot's trees are large and fruit-bearing. The asymmetric structure is particularly pronounced in isolated and small populations. Based on its limited geographical range, the fragmented spatial pattern, and data on distribution and population structure, our study confirms that Z. abelicea is a threatened species (IUCN category Endangered). Our research aim is to promote the development of new approaches for the improvement of conservation strategies for Tertiary relict trees characterized by major local disjunction

Do living ex situ collections capture the genetic variation of wild populations? A molecular analysis of two relict tree species, Zelkova abelica and Zelkova carpinifolia

Botanic gardens and arboreta, particularly in regions where iconic relict trees naturally occur, play a vital role in the conservation of these species. Maintaining well-managed living ex situ collections of rare and threatened relict tree species provides an immediate insurance policy for the future species conservation. The aim of this research was to investigate the origin, representativeness and genetic diversity of relict trees kept in botanic gardens and arboreta. We used as a model two ecologically and biogeographically distinct members of the prominent relict genus Zelkova (Ulmaceae), which survived the last glaciation in disjunct and isolated refugial regions: Z. carpinifolia in Transcaucasia and Z. abelicea endemic to Crete (Greece) in the Mediterranean. Our study revealed substantial differences in the genetic diversity and the origin of living ex situ collections of the two investigated taxa. The living ex situ collections of Z. carpinifolia have relatively high representativeness compared with the global genetic variability of natural stands identified in a previous study. In contrast, Z. abelicea, which possesses an extraordinarily high genetic variability in natural populations, is clearly underrepresented in botanic garden collections. Moreover, all Z. abelicea trees investigated in this study most probably originated from a single region, the Levka Ori in western Crete. Thus, the ex situ conservation of Z. abelicea requires major planning and coordination efforts, including the establishment of well-documented collections in botanic gardens in Greece and especially on Crete. New living ex situ collections should be created using plant material collected from all of the mountain regions where Z. abelicea still occurs. Our study highlights the need for re-evaluating the existing living ex situ collections of trees and the development of new strategies for future conservation efforts in botanic gardens and arboreta. The coordination of conservation efforts between gardens must be enhanced to prioritize actions for the most threatened relict tree species

Conservation of threatened relict trees through living ex situ collections: lessons from the global survey of the genus Zelkova (Ulmaceae)

Maintaining living ex situ collections is one of the key conservation methods in botanic gardens worldwide. Despite of the existence of many other conservation approaches used nowadays, it offers for many endangered plants an important insurance policy for the future, especially for rare and threatened relict trees. The aim of this research was to investigate the global extent of living ex situ collections, to assess and discuss their viability and inform the development of conservation approaches that respond to latest global conservation challenges. We used as a model taxon the tree genus Zelkova (Ulmaceae). The genus includes six prominent Tertiary relict trees which survived the last glaciation in disjunct and isolated refugial regions. Our comprehensive worldwide survey shows that the majority of botanic institutions with Zelkova collections are in countries with a strong horticultural tradition and not in locations of their origin. More importantly, the acutely threatened Zelkova species are not the most represented in collections, and thus safeguarded through ex situ conservation. Less than 20% of the ex situ collections surveyed contain plant material of known wild provenance while the majority (90%) of collections are generally very small (1–10 trees). Botanic gardens and arboreta particularly in regions where iconic relict trees naturally occur should play a vital role in the conservation of these species. The coordination of conservation efforts between gardens has to be enhanced to prioritise action for the most threatened relict trees. Large scale genetic studies should be undertaken, ideally at genus level, in order to verify or clarify the provenance of ex situ collections of relict trees in cultivation. For the most threatened relict tree genera, well-coordinated specialist groups should be created

The Tertiary relict tree Zelkova abelicea (Ulmaceae): distribution, population structure and conservation status on Crete

Relict species provide a unique opportunity to understand past and recent biogeographical and evolutionary processes. Zelkova abelicea (Ulmaceae), which is endemic to the island of Crete (Greece), is one of the most prominent Tertiary relict trees of the Mediterranean region. We collected distribution, threat and population structure data by reviewing literature and herbaria and through field surveys at 14 study plots throughout the range of the species. The present distribution of Z. abelicea is extremely fragmented. Although the total estimated number of individuals is relatively high, the populations are dominated by dwarf, severely browsed, non- flowering individuals. The population structure is asymmetric. At most, 5% of a plot's trees are large and fruit-bearing. The asymmetric structure is particularly pronounced in isolated and small populations. Based on its limited geographical range, the fragmented spatial pattern, and data on distribution and population structure, our study confirms that Z. abelicea is a threatened species (IUCN category Endangered). Our research aim is to promote the development of new approaches for the improvement of conservation strategies for Tertiary relict trees characterized by major local disjunctions

Do living ex situ collections capture the genetic variation of wild populations? A molecular analysis of two relict tree species, <i>Zelkova abelica</i> and <i>Zelkova carpinifolia</i>

Botanic gardens and arboreta, particularly in regions where iconic relict trees naturally occur, play a vital role in the conservation of these species. Maintaining well-managed living ex situ collections of rare and threatened relict tree species provides an immediate insurance policy for the future species conservation. The aim of this research was to investigate the origin, representativeness and genetic diversity of relict trees kept in botanic gardens and arboreta. We used as a model two ecologically and biogeographically distinct members of the prominent relict genus Zelkova (Ulmaceae), which survived the last glaciation in disjunct and isolated refugial regions: Z. carpinifolia in Transcaucasia and Z. abelicea endemic to Crete (Greece) in the Mediterranean. Our study revealed substantial differences in the genetic diversity and the origin of living ex situ collections of the two investigated taxa. The living ex situ collections of Z. carpinifolia have relatively high representativeness compared with the global genetic variability of natural stands identified in a previous study. In contrast, Z. abelicea, which possesses an extraordinarily high genetic variability in natural populations, is clearly underrepresented in botanic garden collections. Moreover, all Z. abelicea trees investigated in this study most probably originated from a single region, the Levka Ori in western Crete. Thus, the ex situ conservation of Z. abelicea requires major planning and coordination efforts, including the establishment of well-documented collections in botanic gardens in Greece and especially on Crete. New living ex situ collections should be created using plant material collected from all of the mountain regions where Z. abelicea still occurs. Our study highlights the need for re-evaluating the existing living ex situ collections of trees and the development of new strategies for future conservation efforts in botanic gardens and arboreta. The coordination of conservation efforts between gardens must be enhanced to prioritize actions for the most threatened relict tree species