Soil Invertebrates Effects on Pine and Oak Deadwood Decomposition in Temperate Forests of Korea

Deadwood in forests serves as a source of food and habitat for living organisms. The interaction between deadwood and organisms has notable effects on organic materials and this has been an objective for the material cycle studies. This study investigated the effects of soil invertebrates on deadwood decompositions of Pinus densiflora (Korean red pine) and Quercus acutissima (sawtooth oak) in temperate mixed forests of Korea. 1,978 pine and oak deadwood samples were placed on the forest floors in three regions (eastern, western, and southern regions) where commonly dominated by pine and oak trees but have different environmental conditions. Half of the samples were put into 0.26mm stainless mesh bags to exclude the invertebrates. After 48 months, a total of 1,200 samples consisting of 310, 310, 299, and 281 from the pine control, oak control, pine exclusion, and oak exclusion samples, respectively, were collected to analyze the decomposition rates. The average mass loss for the pine and oak deadwoods with mesh bags were 23.31.2% and 24.90.7%, respectively, whereas those without mesh bags lost 38.11.2% and 34.30.9%, respectively, of their original mass. For both pine and oak deadwoods, the mass loss was significantly greater in non-treated samples than those treated by mesh bags throughout the regions (P<0.05). Deadwoods in southern and western regions showed statistically higher mass loss than in eastern regions. However, an interaction effect of treatment and regions was significant; regional environmental variables such as temperature and humidity may offset the effect driven by the exclusion treatment. An interaction effect of treatment and species was also significant; species properties such as wood density and nutrient composition may change the treatments effect. The reduction in decomposition rate caused by the treatment differed regionally. Deadwoods in southern regions exhibited the highest reduction in decomposition rate, whereas the western regions showed the least. The overall tendencies of the decomposition rate are considered to reflect regional variations, physiochemical property of deadwoods, and feeding preference of the soil invertebrates. This study is supported by the Korea Forest Service with the Project on Reforestation and Income Generation for Local People in Tajikistan.