Published online September 14, 2022
Journal of Ecology and Environment (2022) 46:24
© The Ecological Society of Korea.
1Climate Change and Carbon Research Team, National Institute of Ecology, Seocheon 33657, Republic of Korea
2Department of Biology, Kongju National University, Gongju 32588, Republic of Korea
3Ecological Adaptation Research Team, National Institute of Ecology, Seocheon 33657, Republic of Korea
Correspondence to:Seungbum Hong
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Background: To assess the carbon sequestration capacity and net ecosystem productivity (NEP) of
Results: The average carbon stock in the above- and below-ground plant biomass was 223.7 Mg C ha–1, while the average amount of organic carbon fixed by photosynthesis was 9.8 Mg C ha–1 yr–1, and the average NPP was 9.6 Mg C ha–1 yr–1. Stems and branches contributed to the majority of the above- and below-ground standing biomass and NPP. The average heterotrophic carbon emission from the soil was 8.7 Mg C ha–1 yr–1, while the average NEP was 1.1 Mg C ha–1 yr–1. Although the carbon stock, carbon absorption, and soil respiration values were higher than those reported in other oak forests in the world, the NEP was similar or lower.
Conclusions: These results indicator that
Keywords: carbon budget, net ecosystem productivity, net primary productivity, soil respiration, standing biomass
Understanding the carbon cycle of terrestrial ecosystems is essential for evaluating an ecosystem’s ability to reduce atmospheric carbon dioxide (CO2) levels. Plants take up atmospheric CO2 through photosynthesis, releasing it into the atmosphere via respiration by plant metabolism or heterotrophic respiration by leaf decomposition. CO2 captured by plants is stored in vegetation and soil in the form of organic matter, and terrestrial ecosystems function as reservoirs for accumulated carbon. Houghton (2007) reported that terrestrial ecosystems contribute to the global carbon cycle, along with the atmosphere and oceans, by storing 550 Pg C year–1 in vegetation, 300 Pg C year–1 in litterfall, and 1,200 Pg C year–1 in soil. As such, terrestrial ecosystems play an important role in the global carbon cycle by absorbing and storing atmospheric carbon and releasing it through respiration. Nevertheless, the carbon budget of terrestrial ecosystems has not been studied in depth in South Korea, with most research examining forest productivity and carbon storage. Studies investigating carbon storage in forests in South Korea have been conducted in Seoraksan National Park (147 Mg C ha–1), Mudeungsan National Park (112 Mg C ha–1), Jirisan National Park (107 to 119 Mg C ha–1), the
Increasing atmospheric CO2 concentrations and global warming are major environmental concerns worldwide. CO2 is widely known to be a major contributor to the greenhouse effect. Due to the influence of CO2, the average global temperature in 2019 was 1.1 ± 0.1°C higher than before industrialization, and the global mean sea level has risen 3.24 ± 0.33 mm per year since January 1993 (WMO 2020). One way to reduce greenhouse gases is to increase carbon sequestration by soil and plants in the forest, which can be realized through efficient forest management and conservation led by government policies. The Intergovernmental Panel on Climate Change (Shukla et al. 2019) mentioned that the land sink including forest ecosystem increased since 1900 and was a net sink of 11.7 Gt CO2 yr–1 (2008–2017), absorbing 29% of global anthropogenic emissions of CO2.
The forested area of South Korea covers 6,335,000 ha, accounting for 63.2% of the total land area (Korea Forest Service 2016). Approximately 0.15% of this forested area (9,669 ha) is covered by evergreen broad-leaved forests (Yoo et al. 2016), including
This study aimed to quantify the net primary production (NPP) and net ecosystem production (NEP) of a
We had established the quadrat (10 × 10 m2) of
The study site was located in a subtropical climate region (Kira 1991), with average annual temperatures of 14.3, 13.7, and 13.6°C in 2016, 2017, and 2018, respectively, which were within the average annual temperature range (10 to 15°C) of South Korea for the last 30 years (Fig. 2, Korea Meteorological Administration www.weather.go.kr). The average monthly maximum and minimum temperatures at the study site were 29.2, 29.8, and 28.7°C, and 0.5, –0.3, and –1.2°C, in 2016, 2017, and 2018, respectively. The average monthly maximum temperatures were higher than the average summer temperature in South Korea (23 to 26°C), whereas the average monthly minimum temperatures were within the range of the average winter temperature (–6 to 3°C), but on the higher side. The annual precipitation at the study site was 2,325.5, 1,034.0, and 2,289.0 mm in 2016, 2017, and 2018, respectively. The annual precipitation at the study site was higher than the average annual precipitation for the last 30 years on Jeju Island (1,500 to 1,900 mm) in 2016 and 2018, but much lower in 2017.
The standing biomass and NPP of the
The below-ground biomass is known to account for 15 to 35% of the plant body for perennials, and the below-ground biomass of
NPP is the net amount of carbon gained through photosynthesis by plants, which can be estimated by the difference between the gross primary production (GPP) and the amount of carbon released by plant respiration (Chapin III and Eviner 2014). The annual NPP of the
The carbon budget of a forest is affected by NPP and processes such as heterotrophic respiration in the soil (Cai et al. 2016). To estimate the amount of carbon storage and absorption of all trees in the
The soil respiration of the forest was estimated using a previously reported correlation equation between temperature and CO2 emission at a soil depth of 10 cm, measured using an infra-red CO2 gas analyzer (EGM-4; PP Systems, Haverhill, MA, USA) from August 2010 to December 2012 (Jeong et al. 2017). In general, the amount of CO2 emitted demonstrates a positive exponential relationship with the soil temperature. In the current study, an automatic weather system (Em50 data logger and Teros 11 Soil Moisture and Temperature Sensor; METER Group, Inc., Pullman, WA, USA) was installed in the study site in April, 2016. And soil temperature and humidity were measured at every 30 minutes in 2016 and 2017. Monthly and annual CO2 effluxes were calculated by substituting hourly soil temperatures into the relationship. CO2 efflux from forests can be largely divided into that caused by heterotrophs and that caused by tree roots. In previous studies, heterotrophic respiration caused 49% of the CO2 efflux from the Pinus densiflora forest (Nakane et al. 1983), 51% of the CO2 efflux from the
The DBH and basal area of all trees in
The basal area in this study site represented high value of about 115.3 m2 ha–1, which was about three times larger than 37.1 in
The total standing biomass of the
The amount of organic carbon in the
The NPP of the
The average soil temperatures in 2016 and 2017 of the
Estimating values based on the total soil respiration of the
Approximately 140 species of the genus
During the study period from 2016 to 2018, the average standing biomass of the
The amount of stored organic carbon was estimated to be 223.7 Mg C ha–1 during the study period, which was greater than that of the
The NPP of the
Based on the NPP of the
Soil respiration is largely divided into heterotrophic respiration by soil microorganisms and root respiration (Lou and Zhou 2006), which needs to be analyzed to accurately estimate NEP. In this study, the carbon efflux was 8.8 and 8.6 Mg C ha–1 yr–1 in 2016 and 2017, respectively, which was similar to the average carbon efflux reported between 2011 and 2012 (8.85 Mg C ha–1 yr–1) (Wang et al. 2010). Moreover, the carbon efflux in the current study was greater than that of the evergreen
The NEP at the study site was 0.6 and 1.6 Mg C ha–1 yr–1 in 2016 and 2017, respectively, which was lower than that previously reported for the same
The above results indicate that while the carbon stock and absorption of the
This study demonstrated the productivity and carbon absorption capacity of the
NPP: Net primary production
NEP: Net ecosystem production
NEE: Net ecosystem exchange
HMJ did conceptualization, methodology, software, formal analysis, investigation, data curation, writing-original draft preparation and visualization. YHY did conceptualization, validation, review and editing, supervision. SH did conceptualization, investigation, review and editing, supervision, project administration.
This study was supported by a grant from the National Institute of Ecology (NIE), funded by the Ministry of Environment (MOE) of the Republic of Korea (NIE-B-2022-35).
The datasets used and analyzed during the current study are available from the corresponding author on reasonable request.
The authors declare that they have no competing interests.