Special Issue "Dragon Trees - Tertiary Relicts in Current Reality"

A special issue of Forests (ISSN 1999-4907). This special issue belongs to the section "Forest Ecology and Management".

Deadline for manuscript submissions: closed (20 January 2020).

Special Issue Editors

Prof. Dr. Petr Maděra
E-Mail Website
Guest Editor
Department of Forest Botany, Dendrology and Geobiocoenology (FFWT), Mendel University, Zemedelska 1, Brno 61300, Czech Republic
Interests: forestry; forest ecology; woody plants ecology
Prof. Dr. Fabio Attorre
E-Mail Website
Guest Editor
Department of Environmental Biology, Sapienza University of Roma, Roma 00815, Italy
Interests: botany; phytosociology; plant ecology
Prof. Dr. Anthony G. Miller
E-Mail Website
Guest Editor
Centre for Middle Eastern Plants, Royal Botanic Garden Edinburgh, UK
Interests: botany; flora of Arabia; plant ecology
Prof. Dr. Nadezhda Nadezhdina
E-Mail Website
Guest Editor
Department of Forest Botany, Dendrology and Geobiocoenology (FFWT), Mendel University, Zemedelska 1, Brno 61300, Czech Republic
Interests: tree eco-physiology

Special Issue Information

Dear Collegues,

Only a few species among more than 60–100 species of the genus Dracaena reach the arborescent form. Arborescent dracaenas were classified into dragon tree group comprising following species: Dracaena cinnabari, D. tamaranae, D. draco s.l., D. ombet s.l., and D. serrulata s.l. present in South Arabia, Macaronesia and North Africa. It is possible to count other species from Neotropics - D. americana, Asia - D. jayniana, D. cochinchinensis, D. yuccifolia, D. cambodiana and D. kaweesakii, and Africa – D. ellenbeckiana and D. steudneri to the dragon tree group due to its tree growth habit. Dragon trees are Tertiary relict species, the ecosystems (woodlands and very rare forests) with these species belong to one of the oldest ecosystems around the world. Most species are endemic with limited (often island) distribution. The distribution of Dragon trees is scattered comprising of a small population with unbalanced age structure, where often young trees are missing because the natural regeneration is damaged by overgrazing. Most species are spread in developing countries of the arid tropical zone where the populations are under pressure of local shepherds. Dragon trees are also an important source of non-timber products, the trees produce red resin called dragon´s blood, which is used for colouring and medical purposes since ancient times. Thus, most species are endangered and listed in IUCN Red List. The main objective of the special issue is to present the latest results of research focused on species of the dragon tree group and to determine main gaps for future investigation as the bases for conservation management. Special Issue will accept studies from broad research topics related to Dragon trees taxonomy and evolution, morphology and anatomy, eco-physiology, distribution and ecology, chemical composition of resin and its medical use, ethnobotany and history of dragon´s blood harvesting, species specific relationships (Dragon trees as a habitat), threat and nature conservation.

Prof. Dr. Petr Maděra
Prof. Dr. Fabio Attorre
Prof. Dr. Anthony G. Miller
Prof. Dr. Nadezhda Nadezhdina
Guest Editors

Manuscript Submission Information

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Keywords

  • dragon tree group
  • taxonomy
  • evolution
  • morphology
  • anatomy
  • eco-physiology
  • distribution
  • ecology
  • ethnobotany
  • resin chemical composition
  • spesies specific relationships
  • nature conservation

Published Papers (9 papers)

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Research

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Open AccessArticle
Germination of Dracaena cinnabari Balf.f. Seeds under Controlled Temperature Conditions
Forests 2020, 11(5), 521; https://doi.org/10.3390/f11050521 - 06 May 2020
Cited by 1 | Viewed by 751
Abstract
Research highlights: This study is focused on the germination of Dracaena cinnabari seeds in order to discover the possibility of natural and artificial regeneration of this species. Background and Objectives: This study aimed to determine the optimal temperature for D. cinnabari seed germination, [...] Read more.
Research highlights: This study is focused on the germination of Dracaena cinnabari seeds in order to discover the possibility of natural and artificial regeneration of this species. Background and Objectives: This study aimed to determine the optimal temperature for D. cinnabari seed germination, e.g., the temperature at which the germination percentage and germination rate (vitality) are the highest. The objectives of this study are to: (1) determine the optimal temperature for the germination of D. cinnabari seeds, (2) compare the suitability of different seed collection methods, and (3) compare the germination parameters of seeds that were collected from different localities. The results of this study will contribute to obtaining the highest number of seedlings from limited seed material for reforestation of the most endangered localities of D. cinnabari species. Materials and methods: Four seed sections were employed. These sections were directly collected from either the fruits of a cut panicle or the ground and were obtained from different localities that differ in altitude. The seeds were tested in a greenhouse while using Petri dishes at three different temperatures—22, 26, and 30 °C—with four replicates of 25 seeds of each section. ANOVA and the t-test were employed for data analysis. Results: The highest germination percentages (GPs) were achieved at 26 °C and 30 °C, which were 84.6% and 82.5%, respectively. The ANOVA and t-test results showed that the germination index (GI) of the species was relatively higher at a temperature of 30 °C relative to that at other temperatures in the study. Although seeds that were collected from the tree achieved a higher GP, the t-test result showed no significant differences in the GI of D. cinnabari seeds that were collected from the ground and from the tree (p > 0.05). Overall, the findings of this study show that temperature has substantial influence on the germination of seeds of D. cinnabari. Therefore, we recommend a temperature of 30 °C to facilitate the germination of D. cinnabari, as it achieved the highest GI at this temperature relative to that at the other temperatures (22 °C, 26 °C) applied in this study. Full article
(This article belongs to the Special Issue Dragon Trees - Tertiary Relicts in Current Reality)
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Open AccessArticle
Local Management System of Dragon’s Blood Tree (Dracaena cinnabari Balf. f.) Resin in Firmihin Forest, Socotra Island, Yemen
Forests 2020, 11(4), 389; https://doi.org/10.3390/f11040389 - 01 Apr 2020
Cited by 2 | Viewed by 872
Abstract
Various nontimber forest products (NTFPs) are produced from the forests and woodlands of Yemen. Dragon’s blood tree resin is one of the commercial NTFPs in Yemen and is produced by tapping Dracaena cinnabari trees, which are listed as vulnerable by the IUCN (International [...] Read more.
Various nontimber forest products (NTFPs) are produced from the forests and woodlands of Yemen. Dragon’s blood tree resin is one of the commercial NTFPs in Yemen and is produced by tapping Dracaena cinnabari trees, which are listed as vulnerable by the IUCN (International Union for Conservation of Nature) Red List. By applying a forest resource assessment, the present study inventoried the D. cinnabari forest with the aim of identifying and evaluating its structure, the harvesting status of the resin, and the current management system. The study was conducted in the Firmihin forest, Socotra Island, Yemen Republic. The forest resource assessment was carried out through a forest inventory by measuring trees from 12 plots following stratified random sampling. The relevant parameters of a total of 819 trees were measured, including the tree height, stem height of lowest branches, height of the highest wound, diameter at breast height (DBH), and presence of wounds. The wounds were measured on a total of 401 trees. Value chain analysis (VCA) was used to clarify the flow of dragon’s blood tree resin from the producers to the local, national, and international markets. Traditional management was examined using questionnaires in the case study area and surrounding villages. There are two tapping techniques: (1) collecting the pure dragon’s blood tree resin and (2) cutting part of the bark along with the pure resin. The second technique resulted in 84% of the trees having wounds. The tappers were mostly from the community in and around the forest. The study found that the traditional management system of tapping dragon’s blood tree resin is not sustainable. Full article
(This article belongs to the Special Issue Dragon Trees - Tertiary Relicts in Current Reality)
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Open AccessArticle
Micro-Hotspots for Conservation: An Umbrella Tree Species for the Unique Socotran Reptile Fauna
Forests 2020, 11(3), 353; https://doi.org/10.3390/f11030353 - 21 Mar 2020
Cited by 7 | Viewed by 1547
Abstract
Umbrella species are defined as species that can be rare and sensitive to human disturbance, whose protection may confer the protection of other co-occurring species. The dragon’s blood tree Dracaena cinnabari Balf.f. was already considered an umbrella species on Socotra Island (Indic Ocean, [...] Read more.
Umbrella species are defined as species that can be rare and sensitive to human disturbance, whose protection may confer the protection of other co-occurring species. The dragon’s blood tree Dracaena cinnabari Balf.f. was already considered an umbrella species on Socotra Island (Indic Ocean, Yemen) due to its ecological importance for some native biota. We studied the reptile community living on D. cinnabari from Socotra Island. We sampled reptiles on trees across most D. cinnabari populations and applied co-occurrence and network partition analyses to check if the presence of reptiles on D. cinnabari populations was random or structured. Regardless of its patched and scarce actual distribution, we report the use of this tree as a habitat by more than half of the reptile community (12 endemic reptiles). Co-occurrence and network partition analyses demonstrate that this community is structured across the distribution of dragon’s blood trees, reflecting complex allopatric, vicariant, and biotic interaction processes. Hence, these trees act as micro-hotspots for reptiles, that is, as areas where endemic and rare species that are under threat at the landscape scale co-occur. This Socotra endemic tree is currently threatened by overgrazing, overmaturity, and climate change. Its protection and declaration as an umbrella species are expected to benefit the reptile community and to protect evolutionary processes that are partially driven by the ecological links between reptiles and this tree. To our knowledge, no tree species has been proposed as an umbrella species for island vertebrate endemics so far, highlighting the ecological uniqueness of Socotra Island. Full article
(This article belongs to the Special Issue Dragon Trees - Tertiary Relicts in Current Reality)
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Open AccessArticle
The Conservation Status and Population Mapping of the Endangered Dracaena serrulata in the Dhofar Mountains, Oman
Forests 2020, 11(3), 322; https://doi.org/10.3390/f11030322 - 14 Mar 2020
Cited by 3 | Viewed by 1340
Abstract
Populations of Dracaena serrulata are disappearing at an alarming rate in the Arabian Peninsula. They are being destroyed by herders who use the leaves as fodder for camels, goats, and sheep during the dry season. Up until now, precise information about the current [...] Read more.
Populations of Dracaena serrulata are disappearing at an alarming rate in the Arabian Peninsula. They are being destroyed by herders who use the leaves as fodder for camels, goats, and sheep during the dry season. Up until now, precise information about the current distribution and population status of D. serrulata in Oman have not been published. To fill this gap, the main aim of this work was to map the species distribution in the Dhofar Mountains (Oman) and to define the conservation and health status of the populations. Three isolated sub-populations of the study species were defined and mapped: the Jabal Samhan, Jabal al Qara, and Jabal al Qamar sub-populations. Dracaena serrulata occupies an area of 227 km2 in the Dhofar Mountains. More than 43,000 trees were counted, and 2387 trees were inventoried in total. The Jabal Samhan sub-population is an example of an extensively damaged population with 59% of the trees recorded as dead and only 21% healthy trees. Populationsin the western portions of the Dhofar Mountains., Jabal al Qamar, and Jabal al Qara are comparatively abundant stands of healthy trees with a higher proportion of seedlings. The health of trees is strongly influenced by accessibility and precipitation provided by the southwest summer monsoon: the healthy individuals predominate on the steep terrain along the seaward facing cliffs. Full article
(This article belongs to the Special Issue Dragon Trees - Tertiary Relicts in Current Reality)
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Open AccessArticle
Complete Chloroplast Genome Sequence and Phylogenetic Inference of the Canary Islands Dragon Tree (Dracaena draco L.)
Forests 2020, 11(3), 309; https://doi.org/10.3390/f11030309 - 12 Mar 2020
Viewed by 911
Abstract
Dracaena draco, which belongs to the genus Dracaena, is an endemic succulent of the Canary Islands. Although it is one of the most popular and widely grown ornamental plants in the world, little is known about its genomic variability. Next generation [...] Read more.
Dracaena draco, which belongs to the genus Dracaena, is an endemic succulent of the Canary Islands. Although it is one of the most popular and widely grown ornamental plants in the world, little is known about its genomic variability. Next generation sequencing, especially in combination with advanced bioinformatics analysis, is a new standard in taxonomic and phylogenetic research. Therefore, in this study, the complete D. draco chloroplast genome (cp) was sequenced and analyzed in order to provide new genomic information and to elucidate phylogenetic relationships, particularly within the genus Dracaena. The D. draco chloroplast genome is 155,422 bp, total guanine-cytosine (GC) content is 37.6%, and it has a typical quadripartite plastid genome structure with four separate regions, including one large single copy region of 83,942 bp length and one small single copy region of 18,472 bp length, separated by two inverted repeat regions, each 26,504 bp in length. One hundred and thirty-two genes were identified, 86 of which are protein-coding genes, 38 are transfer RNAs, and eight are ribosomal RNAs. Seventy-seven simple sequence repeats were also detected. Comparative analysis of the sequence data of various members of Asparagales revealed mutational hotspots potentially useful for their genetic identification. Phylogenetic inference based on 16 complete chloroplast genomes of Asparagales strongly suggested that Dracaena species form one monophyletic group, and that close relationships exist between D. draco, D. cochinchinensis and D. cambodiana. This study provides new and valuable data for further taxonomic, evolutionary and phylogenetic studies within the Dracaena genus. Full article
(This article belongs to the Special Issue Dragon Trees - Tertiary Relicts in Current Reality)
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Open AccessEditor’s ChoiceArticle
First Age-Estimation Model for Dracaena ombet and Dracaena draco subsp. caboverdeana
Forests 2020, 11(3), 264; https://doi.org/10.3390/f11030264 - 27 Feb 2020
Cited by 3 | Viewed by 1078
Abstract
Research Highlights: The first model for crown age estimation was developed for Dracaena ombet Heuglin ex Kotschy and Peyr. and D. draco subsp. caboverdeana Marrero Rodr. and R. Almeida. Background and Objectives: Dracaena species are monocotyledon trees without annual tree rings. Most arborescent [...] Read more.
Research Highlights: The first model for crown age estimation was developed for Dracaena ombet Heuglin ex Kotschy and Peyr. and D. draco subsp. caboverdeana Marrero Rodr. and R. Almeida. Background and Objectives: Dracaena species are monocotyledon trees without annual tree rings. Most arborescent dragon tree species are endangered; thus, it is important to determine the age structures of these populations for proper conservation management strategies, and for modelling of population trends. For these reasons, it is necessary to develop a methodology of crown age estimation. Materials and Methods: Field data were collected in the Desa’a Forest (Ethiopia) and in Santo Antão (Cape Verde Islands). Trees within each age class, as expressed by the number of branch orders, were measured. The diameter at breast height, tree height, stem height, number of branch orders, number of all leaf rosettes and number of flowering leaf rosettes within the crown were recorded for each sampled tree. The flowering probabilities were counted as input data for the model used. Results: The duration of the interval between flowering events was 5.23 years for D. ombet and 4.94 years for D. draco subsp. caboverdeana. The crown of the oldest tree of D. ombet with 18 branch orders was estimated to be 94.2 years old, and the crown of the oldest tree of D. draco subsp. caboverdeana with 22 branch orders was estimated to be 108.6 years old. Full article
(This article belongs to the Special Issue Dragon Trees - Tertiary Relicts in Current Reality)
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Review

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Open AccessReview
Dragon’s Blood from Dracaena cambodiana in China: Applied History and Induction Techniques toward Formation Mechanism
Forests 2020, 11(4), 372; https://doi.org/10.3390/f11040372 - 26 Mar 2020
Cited by 2 | Viewed by 654
Abstract
Dragon’s blood that is extracted from Dracaena plants has been widely used as traditional medicine in various ancient cultures. The application of dragon’s blood has a cherished history in China, even though the original plants were not discovered for some period. Dracaena cochinchinensis [...] Read more.
Dragon’s blood that is extracted from Dracaena plants has been widely used as traditional medicine in various ancient cultures. The application of dragon’s blood has a cherished history in China, even though the original plants were not discovered for some period. Dracaena cochinchinensis and Dracaena cambodiana were successively discovered in southern China during the 1970s–1980s. In the last half of the century, Chinese scientists have extensively investigated the production of dragon’s blood from these two Dracaena species, whereas these results have not been previously systematically summarized, as in the present paper. Herein, we present the applied history in ancient China and artificially induced technologies for dragon’s blood development based on these two Dracaena species, in particular, using tissue cultures seedlings and tender plants of D. cambodiana. Big data research, including transcriptomic and genomic studies, has suggested that dragon’s blood might be a defense substance that is secreted by Dracaena plants in response to (a)biotic stimuli. This review represents an effort to highlight the progress and achievements from applied history as well as induction techniques that are used for the formation of dragon’s blood that have taken place in China. Such knowledge might aid in the global conservation of wild Dracaena species and contribute to understanding dragon blood formation mechanisms, eventually assisting in the efficient utilization of limited Dracaena plant resources for the sustainable production of dragon’s blood. Full article
(This article belongs to the Special Issue Dragon Trees - Tertiary Relicts in Current Reality)
Open AccessEditor’s ChoiceReview
Metrics of Growth Habit Derived from the 3D Tree Point Cloud Used for Species Determination—A New Approach in Botanical Taxonomy Tested on Dragon Tree Group Example
Forests 2020, 11(3), 272; https://doi.org/10.3390/f11030272 - 28 Feb 2020
Cited by 3 | Viewed by 784
Abstract
Detailed, three-dimensional modeling of trees is a new approach in botanical taxonomy. Representations of individual trees are a prerequisite for accurate assessments of tree growth and morphological metronomy. This study tests the abilities of 3D modeling of trees to determine the various metrics [...] Read more.
Detailed, three-dimensional modeling of trees is a new approach in botanical taxonomy. Representations of individual trees are a prerequisite for accurate assessments of tree growth and morphological metronomy. This study tests the abilities of 3D modeling of trees to determine the various metrics of growth habit and compare morphological differences. The study included four species of the genus Dracaena: D. draco, D. cinnabari, D. ombet, and D. serrulata. Forty-nine 3D tree point clouds were created, and their morphological metrics were derived and compared. Our results indicate the possible application of 3D tree point clouds to dendrological taxonomy. Basic metrics of growth habit and coefficients derived from the 3D point clouds developed in the present study enable the statistical evaluation of differences among dragon tree species. Full article
(This article belongs to the Special Issue Dragon Trees - Tertiary Relicts in Current Reality)
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Open AccessEditor’s ChoiceReview
What We Know and What We Do Not Know about Dragon Trees?
Forests 2020, 11(2), 236; https://doi.org/10.3390/f11020236 - 21 Feb 2020
Cited by 8 | Viewed by 2968
Abstract
This article is a broad review focused on dragon trees—one of the most famous groups of trees in the world, well known from ancient times. These tertiary relicts are severely endangered in most of the area where they grow. The characteristic features of [...] Read more.
This article is a broad review focused on dragon trees—one of the most famous groups of trees in the world, well known from ancient times. These tertiary relicts are severely endangered in most of the area where they grow. The characteristic features of the dragon tree group are described and the species belonging to this group are listed. This review gathers together current knowledge regarding the taxonomy, evolution, anatomy and morphology, physiology, and ontogeny of arborescent dragon tree species. Attention is also paid to the composition, harvesting, medicinal, and ethnobotanical use of the resin (dragons’ blood). An evaluation of population structure, distribution, ecology, threats, and nature conservation forms the final part of the review. In the conclusions we recommend further avenues of research that will be needed to effectively protect all dragon tree species. Full article
(This article belongs to the Special Issue Dragon Trees - Tertiary Relicts in Current Reality)
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