Abstract:

Objective: In order to provide a theoretical foundation and basic data for forestry workers to protect and sustainably utilize forest resources, we explore the effects of topography and soil factors on the decay of Korean pine (Pinus koraiensis) living trees, and illustrate the distribution patterns of decay trees. Method: In a monitoring block of 30 hm² typical mixed broadleaved-Korean pine forest at Fenglin National Natural Reserve, Heilongjiang, we selected 329 living trees of Korean pine from 62 plots, consisting of 73 young trees (10 cm≤ DBH < 30 cm), 104 adult trees (30 cm≤ DBH < 50 cm) and 152 old trees (DBH ≥50 cm). We used Resistograph to detect the decay, and measured topographical factors and soil physical-chemical proprieties of sample trees. At individual tree level, we used Mann-Whitney U test to compare comparisons of soil physical-chemical proprieties between healthy and decay trees; at plot level, we used Spearman correlation analysis to explore the relevance between soil physical-chemical proprieties and decay rate, we used Kruskal-Wallis test and Post hoc test to explore influence of topographic factors on decay rate. And we used canonical correspondence analysis to explore the distribution of decay of living Korean pine trees. Result: 1) The average decay rate of Korean pine was 35.87%, and the decay rates of young trees, adult trees and old trees were 42.1%, 39.2%, and 29.2%, respectively. 2) The soil total carbon of the decay trees is significantly lower than healthy trees. And the soil ammonium of the decay trees is significantly higher than the healthy trees(P < 0.05); 3) There is an extremely significant negative correlation between soil volumetric moisture content, total nitrogen, total carbon and total phosphorus content and the decay rate of living Korean pine trees, and a significant negative correlation between total potassium, available phosphorus content and the decay rate. 4) The decay rate of living Korean pine trees on different topographic positions and aspects is significantly different (P < 0.05). The decay rate is significantly higher on upper slope than on lower slope (P < 0.05), and significantly lower on semi-shady slope than on semi-sunny slope. 5) Topographic position and soil phosphorus content are the most important factors associated with decay of living Korean pine trees in different growth phases. Young healthy Korean pine distribute in edaphic condition with higher nitrate nitrogen content, but adult and old decay trees always distribute in edaphic condition with higher ammonium nitrogen content. Conclusion: In Xiaoxing'an Mountains, the decay rate of living Korean pine trees is high, and most severe on upper slope and shady slope, semi-sunny slope. The decayed Korean pine in different growth stages were mostly distributed at higher topographic position with lower contents of soil nutrients and moisture. But nitrogen forms have different effects on Korean pine at different growth stages. The results provide a scientific basis and basic data for the protection and sustainable utilization of Korean pine.

Key words: Korean pine, decay rate of living trees, topographic factors, soil physical-chemical proprieties, mixed broadleaved-Korean pine forest