Spatial Distribution Pattern and Genetic Diversity of Quercus wutaishanica Mayr Population in Loess Plateau of China

The Quercus wutaishanica forest influences the ecological environment and climate characteristics and plays an important ecological role in the Loess Plateau region. However, we still know relatively little about the genetic diversity and spatial distribution of Q. wutaishanica. Here, we assessed the genetic diversity of Q. wutaishanica using simple sequence repeats and used the point pattern method to analyze the spatial distribution patterns as well as intraspecific relationships. Our results indicate that the diameter structure of the Q. wutaishanica population was inverted J-type, showing a growing population. In addition, the population maintained high genetic diversity on a small scale. Due to dispersal constraints, the spatial distribution pattern of Q. wutaishanica seedlings (DBH < 1 cm) tended to aggregate at small scales and the degree of aggregation decreased with increasing spatial scale. However, trees (DBH > 5 cm) and saplings (1 cm <= DBH < 5 cm) showed more random distribution at the scale, indicating that Q. wutaishanica individuals shift from aggregation to random distribution at the spatial scale. In addition, although individuals of different diameter classes showed facilitative (trees vs. saplings, 5-6.5 m) and competitive effects (trees vs. seedlings, 13.5-16 m) on some scales, they showed no correlation on other scales, especially for saplings and seedlings, where they were not correlated on any scale. The results contribute to revealing the status and dynamics of Q. wutaishanica in the Loess Plateau, thereby providing a theoretical basis for further study on the maintenance mechanism of the population.