scholarly journals Carbon–nitrogen interactions in European forests and semi-natural vegetation – Part 2: Untangling climatic, edaphic, management and nitrogen deposition effects on carbon sequestration potentials

2020 ◽  
Vol 17 (6) ◽  
pp. 1621-1654 ◽  
Author(s):  
Chris R. Flechard ◽  
Marcel van Oijen ◽  
David R. Cameron ◽  
Wim de Vries ◽  
Andreas Ibrom ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Nitrogen Deposition ◽  
C Sequestration ◽  
Forest Growth ◽  
Limiting Factors ◽  
Stand Age ◽  
Net Ecosystem Productivity ◽  
Growth Responses ◽  
Ecosystem Productivity ◽  
Forest Growth Model

Abstract. The effects of atmospheric nitrogen deposition (Ndep) on carbon (C) sequestration in forests have often been assessed by relating differences in productivity to spatial variations of Ndep across a large geographic domain. These correlations generally suffer from covariation of other confounding variables related to climate and other growth-limiting factors, as well as large uncertainties in total (dry + wet) reactive nitrogen (Nr) deposition. We propose a methodology for untangling the effects of Ndep from those of meteorological variables, soil water retention capacity and stand age, using a mechanistic forest growth model in combination with eddy covariance CO2 exchange fluxes from a Europe-wide network of 22 forest flux towers. Total Nr deposition rates were estimated from local measurements as far as possible. The forest data were compared with data from natural or semi-natural, non-woody vegetation sites. The response of forest net ecosystem productivity to nitrogen deposition (dNEP ∕ dNdep) was estimated after accounting for the effects on gross primary productivity (GPP) of the co-correlates by means of a meta-modelling standardization procedure, which resulted in a reduction by a factor of about 2 of the uncorrected, apparent dGPP ∕ dNdep value. This model-enhanced analysis of the C and Ndep flux observations at the scale of the European network suggests a mean overall dNEP ∕ dNdep response of forest lifetime C sequestration to Ndep of the order of 40–50 g C per g N, which is slightly larger but not significantly different from the range of estimates published in the most recent reviews. Importantly, patterns of gross primary and net ecosystem productivity versus Ndep were non-linear, with no further growth responses at high Ndep levels (Ndep > 2.5–3 g N m−2 yr−1) but accompanied by increasingly large ecosystem N losses by leaching and gaseous emissions. The reduced increase in productivity per unit N deposited at high Ndep levels implies that the forecast increased Nr emissions and increased Ndep levels in large areas of Asia may not positively impact the continent's forest CO2 sink. The large level of unexplained variability in observed carbon sequestration efficiency (CSE) across sites further adds to the uncertainty in the dC∕dN response.

scholarly journals Carbon / nitrogen interactions in European forests and semi-natural vegetation. Part II: Untangling climatic, edaphic, management and nitrogen deposition effects on carbon sequestration potentials

2019 ◽  
Author(s):  
Chris R. Flechard ◽  
Marcel van Oijen ◽  
David R. Cameron ◽  
Wim de Vries ◽  
Andreas Ibrom ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Nitrogen Deposition ◽  
C Sequestration ◽  
Forest Growth ◽  
Limiting Factors ◽  
Stand Age ◽  
Water Retention Capacity ◽  
Gaseous Emissions ◽  
N Losses ◽  
Forest Growth Model

Abstract. The effects of atmospheric nitrogen deposition (Ndep) on carbon (C) sequestration in forests have often been assessed by relating differences in productivity to spatial variations of Ndep across a large geographic domain. These correlations generally suffer from covariation of other confounding variables related to climate and other growth-limiting factors, as well as large uncertainties in total (dry + wet) reactive nitrogen (Nr) deposition. We propose a methodology for untangling the effects of Ndep from those of meteorological variables, soil water retention capacity and stand age, using a mechanistic forest growth model in combination with eddy covariance CO2 exchange fluxes from a Europe-wide network of forest flux towers. Total Nr deposition rates were estimated from local measurements as far as possible. The forest data were compared with data from natural or semi-natural, non-woody vegetation sites. The carbon sequestration response of forests to nitrogen deposition (dC / dN) was estimated after accounting for the effects of the co-correlates by means of a meta-modelling standardization procedure, which resulted in a reduction by a factor of about 2 of the uncorrected, apparent dC / dN value. This model-enhanced analysis of the C and Ndep flux observations at the scale of the European network suggests a mean overall dC / dN response of forest lifetime C sequestration to Ndep of the order of 40–50 g (C) g−1 (N), which is slightly larger but not significantly different from the range of estimates published in the most recent reviews. Importantly, patterns of gross primary and net ecosystem productivity versus Ndep were non-linear, with no further responses at high Ndep levels (Ndep > 2.5–3 g (N) m−2 yr−1) partly due to large ecosystem N losses by leaching and gaseous emissions. The reduced increase in productivity per unit N deposited at high Ndep levels implies that the forecast increased Nr emissions and increased Ndep levels in large areas of Asia may not positively impact the continent's forest CO2 sink. The large level of unexplained variability in observed carbon sequestration efficiency (CSE) across sites further adds to the uncertainty in the dC / dN response.

scholarly journals Carbon–nitrogen interactions in European forests and semi-natural vegetation – Part 1: Fluxes and budgets of carbon, nitrogen and greenhouse gases from ecosystem monitoring and modelling

2020 ◽  
Vol 17 (6) ◽  
pp. 1583-1620 ◽  
Author(s):  
Chris R. Flechard ◽  
Andreas Ibrom ◽  
Ute M. Skiba ◽  
Wim de Vries ◽  
Marcel van Oijen ◽  
...  
Keyword(s):  
Large Scale ◽  
C Sequestration ◽  
Forest Growth ◽  
Natural Vegetation ◽  
Joint Analysis ◽  
N Saturation ◽  
Net Ecosystem Productivity ◽  
Ecosystem Productivity ◽  
Wide Range ◽  
The Impact

Abstract. The impact of atmospheric reactive nitrogen (Nr) deposition on carbon (C) sequestration in soils and biomass of unfertilized, natural, semi-natural and forest ecosystems has been much debated. Many previous results of this dC∕dN response were based on changes in carbon stocks from periodical soil and ecosystem inventories, associated with estimates of Nr deposition obtained from large-scale chemical transport models. This study and a companion paper (Flechard et al., 2020) strive to reduce uncertainties of N effects on C sequestration by linking multi-annual gross and net ecosystem productivity estimates from 40 eddy covariance flux towers across Europe to local measurement-based estimates of dry and wet Nr deposition from a dedicated collocated monitoring network. To identify possible ecological drivers and processes affecting the interplay between C and Nr inputs and losses, these data were also combined with in situ flux measurements of NO, N2O and CH4 fluxes; soil NO3- leaching sampling; and results of soil incubation experiments for N and greenhouse gas (GHG) emissions, as well as surveys of available data from online databases and from the literature, together with forest ecosystem (BASFOR) modelling. Multi-year averages of net ecosystem productivity (NEP) in forests ranged from −70 to 826 g C m−2 yr−1 at total wet + dry inorganic Nr deposition rates (Ndep) of 0.3 to 4.3 g N m−2 yr−1 and from −4 to 361 g C m−2 yr−1 at Ndep rates of 0.1 to 3.1 g N m−2 yr−1 in short semi-natural vegetation (moorlands, wetlands and unfertilized extensively managed grasslands). The GHG budgets of the forests were strongly dominated by CO2 exchange, while CH4 and N2O exchange comprised a larger proportion of the GHG balance in short semi-natural vegetation. Uncertainties in elemental budgets were much larger for nitrogen than carbon, especially at sites with elevated Ndep where Nr leaching losses were also very large, and compounded by the lack of reliable data on organic nitrogen and N2 losses by denitrification. Nitrogen losses in the form of NO, N2O and especially NO3- were on average 27 % (range 6 %–54 %) of Ndep at sites with Ndep < 1 g N m−2 yr−1 versus 65 % (range 35 %–85 %) for Ndep > 3 g N m−2 yr−1. Such large levels of Nr loss likely indicate that different stages of N saturation occurred at a number of sites. The joint analysis of the C and N budgets provided further hints that N saturation could be detected in altered patterns of forest growth. Net ecosystem productivity increased with Nr deposition up to 2–2.5 g N m−2 yr−1, with large scatter associated with a wide range in carbon sequestration efficiency (CSE, defined as the NEP ∕ GPP ratio). At elevated Ndep levels (> 2.5 g N m−2 yr−1), where inorganic Nr losses were also increasingly large, NEP levelled off and then decreased. The apparent increase in NEP at low to intermediate Ndep levels was partly the result of geographical cross-correlations between Ndep and climate, indicating that the actual mean dC∕dN response at individual sites was significantly lower than would be suggested by a simple, straightforward regression of NEP vs. Ndep.

scholarly journals High-resolution forest carbon flux mapping and monitoring in the Pacific Northwest with time since disturbance and disturbance legacies inferred from remote sensing and inventory data

2016 ◽  
Author(s):  
Huan Gu ◽  
Christopher A. Williams ◽  
Bardan Ghimire ◽  
Feng Zhao ◽  
Chengquan Huang
Keyword(s):  
Remote Sensing ◽  
Pacific Northwest ◽  
Forest Inventory ◽  
Stand Age ◽  
Net Ecosystem Productivity ◽  
Fine Scale ◽  
Ecosystem Productivity ◽  
Inventory Data ◽  
Forest Inventory Data ◽  
The Pacific

Abstract. Assessment of forest carbon storage and uptake is central to understanding the role forests play in the global carbon cycle and policy-making aimed at mitigating climate change. Current U.S. carbon stocks and fluxes are monitored and reported at fine-scale regionally, or coarse-scale nationally. We proposed a new methodology of quantifying carbon uptake and release across forested landscapes in the Pacific Northwest (PNW) at a fine scale (30 m) by combining remote-sensing based disturbance year, disturbance type, and aboveground biomass with forest inventory data in a carbon modelling framework. Time since disturbance is a key intermediate determinant that aided the assessment of disturbance-driven carbon emissions and removals legacies. When a recent disturbance was detected, time since disturbance can be directly determined by remote sensing-derived disturbance products; and if not, time since last stand-clearing was inferred from remote sensing-derived 30 m biomass map and field inventory-derived species-specific biomass regrowth curves. Net ecosystem productivity (NEP) was further mapped based on carbon stock and flux trajectories that described how NEP changes with time following harvest, fire, or bark beetle disturbances of varying severity. Uncertainties from biomass map and forest inventory data were propagated by probabilistic sampling to provide a probabilistic, statistical distribution of stand age and NEP for each forest pixel. We mapped mean, standard deviation and statistical distribution of stand age and NEP at 30 m in the PNW region. Our map indicated a net ecosystem productivity of 5.2 Tg C y−1 for forestlands circa 2010 in the study area, with net uptake in relatively mature (> 24 year old) forests (13.6 Tg C y−1) overwhelming net negative NEP from tracts that have seen recent harvest (−6.4 Tg C y−1), fires (−0.5 Tg C y−1), and bark beetle outbreaks (−1.4 Tg C y−1). The approach will be applied to forestlands in other regions of the conterminous U.S. to advance a more comprehensive monitoring, mapping and reporting the carbon consequences of forest change across the U.S.

scholarly journals Soil respiration and net ecosystem productivity in a chronosequence of hybrid poplar plantations

2020 ◽  
Vol 100 (4) ◽  
pp. 488-502
Author(s):  
Scott X. Chang ◽  
Zheng Shi ◽  
Barb R. Thomas
Keyword(s):  
Soil Respiration ◽  
Soil Temperature ◽  
Populus Deltoides ◽  
Hybrid Poplar ◽  
Stand Age ◽  
Net Ecosystem Productivity ◽  
Ecosystem Productivity ◽  
Short Rotation ◽  
C Dynamics ◽  
Woody Crop

Forest stand age can affect ecosystem carbon (C) cycling and net ecosystem productivity (NEP). In Canada, establishment of short-rotation plantations on previously agricultural lands has been ongoing, but the effect of stand development on soil respiration (Rs) and NEP in such plantations is poorly understood. These types of data are essential for constraining ecosystem models that simulate C dynamics over the rotation of a plantation. We studied Rs (including autotrophic, Ra, and heterotrophic, Rh) and NEP in 2008 and 2009 in a chronosequence of 5-, 8-, 14-, and 16-yr-old (ages in 2009) hybrid poplar (Populus deltoides × Populus × petrowskyana var. Walker) plantations in northern Alberta. The highest Rs and NEP were generally found in the 14-yr-old stand. Seasonal variations in Rs were similar among the plantations, with most of the variation explained by soil temperature at the 10 cm depth in 2008 with far less explained in 2009, a much drier year. In diurnal measurements, hysteresis was found between soil respiration and soil temperature, with the patterns of hysteresis different among stand ages. Soil respiration in the 14-yr-old plantation had the greatest sensitivity to temperature changes. Stand age did not affect the Rh:Rs ratio, whereas the NEP exhibited strong inter-annual variability. We conclude that stand age was a major factor affecting Rs and NEP, and such effects should be considered in empirical models used to simulate ecosystem C dynamics to evaluate potentials for C sequestration and the C source–sink relationship in short-rotation woody crop systems.

scholarly journals Above-ground woody carbon sequestration measured from tree rings is coherent with net ecosystem productivity at five eddy-covariance sites

2013 ◽  
Vol 201 (4) ◽  
pp. 1289-1303 ◽  
Author(s):  
Flurin Babst ◽  
Olivier Bouriaud ◽  
Dario Papale ◽  
Bert Gielen ◽  
Ivan A. Janssens ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Eddy Covariance ◽  
Tree Rings ◽  
Net Ecosystem Productivity ◽  
Ecosystem Productivity

scholarly journals Carbon / nitrogen interactions in European forests and semi-natural vegetation. Part I: Fluxes and budgets of carbon, nitrogen and greenhouse gases from ecosystem monitoring and modelling

2019 ◽  
Author(s):  
Chris R. Flechard ◽  
Andreas Ibrom ◽  
Ute M. Skiba ◽  
Wim de Vries ◽  
Marcel van Oijen ◽  
...  
Keyword(s):  
Large Scale ◽  
Ghg Emissions ◽  
C Sequestration ◽  
Natural Vegetation ◽  
N Saturation ◽  
Net Ecosystem Productivity ◽  
Ecosystem Productivity ◽  
Ecosystem Monitoring ◽  
Wide Range ◽  
The Impact

Abstract. The impact of atmospheric reactive nitrogen (Nr) deposition on carbon (C) sequestration in soils and biomass of unfertilised, natural, semi-natural and forest ecosystems has been much debated. Many previous results of this dC / dN response were based on changes in carbon stocks from periodical soil and ecosystem inventories, associated with estimates of Nr deposition obtained from large-scale chemical transport models. This study and a companion paper (Flechard et al., 2019) strive to reduce uncertainties of N effects on C sequestration by linking multi-annual gross and net ecosystem productivity estimates from 40 eddy covariance flux towers across Europe to local measurement-based estimates of dry and wet Nr deposition from a dedicated collocated monitoring network. To identify possible ecological drivers and processes affecting the interplay between C and Nr inputs and losses, these data were also combined with in situ flux measurements of NO, N2O and CH4 fluxes, soil NO3− leaching sampling, as well as results of soil incubation experiments for N and greenhouse gas (GHG) emissions, surveys of available data from online databases and from the literature, together with forest ecosystem (BASFOR) modelling. Multi-year averages of net ecosystem productivity (NEP) in forests ranged from −70 to 826 g (C) m−2 yr−1 at total wet + dry inorganic Nr deposition rates (Ndep) of 0.3 to 4.3 g (N) m−2 yr−1; and from −4 to 361 g (C) m−2 yr−1 at Ndep rates of 0.1 to 3.1 g (N) m−2 yr−1 in short semi-natural vegetation (moorlands, wetlands and unfertilised extensively managed grasslands). The GHG budgets of the forests were strongly dominated by CO2 exchange, while CH4 and N2O exchange comprised a larger proportion of the GHG balance in short semi-natural vegetation. Nitrogen losses in the form of NO, N2O and especially NO3− were of the order of 10–20 % of Ndep at sites with Ndep  3 g (N) m−2 yr−1, indicating that perhaps one third of the sites were in a state of early to advanced N saturation. Net ecosystem productivity increased with Nr deposition up to 2–2.5 g (N) m−2 yr−1, with large scatter associated with a wide range in carbon sequestration efficiency (CSE, defined as the NEP / GPP ratio). At elevated Ndep levels (> 2.5 g (N) m−2 yr−1), where inorganic Nr losses were also increasingly large, NEP levelled off and then decreased. The apparent increase in NEP at low to intermediate Ndep levels was partly the result of geographical cross-correlations between Ndep and climate, indicating that the actual mean dC / dN response at individual sites was significantly lower than would be suggested by a simple, straightforward regression of NEP vs. Ndep.

scholarly journals Sustained Biomass Carbon Sequestration by China’s Forests from 2010 to 2050

Forests ◽  
2018 ◽  
Vol 9 (11) ◽  
pp. 689 ◽  
Author(s):  
Chunhua Zhang ◽  
Weimin Ju ◽  
Jingming Chen ◽  
Meihong Fang ◽  
Mengquan Wu ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Northern Region ◽  
National Forest Inventory ◽  
Forest Growth ◽  
Forest Area ◽  
Stand Age ◽  
Biomass Carbon ◽  
Forest Types ◽  
Carbon Density ◽  
Middle Aged

China’s forests have functioned as important carbon sinks. They are expected to have substantial future potential for biomass carbon sequestration (BCS) resulting from afforestation and reforestation. However, previous estimates of forest BCS have included large uncertainties due to the limitations of sample size, multiple data sources, and inconsistent methodologies. This study refined the BCS estimation of China’s forests from 2010 to 2050 using the national forest inventory data (FID) of 2009−2013, as well as the relationships between forest biomass and stand age retrieved from field observations for major forest types in different regions of China. The results showed that biomass–age relationships were well-fitted using field data, with respective R2 values more than 0.70 (p < 0.01) for most forest types, indicating the applicability of these relationships developed for BCS estimation in China. National BCS would increase from 130.90 to 159.94 Tg C year−1 during the period of 2010−2050 because of increases in forest area and biomass carbon density, with a maximum of 230.15 Tg C year−1 around 2030. BCS for young and middle-aged forests would increase by 65.35 and 15.38 Tg C year−1, respectively. 187.8% of this increase would be offset by premature, mature, and overmature forests. During the study period, forest BCS would increase in all but the northern region. The largest contributor to the increment would be the southern region (52.5%), followed by the southwest, northeast, northwest, and east regions. Their BCS would be primarily driven by the area expansion and forest growth of young and middle-aged forests as a result of afforestation and reforestation. In the northern region, BCS reduction would occur mainly in the Inner Mongolia province (6.38 Tg C year−1) and be caused predominantly by a slowdown in the increases of forest area and biomass carbon density for different age–class forests. Our findings are in broader agreement with other studies, which provide valuable references for the validation and parameterization of carbon models and climate-change mitigation policies in China.

scholarly journals High-resolution mapping of time since disturbance and forest carbon flux from remote sensing and inventory data to assess harvest, fire, and beetle disturbance legacies in the Pacific Northwest

2016 ◽  
Vol 13 (22) ◽  
pp. 6321-6337 ◽  
Author(s):  
Huan Gu ◽  
Christopher A. Williams ◽  
Bardan Ghimire ◽  
Feng Zhao ◽  
Chengquan Huang
Keyword(s):  
Pacific Northwest ◽  
Forest Inventory ◽  
Carbon Flux ◽  
Forest Carbon ◽  
Stand Age ◽  
Net Ecosystem Productivity ◽  
Ecosystem Productivity ◽  
Inventory Data ◽  
Forest Inventory Data ◽  
The Pacific

Abstract. Accurate assessment of forest carbon storage and uptake is central to policymaking aimed at mitigating climate change and understanding the role forests play in the global carbon cycle. Disturbances have highly diverse impacts on forest carbon dynamics, making them a challenge to quantify and report. Time since disturbance is a key intermediate determinant that aids the assessment of disturbance-driven carbon emissions and removals legacies. We propose a new methodology of quantifying time since disturbance and carbon flux across forested landscapes in the Pacific Northwest (PNW) at a fine scale (30 m) by combining remote sensing (RS)-based disturbance year, disturbance type, and above-ground biomass with forest inventory data. When a recent disturbance is detected, time since disturbance can be directly determined by combining three RS-derived disturbance products, or time since the last stand clearing can be inferred from a RS-derived 30 m biomass map and field inventory-derived species-specific biomass accumulation curves. Net ecosystem productivity (NEP) is further mapped based on carbon stock and flux trajectories derived from the Carnegie-Ames-Stanford Approach (CASA) model in our prior work that described how NEP changes with time following harvest, fire, or bark beetle disturbances of varying severity. Uncertainties from biomass map and forest inventory data were propagated by probabilistic sampling to provide a statistical distribution of stand age and NEP for each forest pixel. We mapped mean, standard deviation, and statistical distribution of stand age and NEP at 30 m in the PNW region. Our map indicated a net ecosystem productivity of 5.9 Tg C yr−1 for forestlands circa 2010 in the study area, with net uptake in relatively mature (> 24 years old) forests (13.6 Tg C yr−1) overwhelming net negative NEP from tracts that had recent harvests (−6.4 Tg C yr−1), fires (−0.5 Tg C yr−1), and bark beetle outbreaks (−0.8 Tg C yr−1). The approach will be applied to forestlands in other regions of the conterminous US to advance a more comprehensive monitoring, mapping, and reporting of the carbon consequences of forest change across the US.

Das nachhaltig verfügbare Holznutzungspotenzial im Schweizer Wald

2016 ◽  
Vol 167 (3) ◽  
pp. 162-171 ◽  
Author(s):  
Ruedi Taverna ◽  
Michael Gautschi ◽  
Peter Hofer
Keyword(s):  
National Level ◽  
Reference Value ◽  
Forest Growth ◽  
Long Term Effects ◽  
Management Scenarios ◽  
Additional Time ◽  
Basic Scenario ◽  
Economic Framework ◽  
Forest Growth Model ◽  
New Findings

The sustainably available wood use potential in Swiss forests Based on the most recent simulations created using the Massimo forest growth model, the sustainably available wood use potential in Swiss forests was calculated for five management scenarios for the next three decades as well as for two additional time periods in the future (to monitor the long-term effects). The term “sustainably available wood use potential” covers those wood quantities that could be put on the market, taking into account socio-ecological and economic restrictions on use. The sustainably available wood use potential is provided for production regions, priority functions as well as the assortment and qualities of timber. The previously used factors of the applied “onion” model were checked and modified, if necessary, in order to take new findings and current cost developments into consideration. The calculations for all scenarios come up with a sustainably available wood use potential that is much lower than in earlier investigations. Depending on the scenario and decade, sustainably available wood use potential accounts for less than 50% of the total use potential. The biggest decrease in total use potential was due to economic framework conditions. Turning to Switzerland as a whole, towards the end of the investigation period (2106) those scenarios including a sharp increase in use in the first three decades result in a sustainably available wood use potential that is clearly lower than the reference value used at the beginning of the simulation. In the basic scenario (constant stock) and in the scenario in which the form of management used to date (increasing stock) was simulated, the sustainably available wood use potential at national level remained more or less the same throughout the simulation period, ranging from 5 to 6 million m3 per year.

Sign in / Sign up

Export Citation Format

Share Document