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The ecosystem services of forests, such as the water conservation function, are the combined results of diverse processes, and the modification of one part of a forest affects each ecosystem service separately via complex processes. It is necessary to develop an ecosystem service assessment model for various tree species to ensure proper forest management. In this study, a model to evaluate three ecosystem services, namely, the water supply, wood supply, and carbon sink, for various tree species in Japan is developed using many observation data from the previous literature. The integrated evaluation model consists of the forest model, hydrological model, and carbon stock assessment model. The forest model consists of the forest growth model and LAI estimation model, based on allometry. The results of the simulations for the major tree species yield the following findings: (1) Water supply varies with tree species but decreases until about 40 years of age, after which it is near constant. (2) Although beech has a larger LAI than needleleaf forests, water supply is not significantly different. (3) Broadleaf forests are more affected by thinning than needleleaf forests and tend to receive increased water supply as a result of processes such as thinning. This study enabled the evaluation of water conservation function in watersheds containing various tree species. [ABSTRACT FROM AUTHOR]

Accurately assessing forest structures at a national level is essential for promoting sustainable development, managing forests effectively, and fulfilling commitments under the Paris Agreement to combat climate change. In Japan, the traditional method of estimating forest carbon stock through National Forest Inventories (NFI) has certain limitations. The limited scope of forest survey data samples, coupled with the extended duration of surveys, typically spanning five years, induces significant biases in the carbon stock estimation. Achieving comprehensive forest mapping through the integration of remote sensing data and ground-referenced data for validation remains challenging due to the limited number and representativeness of referenced data, particularly at large scales. To address these issues, we collected LiDAR data from 17 sites across Japan between 2016 and 2022, covering an area of 4185.50 km2. This effort resulted in 212,067 squared plots, each with a standard size of 40 m × 40 m, which were used to develop regression models for forest structures. We utilized time-series analysis of Sentinel-2 data from 2015 to 2023 and Sentinel-2 data from different seasons in 2020. These datasets were integrated with 10 m resolution ALOS PALSAR-2 Synthetic Aperture Radar (SAR) data from JAXA and topographic data from the Shuttle Radar Topography Mission (SRTM), combined with machine learning algorithms to map forest structures throughout Japan. We initially produced a forest height map with a spatial resolution of 10 m and achieved a Relative Root Mean Square Error (rRMSE) of 21.58%. Subsequently, the estimated forest height was used as an additional predictor in machine learning models to estimate forest volume and aboveground biomass (AGB), achieving rRMSE values of 43.67% and 44.63%, respectively. Based on the predicted AGB, we calculated that the total aboveground carbon stock in Japanese forests is 1440.26 Teragrams (Tg) with an uncertainty of ±564.58 Tg. Our carbon stock estimation results outperformed those from ESA CCI, GEDI L4B, and the Ecosystem Demography Model-LiDAR (ED-LiDAR), representing the lowest rRMSE (18.07%) compared with the airborne LiDAR data. Overall, using time-series data from Sentinel-2 improved the estimation of forest structures. This study presents the first 10 m resolution, national-scale estimation of forest structures (height, volume, AGB), and forest carbon stock for the entirety of Japan. It introduces a new framework for estimating forest structures and carbon stock that supports forest management and sustainable development goals. • Mapping of multiple forest structures and carbon stock at 10-m resolution throughout Japan • Generating uncertainty maps of forest structures and carbon stock at 10-m resolution • Forest carbon stocks predictions outperformed those from other global products. [ABSTRACT FROM AUTHOR]

Highlights: [•] The carbon balance of harvested wood products is modeled for Japan through 2050 under two scenarios. [•] The carbon stock from domestic wood becomes a carbon emission source after 2020 in the BAU scenario. [•] Central Japan in the wood promotion scenario has carbon removals greater than carbon emissions between 2005 and 2045. [•] The removals and the reductions of carbon emissions were higher than the carbon emissions in all three regions. [Copyright &y& Elsevier]

Attempts were made to quantify the carbon and nitrogen pools in a monospecific and pioneer mangrove stand of Kandelia obovata Sheue, Liu & Yong, Okinawa Island, Japan. The leaf C and N concentrations on a leaf area basis decreased with increasing PPFD (Photosysthetic Photon Flux Density). The total C and N stocks in foliage were estimated as 3.55 Mg ha–1 and 0.105 Mg ha–1, respectively. The bark (45.6–48.6% for C and 0.564–0.842% for N) contained significantly higher amount of C ( P < 0.05) and N ( P < 0.01) than wood (46.2–47.8% for C and 0.347–0.914% N). The total C stock of stem was 23.2 Mg ha–1 in wood and 8.33 Mg ha–1 in bark, and the total N stock was 0.222 Mg ha–1 in wood and 0.116 Mg ha–1 in bark. The root wood (37.1–45.0%) contained significantly higher amount of C than root bark (35.4–40.7%) ( P < 0.01). The total C stock of root was 14.2 Mg ha–1 in wood and 12.6 Mg ha–1 in bark, and the total N stock of root was 0.157 Mg ha–1 in wood and 0.155 Mg ha–1 in bark. The soil organic C and total N stocks within 1 m soil depth were estimated as 57.3 Mg ha–1 and 2.73 Mg ha–1, respectively. The C pool in aboveground biomass (35.1 Mg ha–1) was 1.3 times as large as that in belowground biomass (26.9 Mg ha–1). However, the soil organic C pool (57.3 Mg ha–1) was similar to the total C pool (62.0 Mg ha–1) of vegetation, indicating that the mangrove stored a large part of production in the soil. About 50% of the C was in the soil. The N pool in aboveground biomass (0.442 Mg ha–1) was 1.4 times as large as that in belowground biomass (0.312 Mg ha–1). The soil N stock was 3.3 times as large as the biomass N stock (0.754 Mg ha–1). [ABSTRACT FROM AUTHOR]

Soil chambers with 3 types of soil treatment were used to analyze the environmental factors controlling carbon dioxide (CO2) emission in forest soils of Japan and to separately determine CO2 emission from root respiration, microbial decomposition of organic matter in the O layer and in the mineral soil layers. Soil chambers were installed at the Kyoto, Miyazu-Oak, Miyazu-Cedar, Miyazu-Beech and Nobeyama sites; the sites differed from each other in soil temperature, vegetation and parent materials. The soil treatments applied at each of the 5 sites were as follows: (1) control plot, (2) O- plot with removal of the O layer, (3) root- plot with the suppression of root respiration by inserting the chambers to a depth of 20 cm and sealing the bottom. The CO2 emission levels at all sites were significantly correlated with soil temperature, but not with soil moisture levels. The annual rates of soil organic matter decomposition simulated based on the automatically recorded soil temperature were 5.1, 4.0, 5.2, 5.5 and 3.4 Mg C ha−1 at the Kyoto, Miyazu-Oak, Miyazu-Cedar, Miyazu-Beech and Nobeyama sites, respectively. These rates were influenced by soil temperature, litter fall rates and the carbon stocks. In contrast, the ratio of the annual rate of root respiration to the annual rate of soil respiration decreased as soil temperature decreased. Based on the carbon budget, the Miyazu-Cedar and Nobeyama sites appeared to have lost their soil carbon stock. For more accurate analysis, methods for the direct measurement of the input rate of root litter should be developed. [ABSTRACT FROM AUTHOR]

Temporal changes in organic C stock with soil development were assessed by determining organic C stocks in soils on new deposits of andesitic volcanic materials of different ages. The soils included in this study have developed on avalanche debris of 91-year-old at Bandai, 197-year-old at Asama Kanbara, and 1110-year-old at Yatsugatake. Soils at Asama Oiwake had developed on 849-year-old material from pyroclastic flow. All the soils were located in montane zone and had similar cool temperate and humid climate.Organic C in these soils increased with soil age and therefore also in soil depth. However, organic C concentration in the surface 0–10 cm soil varied among sites independent of their age (5.3% in Bandai, 3.4% in Asama Kanbara, 5.5% in Asama Oiwake, and 12.5% in Yatsugatake). The organic C concentration in the surface 0–10 cm depth at Yatsugatake site was similar in the soil developed from the new deposits to that developed in an adjacent area under much older deposit.Organic C contents in 0–100 cm soil depth were: 53±29 t ha−1 (n=11) at Bandai, 55 t ha−1 at Asama Kanbara, 85±18 t ha−1 (n=2) at Asama Oiwake, and 127±36 t ha−1 (n=3) at Yatsugatake sites. Almost half of the organic C in the 0–100 cm depth was present in the surface 10 cm depth. Organic C content in soils on the new deposits was much lower than in those of the adjacent area with much older deposits. Soil organic C at Yatsugatake site maybe approaching a steady-state condition which was supported by the presence of immature soil humic acids in it.Rate of organic C accumulation declined with soil age, with a rapid increase of organic matter occurring during early stages of soil development. Accumulation rates of organic C were 0.10 t ha−1 per year at Asama Oiwake and 0.11 t ha−1 per year at Yatsugatake sites, and these rates were comparable with those reported as maximum values in the literature. [Copyright &y& Elsevier]

• This study was conducted on Andosols in a humid subtropical climate. • No-tillage increased soil CO 2 emissions as compared to moldboard plow in Andosols. • Soil organic carbon & CO 2 emissions were significantly & exponentially correlated. • Higher surface soil organic carbon caused higher CO 2 emissions in no-tillage soils. • Higher soil moisture content caused higher CO 2 emissions in no-tillage soils. Characterization of soil carbon dioxide (CO 2) emissions can help us to understand the effects of agricultural management on climate change and the ability of soil to sequester atmospheric carbon. However, there is a lack of studies on the effects of tillage and cover crops on soil CO 2 emissions on Andosols in the humid, subtropical climate. The present study aimed to quantify soil CO 2 emissions and identify the factors accounting for CO 2 emissions among no-tillage (NT) and moldboard plow (MP) systems under different cover crop treatments at an experimental site established in 2002 in Kanto, Japan. A split-plot field experiment was conducted from May 2017 to November 2018 comprising two tillage systems (NT and MP) and three cover crops: fallow, hairy vetch (HV), and rye (RY). Higher soil CO 2 daily emissions at 80% of the measurements and significantly greater CO 2 seasonal and annual emissions were observed in the NT system as compared to the MP system. The relationship between CO 2 daily flux and soil temperature was well-described by exponential functions (p < 0.001). Soil volumetric water content (θv) was significantly positively associated with soil CO 2 daily emissions when soil temperature ranged from 10 °C to 20 °C (p < 0.05) and 20 °C to 30 °C (p < 0.01), and the response of soil CO 2 flux to soil temperature and θv was well-described by a multiplicative model (RMSE: 1.2920, R2: 0.7777). Although there was no difference in soil temperature between NT and MP, significantly higher soil θv was found in NT than in MP. In addition, significant exponential correlations were observed between soil organic carbon (SOC) stocks and annual CO 2 emissions in four different soil layers (0–2.5 cm, 0–7.5 cm, 0–15 cm, and 0–30 cm). The HV and RY cover crops had a positive effect on SOC stocks. NT increased SOC stocks significantly compared to MP at 0–2.5 cm (p < 0.001) and 0–7.5 cm (p < 0.05) depth while no significant SOC stock difference at 0–15 cm and 0–30 cm depth between NT and MP were observed. These results suggest that surface SOC enrichment and higher soil θv result in higher soil CO 2 emissions in 15-year NT systems on Andosols in the humid, subtropical climate of Kanto, Japan. The carbon sources and their proportions of soil CO 2 emissions require further clarification to properly assess the benefits of NT in soil carbon sequestration. [ABSTRACT FROM AUTHOR]

• Above ground biomass (AGB) and coarse woody debris (CWD) decreased with elevation. • Size of living trees and CWD decreased with elevation. • The decomposition rate was higher at higher elevations due to smaller CWD. • The ratio of CWD to AGB was lower at higher elevations. • Climate change may alter the balance between CWD and AGB with elevation. In recent years, coarse woody debris (CWD) of deadwood has attracted attention as a long-term carbon pool for global warming problems. Environmental factors such as temperature and precipitation vary greatly with elevation. Hence, it is expected that the carbon storage by CWD varies with elevation. However, few studies have examined the abundance of CWD along elevations. Therefore, we investigated the abundance and decay classes of CWD, aboveground biomass (AGB) and aboveground net primary production (ANPP) of living trees along an elevational gradient (1600–2800 m above sea level) in subalpine coniferous forests, central Japan. AGB, ANPP and CWD decreased with increasing elevation. AGB at 2800 m was about 10% of that at 1600 m a.s.l. On the other hand, CWD at 2800 m was only 2.2% of that at 1600 m a.s.l. Thus, the ratio of CWD to AGB was lower at higher elevations. The relative frequency of small CWD increased with elevation. In addition, smaller CWD tended to decay less. The lower ratio of CWD mass to AGB at higher elevations was probably caused by smaller CWD because small CWD rapidly disappears via the high decomposition rate due to its high ratio of surface area to volume. Therefore, this study suggests that the importance of CWD relative to AGB for carbon storage decreases with elevation in subalpine forests. Climate change may alter the balance between CWD and AGB by changing ANPP and decomposition rates along elevation gradients. [ABSTRACT FROM AUTHOR]