PS 27-80 - Soil invertebrate’s effects on pine and oak deadwood decomposition in temperate forests of Korea

Background/Question/Methods

Deadwood in forests is a source of food and habitat for living organisms. The interaction between deadwood and organisms is of great interest in material cycle studies, as it has notable consequences on organic materials in forests. This study investigated the effect of soil invertebrates on deadwood decompositions of Pinus densiflora (Korean red pine) and Quercus acutissima (sawtooth oak) in temperate mixed forests of Korea. In May 2016, a total of 1,978 pine and oak deadwood samples were placed on the forest floors in three regions (eastern, western, and southern regions) where generally dominated by pine and oak trees but have different environmental conditions. The southern region had a higher temperature and more precipitation compared to the other regions. Half of the samples were put into 0.26mm stainless steel mesh bags to exclude the invertebrates. After four years, in May 2020, 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.

Results/Conclusions

The average mass loss of the pine and oak deadwoods with mesh bags were 23.3±1.2% and 24.9±0.7%, respectively, whereas those without mesh bags lost 38.1±1.2% and 34.3±0.9%, respectively. For both pine and oak deadwoods, the loss was greater in controls than those with mesh bags in all regions (P< 0.05). This indicates the significant contributions of invertebrates on deadwood decomposition. Deadwoods in southern and western regions showed higher mass loss than in eastern regions. However, an interaction effect between treatment and regions was significant; regional environmental factors may have counteracted the impact driven by the treatment. Another interaction effect between treatment and species was also significant; species properties such as wood density and nutrient composition may have affected the treatment’s impact. There were regional differences in the reduction of the decomposition rate between treated samples. Deadwoods in southern regions exhibited the highest reduction in decomposition rate, whereas western regions showed the least. The tendencies of the deadwoods’ decomposition are considered to reflect regional variations, physiochemical properties of deadwoods, and feeding preference of the soil invertebrates.

This study is supported by the Korea Forest Service and carried out with the ‘Project on Reforestation and Income Generation For Local People in Tajikistan’.