scholarly journals Evaluating the Community Land Model in a pine stand with shading manipulations and <sup>13</sup>CO<sub>2</sub> labeling

2016 ◽  
Vol 13 (3) ◽  
pp. 641-657 ◽  
Author(s):  
J. Mao ◽  
D. M. Ricciuto ◽  
P. E. Thornton ◽  
J. M. Warren ◽  
A. W. King ◽  
...  
Keyword(s):  
Land Surface ◽  
Carbon Allocation ◽  
Experimental Studies ◽  
Soil Surface ◽  
Co2 Exchange ◽  
Water Dynamics ◽  
Co2 Efflux ◽  
Community Land Model ◽  
Model Project ◽  
Leaf Level

Abstract. Carbon allocation and flow through ecosystems regulates land surface–atmosphere CO2 exchange and thus is a key, albeit uncertain, component of mechanistic models. The Partitioning in Trees and Soil (PiTS) experiment–model project tracked carbon allocation through a young Pinus taeda stand following pulse labeling with 13CO2 and two levels of shading. The field component of this project provided process-oriented data that were used to evaluate terrestrial biosphere model simulations of rapid shifts in carbon allocation and hydrological dynamics under varying environmental conditions. Here we tested the performance of the Community Land Model version 4 (CLM4) in capturing short-term carbon and water dynamics in relation to manipulative shading treatments and the timing and magnitude of carbon fluxes through various compartments of the ecosystem. When calibrated with pretreatment observations, CLM4 was capable of closely simulating stand-level biomass, transpiration, leaf-level photosynthesis, and pre-labeling 13C values. Over the 3-week treatment period, CLM4 generally reproduced the impacts of shading on soil moisture changes, relative change in stem carbon, and soil CO2 efflux rate. Transpiration under moderate shading was also simulated well by the model, but even with optimization we were not able to simulate the high levels of transpiration observed in the heavy shading treatment, suggesting that the Ball–Berry conductance model is inadequate for these conditions. The calibrated version of CLM4 gave reasonable estimates of label concentration in phloem and in soil surface CO2 after 3 weeks of shade treatment, but it lacks the mechanisms needed to track the labeling pulse through plant tissues on shorter timescales. We developed a conceptual model for photosynthate transport based on the experimental observations, and we discussed conditions under which the hypothesized mechanisms could have an important influence on model behavior in larger-scale applications. Implications for future experimental studies are described, some of which are already being implemented in follow-on studies.

scholarly journals Evaluating the Community Land Model in a pine stand with <sup>13</sup>CO<sub>2</sub> labeling and shading manipulations

2015 ◽  
Vol 12 (9) ◽  
pp. 6971-7015 ◽  
Author(s):  
J. Mao ◽  
D. M. Ricciuto ◽  
P. E. Thornton ◽  
J. M. Warren ◽  
A. W. King ◽  
...  
Keyword(s):  
Land Surface ◽  
Carbon Allocation ◽  
Soil Co2 Efflux ◽  
Water Dynamics ◽  
Model Parameters ◽  
Co2 Efflux ◽  
Soil Co2 ◽  
Short Term ◽  
Response Curves ◽  
Community Land Model

Abstract. Carbon allocation and flow through ecosystems regulate land surface–atmosphere CO2 exchange and thus is a key, albeit uncertain, component of mechanistic models. The Partitioning in Trees and Soil (PiTS) experiment-model project tracked carbon allocation through a young Pinus taeda stand following pulse-labeling with 13CO2 and two levels of shading. The field component of this project provided process-oriented data that was used to evaluate and improve terrestrial biosphere model simulations of rapid shifts in carbon allocation and hydrological dynamics under varying environmental conditions. Here we tested the performance of the Community Land Model version 4 (CLM4) in capturing short-term carbon and water dynamics in relation to manipulative shading treatments, and the timing and magnitude of carbon fluxes through various compartments of the ecosystem. For CLM4 to closely simulate pretreatment conditions, we calibrated select model parameters with pretreatment observational data. Compared to CLM4 simulations with default parameters, CLM4 with calibrated model parameters was able to better simulate pretreatment vegetation carbon pools, light response curves, and other initial states and fluxes of carbon and water. Over a 3 week treatment period, the calibrated CLM4 generally reproduced the impacts of shading on average soil moisture at 15–95 cm depth, transpiration, relative change in stem carbon, and soil CO2 efflux rate, although some discrepancies in the estimation of magnitudes and temporal evolutions existed. CLM4, however, was not able to track the progression of the 13CO2 label from the atmosphere through foliage, phloem, roots or surface soil CO2 efflux, even when optimized model parameters were used. This model bias arises, in part, from the lack of a short-term non-structural carbohydrate storage pool and progressive timing of within-plant transport, thus indicating a need for future work to improve the allocation routines in CLM4. Overall, these types of detailed evaluations of CLM4, paired with intensive field manipulations, can help to identify model strengths and weaknesses, model uncertainties, and additional observations necessary for future model development.

scholarly journals Addressing Biases in Arctic-Boreal Carbon Cycling in the Community Land Model Version 5

2020 ◽  
Author(s):  
Leah Birch ◽  
Christopher R. Schwalm ◽  
Sue Natali ◽  
Danica Lombardozzi ◽  
Gretchen Keppel-Aleks ◽  
...  
Keyword(s):  
Carbon Cycling ◽  
Eddy Covariance ◽  
Land Surface ◽  
Large Scale ◽  
Carbon Allocation ◽  
Ecosystem Respiration ◽  
Terrestrial Ecosystem ◽  
The Arctic ◽  
Community Land Model ◽  
Warming World

Abstract. The Arctic-boreal zone (ABZ) is experiencing amplified warming, actively changing biogeochemical cycling of vegetation and soils. The land-to-atmosphere fluxes of CO2 in the ABZ have the potential to increase in magnitude and feedback to the climate causing additional large scale warming. The ability to model and predict this vulnerability is critical to preparation for a warming world, but Earth system models have biases that may hinder understanding the rapidly changing ABZ carbon fluxes. Here we investigate circumpolar carbon cycling represented by the Community Land Model 5 (CLM5.0) with a focus on seasonal gross primary productivity (GPP) in plant functional types (PFTs). We benchmark model results using data from satellite remote sensing products and eddy covariance towers. We find consistent biases in CLM5.0 relative to observational constraints: (1) the onset of deciduous plant productivity to be late, (2) the offset of productivity to lag and remain abnormally high for all PFTs in fall, (3) a high bias of grass, shrub, and needleleaf evergreen tree productivity, and (4) an underestimation of productivity of deciduous trees. Based on these biases, we focus model development of alternate phenology, photosynthesis schemes, and carbon allocation parameters at eddy covariance tower sites. Although our improvements are focused on productivity, our final Model Recommendation results in other component CO2 fluxes, e.g. Net Ecosystem Exchange (NEE) and Terrestrial Ecosystem Respiration (TER), that are more consistent with observations. Results suggest that algorithms developed for lower latitudes and more temperate environments can be inaccurate when extrapolated to the ABZ, and that many land surface models may not accurately represent carbon cycling and its recent rapid changes in high latitude ecosystems, especially when analyzed by individual PFTs.

scholarly journals Addressing biases in Arctic–boreal carbon cycling in the Community Land Model Version 5

2021 ◽  
Vol 14 (6) ◽  
pp. 3361-3382
Author(s):  
Leah Birch ◽  
Christopher R. Schwalm ◽  
Sue Natali ◽  
Danica Lombardozzi ◽  
Gretchen Keppel-Aleks ◽  
...  
Keyword(s):  
Carbon Cycling ◽  
Eddy Covariance ◽  
Land Surface ◽  
Large Scale ◽  
Carbon Allocation ◽  
Ecosystem Respiration ◽  
Terrestrial Ecosystem ◽  
The Arctic ◽  
Community Land Model ◽  
Warming World

Abstract. The Arctic–boreal zone (ABZ) is experiencing amplified warming, actively changing biogeochemical cycling of vegetation and soils. The land-to-atmosphere fluxes of CO2 in the ABZ have the potential to increase in magnitude and feedback to the climate causing additional large-scale warming. The ability to model and predict this vulnerability is critical to preparation for a warming world, but Earth system models have biases that may hinder understanding of the rapidly changing ABZ carbon fluxes. Here we investigate circumpolar carbon cycling represented by the Community Land Model 5 (CLM5.0) with a focus on seasonal gross primary productivity (GPP) in plant functional types (PFTs). We benchmark model results using data from satellite remote sensing products and eddy covariance towers. We find consistent biases in CLM5.0 relative to observational constraints: (1) the onset of deciduous plant productivity to be late; (2) the offset of productivity to lag and remain abnormally high for all PFTs in fall; (3) a high bias of grass, shrub, and needleleaf evergreen tree productivity; and (4) an underestimation of productivity of deciduous trees. Based on these biases, we focus on model development of alternate phenology, photosynthesis schemes, and carbon allocation parameters at eddy covariance tower sites. Although our improvements are focused on productivity, our final model recommendation results in other component CO2 fluxes, e.g., net ecosystem exchange (NEE) and terrestrial ecosystem respiration (TER), that are more consistent with observations. Results suggest that algorithms developed for lower latitudes and more temperate environments can be inaccurate when extrapolated to the ABZ, and that many land surface models may not accurately represent carbon cycling and its recent rapid changes in high-latitude ecosystems, especially when analyzed by individual PFTs.

A laboratory study of the effect of soil-water dynamics on the migration of gases from subsurface sources

2021 ◽  
Author(s):  
Ana M. C. Ilie ◽  
Tissa H. Illangasekare ◽  
Kenichi Soga ◽  
William R. Whalley
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Sandy Soil ◽  
Land Surface ◽  
Soil Gas ◽  
Water Dynamics ◽  
Gas Migration ◽  
Soil Water Dynamics ◽  
Scale Test ◽  
Properties Of Soil

&lt;p&gt;Understanding the soil-gas migration in unsaturated soil is important in a number of problems that include carbon loading to the atmosphere from the bio-geochemical activity and leakage of gases from subsurface sources from carbon storage unconventional energy development. The soil water dynamics in the vadose zone control the soil-gas pathway development and, hence, the gas flux's spatial and temporal distribution at the soil surface. The spatial distribution of soil-water content depends on soil water characteristics. The dynamics are controlled by the water flux at the land surface and water table fluctuations. Physical properties of soil give a better understanding of the soil gas dynamics and migration from greater soil depths. The fundamental process of soil gas migration under dynamic water content was investigated in the laboratory using an intermediate-scale test system under controlled conditions that is not possible in the field. The experiments focus on observing the methane gas migration in relation to the physical properties of soil and the soil moisture patterns. A 2D soil tank with dimensions of 60 cm &amp;#215; 90 cm &amp;#215; 5.6 cm (height &amp;#215; length &amp;#215; width) was used.&amp;#160; The tank was heterogeneously packed with sandy soil along with a distributed network of soil moisture, temperature, and electrical conductivity sensors. The heterogeneous soil configuration was designed using nine uniform silica sands with the effective sieve numbers #16, #70, #8, #40/50, #110, #30/40, #50, and #20/30 (Accusands, Unimin Corp., Ottawa, MN), and a porosity ranging in values from 0.31 to 0.42. Four methane infrared gas sensors and a Flame Ionization detector (HFR400 Fast FID) were used for the soil gas sampling at different depths within the soil profiles and at the land surface.&amp;#160; A complex transient soil moisture distribution and soil gas migration patterns were observed in the 2D tank. These processes were successfully captured by the sensors. These preliminary experiments helped us to understand the mechanism of soil moisture sensor response and methane gas migration into a heterogeneous sandy soil with a view to developing a large-scale test in a 3D tank (4.87 m &amp;#215; 2.44 m &amp;#215; 0.40 m) and finally transition to field deployment.&lt;/p&gt;

Resource-saving Technologies and Some Proposals for the Creation of Automated Reclamation Systems

2021 ◽  
Vol 25 (7) ◽  
pp. 8-12
Author(s):  
Z.G. Lamerdonov ◽  
T.Yu. Khashirova ◽  
S.A. Zhaboev ◽  
L.Zh. Nastueva ◽  
A.А. Shogenov ◽  
...  
Keyword(s):  
Drip Irrigation ◽  
Salt Content ◽  
Experimental Studies ◽  
Soil Surface ◽  
Growing Season ◽  
Resource Saving ◽  
Water Savings ◽  
Irrigation Method ◽  
High Salt Content ◽  
Reclamation System

The results of experimental studies of the local subsurface irrigation method in comparison with drip irrigation carried out in the laboratory, which showed water savings due to a decrease in evaporation from the soil surface by 10–15 percent are presented. The method of irrigation in closed greenhouse farms using water with a high salt content is described. The paper proposes new patented schematic solutions for protecting plants from frost and pests, describes a multifunctional engineering and reclamation system capable of performing various operations depending on the emerging problems during the growing season.

scholarly journals Patterns of longer-term climate change effects on CO<sub>2</sub> efflux from biocrusted soils differ from those observed in the short term

2018 ◽  
Vol 15 (14) ◽  
pp. 4561-4573 ◽  
Author(s):  
Anthony Darrouzet-Nardi ◽  
Sasha C. Reed ◽  
Edmund E. Grote ◽  
Jayne Belnap
Keyword(s):  
Climate Change ◽  
Monsoon Season ◽  
Vascular Plant ◽  
Precipitation Amount ◽  
Co2 Flux ◽  
Co2 Exchange ◽  
Plant Responses ◽  
Co2 Efflux ◽  
Climate Change Effects ◽  
Altered Precipitation

Abstract. Biological soil crusts (biocrusts) are predicted to be sensitive to the increased temperature and altered precipitation associated with climate change. We assessed the effects of these factors on soil carbon dioxide (CO2) balance in biocrusted soils using a sequence of manipulations over a 9-year period. We warmed biocrusted soils by 2 and, later, by 4 ∘C to better capture updated forecasts of future temperature at a site on the Colorado Plateau, USA. We also watered soils to alter monsoon-season precipitation amount and frequency and had plots that received both warming and altered precipitation treatments. Within treatment plots, we used 20 automated flux chambers to monitor net soil exchange (NSE) of CO2 hourly, first in 2006–2007 and then again in 2013–2014, for a total of 39 months. Net CO2 efflux from biocrusted soils in the warming treatment increased a year after the experiment began (2006–2007). However, after 9 years and even greater warming (4 ∘C), results were more mixed, with a reversal of the increase in 2013 (i.e., controls showed higher net CO2 efflux than treatment plots) and with similarly high rates in all treatments during 2014, a wet year. Over the longer term, we saw evidence of reduced photosynthetic capacity of the biocrusts in response to both the temperature and altered precipitation treatments. Patterns in biocrusted soil CO2 exchange under experimentally altered climate suggest that (1) warming stimulation of CO2 efflux was diminished later in the experiment, even in the face of greater warming; and (2) treatment effects on CO2 flux patterns were likely driven by changes in biocrust species composition and by changes in root respiration due to vascular plant responses.

scholarly journals Representing winter wheat in the Community Land Model (version 4.5)

2017 ◽  
Vol 10 (5) ◽  
pp. 1873-1888 ◽  
Author(s):  
Yaqiong Lu ◽  
Ian N. Williams ◽  
Justin E. Bagley ◽  
Margaret S. Torn ◽  
Lara M. Kueppers
Keyword(s):  
Heat Flux ◽  
Winter Wheat ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Latent Heat Flux ◽  
Carbon Allocation ◽  
Net Ecosystem Exchange ◽  
Area Index ◽  
Community Land Model ◽  
The Us

Abstract. Winter wheat is a staple crop for global food security, and is the dominant vegetation cover for a significant fraction of Earth's croplands. As such, it plays an important role in carbon cycling and land–atmosphere interactions in these key regions. Accurate simulation of winter wheat growth is not only crucial for future yield prediction under a changing climate, but also for accurately predicting the energy and water cycles for winter wheat dominated regions. We modified the winter wheat model in the Community Land Model (CLM) to better simulate winter wheat leaf area index, latent heat flux, net ecosystem exchange of CO2, and grain yield. These included schemes to represent vernalization as well as frost tolerance and damage. We calibrated three key parameters (minimum planting temperature, maximum crop growth days, and initial value of leaf carbon allocation coefficient) and modified the grain carbon allocation algorithm for simulations at the US Southern Great Plains ARM site (US-ARM), and validated the model performance at eight additional sites across North America. We found that the new winter wheat model improved the prediction of monthly variation in leaf area index, reduced latent heat flux, and net ecosystem exchange root mean square error (RMSE) by 41 and 35 % during the spring growing season. The model accurately simulated the interannual variation in yield at the US-ARM site, but underestimated yield at sites and in regions (northwestern and southeastern US) with historically greater yields by 35 %.

scholarly journals RESEARCH AND EVALUATION OF KART NOISE SPREAD INTO THE LIVING ENVIRONMENT / GOKARTŲ KELIAMO TRIUKŠMO SKLAIDOS Į GYVENAMĄJĄ APLINKĄ TYRIMAI IR VERTINIMAS

2014 ◽  
Vol 6 (4) ◽  
pp. 356-361
Author(s):  
Giedrius Juozaponis ◽  
Raimondas Grubliauskas
Keyword(s):  
Wind Speed ◽  
Experimental Studies ◽  
Soil Surface ◽  
Sound Level ◽  
Living Environment ◽  
Noise Levels ◽  
Noise Propagation ◽  
Soil Surface Temperature ◽  
Service Data ◽  
Living Area

The paper examines kart noise propagation in the living environment and sought measures for suppressing it. To conduct experimental studies, precision sound level analyzer Bruel & Kjaer 2260th has been used. In cooperation with the Lithuanian Hydrometeorological Service, data on relative humidity, wind speed and direction, soil surface temperature and air temperature have been applied. According to the Lithuanian Hygiene Standard HN 33:2011 Noise Thresholds in Residential and Public Buildings and Their Environment, the areas with an elevated noise level are identified thus selecting noise reduction measures aimed at reducing noise levels up to the permitted ones. The analysis of the obtained results has focused on the regularities between noise propagation and meteorological events and their impact on the spread of noise. The environmental factors more or less influencing the climate and noise spread in the living area have been determined. With reference to the received information, the ways to reduce noise have been suggested. Straipsnyje nagrinėjamas gokartų keliamo triukšmo sklidimas į gyvenamąją aplinką ir ieškoma priemonių jam slopinti. Eksperimentiniams tyrimams atlikti buvo naudojamas precizinis garso lygio analizatorius „Bruel&Kjaer 2260“. Bendradarbiaujant su Lietuvos hidrometeorologijos tarnyba panaudoti santykinės oro drėgmės, vėjo stiprumo ir krypties, dirvožemio paviršiaus temperatūros bei oro temperatūros duomenys. Vadovaujantis Lietuvos higienos normomis HN 33:2011 „Triukšmo ribiniai dydžiai gyvenamuosiuose ir visuomeninės paskirties pastatuose bei jų aplinkoje“ nustatomos zonos, kuriose triukšmo lygis yra viršijamas, ir parenkant triukšmo mažinimo priemones siekiama triukšmą sumažinti iki leidžiamųjų normų. Gautų rezultatų analizės metu ieškoma dėsningumų tarp triukšmo sklidimo ir meteorologinių reiškinių bei jų daroma įtaka triukšmo plitimui. Nustatomi aplinkos klimato veiksniai, darantys įtaką ar mažiau veikiantys triukšmo sklaidą gyvenamojoje teritorijoje. Atsižvelgiant į gautus rezultatus siūlomi triukšmo mažinimo būdai.

scholarly journals A representation of the phosphorus cycle for ORCHIDEE (revision 3985)

2017 ◽  
Author(s):  
Daniel S. Goll ◽  
Nicolas Vuichard ◽  
Fabienne Maignan ◽  
Albert Jornet-Puig ◽  
Jordi Sardans ◽  
...  
Keyword(s):  
Primary Productivity ◽  
Land Surface ◽  
Net Primary Productivity ◽  
Nutrient Content ◽  
Soil Development ◽  
Nutrient Concentrations ◽  
Surface Model ◽  
Phosphorus Cycle ◽  
Area Index ◽  
Leaf Level

Abstract. Land surface models rarely incorporate the terrestrial phosphorus cycle and its interactions with the carbon cycle, despite the extensive scientific debate about the importance of nitrogen and phosphorus supply for future land carbon uptake. We describe a representation of the terrestrial phosphorus cycle for the land surface model ORCHIDEE, and evaluate it with data from nutrient manipulation experiments along a soil formation chronosequence in Hawaii. ORCHIDEE accounts for influence of nutritional state of vegetation on tissue nutrient concentrations, photosynthesis, plant growth, biomass allocation, biochemical (phosphatase-mediated) mineralization and biological nitrogen fixation. Changes in nutrient content (quality) of litter affect the carbon use efficiency of decomposition and in return the nutrient availability to vegetation. The model explicitly accounts for root zone depletion of phosphorus as a function of root phosphorus uptake and phosphorus transport from soil to the root surface. The model captures the observed differences in the foliage stoichiometry of vegetation between an early (300yr) and a late stage (4.1 Myr) of soil development. The contrasting sensitivities of net primary productivity to the addition of either nitrogen, phosphorus or both among sites are in general reproduced by the model. As observed, the model simulates a preferential stimulation of leaf level productivity when nitrogen stress is alleviated, while leaf level productivity and leaf area index are stimulated equally when phosphorus stress is alleviated. The nutrient use efficiencies in the model are lower as observed primarily due to biases in the nutrient content and turnover of woody biomass. We conclude that ORCHIDEE is able to reproduce the shift from nitrogen to phosphorus limited net primary productivity along the soil development chronosequence, as well as the contrasting responses of net primary productivity to nutrient addition.

scholarly journals Patterns of longer-term climate change effects on CO<sub>2</sub> efflux from biocrusted soils differ from those observed in the short-term

2018 ◽  
Author(s):  
Anthony Darrouzet-Nardi ◽  
Sasha C. Reed ◽  
Edmund E. Grote ◽  
Jayne Belnap
Keyword(s):  
Climate Change ◽  
Monsoon Season ◽  
Vascular Plant ◽  
Co2 Exchange ◽  
Plant Responses ◽  
Co2 Efflux ◽  
Climate Change Effects ◽  
Altered Precipitation ◽  
The Face ◽  
Carbon Dioxide Co2

Abstract. Biological soil crusts (biocrusts) are predicted to be sensitive to the increased temperature and altered precipitation associated with climate change. We assessed the effects of these factors on soil carbon dioxide (CO2) balance in biocrusted soils using a sequence of manipulations over a nine-year period. We warmed biocrusted soils by 2 and, later, by 4 °C to better capture updated forecasts of future temperature, as well as altered monsoon-season precipitation at a site on the Colorado Plateau, USA. Within treatment plots, we used 20 automated flux chambers to monitor net soil exchange (NSE) of CO2 hourly, first in 2006–2007 and then again in 2013–2014, for a total of 39 months. Net CO2 efflux from biocrusted soils in the warming treatment increased a year after the experiment began (2006–2007). However, after 9 years and even greater warming (4 °C), results were more mixed, with a reversal of the increase in 2013 (i.e., controls showed higher net CO2 efflux than treatment plots) and with similarly high rates in all treatments during 2014, a wet year. Over the longer-term, we saw evidence of reduced photosynthetic capacity of the biocrusts in response to both the temperature and altered precipitation treatments. Patterns in biocrusted soil CO2 exchange under experimentally altered climate suggest that (1) warming effects were diminished later in the experiment, even in the face of larger warming and (2) likely drivers of the treatment effects were changes in biocrust species composition and changes in root respiration due to vascular plant responses.

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