| Popis: |
Alterations in biotic interactions alongside climatic factors are proposed to affect the extinction risks of alpine and subalpine plant species. We examined the population demography of Primula farinosa along gradients of vegetation coverage to assess how the population viability of high mountain plants would alter in response to changing competitive intensities. Size-based integral projection models were constructed for plots with varying vegetation coverages. Complementary to the demographic survey, the performance of P. farinosa was evaluated in controlled environments when grown with its naturally co-occurring plant, Sanguisorba hakusanensis. In field sites, population growth rates (λ) of P. farinosa declined as surrounding vegetation coverage increased. The means, elasticities, and life-table response experiment (LTRE) contributions of the vital rates also changed, but the alteration patterns depended on the vital rates. Juvenile survival (JS), adult survival (AS), and flowering probability (FP) were lower in plots with denser vegetation while the decrease of AS was not statistically significant. Notably, the elasticity of AS exhibited a positive, whereas the elasticities of JS and FP exhibited negative regression coefficients for vegetative coverage. AS and FP showed more pronounced LTRE contributions in declining λ than JS. Significant reductions in JS and FP were also observed when plants were grown with S. hakusanensis in growth-chamber environments. Both field and chamber studies demonstrated a competitive interaction between P. farinosa and neighboring vegetation, affecting diverse demographic parameters. Altered elasticities would mitigate or exacerbate the impact of decreased mean vital rates on λs in denser vegetation, emphasizing the importance of evaluating both elasticity and the mean of vital rates to predict population persistence under changing biotic interactions. |
