Carbon stock in Japanese forests has been greatly underestimated

Abstract

An accurate estimate of total forest carbon (c) stock and c uptake is crucial for predicting global warming scenarios and planning co 2 emission reductions. Forest inventory, based on field measurements of individual tree sizes, is considered the most accurate estimation method for forest c stock. Japan's national forest inventory (nfi) provides stand-scale stem volume for the entire forested area based on (1) direct field measurements (m-NFI) and (2) prediction using yield tables (p-NFI). Here, we show that Japanese national and local forestry agencies and some research studies have used p-nfi and greatly underestimated the Japanese forest C stock (58-64%) and net annual C uptake (41-48%). This was because approximately 10% of the forest area was not counted in p-NFI and because the yield tables in p-NFI, which were constructed around 1970, were outdated. For accurate estimation of the forest C stock, yield tables used in p-NFI should be reconstructed or ideally field measurement campaigns for m-nfi should be continued. in the future, appropriate forest management plans are necessary to effectively use the high CO 2 absorption capacity of Japanese forests and these should be compared with other industries' co 2 reduction plans from a cost-benefit perspective.

Natural capital for nature’s contributions to people: the case of Japan

“…３ We adopted the same method used in Egusa et al (2020) to calculate the amount of carbon stock per hectare.…”

Lifetimes of buildings in Japan

“…However, approximately 90 % of the carbon stock in building wood is derived from wooden buildings, which are still a primary representative of carbon storage. The latest carbon stock in all buildings as of 2020 was 241 Tg-C, which is equal to 8 %-9 % of the amount of carbon stock [43] in Japan's forest biomass -a size that cannot be ignored when examining current and future carbon balance in forest sinks.…”

Estimation of Forest Aboveground Biomass of Two Major Conifers in Ibaraki Prefecture, Japan, from PALSAR-2 and Sentinel-2 Data

“…Japanese law requires that the forest register be updated every 5 years. The satellite-derived AGB was more significant than the value in the register in Ibaraki, and some previous studies also concluded that the forest register underestimated the forest volume [81]. Japan's Forestry and Forest Products Research Institute compared the register's data with a field measurement at 10,189 sub-compartments throughout Japan, and found that the fieldmeasured forest volume was 1.88 times the value in the forest register for Japan as a whole [82].…”