Effect of pre-soaking substrate and light availability on seed germination and seedling establishment of Dracaena draco (L.) L., a threatened species

Kheloufi, Abdenour; Boukhecha, Mohamed; Ouachi, Aziza

doi:10.21750/refor.9.03.77

Cited by 2 publications

(1 citation statement)

References 41 publications

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“…Preliminary information about the location of the saplings in Arkawiit, i.e., that they grow in the same area as the pre-collapse population, also suggests that presence of a viable soil seed bank is more important than long-range seed dispersal by birds (Gonzalez-Castro et al, 2019). Very high germination rates in other dragon tree species have been reported recently (Bauerova et al, 2020;Kheloufi et al, 2020) and this might indicate that a seed bank is not able to build up. However, Dewir et al (2019) report that only 20% of D. ombet seeds germinated, but it should be noted that only few seeds were included in their experiment.…”

Section: Discussionmentioning

confidence: 66%

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

Andersen

Krzywinski

Talib

et al. 2022

Front. Environ. Sci.

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The endangered and endemic Nubian dragon blood tree, Dracaena ombet, has been feared extirpated from core distribution areas in the Red Sea Hills, Sudan, after reported mass death events in the 20th century. Populations of dragon tree species are generally reported to be in decline, with a noticeable lack of recruitment and possible poor resilience. Rare recruitment events are, however, normal for species with remnant population dynamics, and when eventually occurring, such events can restore seemingly degraded populations. In response to recently reported observations of dracaena saplings in a historically core distribution area of the Red Sea Hills, we assess the status of this long-lived arboreal species. We describe a current realized niche, investigate a potential range shift by comparing the spatial distribution of saplings and older individuals, and assess population recovery based on pre-disturbance system identity derived from qualitative, historical observations. We document a beginning recovery of the dracaena population in the study area. Around half of the mapped population are individuals in the sapling stage, and they are in good health. Its current realized niche is described by higher altitudes, steeper slopes, more concave landscape forms and east-facing aspects compared to areas where dracaena individuals are absent. However, for the new generation of dracaena saplings we find signs of a leaning range shift where saplings are shifted towards higher altitudes near the mist-influenced escarpment. A full collapse and eventual extirpation of the endangered Dracaena ombet population may at best be averted, or at least delayed in the study area. Our resilience analysis indicates that a full recovery will be a slow process due to the inherent natural climate variability of arid lands, only allowing sporadic regeneration. Considering this species’ information legacy, saplings seem to be well equipped to survive such variability, but perhaps within a restricted safe operating space. Conservation measures should therefore be taken to secure the survival of the new generation along with broader spatial scale studies to confirm whether our findings reflect a regional phenomenon.

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Section: Discussionmentioning

confidence: 66%

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

Andersen

Krzywinski

Talib

et al. 2022

Front. Environ. Sci.

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Effect of Different Presowing Treatments to Break Seed Dormancy and Seed Collection Methods on the Germination of Dracaena steudneri Schweinf. Ex Engl.

Alem

Habrová

Houšková

et al. 2022

Forests

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Research Highlights: This study is focused on the germination of Dracaena steudneri Schweinf. Ex Engl. seeds using different presowing treatments. Background and Objectives: The study aimed to overcome the problem of breaking seed dormancy, to facilitate artificial regeneration for conservation and development purposes. The objectives of this study were (1) to evaluate the effect of different seed treatments in breaking seed dormancy of D. steudneri and (2) to assess the effect of the seed collection method (seeds collected on the ground vs. from the tree) on the germination of the seed. Materials and Methods: experimental study with different seed-dormancy-breaking treatments was carried out in a greenhouse and seed laboratory. T testing and one way analysis of variance (ANOVA) were used to analyse the data. Results: The applied seed treatments (hot water, cold water, sodium hypochlorite and nicking) did not improve the germination of the species, nor the breaking of seed dormancy. One-way ANOVA results also showed no significant differences between the different seed treatments and the control on the mean germination of the species in the greenhouse (p < 0.05). The t test result also revealed no significant differences in the mean germination between fallen seeds collected from the ground and in the tree crown (p < 0.05). The tetrazolium test results showed that the percentage of nonviable seeds was greater than that of the viable seeds. Conclusion: The different treatments for breaking seed dormancy did not improve the germination of seeds in the greenhouse (ranging from 0%–7%) nor in the seed laboratory (0%), which might be due to the intermediate characteristics of the seeds of this species. Therefore, we recommend that more research is undertaken on the seed ecophysiology of the species, in order to understand the mechanisms controlling its seed germination.

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Effect of pre-soaking substrate and light availability on seed germination and seedling establishment of Dracaena draco (L.) L., a threatened species

Cited by 2 publications

References 41 publications

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

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

Effect of Different Presowing Treatments to Break Seed Dormancy and Seed Collection Methods on the Germination of Dracaena steudneri Schweinf. Ex Engl.

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