Structure and dynamics of natural populations of the endangered plant Euryodendron excelsum H. T. Chang

Abstract

Euryodendron excelsum H. T. Chang is an endangered species of the family Theaceae endemic to China. It is listed as a second-class endangered plant for state protection in the Red Data Book of Plants in the People's Republic of China. The species is restricted to one remnant population with less than 200 individuals in the Bajia region of Yangchun County, Guangdong Province. This study was conducted to determine the status of the population, analyze the past population structure and forecast the future population dynamics of E. excelsum. The size structure and height structure of the population of E. excelsum were tabulated and analyzed. Based on these data, we estimated the values of the parameters such as survival curve, mortality curve and life expectancy. Population dynamics was predicted by a time-sequence model. The size distribution of the whole population generally fit a reverse "J" type curve, suggesting a stable population. The number of young individuals was larger than that of middle-aged and old individuals. The analysis of life table and survival curves show that under environmental screening and human disturbance, the population had one peak of mortality in size class II and only 11.43% individuals could survive from size class II to size class III. The life expectancy of E. excelsum was the highest in size class IV. The survival curve of the population belongs to the Deevey-III type. Time-sequence models for E. excelsum population predict that the number of different size classes will increase after two and five years. As a result, the crucial factors for the natural regeneration and restoration of E. excelsum are the protection of living individuals and their habitat.

Assessment of population, habitat, and threats to Cycas pectinata Buch.-Ham. (Cycadaceae), a vulnerable cycad in Bhutan

“…Similar declining recruitment of seedlings has been observed in populations of other Cycas species (James et al 2018). Low seedling recruitment directly threatens the viability of the population, as fewer individuals remain to replace old plants, which in the long term can reduce the number of plants in the population (Shen et al 2009;Dian-pei et al 2012). In contrast, the population from Kurizampa showed more sapling recruitments than older plants, a positive sign for sustainability of the population in the area.…”

Assessing Cardiovascular Risk to Guide Hypertension Diagnosis and Treatment

“…Younger adults with a high BP and even several other cardiovascular risk factors rarely have a 10-year risk of 15% or greater but often have high lifetime CVD risk; therefore, selecting treatment goals based on 10-year CVD risk alone may not be ideal. Studies [21][22][23] have found that prolonged exposure to an elevated SBP (120-139 mm Hg) in early adulthood increases the long-term risk of CVD; thus, one could consider using a lower 10-year CVD risk profile or calculate the patient's lifetime risk. Future trials should explore the possible long-term benefits of treating younger patients with an SBP of 120 to 139 mm Hg.…”

An insight into the most threatened flora of China

“…For example, habitat destruction is the main reason for the extirpation of Euryodendron excelsum from Guangxi Province (Appendix 1 and Fig. 1), which is at present surviving only in a small population in Yangchun County, in Guangdong (Shen et al, 2008). Picea neoveitchii, a taxon formerly present in up to 6 provinces according to Flora of China, has reached its current highly threatened status (only 11 mature individuals are remaining; Appendix 1) mainly as a consequence of the combination of overexploitation (due to its use as timber) and habitat fragmentation (Zhang, 2007).…”