Gwangju Institute of Science and Technology, Republic of Korea
Abstract: Due to global warming, plant species living at low altitudes gradually expand their range to higher altitudes. As a result, small populations living in alpine regions may have their habitat threatened. In particular, the need for management has been reported for the population decline of Primulaceae plants due to the effects of the surrounding vegetation. We conducted a demographic study of four Primula farinosa subsp. modesta populations in South Korea living in a mountain above 1000 m sea level. The goal of this demographic study was to determine the effect of surrounding vegetation cover on the population growth rate and vital rate of Primula farinosa in natural habitat.
Our approach to addressing our goal was an integral projection model (IPM) analysis using 3,561 life-history data surveyed from 2018 to 2021. We tagged 1,251 individuals in 2018, and regularly recorded significant life-history, such as the size of the individual, the survivorship, and the flowering through local surveys by 2021. The integral projection model is an individual-level demographic tool built on regression analysis for vital rate kernels (survival, growth, and reproduction) for size. We confirmed changes in population growth rates (𝛌) and vital rates in response to increased coverage by integral projection model analysis. Here we show that Primula farinosa has lower 𝛌 in quadrates with high vegetation coverage (F = 8.37, P = 0.006). The survival rate also decreased with the coverage increase (F = 6.78, P = 0.013) and significantly affected juvenile survivorship (F = 11.74, P = 0.002). On the other hand, the size growth of adults with flowering potential decreased as the high coverage (F = 4.73, P = 0.036). In conclusion, this study suggests that Primula farinosa may be threatened by warming-induced vegetation expansion. Furthermore, it is suggested to manage juvenile plants to mitigate the population decline and evaluate the phenotypic responses by conducting competition experiments with invasive species.
