scholarly journals Representation of phosphorus cycle in Joint UK Land Environment Simulator (vn5.5_JULES-CNP)

2021 ◽  
Author(s):  
Mahdi Nakhavali ◽  
Lina M. Mercado ◽  
Iain P. Hartley ◽  
Stephen Sitch ◽  
Fernanda V. Cunha ◽  
...  
Keyword(s):  
Elevated Co2 ◽  
Land Surface ◽  
Net Primary Productivity ◽  
Low Fertility ◽  
Amazon Forest ◽  
Phosphorus Cycle ◽  
Soil P ◽  
P Limitation ◽  
P Cycling ◽  
Ambient Co2

Abstract. Most Land Surface Models (LSMs), the land components of Earth system models (ESMs), include representation of N limitation on ecosystem productivity. However only few of these models have incorporated phosphorus (P) cycling. In tropical ecosystems, this is likely to be particularly important as N tends to be abundant but the availability of rock-derived elements, such as P, can be very low. Thus, without a representation of P cycling, tropical forest response in areas such as Amazonia to rising atmospheric CO2 conditions remains highly uncertain. In this study, we introduced P dynamics and its interactions with the N and carbon (C) cycles into the Joint UK Land Environment Simulator (JULES). The new model (JULES-CNP) includes the representation of P stocks in vegetation and soil pools, as well as key processes controlling fluxes between these pools. We evaluate JULES-CNP at the Amazon nutrient fertilization experiment (AFEX), a low fertility site, representative of about 60 % of Amazon soils. We apply the model under ambient CO2 and elevated CO2. The model is able to reproduce the observed plant and soil P pools and fluxes under ambient CO2. We estimate P to limit net primary productivity (NPP) by 24 % under current CO2 and by 46 % under elevated CO2. Under elevated CO2, biomass in simulations accounting for CNP increase by 10 % relative to at contemporary CO2, although it is 5 % lower compared with CN and C-only simulations. Our results highlight the potential for high P limitation and therefore lower CO2 fertilization capacity in the Amazon forest with low fertility soils.

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 Some aspects of ecophysiological and biogeochemical responses of tropical forests to atmospheric change

2004 ◽  
Vol 359 (1443) ◽  
pp. 463-476 ◽  
Author(s):  
Jeffrey Q. Chambers ◽  
Whendee L. Silver
Keyword(s):  
Environmental Factors ◽  
Carbon Storage ◽  
Tropical Forests ◽  
Land Surface ◽  
Net Primary Productivity ◽  
Amazon Forest ◽  
Old Growth ◽  
Individual Tree ◽  
Ecosystem Carbon ◽  
Sequestration Rate

Atmospheric changes that may affect physiological and biogeochemical processes in old–growth tropical forests include: (i) rising atmospheric CO 2 concentration; (ii) an increase in land surface temperature; (iii) changes in precipitation and ecosystem moisture status; and (iv) altered disturbance regimes. Elevated CO 2 is likely to directly influence numerous leaf–level physiological processes, but whether these changes are ultimately reflected in altered ecosystem carbon storage is unclear. The net primary productivity (NPP) response of old–growth tropical forests to elevated CO 2 is unknown, but unlikely to exceed the maximum experimentally measured 25% increase in NPP with a doubling of atmospheric CO 2 from pre–industrial levels. In addition, evolutionary constraints exhibited by tropical plants adapted to low CO 2 levels during most of the Late Pleistocene, may result in little response to increased carbon availability. To set a maximum potential response for a Central Amazon forest, using an individual–tree–based carbon cycling model, a modelling experiment was performed constituting a 25% increase in tree growth rate, linked to the known and expected increase in atmospheric CO 2 . Results demonstrated a maximum carbon sequestration rate of ca . 0.2 Mg C per hectare per year (ha −1 yr −1 , where 1 ha = 10 4 m 2 ), and a sequestration rate of only 0.05 Mg C ha −1 yr −1 for an interval centred on calendar years 1980–2020. This low rate results from slow growing trees and the long residence time of carbon in woody tissues. By contrast, changes in disturbance frequency, precipitation patterns and other environmental factors can cause marked and relatively rapid shifts in ecosystem carbon storage. It is our view that observed changes in tropical forest inventory plots over the past few decades is more probably being driven by changes in disturbance or other environmental factors, than by a response to elevated CO 2 . Whether these observed changes in tropical forests are the beginning of long–term permanent shifts or a transient response is uncertain and remains an important research priority.

scholarly journals A representation of the phosphorus cycle for ORCHIDEE (revision 4520)

2017 ◽  
Vol 10 (10) ◽  
pp. 3745-3770 ◽  
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 ORCHIDEE land surface model, and evaluate it with data from nutrient manipulation experiments along a soil formation chronosequence in Hawaii. ORCHIDEE accounts for the influence of the nutritional state of vegetation on tissue nutrient concentrations, photosynthesis, plant growth, biomass allocation, biochemical (phosphatase-mediated) mineralization, and biological nitrogen fixation. Changes in the 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 the soil to the root surface. The model captures the observed differences in the foliage stoichiometry of vegetation between an early (300-year) and a late (4.1 Myr) stage 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 than 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 Diagnosing Phosphorus Limitation in Subtropical Forests in China under Climate Warming

2019 ◽  
Vol 11 (8) ◽  
pp. 2202
Author(s):  
Na Wang ◽  
Mei Huang ◽  
Fengxue Gu ◽  
Huimin Yan ◽  
Shaoqiang Wang ◽  
...  
Keyword(s):  
Climate Warming ◽  
Net Primary Productivity ◽  
Interaction Model ◽  
Phosphorus Limitation ◽  
Subtropical China ◽  
Soil P ◽  
P Limitation ◽  
Forest Sites ◽  
Broad Leaved Forest ◽  
Leaved Forest

Phosphorus (P) is a fundamental component of plant organisms. Most of the Earth System Models (ESMs) project increases in future Net Primary Productivity (NPP) due to climate warming. However, large uncertainty exists in projected NPP due to future P limitation. Subtropical China is a region with high vegetation NPP, but its forests are mostly P limited. In this study, we used the simulations of Atmospheric-Vegetation Interaction Model 2 (AVIM2) to diagnose the P limitation in forests in this region, and found that climate warming in the period of 1951–2010 had enhanced P limitation. The P demand during 1981–2010 for Evergreen Broad-leaved Forest (EBF) and Evergreen Needle-leaved Forest (ENF) are 1.67 and 1.8 times than that during 1951–1980, respectively. The observed current Available Soil P (ASP) density in 4 representative forest sites in subtropical China varied between 940 mg · m − 2 and 2365 mg · m − 2 , and the P demands account for 0.86% to 25.5% of the ASP for the period of 1951–2010. Future P demands are estimated to account for 3.2% to 68.3% of the current ASP at the end of this century for RCP8.5. Therefore, forests, especially plantations, in subtropical China are facing high risks of P limitation.

scholarly journals Towards quantifying uncertainty in predictions of Amazon ‘dieback’

2008 ◽  
Vol 363 (1498) ◽  
pp. 1857-1864 ◽  
Author(s):  
Chris Huntingford ◽  
Rosie A Fisher ◽  
Lina Mercado ◽  
Ben B.B Booth ◽  
Stephen Sitch ◽  
...  
Keyword(s):  
Land Surface ◽  
General Circulation ◽  
Net Primary Productivity ◽  
Circulation Model ◽  
Light Interception ◽  
Rooting Depth ◽  
Amazon Forest ◽  
Carbon Cycle Model ◽  
Wide Range ◽  
Amazonian Rainforest

Simulations with the Hadley Centre general circulation model (HadCM3), including carbon cycle model and forced by a ‘business-as-usual’ emissions scenario, predict a rapid loss of Amazonian rainforest from the middle of this century onwards. The robustness of this projection to both uncertainty in physical climate drivers and the formulation of the land surface scheme is investigated. We analyse how the modelled vegetation cover in Amazonia responds to (i) uncertainty in the parameters specified in the atmosphere component of HadCM3 and their associated influence on predicted surface climate. We then enhance the land surface description and (ii) implement a multilayer canopy light interception model and compare with the simple ‘big-leaf’ approach used in the original simulations. Finally, (iii) we investigate the effect of changing the method of simulating vegetation dynamics from an area-based model (TRIFFID) to a more complex size- and age-structured approximation of an individual-based model (ecosystem demography). We find that the loss of Amazonian rainforest is robust across the climate uncertainty explored by perturbed physics simulations covering a wide range of global climate sensitivity. The introduction of the refined light interception model leads to an increase in simulated gross plant carbon uptake for the present day, but, with altered respiration, the net effect is a decrease in net primary productivity. However, this does not significantly affect the carbon loss from vegetation and soil as a consequence of future simulated depletion in soil moisture; the Amazon forest is still lost. The introduction of the more sophisticated dynamic vegetation model reduces but does not halt the rate of forest dieback. The potential for human-induced climate change to trigger the loss of Amazon rainforest appears robust within the context of the uncertainties explored in this paper. Some further uncertainties should be explored, particularly with respect to the representation of rooting depth.

scholarly journals Responses of soil respiration to elevated carbon dioxide and nitrogen addition in young subtropical forest ecosystems in China

2010 ◽  
Vol 7 (1) ◽  
pp. 315-328 ◽  
Author(s):  
Q. Deng ◽  
G. Zhou ◽  
J. Liu ◽  
S. Liu ◽  
H. Duan ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Elevated Co2 ◽  
Forest Ecosystems ◽  
N Deposition ◽  
Subtropical Forest ◽  
N Addition ◽  
Above Ground Biomass ◽  
Respiration Rates ◽  
Ambient Co2 ◽  
Ambient N Deposition

Abstract. Global climate change in the real world always exhibits simultaneous changes in multiple factors. Prediction of ecosystem responses to multi-factor global changes in a future world strongly relies on our understanding of their interactions. However, it is still unclear how nitrogen (N) deposition and elevated atmospheric carbon dioxide concentration [CO2] would interactively influence forest floor soil respiration in subtropical China. We assessed the main and interactive effects of elevated [CO2] and N addition on soil respiration by growing tree seedlings in ten large open-top chambers under CO2 (ambient CO2 and 700 μmol mol−1) and nitrogen (ambient and 100 kg N ha−1 yr−1) treatments. Soil respiration, soil temperature and soil moisture were measured for 30 months, as well as above-ground biomass, root biomass and soil organic matter (SOM). Results showed that soil respiration displayed strong seasonal patterns with higher values observed in the wet season (April–September) and lower values in the dry season (October–March) in all treatments. Significant exponential relationships between soil respiration rates and soil temperatures, as well as significant linear relationships between soil respiration rates and soil moistures (below 15%) were found. Both CO2 and N treatments significantly affected soil respiration, and there was significant interaction between elevated [CO2] and N addition (p<0.001, p=0.003, and p=0.006, respectively). We also observed that the stimulatory effect of individual elevated [CO2] (about 29% increased) was maintained throughout the experimental period. The positive effect of N addition was found only in 2006 (8.17% increased), and then had been weakened over time. Their combined effect on soil respiration (about 50% increased) was greater than the impact of either one alone. Mean value of annual soil respiration was 5.32 ± 0.08, 4.54 ± 0.10, 3.56 ± 0.03 and 3.53 ± 0.03 kg CO2 m−2 yr−1 in the chambers exposed to elevated [CO2] and high N deposition (CN), elevated [CO2] and ambient N deposition (CC), ambient [CO2] and high N deposition (NN), and ambient [CO2] and ambient N deposition (CK as a control), respectively. Greater above-ground biomass and root biomass was obtained in the CN, CC and NN treatments, and higher soil organic matter was observed only in the CN treatment. In conclusion, the combined effect of elevated [CO2] and N addition on soil respiration was apparent interaction. They should be evaluated in combination in subtropical forest ecosystems in China where the atmospheric CO2 and N deposition have been increasing simultaneously and remarkably.

scholarly journals Evaluation of MEGAN-CLM parameter sensitivity to predictions of isoprene emissions from an Amazonian rainforest

2014 ◽  
Vol 14 (17) ◽  
pp. 23995-24041 ◽  
Author(s):  
J. A. Holm ◽  
K. Jardine ◽  
A. B. Guenther ◽  
J. Q. Chambers ◽  
E. Tribuzy
Keyword(s):  
Land Surface ◽  
Field Measurements ◽  
Leaf Temperature ◽  
Surface Model ◽  
Amazon Forest ◽  
Biophysical Parameters ◽  
Area Index ◽  
Central Amazon ◽  
Community Land Model ◽  
Environmental Controls

Abstract. Tropical trees are known to be large emitters of biogenic volatile organic compounds (BVOC), accounting for up to 75% of the global isoprene budget. Once in the atmosphere, these compounds influence multiple processes associated with air quality and climate. However, uncertainty in biogenic emissions is two-fold, (1) the environmental controls over isoprene emissions from tropical forests remain highly uncertain; and (2) our ability to accurately represent these environmental controls within models is lacking. This study evaluated the biophysical parameters that drive the global Model of Emissions of Gases and Aerosols from Nature (MEGAN) embedded in a biogeochemistry land surface model, the Community Land Model (CLM), with a focus on isoprene emissions from an Amazonian forest. Upon evaluating the sensitivity of 19 parameters in CLM that currently influence isoprene emissions by using a Monte Carlo analysis, up to 61% of the uncertainty in mean isoprene emissions was caused by the uncertainty in the parameters related to leaf temperature. The eight parameters associated with photosynthetic active radiation (PAR) contributed in total to only 15% of the uncertainty in mean isoprene emissions. Leaf temperature was strongly correlated with isoprene emission activity (R2 = 0.89). However, when compared to field measurements in the Central Amazon, CLM failed to capture the upper 10–14 °C of leaf temperatures throughout the year (i.e., failed to represent ~32 to 46 °C), and the spread observed in field measurements was not representative in CLM. This is an important parameter to accurately simulate due to the non-linear response of emissions to temperature. MEGAN-CLM 4.0 overestimated isoprene emissions by 60% for a Central Amazon forest (5.7 mg m−2 h−1 vs. 3.6 mg m−2 h−1), but due to reductions in leaf area index (LAI) by 28% in MEGAN-CLM 4.5 isoprene emissions were within 7% of observed data (3.8 mg m−2 h−1). When a slight adjustment to leaf temperature was made to match observations, isoprene emissions increased 24%, up to 4.8 mg m−2 h−1. Air temperatures are very likely to increase in tropical regions as a result of human induced climate change. Reducing the uncertainty of leaf temperature in BVOC algorithms, as well as improving the accuracy of replicating leaf temperature output in land surface models is warranted in order to improve estimations of tropical BVOC emissions.

scholarly journals Response of in vitro Cultured Palm Oil Seedling Under Saline Condition to Elevated Carbon Dioxide and Photosynthetic Photon Flux Density

2012 ◽  
pp. 52-64
Author(s):  
Pet Roey Pascual ◽  
Krienkai Mosaleeyanon ◽  
Kanokwan Romyanon ◽  
Chalermpol Kirdmanee
Keyword(s):  
Stomatal Conductance ◽  
Net Photosynthetic Rate ◽  
Elevated Co2 ◽  
Photosynthetic Rate ◽  
Transpiration Rate ◽  
Pigment Contents ◽  
Salinity Levels ◽  
Oil Palms ◽  
Ambient Co2

Salt stress elicits various physiological and growth responses of oil palm. A laboratory experiment was conducted to determine the responses of oil palms cultured in vitro under varying salinity levels (0, 85.5, 171.11, 342.21 and 684.43 mM NaCl) to elevated CO2 (1000 μmol CO2/mol) and PPFD (100±5 μmol m-2s-1) in terms of growth characteristics, pigment contents and photosynthetic abilities. After 14 days of culture, net photosynthetic rate (μmol CO2 m-2s-1) of oil palms across varying salinity levels was 5.33 times higher than those cultured under ambient CO, (380±100 Mmol CO2/mol) and PPFD (50±5 μmol m-2s -1). At increased net photosynthetic rate (elevated CO2 and PPFD), despite having no significant difference in pigment contents (chlorophyll a, chlorophyll b, total chlorophyll and carotenoid) between different CO2 and PPFD levels, dry weight and percent dry matter were 0.26 and 0.11 times higher, respectively, as compared to those cultured under ambient CO2 and PPFD. In the same elevated CO2 and PPFD level, across all salinity levels, stomatal conductance was 0.30 times lower than those cultured under ambient CO2 and PPFD. At reduced stomatal conductance (elevated CO2 and PPFD), transpiration rate was also reduced by 0.30 times. Thus with increased net photosynthetic rate and reduced transpiration rate, water use efficiency was increased by 7.22 times, across all salinity levels, than those cultured at ambient CO2 and PPFD. These were considered essential for NaCl produces iso-osmotic stress.

scholarly journals A gender bias in the calcification response to ocean acidification

2011 ◽  
Vol 8 (4) ◽  
pp. 8485-8513 ◽  
Author(s):  
M. Holcomb ◽  
A. L. Cohen ◽  
D. C. McCorkle
Keyword(s):  
Ocean Acidification ◽  
Elevated Co2 ◽  
Egg Production ◽  
Elevated Pco2 ◽  
Future Research ◽  
Astrangia Poculata ◽  
Population Structures ◽  
Different Temperatures ◽  
Increased Sensitivity ◽  
Ambient Co2

Abstract. The effects of nutrients and pCO2 on zooxanthellate and azooxanthellate colonies of the temperate scleractinian coral Astrangia poculata (Ellis and Solander, 1786) were investigated at two different temperatures (16 °C and 24 °C). Corals exposed to elevated pCO2 tended to have lower relative calcification rates, as estimated from changes in buoyant weights. No nutrient effect was observed. At 16 °C, gamete release was not observed, and no gender differences in calcification rate were observed. However, corals grown at 24 °C spawned repeatedly and male and female corals exhibited two different growth rate patterns. Female corals grown at 24 °C and exposed to CO2 had calcification rates 39 % lower than females grown at ambient CO2, while males showed only a 5 % decline in calcification under elevated CO2. At 16 °C, female and male corals showed similar reductions in calcification rates in response to elevated CO2 (15 % and 19 % respectively). At 24 °C, corals spawned repeatedly, while no spawning was observed at 16 °C. The increased sensitivity of females to elevated pCO2 may reflect a greater investment of energy in reproduction (egg production) relative to males (sperm production). These results suggest that both gender and spawning are important factors in determining the sensitivity of corals to ocean acidification and their inclusion in future research may be critical to predicting how the population structures of marine calcifiers will change in response to ocean acidification.

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