Presentation Information
[POS-35]A Model of Shading Countermeasure against Invasive Dandelion
*Iku Fujii1, Satoshi Takahashi2 (1. Graduate School of Humanities, Nara Women's University (Japan), 2. Nara Women's University (Japan))
Keywords:
reproductive interference,lattice model,invasive dandelion,shading strategy
The dandelion Taraxacum japonicum native to Japan undergo reproductive interference by T. officinale. Pollination from the invasive dandelion T. offcinale reduces T. japonicum's reproductive success. However, T. officinale's survival rate during summer decreases when it is shaded by other plants, while T. japonicum survives by dormancy in summer. In this study, I develop a model of T. japonicum and T. officinale which incorporates reproductive interference. I use this model to search effective shading strategies for mitigating the invasion of T. officinale.
I use a lattice model in which individuals of T. japonicum or T. officinale exist at lattice points, reproduce each year and die according to mortality. Since the inflorescence of T. japonicum close after first pollination, the probability of fruition is given by the proportion of T. japonicum among all individuals of T. japonicum and T. officinale those contribute to pollination. The light intensity is highest at the center and decreases toward the periphery. Seeds dispersion follows normal distribution.
As shading strategies, I consider (a) keeping the size constant and changing the position depending on the strategy, (b) fixing the position and varying the shade area depending on the strategy, and (c) keeping the size constant and changing the position annually. I examine these strategies to search the most effective strategy for suppressing the invasive T. officinale.
I defined the probability of pollination by a single T. officinale individual as the degree of reproductive interference. I examined the change of T. japonicum's density after 100 generations depending on strategies and the degree of reproductive interference and obtained the following results. Reproductive interference reduces density of T. japonicum, regardless of strategies. Shading increases the fraction of T. japonicum. Larger but brighter shade leads to slight increase in T. japonicum fraction. Moving the shade annually covering all lattice over 4 years results in the highest fraction of T. japonicum. These findings suggest that moving the shade annually and increasing its area is an effective strategy for suppressing the invasion of T. officinale.
I use a lattice model in which individuals of T. japonicum or T. officinale exist at lattice points, reproduce each year and die according to mortality. Since the inflorescence of T. japonicum close after first pollination, the probability of fruition is given by the proportion of T. japonicum among all individuals of T. japonicum and T. officinale those contribute to pollination. The light intensity is highest at the center and decreases toward the periphery. Seeds dispersion follows normal distribution.
As shading strategies, I consider (a) keeping the size constant and changing the position depending on the strategy, (b) fixing the position and varying the shade area depending on the strategy, and (c) keeping the size constant and changing the position annually. I examine these strategies to search the most effective strategy for suppressing the invasive T. officinale.
I defined the probability of pollination by a single T. officinale individual as the degree of reproductive interference. I examined the change of T. japonicum's density after 100 generations depending on strategies and the degree of reproductive interference and obtained the following results. Reproductive interference reduces density of T. japonicum, regardless of strategies. Shading increases the fraction of T. japonicum. Larger but brighter shade leads to slight increase in T. japonicum fraction. Moving the shade annually covering all lattice over 4 years results in the highest fraction of T. japonicum. These findings suggest that moving the shade annually and increasing its area is an effective strategy for suppressing the invasion of T. officinale.