Changes In Carbon Stocks Research Articles

Analysis of the driving role and impact of road construction on carbon stock

Road construction will have a large impact on the ecosystem in the road area, and carbon stock, as an important indicator to measure the scale and quantity of primary productivity of the ecosystem, will also change, but the specific pattern is not clear. It is important to study the impact of road construction on carbon stock for regional ecosystem protection and sustainable economic and social development. Based on the InVEST model, this paper quantifies the spatial and temporal changes of carbon stocks in Jinhua, Zhejiang Province, from 2002 to 2017, using remote sensing image classification data land cover types as model driving data, geodetector, trend analysis, and buffer zone analysis methods, explores the driving effect of road construction on carbon stocks, and analyzes the spatial and temporal impacts of road construction on carbon stocks within the buffer zone. Results indicate that the total carbon stock in the Jinhua area showed a decreasing trend during the 16 years, decreasing by about 8.58 × 106 t. The spatial changes in the areas with higher carbon stocks were not significant. The explanatory power of road network density on carbon stock reaches 37%, and the anisotropic effect of road construction on carbon stock is strong and had a significant driving effect on carbon storage reduction. The new highway construction will accelerate the rate of carbon stock decline in the buffer zone, and the spatial situation is generally "the farther away from the highway, the higher the carbon stock."

An analysis of regional carbon stock response under land use structure change and multi-scenario prediction, a case study of Hefei, China

As the largest global carbon pool system, terrestrial ecosystems have an important role to maintain the stability of ecosystems. Human activities affect the structural changes in the ground surface and interfere with terrestrial ecosystem evolution, and consequently, carbon stock is changed in the region. Therefore, forecasting future carbon stock changes under different land use scenarios has important research implications for promoting stable evolution and cycling of terrestrial ecosystems. This study is conducted with the land use data from 2000 to 2020, and incorporates the Patch-generating Land Use Simulation model with the Integrated Valuation of Ecosystem Services and Trade-Offs model to analyze the changes in land use in Hefei, and its influence on the carbon stock in Hefei in various scenarios. During the study period, the mutual conversion between different land types in Hefei City made the land structure change within the study area more significant. The rapidly evolving surface structure is the reason for the decrease of carbon storage in terrestrial ecosystems, with a cumulative decrease of 1.2 × 108 t. The spatial distribution in carbon storage in the study area shows a distribution pattern of low in the north and high in the south. The high carbon storage area is obviously banded in the study area. The area with obvious changes in surface structure has more obvious changes in carbon storage. Compared with the natural development scenario, the downward trend of carbon storage in the ecological protection scenario and the comprehensive development scenario has slowed down due to the restrictions on the structural transformation of land types and the implementation of relevant ecological protection policies. Therefore, this study will support the future management and policy making of Hefei City with the background of China's “double carbon” target and the significant position of Hefei City.

Variation in methodology obscures clarity of cropland global warming potential estimates.

Global warming potential (GWP) estimates from agroecosystems are valuable for understanding management effects on climate regulation services. However, GWP estimates are complex, including attributes with high spatiotemporal variability. Published GWP estimates from cropland were compiled and methodological attributes known to influence GWP were extracted. Results revealed considerable variation in approaches to estimate GWP. Among carbon balance methods, respiration methods were used most frequently (33%), followed by soil carbon stock change over time (30%). Twenty-six percent of studies did not account for carbon change in GWP estimates. Duration of gas flux measurements ranged from 0.5 to 60 months, with weekly and sub-weekly sampling most common (34% and 33%, respectively). Carbon dioxide equivalent conversion factors generally aligned with Intergovernmental Panel on Climate Change recommendations through 2014 but diverged thereafter. This review suggests the need for increased transparency in how GWP estimates are derived and communicated. Presentation of key metadata alongside GWP estimates is recommended.

Assessment of deforestation impacts on carbon sequestration in Edo State south Southern Nigeria

The stocking and sequestering of increasing atmospheric carbon dioxide (CO2) and the reduction of greenhouse gas (GHG) emissions that result from improving the carbon sink are two important ways that forested land contributes to the fight against global warming. The purpose of the study is to estimate the rate of carbon sequestration (CS) in Edo State, Nigeria, as well as the volume of deforestation and its impact on CS. To gauge the changes in carbon stock, stock-difference and gain-loss methods were employed. The gain-loss method predicts gains and losses based on off-take and growth rates, while the stock-difference approach uses actual measurements of carbon stocks over a given period of time. These two methods presuppose that changes in carbon stock and CO2 flows to or from the atmosphere are equal. To quantify the decline of the forest, geographical studies and satellite imagery were used. Comparing the area covered by forest in the same region at two distinct eras allowed researchers to determine the annual rate of change. The outcome showed that tree cover loss (TCL, kg/ha) was decreased in 18 local government regions (LGAs). As a result, throughout the baseline consideration period of 2010 to 2022, Etasko East (EE) and Estako West (ES), Ovia South East (OSW), and Ovia North have had the least loss in tree cover. The increased demand on human survival brought on by the expanding population may provide an explanation for this observation and discovery. As a result of this development, forests underwent transformation and were used to produce food, build cities and homes, and generate energy. The region with the highest rates of tree cover loss and deforestation was associated with the highest CS, which was calculated at 2700 tC/ha at OSW, and the lowest CS value point at 22.2 tC/ha at Oredo Edo (OE). As a result, OSW showed that dense forests had higher biomass carbon storage than grazing land and open forests. In conclusion, the study showed that Edo State has a significant potential for raising the level of carbon sequestration in order for the state to generate a profit from the sale of carbon stock and enhance climate change mitigation efforts.

Baseline high-resolution maps of organic carbon content in Australian soils

We introduce a new dataset of high-resolution gridded total soil organic carbon content data produced at 30 m × 30 m and 90 m × 90 m resolutions across Australia. For each product resolution, the dataset consists of six maps of soil organic carbon content along with an estimate of the uncertainty represented by the 90% prediction interval. Soil organic carbon maps were produced up to a depth of 200 cm, for six intervals: 0–5 cm, 5–15 cm, 15–30 cm, 30–60 cm, 60–100 cm and 100–200 cm. The maps were obtained through interpolation of 90,025 depth-harmonized organic carbon measurements using quantile regression forest and a large set of environmental covariates. Validation with 10-fold cross-validation showed that all six maps had relatively small errors and that prediction uncertainty was adequately estimated. The soil carbon maps provide a new baseline from which change in future carbon stocks can be monitored and the influence of climate change, land management, and greenhouse gas offset can be assessed.

Post-farming land restoration schemes exhibit higher soil aggregate stability and organic carbon: Evidence in the Three Gorges Reservoir Area, China

The Three Gorges Reservoir Area was dominated by a farming landscape but has been the target of restorative land management schemes over recent decades, wherein croplands have been converted to forests or citrus woodlands run by commercial enterprises or, alternatively, abandoned for natural vegetation succession. How these ongoing restorative land management schemes imprint soil systems remains poorly understood. Accordingly, in this study, a space-for-time substitution approach was applied to compare soil aggregate stability and organic carbon stocks between lands used for ongoing arable production and areas subjected to restorative practices. Composite soil samples from reforestation woodlands, abandoned croplands, citrus woodlands, and present-day croplands were collected, and a variety of soil metrics (i.e., water-stable aggregate percentage, mean weight diameter, geometric mean diameter, erosion resistance of the aggregates, bulk soil organic carbon and aggregate-specific soil organic carbon) were used as a basis for comparison. Reforestation woodlands and abandoned croplands exhibited a higher mass percentage of macro-aggregates, higher values of mean weight diameter and geometric mean diameter, and higher organic carbon content within the sampled 0–40 cm depth soil profiles. Reforestation and cropland abandonment significantly increased the stability of soil aggregates and organic carbon stocks. Moreover, abandoned cropland samples exhibited higher soil aggregate stability and organic carbon stocks than reforestation woodlands. In contrast, soil aggregate stability for all sampled soil depths and organic carbon content except for the topsoil (0–10 cm) of citrus woodlands exhibited lower values than those for present day croplands. Exclusion of crop farming and reestablishment of restorative vegetation have therefore contributed to changes in soil physical structure and organic carbon stocks, with reforestation and cropland abandonment being more beneficial for soil aggregate stability and soil organic carbon stocks in the Three Gorges Reservoir Area.

Estimating Carbon Stock Change Caused by Multi-Scenario Land-Use Structure in Urban Agglomeration

Land-use changes remain a major source of terrestrial ecosystem carbon stock (TECS) change. However, existing studies estimating TECS change caused by land-use changes, considering the mixed land-use structure and its continuous structural changes in the land-use change model, are still absent. Our study first analyzed land-use changes during the years 2000–2020 in the Changsha-Zhuzhou-Xiangtan (CZX) urban agglomeration, and then simulated the multi-scenario mixed land-use structure pattern in 2030, and finally estimated its effects on TECS change. Results show that: (1) The TECS change in CZX urban agglomeration during the years 2000–2020 are trending downward, decreasing 5.62 Tg. (2) Over the past 20 years, land-use changes in CZX urban agglomeration were dominated by the increase of artificial surfaces, and the decrease of forest, farmland, and grassland, which are major sources of TECS reduction. (3) The total TECS in inertial development, cultivated land protection, and ecological priority scenarios, are 95.82 Tg, 95.97 Tg, and 97.31 Tg, respectively. Compared to TECS in 2020, the decrease is 2.61 Tg, 2.46 Tg, and 1.12 Tg, respectively. While the spatial pattern of losses in TECS is trending toward sustained expansion in the inertial development and cultivated land protection scenario, the ecological priority scenario is more concentrated. The results can provide decision support for regional carbon accounting, for the assessment of terrestrial carbon stock, and for the planning of the “dual-carbon” (refer to peak carbon and carbon neutrality in dioxide emissions) goal.

Impact of silicate and lime application on soil fertility and temporal changes in soil properties and carbon stocks in a temperate ecosystem

Most agricultural soils are unproductive due to soil acidity which limits crop growth and yield. To ameliorate soil acidity constraints and enhance the ecosystem services the soil renders to achieve optimum crop yields, lime, and silicate are mostly used. However, there are few studies reporting the impacts of the combined application of silicate and lime on soil properties, soil fertility and carbon stocks and stratification in long-term experiments. This study evaluated the impacts of the combined application of silicate and lime on soil fertility indicators (pH, soil organic matter (SOM), available phosphorus, exchangeable potassium, magnesium, and calcium, and available SiO2), carbon stratification and stocks in comparison to sole lime and sole silicate applied to a Fluvaquentic Eutrudepts over a 67-year period. Each treatment’s rate of application was calculated to raise the soil pH to 6.5. Incorporation of the treatments increased the soil pH by 1.30, 1.22, and 1.35 folds in the sole silicate, sole lime, and combined silicate and lime-treated soils, respectively, relative to the baseline soil pH (5.5). The combined application of silicate and lime resulted in significant decreases in C stratification and C stocks. The significant reduction in the C stocks in the silicate and lime-treated soils implies that its long-term application could potentially reduce carbon sequestration and increase the carbon footprint of rice cultivation. This information is crucial to develop sustainable soil management interventions to curtail the environmental footprint in rice paddy ecosystems. Comparatively, the combined silicate and lime treatment caused an increase in the relative change of soil fertility by 65.7% and the average annual growth rate in the soil fertility improvement by 0.0115, as compared to the untreated soil. Among the soil variables, soil pH, exchangeable calcium, and available silicate contributed most to the variation the soil fertility. The obtained results could serve as a guide in revising the lime and silicate fertilization programs instituted by the Korean Government and reviewing national soil fertility management systems in temperate paddy ecosystems.

Forest Resources Projection Tools: Comparison of Available Tools and Their Adaptation to Polish Conditions

Over the years, various methods for estimating and projecting forest resources have been developed and are used by countries where the forest sector is important. Therefore, the obligation to report and account for forest resources, including changes in carbon stocks in a forest area, has gained attention. The latest regulations (Land Use, Land Use Change and Forestry—LULUCF) requires European Union (EU) members to annually report and publish national accounting plans estimating emissions and removals from managed forest areas (Regulation EU 2018/841). The major challenge is to choose and adapt a unique tool for this accounting. At the same time, they need to provide reliable estimates that are recognized by regulators and control authorities. This study focuses on comparing the adaptation of two accounting frameworks: the Operational-Scale Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3) and the European Forest Dynamics Model (EFDM). Both tools are based on National Forest Inventory (NFI) data. It is assumed that the EFDM can provide similar results to the CBM-CFS3, which is already used in Poland. Implementing the EFDM and adapting it to Polish conditions could facilitate forest management decision-making and the preparation of forest policies. The main objective of this study was to compare and validate the accuracy of the results obtained with the EFDM framework. Metrics compared using both tools included growing stock volume, biomass of growing stock expressed in carbon units and age–class distribution over area. The comparison was based on the agreement of EFDM with CBM-CFS3 results. The volume of logging was taken from the EFDM and compared with the values obtained by Statistics Poland. This study also provides a guide for framework parameterization directly from the Polish National Forest Inventory data from the 2010–2015 cycle. Our main findings are that the results of the two models are reasonably comparable (the extent of deviation is acceptable). Moreover, the first implementation of the EFDM showed that it is an easy-to-use open-source program that allows forest managers to implement their own settings according to their needs. This document elucidates the concept of using both frameworks under Polish conditions and provides an impression of their performance for future modelers, students and researchers.

National CO2budgets (2015–2020) inferred from atmospheric CO2observations in support of the global stocktake

Abstract. Accurate accounting of emissions and removals of CO2 is critical for the planning and verification of emission reduction targets in support of the Paris Agreement. Here, we present a pilot dataset of country-specific net carbon exchange (NCE; fossil plus terrestrial ecosystem fluxes) and terrestrial carbon stock changes aimed at informing countries' carbon budgets. These estimates are based on “top-down” NCE outputs from the v10 Orbiting Carbon Observatory (OCO-2) modeling intercomparison project (MIP), wherein an ensemble of inverse modeling groups conducted standardized experiments assimilating OCO-2 column-averaged dry-air mole fraction (XCO2) retrievals (ACOS v10), in situ CO2 measurements or combinations of these data. The v10 OCO-2 MIP NCE estimates are combined with “bottom-up” estimates of fossil fuel emissions and lateral carbon fluxes to estimate changes in terrestrial carbon stocks, which are impacted by anthropogenic and natural drivers. These flux and stock change estimates are reported annually (2015–2020) as both a global 1∘ × 1∘ gridded dataset and a country-level dataset and are available for download from the Committee on Earth Observation Satellites' (CEOS) website: https://doi.org/10.48588/npf6-sw92 (Byrne et al., 2022). Across the v10 OCO-2 MIP experiments, we obtain increases in the ensemble median terrestrial carbon stocks of 3.29–4.58 Pg CO2 yr−1 (0.90–1.25 Pg C yr−1). This is a result of broad increases in terrestrial carbon stocks across the northern extratropics, while the tropics generally have stock losses but with considerable regional variability and differences between v10 OCO-2 MIP experiments. We discuss the state of the science for tracking emissions and removals using top-down methods, including current limitations and future developments towards top-down monitoring and verification systems.

Spatial Downscaling of Forest Above-Ground Biomass Distribution Patterns Based on Landsat 8 OLI Images and a Multiscale Geographically Weighted Regression Algorithm

Forest above-ground biomass (AGB) is an excellent indicator for the health status and carbon sink potential of forest ecosystems, as well as the effectiveness of sustainable forest management practices. However, due to the strong heterogeneity of forest structures, acquiring high-accuracy and high-resolution AGB distributions over wide regions is often prohibitively expensive. To fill the resulting gap, this paper uses part of Lishui city, Zhejiang province as the study area, based on 168 forest sample observations, and proposes a novel integrated framework that combines a multi-scale geographically weighted regression (MGWR) with the co-kriging algorithm to refine the spatial downscaling of AGB. Specifically, optimal predictor variable sets identified by random forest importance ranking, multiple stepwise regression, and Pearson VIF methods were first assessed based on their total explanatory power (R square), followed by reconfirmation of the optimal predictor variable set based on the non-stationarity impact of each variable’s action scale (bandwidth) on the output pattern of AGB downscaling. The AGB downscaling statistical algorithms included MGWR, GWR, random forest (RF), and the ordinary least square (OLS), and their downscaling performances were quantitatively compared to determine the best downscaling method. Ultimately, the downscaled AGB pattern was produced using the best method, which was further refined by considering the spatial autocorrelation in AGB samples by implementing a co-kriging interpolation analysis of the predicted AGB downscaling residuals. The results indicated that the variable set selected by random forest importance ranking had the strongest explanatory power, with a validation R square of 0.58. This was further confirmed by the MGWR analysis which showed that the set of variables produced a more spatially smooth downscaled AGB pattern. Among the set of optimal variables, elevation and aspect affected AGB at local scales, representing a strong spatial heterogeneity. Some textural features and spectral features showed a smooth action scale relative to AGB, showing insignificant spatial scale processes. In the study area with complex terrain, using aspect as a covariant, the co-kriging (CK) model achieved a higher simulation accuracy for the MGWR-predicted AGB residuals than the ordinary kriging model. Overall, the proposed MGWR-CK model, with a final validation R square value of 0.62, effectively improved the spatial distribution characteristics and textural details of AGB mapping without the additional costs of procuring finer satellite images and GIS-based features. This will contribute to the accurate assessment of carbon sinks and carbon stock changes in subtropical forest ecosystems globally.

Analysis of Changes in Vegetation Carbon Storage and Net Primary Productivity as Influenced by Land-Cover Change in Inner Mongolia, China

Exploring the influence of vegetation carbon stocks over land-cover change and the relationship between land-cover change and net primary production (NPP) is of great practical importance for achieving China’s carbon neutrality target. Therefore, this paper analyses the spatio-temporal distribution of land-cover change and NPP change in Inner Mongolia from 2000 to 2020 and explores the vegetation carbon stock change caused by land-cover change, the relationship between land cover and NPP, and the relationship between land-cover change and NPP change. The results show that the main land-cover change in Inner Mongolia during 2000–2020 was the conversion from other land-cover types to grassland, with the conversion of bare land to grassland from 2000 to 2010 covering an area of 20,634.87 km2. During the period of 2000–2020, the high values of NPP were mainly located in northeastern Inner Mongolia, and the low values were mainly distributed in southwestern Inner Mongolia. The total carbon storage changes in vegetation affected by land-cover change during 2000–2010 and 2010–2020 were 10,736,986.11 t and 3,894,272.41 t. The mean values of NPP for different land covers were, in descending order, forest > cultivated land > wetland > grassland > artificial surfaces > shrubland > water bodies > bare land. Between 2000 and 2010, the change in land-cover type to water bodies was the main cause of the decrease in NPP, and the increase in NPP was mainly due to the conversion of other land-cover types to cultivated land, forest, and grassland. The implementation of appropriate conservation and management measures (e.g., the construction of forest and grass ecological protection), planting, and the protection of high-vegetation carbon storage plants and other means can improve the level of vegetation carbon sequestration and protect the ecological environment of Inner Mongolia.

Unraveling the link between sediment acoustics and organic carbon

The top meter of marine sediments is estimated to store a total of 2322 Pg of carbon [Atwood et al., 2020. Front. Mar. Sci., vol. 7 p.165], which is twice that of terrestrial soils. Physical disturbance and remineralization of these carbon stocks could further accelerate climate change. Rapid and accurate quantification of sediment carbon stocks can (1) better inform carbon budgets and management of human activities in the ocean to minimize carbon remineralization and (2) monitor changes in sediment carbon stocks due to anthropogenic and natural disturbances. Sediment acoustics, which have been linked with sediment total organic carbon/content in mud banks, seagrass beds, and estuarine environments, can be measured in situ and offer a scalable solution toward rapid estimation of carbon stocks. However, before this modality can be applied broadly, a fundamental understanding between sediment acoustic properties and sediment organic/inorganic constituents must be realized. Here, direct ex situ measurements of sediment acoustic properties, sediment organic carbon, and grain size distribution will be compiled and compared across a variety of sediment types and locations from our own measurements and from published datasets. The development of a non-site-specific constitutive-based relationship will be discussed. [Work supported in part by ONR.]

Monitoring carbon stock changes in Solan Forest Division of Indian Western Himalayas

Monitoring carbon stock changes in Solan Forest Division of Indian Western Himalayas

Maps with 1 km resolution reveal increases in above- and belowground forest biomass carbon pools in China over the past 20 years

Abstract. To quantify the ecological consequences of recent nationwide restoration efforts in China, spatially explicit information on forest biomass carbon stock changes over the past 20 years is critical. However, long-term biomass tracking at the national scale remains challenging as it requires continuous and high-resolution monitoring. Here, we characterize the changes in the above- and belowground biomass carbon (AGBC and BGBC) of forests in China between 2002 and 2021 at 1 km spatial resolution by integrating multiple types of remote sensing observations with intensive field measurements through regression and machine learning approaches. On average, 8.6 ± 0.6 and 2.2 ± 0.1 PgC were stored in above- and belowground live forests in China. Over the last 20 years, the total forest biomass carbon pool in China has increased at a rate of 114.5 ± 16.3 TgC yr−1 (approximately 1.1 % yr−1). The most pronounced forest biomass carbon stock gains occurred in central to southern China, including the southern Loess Plateau, Qinling mountains, southwestern karsts and southeastern forests. While the combined use of multi-source remote sensing data provides a powerful tool to assess the forest biomass carbon changes, future research is also needed to explore the drivers of the observed woody biomass trends and to evaluate the degree to which biomass gains will translate into biodiverse, healthy ecosystems that are sustainable. Annual forest above- and belowground biomass maps for China are now available at https://doi.org/10.6084/m9.figshare.21931161.v1 (Chen, 2023).

Effects of forest degradation classification on the uncertainty of aboveground carbon estimates in the Amazon

BackgroundTropical forests are critical for the global carbon budget, yet they have been threatened by deforestation and forest degradation by fire, selective logging, and fragmentation. Existing uncertainties on land cover classification and in biomass estimates hinder accurate attribution of carbon emissions to specific forest classes. In this study, we used textural metrics derived from PlanetScope images to implement a probabilistic classification framework to identify intact, logged and burned forests in three Amazonian sites. We also estimated biomass for these forest classes using airborne lidar and compared biomass uncertainties using the lidar-derived estimates only to biomass uncertainties considering the forest degradation classification as well.ResultsOur classification approach reached overall accuracy of 0.86, with accuracy at individual sites varying from 0.69 to 0.93. Logged forests showed variable biomass changes, while burned forests showed an average carbon loss of 35%. We found that including uncertainty in forest degradation classification significantly increased uncertainty and decreased estimates of mean carbon density in two of the three test sites.ConclusionsOur findings indicate that the attribution of biomass changes to forest degradation classes needs to account for the uncertainty in forest degradation classification. By combining very high-resolution images with lidar data, we could attribute carbon stock changes to specific pathways of forest degradation. This approach also allows quantifying uncertainties of carbon emissions associated with forest degradation through logging and fire. Both the attribution and uncertainty quantification provide critical information for national greenhouse gas inventories.

Semantics about soil organic carbon storage: DATA4C+, a comprehensive thesaurus and classification of management practices in agriculture and forestry

Abstract. Identifying the drivers of soil organic carbon (SOC) stock changes is of the utmost importance to contribute to global challenges like climate change, land degradation, biodiversity loss, or food security. Evaluating the impacts of land use and management practices in agriculture and forestry on SOC is still challenging. Merging datasets or making databases interoperable is a promising way, but still has several semantic challenges. So far, a comprehensive thesaurus and classification of management practices in agriculture and forestry has been lacking, especially while focusing on SOC storage. Therefore, the aim of this paper is to present a first comprehensive thesaurus for management practices driving SOC storage (DATA4C+). The DATA4C+ thesaurus contains 224 classified and defined terms related to land management practices in agriculture and forestry. It is organized as a hierarchical tree reflecting the drivers of SOC storage. It is oriented to be used by scientists in agronomy, forestry, and soil sciences with the aim of uniformizing the description of practices influencing SOC in their original research. It is accessible in Agroportal (http://agroportal.lirmm.fr/ontologies/DATA4CPLUS, last access: 24 March 2022) to enhance its findability, accessibility, interoperability, and reuse by scientists and others such as laboratories or land managers. Future uses of the DATA4C+ thesaurus will be crucial to improve and enrich it, but also to raise the quality of meta-analyses on SOC, and ultimately help policymakers to identify efficient agricultural and forest management practices to enhance SOC storage.

Biomass carbon stocks and stock changes in managed hedgerows

Landscape features, such as hedgerows, can play a role in enhancing terrestrial carbon (C) sinks, especially in North-western Europe, where they form a large part of the agricultural landscape. To date, there are few studies relating aerial imagery to ground-truthed biomass measurements and relating changes in biomass to hedgerow management. This study sought to develop relationships between measured biomass of hedgerows and digital elevation model (DEM) data from drones and aircraft. Furthermore, changes in hedgerow above-ground and below-ground biomass stocks were assessed using a systematic grid sample, DEM data and developed volume-biomass regression models. The developed inventory framework was then applied to a pilot study area of 419,701 ha in Ireland.Robust relationships were developed relating DEM data to volume and above-ground biomass. Model equations were also developed linking above-ground and below-ground biomass. However, these were less robust due to the confounding impacts of hedgerow management intensity, hedgerow type and dominant species. Above-ground biomass density was linearly correlated with hedge volume. Wider, less intensively managed, irregular hedges exhibit a higher biomass stocks per km, when compared to regular, more intensively managed hedgerows. When the models were extrapolated to the county level, hedgerow biomass C pools for Co Wexford and Waterford are suggested to be a net emission of −0.3 tC ha−1 year−1 due to hedgerow removals and management. Flailing or coppicing of hedgerows, in particular irregular profile hedgerows, had the largest impact on the biomass C balance in the pilot study area. Re-introduction of traditional management practices such as layering and increasing the allowable hedgerow width in areas qualifying for farm payments could be considered with the aim of increasing the maximum sink potential of established hedgerows.

A simple soil mass correction for a more accurate determination of soil carbon stock changes

Agricultural soils can act as a sink for large quantities of soil organic carbon (SOC) but can also be sources of carbon to the atmosphere. The international standard for assessing SOC stock and measuring stock change stipulates fixed depth sampling to at least 30 cm. The tendency of bulk density (BD) to decrease with decreasing disturbance and increasing SOC concentration and the assumption of constant SOC and BD within this depth profile promotes error in the estimates of SOC stock. A hypothetical but realistic change in BD from 1.5 to 1.1 g cm−3 from successive fixed depth sampling to 30 cm underestimates SOC stock change by 17%. Significant effort has been made to evaluate and reduce this fixed depth error by using the equivalent soil mass (ESM) approach, but with limited adoption. We evaluate the error in SOC stock assessment and change generated from fixed depth measurements over time relative to the ESM approach and propose a correction that can be readily adopted under current sampling and analytical methods. Our approach provides a more accurate estimate of SOC stock accumulation or loss that will help incentivize management practice changes that reduce the environmental impacts of agriculture and further legitimize the accounting practices used by the emerging carbon market and organizations that have pledged to reduce their supply chain greenhouse gas (GHG) footprints.

Change in soil carbon, nitrogen, and phosphorus after timber harvesting in northern hardwood forests

AbstractQuantifying changes in soil carbon (C) and nutrient stocks after timber harvesting is needed to inform C management and to ensure that forest productivity is sustained over time. Our objective was to assess changes in soil C, nitrogen (N), and phosphorus (P) 1 year after timber harvesting in temperate northern hardwood forests. We established permanent plots in forest stands for measuring forest attributes before and after harvesting. We collected soils from quantitative soil pits, which were associated with permanent plots, to determine total C, total N, and extractable P stocks and concentrations. Mean post‐harvest fine fraction organic (O) horizon C was less than the pre‐harvest stock, but we did not detect a statistically significant change in total O horizon or mineral soil C stocks. For the fine fractions of the O horizon and mineral soil from the 0–5 and 5–30 cm depth increments of the B horizon, total N and extractable P stocks were positively correlated with total C stocks. For all of these soil components, extractable P stocks and concentrations declined over time, which could be related to post‐harvest stand conditions that favored microbial activity and immobilization of available P. These findings indicate that P availability could be a concern in these forests and that long‐term monitoring is needed to consider potential management actions for ensuring that forest productivity is sustained.