scholarly journals Thinning Effect of C Sequestration along an Elevation Gradient of Mediterranean Pinus spp. Plantations

Forests ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1583
Author(s):  
Antonio M. Cachinero-Vivar ◽  
Guillermo Palacios-Rodríguez ◽  
Miguel A. Lara-Gómez ◽  
Rafael M. Navarro-Cerrillo
Keyword(s):  
Carbon Sequestration ◽  
Elevation Gradient ◽  
Fold Increase ◽  
C Sequestration ◽  
Positive Influence ◽  
Growth Patterns ◽  
Fixation Capacity ◽  
Mediterranean Pine ◽  
Pinus Spp ◽  
Thinning Effect

Forests are key elements in mitigating the effects of climate change due to the fact of their carbon sequestration capacity. Forest management can be oriented to optimise the carbon sequestration capacity of forest stands, in line with other productive objectives and the generation of ecosystem services. This research aimed to determine whether thinning treatments have a positive influence on the growth patterns of some of the main Mediterranean pine species and, therefore, on their Carbon (C) fixation capacity, both in terms of living biomass and soil organic carbon. The results obtained show that C sequestration capacity (biomass and SOC) increased at higher thinning intensities due to the induced alterations in tree growth patterns. We observed almost a 1.5-fold increase in P. nigra and P. sylvestris, respectively, and over a two-fold increase in P. pinaster under heavy thinning treatments; SOC stocks were affected by the intensity of the thinning treatments. These results can contribute to improving silvicultural practices aimed at C sequestration in forest plantations located in dry areas of the Mediterranean.

scholarly journals How Do Mediterranean Pine Trees Respond to Drought and Precipitation Events along an Elevation Gradient?

Forests ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 758 ◽  
Author(s):  
Sonja Szymczak ◽  
Martin Häusser ◽  
Emilie Garel ◽  
Sébastien Santoni ◽  
Frédéric Huneau ◽  
...  
Keyword(s):  
Tree Growth ◽  
Elevation Gradient ◽  
Growth Patterns ◽  
Precipitation Event ◽  
Cold Environments ◽  
Pine Trees ◽  
The Mediterranean ◽  
Mediterranean Pine ◽  
Study Sites ◽  
Precipitation Events

Drought is a major factor limiting tree growth and plant vitality. In the Mediterranean region, the length and intensity of drought stress strongly varies with altitude and site conditions. We used electronic dendrometers to analyze the response of two native pine species to drought and precipitation events. The five study sites were located along an elevation gradient on the Mediterranean island of Corsica (France). Positive stem increment in the raw dendrometer measurements was separated into radial stem growth and stem swelling/shrinkage in order to determine which part of the trees’ response to climate signals can be attributed to growth. Precipitation events of at least 5 mm and dry periods of at least seven consecutive days without precipitation were determined over a period of two years. Seasonal dynamics of stem circumference changes were highly variable among the five study sites. At higher elevations, seasonal tree growth showed patterns characteristic for cold environments, while low-elevation sites showed bimodal growth patterns characteristic of drought prone areas. The response to precipitation events was uniform and occurred within the first six hours after the beginning of a precipitation event. The majority of stem circumference increases were caused by radial growth, not by stem swelling due to water uptake. Growth-induced stem circumference increase occurred at three of the five sites even during dry periods, which could be attributed to stored water reserves within the trees or the soils. Trees at sites with soils of low water-holding capacity were most vulnerable to dry periods.

Six-fold increase in historical Northern Hemisphere concurrent large heatwaves driven by warming and changing atmospheric circulations

2021 ◽  
pp. 1-39
Author(s):  
Cassandra D.W. Rogers ◽  
Kai Kornhuber ◽  
Sarah E. Perkins-Kirkpatrick ◽  
Paul C. Loikith ◽  
Deepti Singh
Keyword(s):  
Northern Hemisphere ◽  
Large Scale ◽  
Warm Season ◽  
Fold Increase ◽  
Circulation Pattern ◽  
Positive Influence ◽  
Climate Risks ◽  
Circulation Patterns ◽  
Multiple Regions ◽  
Barents And Kara Seas

AbstractSimultaneous heatwaves affecting multiple regions (referred to as concurrent heatwaves), pose compounding threats to various natural and societal systems, including global food chains, emergency response systems, and reinsurance industries. While anthropogenic climate change is increasing heatwave risks across most regions, the interactions between warming and circulation changes that yield concurrent heatwaves remain understudied. Here, we quantify historical (1979-2019) trends in concurrent heatwaves during the warm-season (May-September, MJJAS) across the Northern Hemisphere mid- to high-latitudes. We find a significant increase of ~46% in the mean spatial extent of concurrent heatwaves, ~17% increase in their maximum intensity, and ~6-fold increase in their frequency. Using Self-Organising Maps, we identify large-scale circulation patterns (300 hPa) associated with specific concurrent heatwave configurations across Northern Hemisphere regions. We show that observed changes in the frequency of specific circulation patterns preferentially increase the risk of concurrent heatwaves across particular regions. Patterns linking concurrent heatwaves across eastern North America, eastern and northern Europe, parts of Asia, and the Barents and Kara Seas, show the largest increases in frequency (~5.9 additional days per decade). We also quantify the relative contributions of circulation pattern changes and warming to overall observed concurrent heatwave day frequency trends. While warming has a predominant and positive influence on increasing concurrent heatwaves, circulation pattern changes have a varying influence and account for up to 0.8 additional concurrent heatwave days per decade. Identifying regions with an elevated risk of concurrent heatwaves and understanding their drivers is indispensable for evaluating projected climate risks on interconnected societal systems and fostering regional preparedness in a changing climate.

scholarly journals Effects of Wetland Restoration and Conservation Projects on Soil Carbon Sequestration in the Ningxia Basin of the Yellow River in China from 2000 to 2015

2020 ◽  
Vol 12 (24) ◽  
pp. 10284
Author(s):  
Xiaoyan Bu ◽  
Dan Cui ◽  
Suocheng Dong ◽  
Wenbao Mi ◽  
Yu Li ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Soil Carbon ◽  
Wetland Restoration ◽  
Yellow River ◽  
C Sequestration ◽  
Soil Carbon Sequestration ◽  
The Yellow River ◽  
Wetland Soil ◽  
Landsat 8 ◽  
Conservation Projects

The long-term use of wetlands stresses wetland ecosystems and leads to degradation and C loss. This study explored an optimal remote sensing-multivariate linear regression model (RS-MLRM) for estimating wetland soil organic carbon (SOC) by using a combination of the measured SOC and above ground biomass (AGB) from 273 samples, textural features, spectral information, and a vegetation index calculated from Landsat-8 images using the Ningxia Basin of the Yellow River as the study area. To derive the optimal predictor model for SOC, these variables were regressed against the measured SOC. These were used to predict SOC and evaluate the contribution of wetland restoration and conservation projects to soil carbon sequestration and sinks on the Ningxia Basin of the Yellow River in early (2000 and 2005), intermediate (2010), and recent (2015) years. The results show that from 2000 to 2015, the project-induced contribution to C sequestration was 20.49 TC, with an annual sink of 1.37 TC. This accounted for 54.06% of the total wetland ecosystem C sequestration on the Ningxia Basin of the Yellow River. Moreover, there was a significant success of restoration and conservation projects regarding C sequestration. These restoration and conservation projects have substantially contributed to CO2 mitigation in the arid area.

Predicting a ceiling for soil carbon sequestration on variable landscapes under no-till in eastern Canada

2008 ◽  
Vol 88 (5) ◽  
pp. 775-785 ◽  
Author(s):  
C. Chan ◽  
B D Kay ◽  
E G Gregorich
Keyword(s):  
Steady State ◽  
Carbon Sequestration ◽  
Crop Production ◽  
C Sequestration ◽  
Saturation Ratio ◽  
Eastern Canada ◽  
Biochemical Basis ◽  
No Till ◽  
Variable Landscapes ◽  
Variable Topography

Much of the crop production in eastern Canada occurs on landscapes where erosion/deposition has occurred. The potential to sequester C by reducing tillage will be greatest in those parts of landscapes where the organic carbon (OC) stocks are below a ceiling (OCc). However, the physical/biochemical basis for OCc is not understood and therefore it is difficult to predict where C sequestration will occur in landscapes with variable topography. In this research we tested two hypotheses proposed as the physical/biochemical basis for OCc: (1) OCc coincides with the steady state OC (OCss) stocks on non-eroded sites and (2) OCc coincides with a critical proportion of the capacity of the clay and silt fraction to absorb and retain OC (i.e., a critical saturation ratio). Comparison of data from sites with level and variable topography disproved the first hypothesis; OC stocks on level sites were, on average, 14 Mg ha-1 larger than OCc 15 yr after implementing no-till (NT) on variable landscapes. Further analyses of data from sites with variable topography indicated the saturation ratio in the surface 10 cm of soil must be less than 0.45 before NT results in C sequestration in the profile. Although the analyses are not incompatible with the second hypothesis, the critical saturation ratio is surprisingly small compared with values obtained from level sites. Additional tests of the second hypothesis are warranted on sites with variable topography in which C sequestration has been documented. Key words: Erosion, C capacity, saturation ratio, spatial variability, C sequestration

scholarly journals Low assimilate partitioning to root biomass is associated with carbon losses at an intensively managed temperate grassland

2020 ◽  
Author(s):  
Arne Poyda ◽  
Thorsten Reinsch ◽  
Inger J. Struck ◽  
R. Howard Skinner ◽  
Christof Kluß ◽  
...  
Keyword(s):  
Plant Biomass ◽  
Net Primary Production ◽  
C Sequestration ◽  
Growth Patterns ◽  
High Productivity ◽  
Grass Root ◽  
Use Efficiency ◽  
Intensively Managed ◽  
Carbon Losses ◽  
Grassland Site

Abstract Aims This study aimed to investigate how efficiently assimilated carbon (C) is incorporated in plant biomass at an intensively managed old permanent grassland, how C is partitioned between shoots and roots and what are the implications for C sequestration. Methods Using the eddy covariance technique, the atmosphere-biosphere exchange of CO2 was measured for two years at a sandy grassland site in northern Germany. In addition to aboveground net primary production (ANPP), belowground NPP (BNPP) was observed using the ingrowth core method. Results The grassland showed a high productivity in terms of biomass yield (14.8 Mg dry matter ha−1 yr−1) and net CO2 uptake (−2.82 Mg CO2-C ha−1 yr−1). Photosynthetically assimilated C was converted to biomass with a high carbon use efficiency (CUE) of 71% during the growing season. However, a comparably low fraction of 17% of NPP was allocated to roots (fBNPP). Consequently, the main fraction of NPP was removed during harvest, turning the site into a net source of 0.29 Mg C ha−1 yr−1. Conclusions Our study showed the flexibility of grass root growth patterns in response to alterations in resource availability. We conclude that highly fertilized grasslands can lose their ability for C sequestration due to low belowground C allocation.

Can growth be used as a surrogate measure of walleye (Sander vitreus) abundance change?

2005 ◽  
Vol 62 (9) ◽  
pp. 2159-2168 ◽  
Author(s):  
Greg G Sass ◽  
James F Kitchell
Keyword(s):  
Positive Influence ◽  
Growth Patterns ◽  
Sander Vitreus ◽  
Adult Density ◽  
Lake Productivity ◽  
Regional Patterns ◽  
Density Dependent ◽  
Morphoedaphic Index ◽  
Improved Model ◽  
Surrogate Measures

We examined several models to determine the relative contributions of density-dependent and density-independent factors on walleye (Sander vitreus) growth in the ceded territory of Wisconsin from 1990 to 1999. We then used independent data from 2000 to determine how well each model predicted walleye growth and examined several models to determine if growth could be used to predict density. Adult density best predicted the mean size of age-3 males ( [Formula: see text]3m) and age-5 females ( [Formula: see text]5f). Density-independent measures of pH, the morphoedaphic index, maximum depth, and conductance had a positive influence on growth, while adult density negatively affected growth. The solely density-dependent models predicted [Formula: see text]3m and [Formula: see text]5f poorly in 2000. The addition of density-independent factors improved model predictions of [Formula: see text]3m and [Formula: see text]5f. Walleye growth did not predict adult walleye densities. Regional patterns in walleye growth were correlated with surrogate measures of lake productivity and to a lesser extent adult density. Density dependence had a relatively weak affect on growth patterns, suggesting that growth cannot be used as a surrogate method for monitoring abundance change.

scholarly journals Carbon sequestration

2007 ◽  
Vol 363 (1492) ◽  
pp. 815-830 ◽  
Author(s):  
Rattan Lal
Keyword(s):  
Carbon Sequestration ◽  
Energy Use ◽  
Deep Ocean ◽  
Cost Effective ◽  
C Sequestration ◽  
First Century ◽  
Ancillary Benefits ◽  
Atmospheric Concentration ◽  
Rate Of Increase ◽  
Climate Change Risks

Developing technologies to reduce the rate of increase of atmospheric concentration of carbon dioxide (CO 2 ) from annual emissions of 8.6 Pg C yr –1 from energy, process industry, land-use conversion and soil cultivation is an important issue of the twenty-first century. Of the three options of reducing the global energy use, developing low or no-carbon fuel and sequestering emissions, this manuscript describes processes for carbon (CO 2 ) sequestration and discusses abiotic and biotic technologies. Carbon sequestration implies transfer of atmospheric CO 2 into other long-lived global pools including oceanic, pedologic, biotic and geological strata to reduce the net rate of increase in atmospheric CO 2 . Engineering techniques of CO 2 injection in deep ocean, geological strata, old coal mines and oil wells, and saline aquifers along with mineral carbonation of CO 2 constitute abiotic techniques. These techniques have a large potential of thousands of Pg, are expensive, have leakage risks and may be available for routine use by 2025 and beyond. In comparison, biotic techniques are natural and cost-effective processes, have numerous ancillary benefits, are immediately applicable but have finite sink capacity. Biotic and abiotic C sequestration options have specific nitches, are complementary, and have potential to mitigate the climate change risks.

scholarly journals Variations in diurnal and seasonal net ecosystem carbon dioxide exchange in a semiarid sandy grassland ecosystem in China's Horqin Sandy Land

2020 ◽  
Vol 17 (24) ◽  
pp. 6309-6326
Author(s):  
Yayi Niu ◽  
Yuqiang Li ◽  
Hanbo Yun ◽  
Xuyang Wang ◽  
Xiangwen Gong ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Carbon Sequestration ◽  
C Sequestration ◽  
Annual Precipitation ◽  
Horqin Sandy Land ◽  
Sandy Land ◽  
Near Surface ◽  
Effective Precipitation ◽  
Precipitation Pulses ◽  
Sandy Grassland

Abstract. Grasslands are major terrestrial ecosystems in arid and semiarid regions, and they play important roles in the regional carbon dioxide (CO2) balance and cycles. Sandy grasslands are sensitive to climate change, yet the magnitudes, patterns, and environmental controls of their CO2 flows are poorly understood for some regions (e.g., China's Horqin Sandy Land). Here, we report the results from continuous year-round CO2 flux measurements for 5 years from a sandy grassland in China's Horqin Sandy Land. The grassland was a net CO2 source at an annual scale with a mean annual net ecosystem CO2 exchange (NEE) of 49 ± 8 gCm-2yr-1 for the years for which a complete dataset was available (2015, 2016, and 2018). Annual precipitation had the strongest effect on annual NEE; grassland carbon sequestration increased with the increasing precipitation since NEE depended on annual precipitation. In the spring, NEE decreased (i.e., C sequestration increased) with increasing magnitude of effective precipitation pulses, total monthly precipitation, and soil temperature (Tsoil). In the summer, NEE was dominated by the total seasonal precipitation and high precipitation pulses (> 20 mm). In the autumn, NEE increased (i.e., C sequestration decreased) with increasing effective precipitation pulses, Tsoil, and near-surface soil water content (SWC) but decreased with increased SWC deeper in the soil. In the winter, NEE decreased with increasing Tsoil and SWC. The sandy grassland was a net annual CO2 source because drought decreased carbon sequestration by the annual plants. Long-term observations will be necessary to reveal the true source or sink intensity and its response to environmental and biological factors.

scholarly journals Divergent Growth Responses to Warming between Stand-Grown and Open-Grown Trees in a Dryland Montane Forest in Northwestern China

Forests ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 1133 ◽  
Author(s):  
Lei Zhang ◽  
Hao Shi ◽  
Pengtao Yu ◽  
Yanhui Wang ◽  
Shufen Pan ◽  
...  
Keyword(s):  
Climate Change ◽  
Tree Growth ◽  
Elevation Gradient ◽  
Montane Forest ◽  
Growth Patterns ◽  
Forest Growth ◽  
Northwestern China ◽  
Growth Responses ◽  
Internal Factors ◽  
High Elevations

Dryland montane forests conserve water for people living in the fluvial plains. The fate of these forests under climate warming is strongly affected by local environmental factors. The question remains of how internal factors contribute to climate change impacts on forest growth in these regions. Here, we investigated tree ring records for similar-aged stand-grown trees and their neighboring open-grown trees at elevation in a dryland montane forest (Picea crassifolia Kom.) in northwestern China. The growth rate of open-grown trees is much higher than their neighboring stand-grown trees across the entire elevation gradient, and the lower the altitude, the greater the difference. Open-grown trees at different elevations showed similar growth patterns, as tree growth at all sites was accelerated over time. In contrast, growth patterns of stand-grown trees were divergent at different altitudes, as growth at high elevations (3100–3300 m a.s.l.) was accelerated, whereas growth at low elevations (2700–2900 m a.s.l.) became stable after the year 1990. Analysis of growth–climate relationships indicated that warming promoted open-grown tree growth across the entire altitude gradient, and also stand-grown tree growth at high elevations, but negatively affected the growth of stand-grown trees at low elevations. Water scarcity can be exacerbated by competition within forests, inhibiting the warming-induced benefits on tree growth. Moving window correlation analysis suggested the negative effect of warming on tree growth at low elevations was diminished after the late 1990s, as the drought stress was alleviated. Our research shows the divergent growth responses to warming of stand-grown and open-grown trees along elevation. It reveals effects of internal factors in determining tree growth response to warming and holds the potential to aid forest management and ecosystem models in responding to climate change.

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.

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