Carbon and nitrogen status in litterfall of a red pine stand with varying degrees of damage from pine wilt disease

Abstract

We evaluated the carbon (C) and nitrogen (N) status of litterfall in a natural red pine (Pinus densiflora) stand damaged by pine wilt disease in Jinju City, which was one of the areas severely affected by the disease in Korea. A significant correlation (P < 0.05) was found between tree density and basal area and the C and N status of litterfall components, but C and N status was not correlated with mean diameter at breast height in the pine wilt disease stands. Needle-litter C and N concentrations were linearly related (P < 0.05) to basal area in pine wilt disease stands. Needle-litter C concentration decreased with a decrease in damage intensity due to pine wilt disease, whereas litter N concentration increased with an increase of basal area in pine wilt disease stands. The linear regression equations developed for litterfall C and N inputs were significant (P < 0.05), with basal area accounting for 50-86% of the variation, except for cone and flower litter. The results indicated that the incidence of pine wilt disease could impact the quality and quantity of C and N in litterfall of pine stands suffering from pine wilt disease.

Carbon and Nitrogen Responses in Litterfall and Litter Decomposition in Red Pine (Pinus densiflora S. et Z.) Stands Disturbed by Pine Wilt Disease

“…This study was conducted in approximately 40-year-old natural red pine stands (35 • 12 21 N, 128 • 10 24 E, 150 m) in the Wola National Experimental Forest, which is one of the most severe pine wilt disease-disturbed forests in Korea [5,12]. The average annual precipitation and temperature in this area are 1490 mm yr −1 and 13.1 • C, respectively.…”

“…The site index in dominant pine trees indicated a low forest productivity (site index, 8 at 20-year-old base age). The understory tree species include Juniperus rigida S. et Z., Lespedeza spp., Lindera glauca Blume, Quercus variabilis Blume, Q. serrata Thunb., Robinia pseudoacacia L., and Smilax china L. More information on the study sites is available in References [5,12].…”

“…However, forest disturbance by epidemic outbreaks of insects or disease can have a significant influence on nutrient returns as the death or removal of damaged trees causes changes in biotic and abiotic factors [2][3][4]. For example, nutrient inputs caused by litterfall are linearly decreased with increased intensities of forest disease [5], whereas the decomposition rates of needle litter are increased [6], unchanged [7], or decreased [8,9] with the degree of tree removal.…”

“…They also affect soil properties, such as water-holding capacity, and other influential factors affecting litter decomposition. The mortality of the infected trees leads to a decrease in litterfall as a result of the reduced tree density [5]. In addition, wood debris, such as dead logs, branches, and stumps, collects on the forest floor during the removal of infected trees; the removal of infected trees is one of the most important control strategies for pine wilt disease disturbed forests in Korea [5,14].…”

“…The mortality of the infected trees leads to a decrease in litterfall as a result of the reduced tree density [5]. In addition, wood debris, such as dead logs, branches, and stumps, collects on the forest floor during the removal of infected trees; the removal of infected trees is one of the most important control strategies for pine wilt disease disturbed forests in Korea [5,14]. However, since information along the gradient of infection is scarce, it is difficult to evaluate the quantitative changes in nutrient inputs through litterfall and decomposition processes because of the spatial variation of infected pines in small-scale stands [12,15].…”