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 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 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.

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.

scholarly journals Model-Based Estimation of Amazonian Forests Recovery Time after Drought and Fire Events

Forests ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 8
Author(s):  
Bruno L. De Faria ◽  
Gina Marano ◽  
Camille Piponiot ◽  
Carlos A. Silva ◽  
Vinícius de L. Dantas ◽  
...  
Keyword(s):  
Recovery Time ◽  
Regional Scale ◽  
Forest Growth ◽  
Forest Recovery ◽  
Fire Intensity ◽  
Natural Ecosystems ◽  
Spatial And Temporal Patterns ◽  
Southeastern Part ◽  
Forest Growth Model ◽  
Carbon Losses

In recent decades, droughts, deforestation and wildfires have become recurring phenomena that have heavily affected both human activities and natural ecosystems in Amazonia. The time needed for an ecosystem to recover from carbon losses is a crucial metric to evaluate disturbance impacts on forests. However, little is known about the impacts of these disturbances, alone and synergistically, on forest recovery time and the resulting spatiotemporal patterns at the regional scale. In this study, we combined the 3-PG forest growth model, remote sensing and field derived equations, to map the Amazonia-wide (3 km of spatial resolution) impact and recovery time of aboveground biomass (AGB) after drought, fire and a combination of logging and fire. Our results indicate that AGB decreases by 4%, 19% and 46% in forests affected by drought, fire and logging + fire, respectively, with an average AGB recovery time of 27 years for drought, 44 years for burned and 63 years for logged + burned areas and with maximum values reaching 184 years in areas of high fire intensity. Our findings provide two major insights in the spatial and temporal patterns of drought and wildfire in the Amazon: (1) the recovery time of the forests takes longer in the southeastern part of the basin, and, (2) as droughts and wildfires become more frequent—since the intervals between the disturbances are getting shorter than the rate of forest regeneration—the long lasting damage they cause potentially results in a permanent and increasing carbon losses from these fragile ecosystems.

scholarly journals Environmental change impacts on the C- and N-cycle of European forests: a model comparison study

2013 ◽  
Vol 10 (3) ◽  
pp. 1751-1773 ◽  
Author(s):  
D. R. Cameron ◽  
M. Van Oijen ◽  
C. Werner ◽  
K. Butterbach-Bahl ◽  
R. Grote ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Central Europe ◽  
Tree Species ◽  
Carbon Sink ◽  
N2o Emission ◽  
Forest Growth ◽  
N2o Emissions ◽  
European Forests ◽  
Considerable Uncertainty ◽  
Carbon And Nitrogen

Abstract. Forests are important components of the greenhouse gas balance of Europe. There is considerable uncertainty about how predicted changes to climate and nitrogen deposition will perturb the carbon and nitrogen cycles of European forests and thereby alter forest growth, carbon sequestration and N2O emission. The present study aimed to quantify the carbon and nitrogen balance, including the exchange of greenhouse gases, of European forests over the period 2010–2030, with a particular emphasis on the spatial variability of change. The analysis was carried out for two tree species: European beech and Scots pine. For this purpose, four different dynamic models were used: BASFOR, DailyDayCent, INTEGRATOR and Landscape-DNDC. These models span a range from semi-empirical to complex mechanistic. Comparison of these models allowed assessment of the extent to which model predictions depended on differences in model inputs and structure. We found a European average carbon sink of 0.160 ± 0.020 kgC m−2 yr−1 (pine) and 0.138 ± 0.062 kgC m−2 yr−1 (beech) and N2O source of 0.285 ± 0.125 kgN ha−1 yr−1 (pine) and 0.575 ± 0.105 kgN ha−1 yr−1 (beech). The European average greenhouse gas potential of the carbon sink was 18 (pine) and 8 (beech) times that of the N2O source. Carbon sequestration was larger in the trees than in the soil. Carbon sequestration and forest growth were largest in central Europe and lowest in northern Sweden and Finland, N. Poland and S. Spain. No single driver was found to dominate change across Europe. Forests were found to be most sensitive to change in environmental drivers where the drivers were limiting growth, where changes were particularly large or where changes acted in concert. The models disagreed as to which environmental changes were most significant for the geographical variation in forest growth and as to which tree species showed the largest rate of carbon sequestration. Pine and beech forests were found to have differing sensitivities to environmental change, in particular the response to changes in nitrogen and precipitation, with beech forest more vulnerable to drought. There was considerable uncertainty about the geographical location of N2O emissions. Two of the models BASFOR and LandscapeDNDC had largest emissions in central Europe where nitrogen deposition and soil nitrogen were largest, whereas the two other models identified different regions with large N2O emission. N2O emissions were found to be larger from beech than pine forests and were found to be particularly sensitive to forest growth.

scholarly journals Tree species richness increases ecosystem carbon storage in subtropical forests

2018 ◽  
Vol 285 (1885) ◽  
pp. 20181240 ◽  
Author(s):  
Xiaojuan Liu ◽  
Stefan Trogisch ◽  
Jin-Sheng He ◽  
Pascal A. Niklaus ◽  
Helge Bruelheide ◽  
...  
Keyword(s):  
Species Richness ◽  
Tree Species ◽  
C Sequestration ◽  
Stand Age ◽  
Southeast China ◽  
Subtropical Forests ◽  
C Stocks ◽  
C Stock ◽  
Below Ground ◽  
Time Periods

Forest ecosystems are an integral component of the global carbon cycle as they take up and release large amounts of C over short time periods (C flux) or accumulate it over longer time periods (C stock). However, there remains uncertainty about whether and in which direction C fluxes and in particular C stocks may differ between forests of high versus low species richness. Based on a comprehensive dataset derived from field-based measurements, we tested the effect of species richness (3–20 tree species) and stand age (22–116 years) on six compartments of above- and below-ground C stocks and four components of C fluxes in subtropical forests in southeast China. Across forest stands, total C stock was 149 ± 12 Mg ha −1 with richness explaining 28.5% and age explaining 29.4% of variation in this measure. Species-rich stands had higher C stocks and fluxes than stands with low richness; and, in addition, old stands had higher C stocks than young ones. Overall, for each additional tree species, the total C stock increased by 6.4%. Our results provide comprehensive evidence for diversity-mediated above- and below-ground C sequestration in species-rich subtropical forests in southeast China. Therefore, afforestation policies in this region and elsewhere should consider a change from the current focus on monocultures to multi-species plantations to increase C fixation and thus slow increasing atmospheric CO 2 concentrations and global warming.

scholarly journals Improved understanding of drought controls on seasonal variation in Mediterranean forest canopy CO<sub>2</sub> and water fluxes through combined in situ measurements and ecosystem modelling

2009 ◽  
Vol 6 (8) ◽  
pp. 1423-1444 ◽  
Author(s):  
T. Keenan ◽  
R. García ◽  
A. D. Friend ◽  
S. Zaehle ◽  
C. Gracia ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Forest Canopy ◽  
Moisture Stress ◽  
Mediterranean Ecosystems ◽  
Forest Growth ◽  
Water Fluxes ◽  
Soil Moisture Stress ◽  
Dynamic Global Vegetation Model ◽  
Forest Growth Model

Abstract. Water stress is a defining characteristic of Mediterranean ecosystems, and is likely to become more severe in the coming decades. Simulation models are key tools for making predictions, but our current understanding of how soil moisture controls ecosystem functioning is not sufficient to adequately constrain parameterisations. Canopy-scale flux data from four forest ecosystems with Mediterranean-type climates were used in order to analyse the physiological controls on carbon and water flues through the year. Significant non-stomatal limitations on photosynthesis were detected, along with lesser changes in the conductance-assimilation relationship. New model parameterisations were derived and implemented in two contrasting modelling approaches. The effectiveness of two models, one a dynamic global vegetation model ("ORCHIDEE"), and the other a forest growth model particularly developed for Mediterranean simulations ("GOTILWA+"), was assessed and modelled canopy responses to seasonal changes in soil moisture were analysed in comparison with in situ flux measurements. In contrast to commonly held assumptions, we find that changing the ratio of conductance to assimilation under natural, seasonally-developing, soil moisture stress is not sufficient to reproduce forest canopy CO2 and water fluxes. However, accurate predictions of both CO2 and water fluxes under all soil moisture levels encountered in the field are obtained if photosynthetic capacity is assumed to vary with soil moisture. This new parameterisation has important consequences for simulated responses of carbon and water fluxes to seasonal soil moisture stress, and should greatly improve our ability to anticipate future impacts of climate changes on the functioning of ecosystems in Mediterranean-type climates.

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