Carbon storage and soil CO 2 efflux rates at varying degrees of damage from pine wilt disease in red pine stands Jaeyeob Jeong a , Choonsig Kim b, ⁎, Kwang-Soo Lee c , Nanthi S. Bolan a , Ravi Naidu a a Center for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes Campus, Adelaide 5095, Australia b Department of Forest Resources, Gyeongnam National University of Science and Technology, Jinju 660-758, Republic of Korea c Southern Forest Research Center, Korea Forest Research Institute, Jinju 660-330, Republic of Korea HIGHLIGHTS ► The first report on the estimation of carbon storage at varying degrees of damage due to pine wilt disease. ► Soil CO 2 efflux rates were measured at varying degrees of damage due to pine wilt disease. ► We evaluated the relationship between soil CO 2 efflux and soil environmental factors due to pine wilt disease. abstract article info Article history: Received 25 September 2012 Received in revised form 24 November 2012 Accepted 24 November 2012 Available online 20 December 2012 Keywords: Carbon cycle Pine wilt disease Red pine Soil respiration We evaluated the carbon (C) storage and soil CO 2 efflux rates of red pine (Pinus densiflora S. et Z.) stands damaged by pine wilt disease (PWD) in Korea. Ten red pine plots at varying degrees of damage from PWD were established and grouped into five categories (very slightly, slightly, moderately, severely, and very severely damaged plots) based on differences in the tree density. The incidence of PWD was a major cause of C loss from forest ecosystems, but the magnitude of loss depended on the severity of disease damage. An exponential regression of the CO 2 efflux rates against the corresponding soil temperature was highly significant (R 2 = 0.82–0.95, P b 0.01) for the varying degrees of damage from PWD. The rates of change in the CO 2 efflux rates with temperature, as defined by the Q 10 values, were generally lower in the slightly (2.94) versus the moderately (3.60) or severely (4.26) PWD-damaged stands. The cumulative soil CO 2 –C efflux rates for two years were significantly higher in the slightly (10.8 Mg C ha -1 yr -1 ) or moderately (10.9 Mg Cha -1 yr -1 ) versus the very severely (7.9 Mg Cha -1 yr -1 ) PWD-damaged stands. The results indicate that the C storage and soil CO 2 efflux rates in red pine stands can be impacted by the incidence of PWD, with a significant C reduction in the severely damaged stands. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Recently, epidemic outbreaks of insects or disease in forest ecosystems have been more intense than at any previous time because global warming is permitting the invasion of tree populations that have been previously inaccessible due to a short growing season (Robetez and Dobbertin, 2004; Hicke et al., 2012). Vegetation disturbances, such as de- foliation or damage by such outbreaks, have resulted in changes in the carbon (C) dynamics because of the reduced litter production from trees (Morehouse et al., 2008; Clark et al., 2010; Kim et al., 2011a) and soil environmental changes resulting from the death or removal of dam- aged trees (Morehouse et al., 2008; Kim et al., 2010; Lorenz and Lal, 2010). For example, the pine forest area in Canada affected by the moun- tain pine beetle turned from a C sink into a C source because widespread tree mortality reduced the forest C uptake and increased the C emissions from the decay of the dead trees (Kurz et al., 2008). The C dynamics in disturbed forest ecosystems depend on several silvicultural treatments (Tang et al., 2005; Balboa-Murias et al., 2006; Kim et al., 2012), and the type of forest disturbance, such as the incidence of insect pests or disease (Kurz et al., 2008; Morehouse et al., 2008; Clark et al., 2010; Kim et al., 2010; Lorenz and Lal, 2010). For example, distur- bances by forest insects or disease infestations may reduce autotrophic soil respiration due to the death of trees or increase heterotrophic soil respiration from the decay of dead trees. Although forest insects and dis- ease can have large effects on the overall soil respiration (Morehouse et al., 2008; Lorenz and Lal, 2010), the impact of insect or disease on C stor- age and forest soil respiration is not well documented (Kim et al., 2011a; Hicke et al., 2012). Pine wilt disease (PWD) is caused by the pine wood nematode [Bursaphelenchus xylophilus (Steiner et Buhrer) Nickle], a highly destruc- tive plant pathogen (Pérez et al., 2009), and has become a serious threat to pine ecosystems in many countries, including Korea (Kwon et al., 2011), Japan (Mabuhay and Nakagoshi, 2012), China, and Spain (Pérez et al., 2009). Pine wilt disease epidemics in Korean pine ecosystems, including red pine (Pinus densiflora S. et Z.) and black pine (P. thunbergii Science of the Total Environment 465 (2013) 273–278 ⁎ Corresponding author. Tel.: +82 55 751 3247; fax: +82 55 751 3241. E-mail address: ckim@gntech.ac.kr (C. Kim). 0048-9697/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.scitotenv.2012.11.080 Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv