scholarly journals Linking Soil CO2 Efflux to Individual Trees: Size-Dependent Variation and the Importance of the Birch Effect

2020 ◽  
Author(s):  
Sean C. Thomas ◽  
Jonathan S. Schurman
Keyword(s):  
Acer Saccharum ◽  
Dominant Role ◽  
Proximity Effects ◽  
Co2 Efflux ◽  
Plant Soil ◽  
C Cycle ◽  
Before And After ◽  
Recalcitrant Organic Matter ◽  
Individual Trees ◽  
Birch Effect

Soil CO2 efflux (FCO2) plays a dominant role in the terrestrial carbon (C) cycle but interpreting constraints on local observations is impeded by challenges in disentangling belowground CO2 sources. Trees contribute most C to forest soils, so linking aboveground properties to FCO2 could open new avenues to study plant-soil feedbacks and facilitate scaling; furthermore, FCO2 responds dynamically to meteorological conditions, complicating predictions of total FCO2 and forest C balance. We tested for proximity effects of individual Acer saccharum Marsh. trees on FCO2, comparing FCO2 within 1 m of mature stems to background fluxes before and after an intense rainfall event. Wetting significantly increased background FCO2 (6.4±0.3 vs. 8.6±0.6 s.e. μmol CO2 m-2s-1), with a much larger enhancement near tree stems (6.3±0.3 vs. 10.8±0.4 μmol CO2 m-2s-1). FCO2 varied significantly among individual trees and post-rain values increased with tree diameter (with a slope of 0.058 μmol CO2 m-2s-1 cm-1). Post-wetting amplification of FCO2 (the ‘Birch effect’) in root zones often results from the improved mobility of labile carbohydrates and further metabolization of recalcitrant organic matter, which may both occur at higher densities near larger trees. Our results indicate that plant-soil feedbacks change through tree ontogeny and provide evidence for a novel link between whole-system carbon fluxes and forest structure.

scholarly journals Linking Soil CO2 Efflux to Individual Trees: Size-Dependent Variation and the Importance of the Birch Effect

Soil Systems ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 7
Author(s):  
Jonathan S. Schurman ◽  
Sean C. Thomas
Keyword(s):  
Acer Saccharum ◽  
Soil Co2 Efflux ◽  
Proximity Effects ◽  
Co2 Efflux ◽  
Soil Co2 ◽  
Plant Soil ◽  
C Cycle ◽  
Before And After ◽  
Individual Trees ◽  
Birch Effect

Soil CO2 efflux (FCO2) is a major component of the terrestrial carbon (C) cycle but challenges in explaining local variability hamper efforts to link broad-scale fluxes to their biotic drivers. Trees are the dominant C source for forest soils, so linking tree properties to FCO2 could open new avenues to study plant-soil feedbacks and facilitate scaling; furthermore, FCO2 responds dynamically to meteorological conditions, complicating predictions of total FCO2 and forest C balance. We tested for proximity effects of individual Acer saccharum Marsh. trees on FCO2, comparing FCO2 within 1 m of mature stems to background fluxes before and after an intense rainfall event. Wetting significantly increased background FCO2 (6.4 ± 0.3 vs. 8.6 ± 0.6 s.e. μmol CO2 m−2s−1), with a much larger enhancement near tree stems (6.3 ± 0.3 vs. 10.8 ± 0.4 μmol CO2 m−2s−1). FCO2 varied significantly among individual trees and post-rain values increased with tree diameter (with a slope of 0.058 μmol CO2 m−2s−1cm−1). Post-wetting amplification of FCO2 (the ‘Birch effect’) in root zones often results from the improved mobility of labile carbohydrates and further metabolization of recalcitrant organic matter, which may both occur at higher densities near larger trees. Our results indicate that plant-soil feedbacks change through tree ontogeny and provide evidence for a novel link between whole-system carbon fluxes and forest structure.

scholarly journals Distinct patterns in the diurnal and seasonal variability in four components of soil respiration in a temperate forest under free-air CO<sub>2</sub> enrichment

2011 ◽  
Vol 8 (10) ◽  
pp. 3077-3092 ◽  
Author(s):  
L. Taneva ◽  
M. A. Gonzalez-Meler
Keyword(s):  
Soil Respiration ◽  
Seasonal Variability ◽  
Ecosystem Respiration ◽  
Co2 Efflux ◽  
Diurnal Variability ◽  
Soil C ◽  
Free Air ◽  
C Cycle ◽  
Strong Control ◽  
Average Contribution

Abstract. Soil respiration (RS) is a major flux in the global carbon (C) cycle. Responses of RS to changing environmental conditions may exert a strong control on the residence time of C in terrestrial ecosystems and in turn influence the atmospheric concentration of greenhouse gases. Soil respiration consists of several components oxidizing soil C from different pools, age and chemistry. The mechanisms underlying the temporal variability of RS components are poorly understood. In this study, we used the long-term whole-ecosystem 13C tracer at the Duke Forest Free Air CO2 Enrichment site to separate forest RS into its autotrophic (RR) and heterotrophic components (RH). The contribution of RH to RS was further partitioned into litter decomposition (RL), and decomposition of soil organic matter (RSOM) of two age classes – up to 8 yr old and SOM older than 8 yr. Soil respiration was generally dominated by RSOM during the growing season (44% of daytime RS), especially at night. The contribution of heterotrophic respiration (RSOM and RL) to RS was not constant, indicating that the seasonal variability in RR alone cannot explain seasonal variation in RS. Although there was no diurnal variability in RS, there were significant compensatory differences in the contribution of individual RS components to daytime and nighttime rates. The average contribution of RSOM to RS was greater at night (54%) than during the day (44%). The average contribution of RR to total RS was ~30% during the day and ~34% during the night. In contrast, RL constituted 26% of RS during the day and only 12% at night. About 95% of the decomposition of soil C older than 8 yr (Rpre-tr) originated from RSOM and showed more pronounced and consistent diurnal variability than any other RS component; nighttime rates were on average 29% higher than daytime rates. In contrast, the decomposition of more recent, post-treatment C (Rpre-tr) did not vary diurnally. None of the diurnal variations in components of RH could be explained by only temperature and moisture variations. Our results indicate that the variation observed in the components of RS is the result of complex interaction between dominant biotic controls (e.g. plant activity, mineralization kinetics, competition for substrates) over abiotic controls (temperature, moisture). The interactions and controls among roots and other soil organisms that utilize C of different chemistry, accessibility and ages, results in the overall soil CO2 efflux. Therefore understanding the controls on the components of RS is necessary to elucidate the influence of ecosystem respiration on atmospheric C-pools at different time scales.

scholarly journals Experimental Investigation of Rubber Swelling in Bitumen

2020 ◽  
Vol 2674 (2) ◽  
pp. 203-212 ◽  
Author(s):  
Haopeng Wang ◽  
Xueyan Liu ◽  
Panos Apostolidis ◽  
Sandra Erkens ◽  
Athanasios Skarpas
Keyword(s):  
Volume Expansion ◽  
Dominant Role ◽  
Gravimetric Method ◽  
Crumb Rubber ◽  
Mechanical Tests ◽  
Modified Bitumen ◽  
Truck Tire ◽  
Before And After ◽  
Swelling Characteristics ◽  
X Ray Computed

Rubber swelling in bitumen, which is a diffusion-induced volume expansion process, plays a dominant role in the design of crumb rubber modified bitumen binders and their properties development. This study aims to investigate the kinetics of bitumen diffusion into truck tire rubber, the equilibrium swelling characteristics of rubber, and the mechanical properties of rubber before and after swelling at different high temperatures. Fourier transform infrared spectroscopy results indicate that no rubber dissolution happens during the interaction in the temperature range from 160°C to 200°C. Aliphatic compounds from bitumen preferentially diffused into rubber during the swelling process. The diffusion coefficients of bitumen into rubber were determined by the sorption test using the gravimetric method. The diffusion coefficient increases with the increase of temperature in an Arrhenius form. The volume expansion of rubber during swelling was captured by the X-ray computed tomography scan images. Rubber swells faster at the earlier stages, then the expansion rate slows down. The swelling ratio of rubber increased from 1.97 at 160°C to 3.03 at 200°C after 36 h interaction. Mechanical tests by dynamic shear rheometer reveal that swollen rubber becomes softer compared with the dry rubber and exhibits obvious viscoelastic behaviors. With the increase of temperature, the softening and viscous effect are more significant. The obtained parameters can be implemented to swelling and micromechanical models to better predict the binder properties.

scholarly journals Scaling from individual trees to forests in an Earth system modeling framework using a mathematically tractable model of height-structured competition

2015 ◽  
Vol 12 (9) ◽  
pp. 2655-2694 ◽  
Author(s):  
E. S. Weng ◽  
S. Malyshev ◽  
J. W. Lichstein ◽  
C. E. Farrior ◽  
R. Dybzinski ◽  
...  
Keyword(s):  
Atmospheric Co2 ◽  
Geophysical Fluid Dynamics Laboratory ◽  
Earth System ◽  
Modeling Framework ◽  
Light Water ◽  
System Models ◽  
C Cycle ◽  
Competition For Light ◽  
Individual Trees ◽  
Earth System Models

Abstract. The long-term and large-scale dynamics of ecosystems are in large part determined by the performances of individual plants in competition with one another for light, water, and nutrients. Woody biomass, a pool of carbon (C) larger than 50% of atmospheric CO2, exists because of height-structured competition for light. However, most of the current Earth system models that predict climate change and C cycle feedbacks lack both a mechanistic formulation for height-structured competition for light and an explicit scaling from individual plants to the globe. In this study, we incorporate height-structured competition for light, competition for water, and explicit scaling from individuals to ecosystems into the land model version 3 (LM3) currently used in the Earth system models developed by the Geophysical Fluid Dynamics Laboratory (GFDL). The height-structured formulation is based on the perfect plasticity approximation (PPA), which has been shown to accurately scale from individual-level plant competition for light, water, and nutrients to the dynamics of whole communities. Because of the tractability of the PPA, the coupled LM3-PPA model is able to include a large number of phenomena across a range of spatial and temporal scales and still retain computational tractability, as well as close linkages to mathematically tractable forms of the model. We test a range of predictions against data from temperate broadleaved forests in the northern USA. The results show the model predictions agree with diurnal and annual C fluxes, growth rates of individual trees in the canopy and understory, tree size distributions, and species-level population dynamics during succession. We also show how the competitively optimal allocation strategy – the strategy that can competitively exclude all others – shifts as a function of the atmospheric CO2 concentration. This strategy is referred to as an evolutionarily stable strategy (ESS) in the ecological literature and is typically not the same as a productivity- or growth-maximizing strategy. Model simulations predict that C sinks caused by CO2 fertilization in forests limited by light and water will be down-regulated if allocation tracks changes in the competitive optimum. The implementation of the model in this paper is for temperate broadleaved forest trees, but the formulation of the model is general. It can be expanded to include other growth forms and physiologies simply by altering parameter values.

scholarly journals Synthetic Constraint of Soil C Dynamics Using 50 Years of 14C and Net Primary Production (NPP) in a New Zealand Grassland Site

Radiocarbon ◽  
2013 ◽  
Vol 55 (2) ◽  
pp. 1071-1076 ◽  
Author(s):  
W Troy Baisden ◽  
E D Keller
Keyword(s):  
Time Series ◽  
New Zealand ◽  
Net Primary Productivity ◽  
Net Primary Production ◽  
Turnover Rates ◽  
Full Data ◽  
Soil System ◽  
Soil C ◽  
Plant Soil ◽  
C Cycle

Time-series radiocarbon measurements have substantial ability to constrain the size and residence time of the soil C pools commonly represented in ecosystem models. 14C remains unique in its ability to constrain the size and turnover rate of the large stabilized soil C pool with roughly decadal residence times. The Judgeford soil, near Wellington, New Zealand, provides a detailed 11-point 14C time series enabling observation of the incorporation and loss of bomb 14C in surface soil from 1959–2002. Calculations of the flow of C through the plant-soil system can be improved further by combining the known constraints of net primary productivity (NPP) and 14C-derived C turnover. We show the Biome-BGC model provides good estimates of NPP for the Judgeford site and estimates NPP from 1956–2010. Synthesis of NPP and 14C data allows parameters associated with the rapid turnover “active” soil C pool to be estimated. This step is important because it demonstrates that NPP and 14C can provide full data-based constraint of pool sizes and turnover rates for the 3 pools of soil C used in nearly all ecosystem and global C-cycle models.

scholarly journals Estimating the carbon dynamics of South Korean forests from 1954 to 2012

2014 ◽  
Vol 11 (3) ◽  
pp. 5023-5052 ◽  
Author(s):  
J. Lee ◽  
T. K. Yoon ◽  
S. Han ◽  
S. Kim ◽  
M. J. Yi ◽  
...  
Keyword(s):  
Korean War ◽  
National Forest Inventory ◽  
The South ◽  
Data Simulation ◽  
South Korean ◽  
Long Term Study ◽  
C Cycle ◽  
C Stocks ◽  
Before And After ◽  
The Korean War

Abstract. Forests play an important role in the global carbon (C) cycle, and the South Korean forests also contribute to this global C cycle. While the South Korean forest ecosystem was almost completely destroyed by exploitation and the Korean War, it has successfully recovered because of national-scale reforestation programs since 1973. There have been several studies on the estimation of C stocks and balances in the South Korean forests over the past decades. However, a retrospective long-term study including biomass and dead organic matter (DOM) C and validating DOM C is still insufficient. Accordingly, we estimated the C stocks and balances of both biomass and DOM C during 1954–2012 using a~process-based model, the Korean Forest Soil Carbon model, and the 5th Korean National Forest Inventory (NFI) report. Validation processes were also conducted based on the 5th NFI and statistical data. Simulation results showed that the biomass C stocks increased from 36.4 to 440.4 Tg C and sequestered C at a rate of 7.0 Tg C yr−1 during 1954–2012. The DOM C stocks increased from 386.0 to 463.1 Tg C and sequestered C at a rate of 1.3 Tg C yr−1 during the same period. The estimates of biomass and DOM C stocks agreed well with observed C stock data. The annual net biome production (NBP) during 1954–2012 was 141.3 g C m−2 yr−1, which increased from −8.8 to 436.6 g C m−2 yr−1 in 1955 and 2012, respectively. Compared to forests in other countries and global forests, the annual C sink rate of South Korean forests was much lower, but the NBP was much higher. Our results could provide the forest C dynamics in South Korean forests before and after the onset of reforestation programs.

scholarly journals Small-Scale Forest Structure Influences Spatial Variability of Belowground Carbon Fluxes in a Mature Mediterranean Beech Forest

Forests ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 255 ◽  
Author(s):  
Ettore D’Andrea ◽  
Gabriele Guidolotti ◽  
Andrea Scartazza ◽  
Paolo De Angelis ◽  
Giorgio Matteucci
Keyword(s):  
Spatial Variability ◽  
Forest Structure ◽  
Net Primary Production ◽  
Beech Forest ◽  
Environmental Drivers ◽  
Root Production ◽  
Small Scale ◽  
Co2 Efflux ◽  
Area Index ◽  
C Cycle

The tree belowground compartment, especially fine roots, plays a relevant role in the forest ecosystem carbon (C) cycle, contributing largely to soil CO2 efflux (SR) and to net primary production (NPP). Beyond the well-known role of environmental drivers on fine root production (FRP) and SR, other determinants such as forest structure are still poorly understood. We investigated spatial variability of FRP, SR, forest structural traits, and their reciprocal interactions in a mature beech forest in the Mediterranean mountains. In the year of study, FRP resulted in the main component of NPP and explained about 70% of spatial variability of SR. Moreover, FRP was strictly driven by leaf area index (LAI) and soil water content (SWC). These results suggest a framework of close interactions between structural and functional forest features at the local scale to optimize C source–sink relationships under climate variability in a Mediterranean mature beech forest.

SUPREME : developping tools for SUstainable food PRoduction in mEditerranean area using MicrobEs

2020 ◽  
Author(s):  
Giovanni De Giudici ◽  
Anna Rosa Sprocati ◽  
Flavia Tasso ◽  
Chiara Alisi ◽  
Patrizia Paganin ◽  
...  
Keyword(s):  
Mycorrhizal Fungi ◽  
Crop Production ◽  
Leading Edge ◽  
Mediterranean Area ◽  
Soil Functions ◽  
Soil Biodiversity ◽  
Sustainable Food ◽  
Plant Soil ◽  
Before And After ◽  
Bacteria And Fungi

&lt;p&gt;SUPREME&amp;#8217;s goal is to support the safe and efficient use of microbial inocula to assist crops growth. We aim at scaling up the use of autochthonous microbes from greenhouse experiments to field scale pilot plants. Different soils and crops meaningful for the regional economies (tomatoes, sunflowers, onions, legumes such as faba beans and vetch, barely, wheat or high biomass leading grasses like sorghum, health crops and cereals as konjac, orchidaceae, amaranth and quinoa) will be considered in the test sites. Test sites are distributed over 6 different areas of the Mediterranean (figure 1). Leading edge characterization and monitoring techniques will be set up to measure: i) soil biodiversity before and after inoculation, ii) crop growth, iii) water and fertilizer consumption, iv) and mineral consumption and formation through biosphere-geosphere interactions allowing to long term assessment of soil mineral.&lt;/p&gt;&lt;p&gt;Bacteria and fungi can effectively influence plant physiology, growth, defence mechanisms and nutrient uptake (1-5). Mycorrhizal fungi associated with plant roots increase the absorption of nutrients, particularly phosphorus and nitrogen, and distribution of water between different plants is achieved through the hyphal networks. As a result, growth of crops and trees is enhanced or even only possible as in the case of mycoheterotrophy in ectomycorrhizas. Inocula of PGP bacteria can be used to improve soil functions and the resistance of plants to drought periods contributing to reduce irrigation needs. Especially on arid and bare soils, bacterial inoculants can positively influence biogeochemical element cycles and formation of soil. Thus, they can help to reduce water, N and P requirements by augmenting the soil functions, and to reduce the effect of climate change on crop production. In this work, the first results of the project will be shown.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;1&amp;#160; &amp;#160; &amp;#160; &amp;#160; &amp;#160; &amp;#160; &amp;#160; &amp;#160; &amp;#160;Gianinazzi-Pearson and Gianinazzi (1983)-Plant Soil, 71, 211&amp;#8211;215&lt;/p&gt;&lt;p&gt;2&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; Smith and Read (1997)- Academic Press&lt;/p&gt;&lt;p&gt;3&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; Gianinazzi et al. (2002) Basel. Switzerland: Birkh&amp;#228;userVerlag&lt;/p&gt;&lt;p&gt;4&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; Van der Heijden et al. (2008) Ecol. Let., 11, 296&amp;#8211;310&lt;/p&gt;&lt;p&gt;5&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; Peterson et al. (1984 )Biotech. Adv., 2, 101-12&lt;/p&gt;

Photoinhibition of primary photosynthetic processes in hydrated Polytrichum commune: Analysis of non-photochemical quenching affecting species resistance

2019 ◽  
Vol 9 (2) ◽  
pp. 160-169
Author(s):  
Gabriella Nora Maria Giudici
Keyword(s):  
Stress Response ◽  
Dominant Role ◽  
Recovery Period ◽  
Light Stress ◽  
Photochemical Quenching ◽  
Ps Ii ◽  
Chlorophyll Fluorescence Parameters ◽  
Polytrichum Commune ◽  
Before And After ◽  
Pi Stress

A moss from the alpine environment of the Jeseníky mountains, Polytrichum commune, was studied under lab-induced light stress to analyse photoinhibition (PI) stress response; three PI doses were used: PAR 1500 µmol m-2 s-1 for 60 min., 1200 µmol m-2 s-1 for 60 min. and 1200 µmol m-2 s-1 for 30 min.; in the last one the added component of slight desiccation stress was added. Chlorophyll fluorescence parameters were plotted as time series, immediately before and after the PI treatments, then every 20 minutes for three hours (recovery period). FV/FM, ΦPSII and NPQ parameters and quenching components were analysed. Decreasing courses and final values of FV/FM and ΦPSII parameters along with increased values of NPQ clearly indicated PI stress response, although not very severe. Quenching parameters analysis showed a dominant role played by xanthophyll pigments along with changes in PS II in the non-photochemical energy quenching. Dehydration contributed additional value to NPQ. All these factors are consistent with the adaptation of the species to harsh conditions of alpine environments.

Seed quality and germination characteristics of tamarack in northwestern Ontario

1986 ◽  
Vol 16 (3) ◽  
pp. 680-683 ◽  
Author(s):  
Robert E. Farmer Jr. ◽  
Ronald W. Reinholt
Keyword(s):  
Seed Quality ◽  
Northwestern Ontario ◽  
Temperature Regimes ◽  
Germination Characteristics ◽  
Before And After ◽  
Alternating Temperature ◽  
Individual Trees ◽  
Incubation Temperatures

Tamarack seed from provenances in northwestern Ontario were incubated in light and dark under a range of alternating temperature regimes (5–15, 10–20, and 20–30 °C) before and after 33 days stratification. Unstratified sound seed germinated completely in light at all incubation temperatures. Partial germination of unstratified seed took place in the dark at 20–30 °C, but stratification was required for dark germination at lower temperatures. Wide variation in dark germination was noted among seed lots from individual trees, but stand and provenance differences were nonsignificant. Much of the variation in seed quality among tree lots was related to differences in the degree of embryo failure.

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