Rodent population dynamics affect seedling recruitment in alpine habitats

Questions: How do rodents with cyclic population dynamics affect seedling recruitment in alpine habitats? Does disturbance fromrodents have larger implications on seedling recruitment in some plant communities than in others? Location: Snowbeds and sheltered heaths in the low-alpine zone in areas of Børgefjell and Dovrefjell, Norway. Methods: We recorded seedling emergence, rodent activity and cover of mosses, lichens, litter and bare ground in 270 plots in snowbeds and sheltered heaths in a rodent population peak year and in the following low-density year. Results: Seedling recruitment was positively correlated with disturbances from lemmings and voles in both years. More seedlings emerged in the low-density year than in the year of the population peak. Snowbeds had higher seedling recruitment than the sheltered heaths, but both habitats were equally affected by disturbances fromrodents. Conclusions: Rodent activity created gaps and increased seedling emergence in these alpine plant communities, particularly in the year after the rodent peak, both in snowbeds and sheltered heath habitats. Our study therefore suggests that regeneration patterns in alpine vegetation are tightly linked to the population cycles of lemmings and voles,which peak in density at 3- to 5-yr intervals.publishedVersionPaid Open Acces

Aortic pulse wave velocity in individuals of Asian and African ancestry: the HELISUR study

Aortic pulse wave velocity has emerged as an important predictor of cardiovascular events, but data on ethnic differences in pulse wave velocity remain scarce. We explored differences in pulse wave velocity between people of Asian and African ancestry. Data were used from the cross-sectional Healthy Life in Suriname (HELISUR) study. Pulse wave velocity was estimated oscillometrically with the Arteriograph. We included 353 Asians and 364 Africans, aged respectively 44.9 (SD 13.5) and 42.8 (SD 14.1) years (p = 0.05). Crude median PWV was higher in Asians than in Africans (8.1 [IQR 6.9–10.1] m/s vs. 7.7 [IQR 6.5–9.3] m/s, p = 0.03), which was mainly attributable to an increased PWV in Asians ≥ 50 years (10.1 [IQR 8.7–11.8] m/s vs. 9.1 [IQR 7.9–11.3] m/s in Africans ≥50 years, p < 0.01). After adjustment for age and MAP in multivariable linear regression, Asians had a 1.044 [95% CI 1.019–1.072] m/s higher PWV compared to Africans. Additional adjustment for sex, glucose, total cholesterol, HDL cholesterol, triglycerides, BMI, and waist circumference did not substantially change the difference in pulse wave velocity between Asians and Africans (+1.044 [95% CI 1.016–1.074] m/s for Asians vs. Africans). In conclusion, persons of Asian ancestry have a higher pulse wave velocity than those of African ancestry. This persisted after adjustment for important cardiovascular risk parameters, including age and blood pressure. The higher PWV found in Asians could be consistent with their increased coronary heart disease risk