2:45 PM - 3:00 PM
[ACG37-05] Spatial and temporal variations in soil respiration rate and their controlling factors in a Pinus thunbergii plantation on a coastal dune
Keywords:soil carbon, water-extractable organic carbon content, soil temperature, soil-drying
Climate change caused by increasing concentration of carbon dioxide in the atmosphere is a global environmental problem. Carbon dioxide released from the soil, known as soil respiration, is a major component of the carbon cycle in terrestrial ecosystems, but it is highly spatiotemporally variable. Therefore, observations of soil respiration have been conducted around the world to accurately estimate the total amount of soil respiration, but observations in coastal dune environments are very limited. To quantify the response of soil respiration to climate change, it is necessary to understand soil respiration in different regions and ecosystems and to clarify its controlling factors.
The objective of this study was to determine the spatiotemporal variability of soil respiration rates and its controlling factors in coastal dune environments. The study site was a Pinus thunbergii plantation on a coastal dune in the Arid Land Research Center of Tottori University. In June 2023, we established 20 points for soil respiration measurement within the study site and started measuring soil respiration rates. In addition, soil samples were collected every 3 months at a depth of 0-5 cm from the soil around the measurement points to measure soil carbon content, microbial biomass, and water-extractable organic carbon content (WEOC).
Large spatial variability was observed in soil respiration rates from June to December 2023, with coefficients of variation ranging from 43 to 67%. Seasonal changes in soil respiration rates from June to December 2023 were exponential with increasing soil temperatures, but a temporary decrease was observed in August. The high soil temperatures in summer and associated soil-drying may have decreased the soil respiration rate in August. Soil respiration rates in June, September, and December 2023 were positively correlated with WEOC in all months. This suggests that WEOC may contribute to the spatial variability in soil respiration rate in sandy soils with a low organic matter content.
The objective of this study was to determine the spatiotemporal variability of soil respiration rates and its controlling factors in coastal dune environments. The study site was a Pinus thunbergii plantation on a coastal dune in the Arid Land Research Center of Tottori University. In June 2023, we established 20 points for soil respiration measurement within the study site and started measuring soil respiration rates. In addition, soil samples were collected every 3 months at a depth of 0-5 cm from the soil around the measurement points to measure soil carbon content, microbial biomass, and water-extractable organic carbon content (WEOC).
Large spatial variability was observed in soil respiration rates from June to December 2023, with coefficients of variation ranging from 43 to 67%. Seasonal changes in soil respiration rates from June to December 2023 were exponential with increasing soil temperatures, but a temporary decrease was observed in August. The high soil temperatures in summer and associated soil-drying may have decreased the soil respiration rate in August. Soil respiration rates in June, September, and December 2023 were positively correlated with WEOC in all months. This suggests that WEOC may contribute to the spatial variability in soil respiration rate in sandy soils with a low organic matter content.