Stand characteristics and soil properties in Japanese red pine (Pinus densiflora) pure forests with different disease severity index in Kunyushan Mountains Region, China

Abstract

Pine needle blight (Pestalotiopsis funereal Desm. Steyaert) has caused major damage to the Japanese red pine (P. densiflora Sieb. et Zucc.) pure forests in the Kunyushan Mountains region of China. In this study, six P. densiflora stand types (ST- 1-6) were selected and surveyed to determine the relationships between the stand characteristics, soil properties and the disease occurrence. Our results showed that the stem densities in the sampled plots of infected stands (ST- 2-6) differed significantly from those in healthy plots (ST- 1) (P < 0.01), with similar patterns found for diameter at breast height (DBH) and basal area at breast in infected plots versus healthy ones (P < 0.05). Soil bulk densities among the six stand types were significantly different (P < 0.05), being lowest in ST- 1. Generally, soil water-related physical properties, except for bulk density and maximum moisture, did not differ remarkably among the stands. Regarding their soil chemical properties, organic matter and total nitrogen were higher in ST- 1, on average, whereas the total potassium was lower there than infected stands. The differences in organic matter, total nitrogen and total potassium among the six stand types were all significant (P < 0.05). Furthermore, the redundancy analysis suggested that 12 of 19 examined soil variables that were strongly related with the ordinations of stand characteristics. Key among these soil factors was available nitrogen, bulk density, pH, organic matter and total nitrogen. Taken together, these empirical results demonstrate the response of pine stands to disease, and are potentially valuable for guiding applications of ecological control of pine needle blight.