First Age-Estimation Model for Dracaena ombet and Dracaena draco subsp. caboverdeana

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 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.

Endangered Dracaena ombet Population in the Red Sea Hills, Sudan, Recovers After Abrupt Change

“…Our classification of the seedling stage corresponds with the juvenile and partly with the medium juvenile stages of the classification used in studies of D. cinnabari (Maděra et al, 2020). Growth rate of dragon trees is still poorly known, but based on available growth rates (Adolt and Pavlis, 2004;Lengálová et al, 2020;Maděra et al, 2020), we assume saplings can be up to c. 25 years.…”

A chromosome-level genome assembly for Dracaena cochinchinensis reveals the molecular basis of its longevity and formation of dragon’s blood

“…According to previous research, the juvenile stages of D. cinnabari from seedling to first flowering can take 200–250 years or even more ( Maděra et al., 2018 ), thus demonstrating that this species takes an extremely long time to grow and mature. Owing to difficulties related to investigating natural population aging, several methodologies have been developed for age estimation in such trees ( Adolt and Pavliš, 2004 ; Adolt et al., 2012 ; Jura-Morawiec, 2019 ; Lengálová et al., 2020 ). These methods have all demonstrated that the dragon tree is a long-lived species.…”

The Chromosome-level Genome of Dracaena cochinchinesis Provides Insights into its Biological Features and the Mechanism of Dragon’s Blood Formation

“…According to the research of Maděra (2018), the juvenile stages of D. cinnabari from seedling to the first flowering will take about 200-250 years, even more (Maděra et al ., 2018), demonstrating it is an extremely slowly growth and slowly maturing species. Due to the difficulties in the authentic study of natural population aging, several methodologies of age estimation were developed and improved (Adolt & Pavliš, 2004; Adolt et al ., 2012; Jura Morawiec, 2019; Lengálová et al ., 2020). Anyway, they all showed that the dragon tree is a long-lived species.…”