•Updated forest biomass carbon sinks and density of China from 1977 to 2013.•Used carbon fraction coefficients of 46 tree species replaced 0.5.•The spatiotemporal variation of forest carbon storage ...and density is discussed;•Analysis of natural and planted forests in the past two inventories.•Compared the carbon estimation of forest by different methods.
Forests are a major contributor of terrestrial ecosystem carbon pools. Accurate estimates of forest biomass carbon sinks can improve our understanding of carbon cycles and help in developing sustainable forest management policies in the face of climate change. In this study, we update estimates of the biomass carbon stocks of China’s forests based on seven forest inventory datasets from 1977 to 2013 and carbon fraction coefficients of 46 tree species in the continuous biomass expansion factor (CBEF) model. Our findings suggest that: (1) China’s forest stands acted as an average biomass carbon sink of 99.07 Tg C year−1; and (2) biomass carbon stocks increased by 72.62% from 1977 to 2013 and recently reached 7.27 Pg C, driven by forest area expansion and forest growth. The biomass carbon density of forest stands (canopy coverage >20%) increased from 38.18 to 44.52 Mg C ha−1 during the study period, with higher carbon densities in natural compared to planted forests, and the gap increasing with forest age. The largest increases in the biomass of carbon stocks of forest stands occurred in the eastern and northern regions. Our results suggest that biomass carbon stocks of natural forests account for about 85% in the most recent inventory and that the total biomass carbon stocks of forest stands in China will keep increasing in the future because of the large area of planted forests with young and middle-aged forest growth. The results from this study can help with comprehensive investigations of forest carbon budgets and the calibration and validation of simulation model results.
We present a new synthesis, based on a suite of complementary approaches, of the primary production and carbon sink in forests of the 25 member states of the European Union (EU-25) during 1990-2005. ...Upscaled terrestrial observations and model-based approaches agree within 25% on the mean net primary production (NPP) of forests, i.e. 520±75 g C m⁻² yr⁻¹ over a forest area of 1.32 x 10⁶ km² to 1.55 x 10⁶ km² (EU-25). New estimates of the mean long-term carbon forest sink (net biome production, NBP) of EU-25 forests amounts 75±20 g C m⁻² yr⁻¹. The ratio of NBP to NPP is 0.15±0.05. Estimates of the fate of the carbon inputs via NPP in wood harvests, forest fires, losses to lakes and rivers and heterotrophic respiration remain uncertain, which explains the considerable uncertainty of NBP. Inventory-based assessments and assumptions suggest that 29±15% of the NBP (i.e., 22 g C m⁻² yr⁻¹) is sequestered in the forest soil, but large uncertainty remains concerning the drivers and future of the soil organic carbon. The remaining 71±15% of the NBP (i.e., 53 g C m⁻² yr⁻¹) is realized as woody biomass increments. In the EU-25, the relatively large forest NBP is thought to be the result of a sustained difference between NPP, which increased during the past decades, and carbon losses primarily by harvest and heterotrophic respiration, which increased less over the same period.
National Forest Inventories Tomppo, Erkki; Gschwantner, Thomas; Lawrence, Mark
2010, 20091010, 2010-04-15
eBook
Traditionally the purpose of National Forest Inventories (NFIs) has been to provide continuously updated information regarding the state of a given nation's forest resources, including their timber ...volumes, species composition and sustainable development. But with increased international reporting requirements to the FAO, the ITTO, the UN's Framework Convention on Climate Change, the Ministerial Conference Protecting Forest in Europe and other international bodies the potential role of how NFIs can accurately respond to these requirements has received some considerable attention. Addressing the issue of how well countries are able to respond to current international reporting requirements, this book discusses the importance of comparable reporting, and the possible approaches for achieving comparability across Europe and globally. It includes country status reports from 37 countries, worldwide, and it discusses methodologies and techniques for a common reporting system. With its collection of inventories and detailed discussions on the current status and future needs of NFIs, this book provides an invaluable resource for anyone involved in developing, managing, monitoring or contributing to forest inventories, as well as to those who are researching or practising forest resource management.
Key message
Despite agreements on definitions, the national data provided for international reporting are lacking comparability. To address this limitation the European National Forest Inventory ...Network has established criteria to harmonise definitions and to provide tools to transform national data into internationally comparable data
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Context
Forest reporting presents a series of challenges for countries, owing to diverse processes at international level such as the Global Forest Resources Assessment (FRA), Convention on Biological Diversity, United Nations Framework Convention on Climate Change and its Kyoto Protocol. Further challenges are faced at European level with Forest Europe and policy needs.
Aims
The aim of this paper is to provide a comprehensive review of the national and international forest reporting processes and of the role of the National Forest Inventories (NFIs) and the long-associated challenges resulting from a lack of comparability in definitions used. In addition, there is a discussion on the role of the European National Forest Inventory Network (ENFIN) as a facilitator for enhancing harmonization and comparability of national data and the ancillary information required to monitor European forestry-related policies.
Methods
NFIs take part to international reporting processes as providers of information. They are correspondent to the FRA process, and then they know very well the context of harmonization. Participating in the ENFIN research projects, NFIs, and particularly authors, conducted a screening exercise on harmonization status at European and World level.
Results
This review article is a synthesis of the main findings of the abovementioned screening exercise. It highlights the main gaps in terms of comparability of result in international reporting. Thanks to ENFIN harmonization research project, it gives same ways of working as a possible benchmark for the rest of the world.
Conclusion
Based on the international reporting exercises, their interactions, and impacts on new forestry policy requirements, the need for a strengthened harmonization process can clearly be demonstrated. Due to European policy needs, research work within ENFIN has been initiated to develop tools for building comparable results at international level. This work is an important benchmark particularly for countries outside Europe from which to base future harmonization work.
In 2009, the Swiss National Forest Inventory (NFI) turned from a periodic into an annual measurement design in which only one-ninth of the overall sample of permanent plots is measured every year. ...The reduction in sample size due to the implementation of the annual design results in an unacceptably large increase in variance when using the standard simple random sampling estimator. Thus, a flexible estimation procedure using two- and three-phase regression estimators is presented with a special focus on utilizing updating techniques to account for disturbances and growth and is applied to the second and third Swiss NFIs. The first phase consists of a dense sample of systematically distributed plots on a 500 m à 500 m grid for which auxiliary variables are obtained through the interpretation of aerial photographs. The second phase is an eightfold looser subgrid with terrestrial plot data collected from the past inventory, and the third and final phase consists of the three most recent annual subgrids with the current state of the target variable (stem volume). The proposed three-phase estimators reduce the increase in variance from 294% to 145% compared with the estimator based on the full periodic sample while remaining unbiased.
Accurate assessments of forest resources rely on ground truth data that are collected via in-situ measurements, which are fundamental for all other statistical- and/or remote-sensing-based deductions ...on quantified forest attributes. The major bottleneck of the current in-situ observation system is that the data collection is time consuming, and, thus, limited in extent, which potentially biases any further inferences made. Consequently, conventional field-data-collection approaches can hardly keep pace with the coverage, scale and frequency required for contemporary and future forest inventories. In-situ measurements from mobile platforms seem to be a promising technique to solve this problem and are estimated at least 10 times faster than static techniques (e.g., terrestrial laser scanning, TLS) at the plot level. However, the mobile platforms are still at the very early stages of development, and it is unclear which three-dimensional (3D) forest measurements the mobile systems can provide and at what accuracy. This study presents a quantitative evaluation of the performance of mobile platforms in a variety of forest conditions and through a comparison with state-of-the-art static in-situ observations. Two mobile platforms were used to collect field data, where the same laser-scanning system was both mounted on top of a vehicle and wore by an operator. The static in-situ observation from TLS is used as a baseline for the evaluation. All point clouds involved were processed through the same processing chain and compared to conventional manual measurement. The evaluation results indicate that the mobile platforms can assess homogeneous forests as well as static observations, but they cannot yet assess heterogeneous forest as required by practical applications. The major challenge is twofold: mobile-data coverage and accuracy. Future research should focus on the robust registration techniques between strips, especially in complex forest conditions, since errors of data registration results in significant impacts on tree attributes estimation accuracy. In cases that the spatial inconstancy cannot be eliminated, attributes estimation in single strips, i.e., the multi-single-scan approach, is an alternative. Meanwhile, operator training deserves attention since the data quality from mobile platforms is partly determined by the operators’ selection of trajectory in the field.
As a prominent part of global and regional terrestrial carbon (C) pools, increases in forest biomass C sinks can be attributed to either forest areal expansion (FAE) or increased biomass C density ...(IBCD). Accurate estimates of the relative contributions of FAE and IBCD to forest C sequestration can improve our understanding of forest C cycling processes and will help to formulate rational afforestation policies to cope with global warming. In this study, the Continuous Biomass Expansion Factor (CBEF) model and Forest Identity concept were used to map the spatiotemporal variation of the relative contribution of FAE and IBCD to the C sequestration of forest (natural and planted forests) in China and seven regions during the past 40 years. Our results suggest that: (1) total forest biomass C density and stocks of forest increased from 35.41 Mg C ha−1 and 4128.50 Tg C to 43.95 Mg C ha−1 and 7906.23 Tg C in China from 1977 to 2018, respectively; (2) for all forests, the IBCD has been a smaller contributor to C sinks than FAE in China from 1977 to 2018 (33.27 vs. 66.73%); (3) the contribution of FAE to C sinks is greater than that of IBCD in planted forests (63.99 vs. 36.01%), while in natural forests, IBCD has a larger contribution than FAE (57.82 vs. 42.18%) from 1977 to 2018 and the relative contribution of FAE has exceeded IBCD in the last decade; and (4) these patterns varied at the regional level such that the relative contribution of FAE increased for planted forests in most regions but for natural forests, IBCD gradually reached saturation and C stocks declined in northern regions in the last decade. The results from this study suggest that total biomass C sinks will keep increasing because of the increased forest area contributed by afforestation and the relatively young trees in planted forests. This study facilitates a more comprehensive assessment of forest C budgets and improves our understanding of ecological mechanisms of forest biomass carbon stock and dynamics.
•Updated forest biomass carbon sinks and density of China from 1977 to 2018.•The spatiotemporal variation of relative contributions is discussed.•Calculated the proportion to C sinks attributed of natural and planted forests.•Discuss the effects of afforestation on C sinks in the past four decades.
Background： National forest resource assessments Inventories （NFI＇s）, constitute an important nationa and monitoring, commonly known as National Forest information infrastructure in many countries. ...Methods： This study presents details about developments of the NFI in China, including sampling and plot design and the uses of alternative data sources, and specifically · reviews the evolution of the national forest inventory in China through the 20th and 21st centuries, with some reference to Europe and the US; · highlights the emergence of some common international themes： consistency of measurement; sampling designs; implementation of improved technology; expansion of the variables monitored more efficient scientific transparency;· presents an example of how China＇s expanding NFI exemplifies these global trends. Results： Main results and important changes in China＇s NFI are documented, both to support continued trend analysis and to provide data users with historical perspective. Conclusions： New technologies and data needs ensure that the Chinese NFI, like the national inventories in other countries, will continue to evolve. Within the context of historical change and current conditions, likely directions for this evolution are suggested.
•We reconstructed time series of boreal tree growth with a biometric approach.•Aboveground tree growth was a minor and decoupled fraction of carbon input.•Partitioned estimates of tree carbon sink ...are valuable observational constraints.•Such observational constraints can be used for model validation and policy making.
The boreal biome accounts for approximately one third of the terrestrial carbon (C) sink. However, estimates of its individual C pools remain uncertain. Here, focusing on the southern boreal forest, we quantified the magnitude and temporal dynamics of C allocation to aboveground tree growth at a mature black spruce (Picea mariana)-dominated forest stand in Saskatchewan, Canada. We reconstructed aboveground tree biomass increments (AGBi) using a biometric approach, i.e., species-specific allometry combined with forest stand characteristics and tree ring widths collected with a C-oriented sampling design. We explored the links between boreal tree growth and ecosystem C input by comparing AGBi with eddy-covariance-derived ecosystem C fluxes from 1999 to 2015 and we synthesized our findings with a refined meta-analysis of published values of boreal forest C use efficiency (CUE). Mean AGBi at the study site was decoupled from ecosystem C input and equal to 71 ± 7 g C m–2 (1999–2015), which is only a minor fraction of gross ecosystem production (GEP; i.e., AGBi / GEP ≈ 9 %). Moreover, C allocation to AGBi remained stable over time (AGBi / GEP; –0.0001 yr–1; p-value=0.775), contrary to significant trends in GEP (+5.72 g C m–2 yr–2; p-value=0.02) and CUE (–0.0041 yr–1, p-value=0.007). CUE was estimated as 0.50 ± 0.03 at the study area and 0.41 ± 0.12 across the reviewed boreal forests. These findings highlight the importance of belowground tree C investments, together with the substantial contribution of understory, ground cover and soil to the boreal forest C balance. Our quantitative insights into the dynamics of aboveground boreal tree C allocation offer additional observational constraints for terrestrial ecosystem models that are often biased in converting C input to biomass, and can guide forest-management strategies for mitigating carbon dioxide emissions.
► Six dynamic models for Scots pine were tested on 12 sites in four European countries. ► Bayesian calibration reduced uncertainties in parameters and predictions of five models. ► Country-specific ...and generic calibration led to similar predictive capacity. ► Bayesian model comparison slightly favoured the simpler models. ► Bayesian model averaging afforded good out-of-sample forecasts of forest growth.
Forest management requires prediction of forest growth, but there is no general agreement about which models best predict growth, how to quantify model parameters, and how to assess the uncertainty of model predictions. In this paper, we show how Bayesian calibration (BC), Bayesian model comparison (BMC) and Bayesian model averaging (BMA) can help address these issues.
We used six models, ranging from simple parameter-sparse models to complex process-based models: 3PG, 4C, ANAFORE, BASFOR, BRIDGING and FORMIND. For each model, the initial degree of uncertainty about parameter values was expressed in a prior probability distribution. Inventory data for Scots pine on tree height and diameter, with estimates of measurement uncertainty, were assembled for twelve sites, from four countries: Austria, Belgium, Estonia and Finland. From each country, we used data from two sites of the National Forest Inventories (NFIs), and one Permanent Sample Plot (PSP). The models were calibrated using the NFI-data and tested against the PSP-data. Calibration was done both per country and for all countries simultaneously, thus yielding country-specific and generic parameter distributions. We assessed model performance by sampling from prior and posterior distributions and comparing the growth predictions of these samples to the observations at the PSPs.
We found that BC reduced uncertainties strongly in all but the most complex model. Surprisingly, country-specific BC did not lead to clearly better within-country predictions than generic BC. BMC identified the BRIDGING model, which is of intermediate complexity, as the most plausible model before calibration, with 4C taking its place after calibration. In this BMC, model plausibility was quantified as the relative probability of a model being correct given the information in the PSP-data. We discuss how the method of model initialisation affects model performance. Finally, we show how BMA affords a robust way of predicting forest growth that accounts for both parametric and model structural uncertainty.
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