Seasonal variation of morphological traits, wood formation, and soil properties differs between Quercus robur L. and Robinia pseudoacacia L. saplings

Climate seasonality is one of the important environmental variables that can drive changes in many properties of trees. However, how different tree species regulate their growth and development during changes of the growing period particularly at sapling stage is little known. This study, therefore, evaluated how morphological, anatomical, and soil properties differed in two growing season periods (March vs. September) between oak and black locust saplings across one growing season. Wood cell anatomical properties and soil characteristics were considerably influenced by seasonality. Each species showed greater wood cell anatomical characteristics in March than in September. Soil physical and chemical properties also showed great variance between March and September: soil pH, amount of Mg and Al concentrations in soil were higher in March while organic matter and total N concentration in soil showed greater values in September. Growth and development performance were also compared between two species. We found fibre cell characteristics, stem height, stem diameter and node number were to be greater in oak than in black locust for both early- and late growing periods. The results suggested that oak showed better adaptation to their local environments than black locust.