scholarly journals A “toy” model of biogeochemical dynamics on climate gradients

2021 ◽  
Author(s):  
Peter M. Vitousek ◽  
Jesse Bloom Bateman ◽  
Oliver A. Chadwick
Keyword(s):  
Water Balance ◽  
Plant Biomass ◽  
Potential Evapotranspiration ◽  
Net Primary Production ◽  
N Fixation ◽  
Climate Gradients ◽  
P Limitation ◽  
Biological N Fixation ◽  
Total P ◽  
P Supply

AbstractWe used a simple “toy” model to aid in the evaluation of the controls of biogeochemical patterns along a climate gradient. The model includes simplified treatments of water balance (precipitation minus Potential Evapotranspiration), leaching, weathering of cation- and P-bearing minerals, N cycling and loss, biomass production, and biological N fixation. We use δ15N as a central integrator of biogeochemical processes, because δ15N integrates multiple pathways of N input, output, and transformation in ecosystems. The model simulated the location and magnitude of a peak in δ15N on a gradient on Kohala Volcano, Hawai‘i which peaked ~  + 14 ‰ in sites receiving ~ 3.5 cm/month average precipitation (− 1300 mm/year water balance); the model also captured a peak in total P in surface soil at intermediate levels of precipitation and water balance, and other biogeochemical features on the gradient. We then applied the model to understanding the patterns of and mechanisms underlying nutrient limitation to net primary production (NPP) and plant biomass on the gradient, testing for the existence and extent of N and P limitation by simulated additions of N and/or P in the model. Both a simulated symbiotic biological N fixer and a simulated non-fixer were limited by P supply across the gradient; the non-fixer was independently limited by N supply in wetter sites. By running the toy model with and without the influence of temperature, we demonstrated that water is the most important factor shaping biogeochemical patterns on this gradient.

scholarly journals Modelling the demand for new nitrogen fixation by terrestrial ecosystems

2017 ◽  
Vol 14 (7) ◽  
pp. 2003-2017 ◽  
Author(s):  
◽  
I. Colin Prentice
Keyword(s):  
Net Primary Production ◽  
N Uptake ◽  
Terrestrial Ecosystems ◽  
Co2 Concentration ◽  
N Deposition ◽  
Anthropogenic Sources ◽  
N Fixation ◽  
Biological N Fixation ◽  
Global Dynamic ◽  
Geographic Patterns

Abstract. Continual input of reactive nitrogen (N) is required to support the natural turnover of N in terrestrial ecosystems. This N demand can be satisfied in various ways, including biological N fixation (BNF) (the dominant pathway under natural conditions), lightning-induced abiotic N fixation, N uptake from sedimentary substrates, and N deposition from natural and anthropogenic sources. We estimated the global new N fixation demand (NNF), i.e. the total new N input required to sustain net primary production (NPP) in non-agricultural terrestrial ecosystems regardless of its origin, using a N-enabled global dynamic vegetation model (DyN-LPJ). DyN-LPJ does not explicitly simulate BNF; rather, it estimates total NNF using a mass balance criterion and assumes that this demand is met from one source or another. The model was run in steady state and then in transient mode driven by recent changes in CO2 concentration and climate. A range of values for key stoichiometric parameters was considered, based on recently published analyses. Modelled NPP and C : N ratios of litter and soil organic matter were consistent with independent estimates. Modelled geographic patterns of ecosystem NNF were similar to other analyses, but actual estimated values exceeded recent estimates of global BNF. The results were sensitive to a few key parameters: the fraction of litter carbon respired to CO2 during decomposition and plant-type-specific C : N ratios of litter and soil. The modelled annual NNF increased by about 15 % during the course of the transient run, mainly due to increasing CO2 concentration. The model did not overestimate recent terrestrial carbon uptake, suggesting that the increase in NNF demand has so far been met. Rising CO2 is further increasing the NNF demand, while the future capacity of N sources to support this is unknown.

scholarly journals Modelling the demand for new nitrogen fixation by terrestrial ecosystems

2016 ◽  
Author(s):  
◽  
I. Colin Prentice
Keyword(s):  
Net Primary Production ◽  
N Uptake ◽  
Terrestrial Ecosystems ◽  
Co2 Concentration ◽  
N Deposition ◽  
Anthropogenic Sources ◽  
N Fixation ◽  
Biological N Fixation ◽  
Global Dynamic ◽  
Geographic Patterns

Abstract. Continual input of reactive nitrogen (N) is required to support the natural turnover of N in terrestrial ecosystems. This “N demand” can be satisfied in various ways including biological N fixation (BNF) (the dominant pathway under natural conditions), lightning-induced abiotic N fixation, N uptake from sedimentary substrates, and N deposition from natural and anthropogenic sources. We estimated the global new N fixation demand (NNF), i.e. the total new N input required to sustain net primary production (NPP) in non-agricultural terrestrial ecosystems regardless of its origin, using a N-enabled global dynamic vegetation model (DyN-LPJ). DyN-LPJ does not explicitly simulate BNF; rather, it estimates total NNF using a mass balance criterion and assumes that this demand is met from one source or another. The model was run in steady state, and then in transient mode driven by recent changes in CO2 concentration and climate. A range of values for key stoichiometric parameters was considered, based on recently published analyses. Modelled NPP, and C:N ratios of litter and soil organic matter, were consistent with independent estimates. Modelled geographic patterns of ecosystem NNF were similar to other analyses, but actual estimated values exceeded recent estimates of global BNF. The results were sensitive to a few key parameters: the fraction of litter carbon respired to CO2 during decomposition, and plant type-specific C:N ratios of litter and soil. The modelled annual NNF increased by about 15% during the course of the transient run, mainly due to increasing CO2 concentration. The model did not overestimate recent terrestrial carbon uptake, suggesting that the increase in NNF demand has so far been met. Rising CO2 is further increasing the NNF demand, while the future capacity of N sources to support this is unknown.

scholarly journals Biomass Burning and Water Balance Dynamics in the Lake Chad Basin in Africa

Earth ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 340-356
Author(s):  
Forrest W. Black ◽  
Jejung Lee ◽  
Charles M. Ichoku ◽  
Luke Ellison ◽  
Charles K. Gatebe ◽  
...  
Keyword(s):  
Water Balance ◽  
Biomass Burning ◽  
Water Cycle ◽  
Potential Evapotranspiration ◽  
Southern Oscillation ◽  
Wet Season ◽  
Lake Chad ◽  
Chad Basin ◽  
Lake Chad Basin ◽  
Logone Catchment

The present study investigated the effect of biomass burning on the water cycle using a case study of the Chari–Logone Catchment of the Lake Chad Basin (LCB). The Chari–Logone catchment was selected because it supplies over 90% of the water input to the lake, which is the largest basin in central Africa. Two water balance simulations, one considering burning and one without, were compared from the years 2003 to 2011. For a more comprehensive assessment of the effects of burning, albedo change, which has been shown to have a significant impact on a number of environmental factors, was used as a model input for calculating potential evapotranspiration (ET). Analysis of the burning scenario showed that burning grassland, which comprises almost 75% of the total Chari–Logone land cover, causes increased ET and runoff during the dry season (November–March). Recent studies have demonstrated that there is an increasing trend in the LCB of converting shrubland, grassland, and wetlands to cropland. This change from grassland to cropland has the potential to decrease the amount of water available to water bodies during the winter. All vegetative classes in a burning scenario showed a decrease in ET during the wet season. Although a decrease in annual precipitation in global circulation processes such as the El Niño Southern Oscillation would cause droughts and induce wildfires in the Sahel, the present study shows that a decrease in ET by the human-induced burning would cause a severe decrease in precipitation as well.

scholarly journals Accumulation of Silicon and Changes in Water Balance under Drought Stress in Brassica napus var. napus L.

Plants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 280
Author(s):  
Diana Saja-Garbarz ◽  
Agnieszka Ostrowska ◽  
Katarzyna Kaczanowska ◽  
Franciszek Janowiak
Keyword(s):  
Abscisic Acid ◽  
Drought Stress ◽  
Stomatal Conductance ◽  
Water Balance ◽  
Water Content ◽  
Oilseed Rape ◽  
Potential Evapotranspiration ◽  
Leaf Water Content ◽  
Optimal Conditions ◽  
Abscisic Acid Level

The aim of this study was to investigate the accumulation of silicon in oilseed rape and to characterize the changes in chosen water balance parameters in response to drought. The following parameters were estimated: water content, osmotic and water potential, evapotranspiration, stomatal conductance and abscisic acid level under optimal and drought conditions. It was shown that oilseed rape plants accumulate silicon after its supplementation to the soil, both in the case of silicon alone and silicon together with iron. It was revealed that silicon (without iron) helps maintain constant water content under optimal conditions. While no silicon influence on osmotic regulation was observed, a transpiration decrease was detected under optimal conditions after silicon application. Under drought, a reduction in stomatal conductance was observed, but it was similar for all plants. The decrease in leaf water content under drought was accompanied by a significant increase in abscisic acid content in leaves of control plants and those treated with silicon together with iron. To sum up, under certain conditions, silicon is accumulated even in non-accumulator species, such as oilseed rape, and presumably improves water uptake under drought stress.

scholarly journals Sensitivity of groundwater recharge using climatic analogues and HYDRUS-1D

2012 ◽  
Vol 16 (8) ◽  
pp. 2485-2497 ◽  
Author(s):  
B. Leterme ◽  
D. Mallants ◽  
D. Jacques
Keyword(s):  
Water Balance ◽  
Groundwater Recharge ◽  
Potential Evapotranspiration ◽  
Future Climate ◽  
Annual Precipitation ◽  
Balance Model ◽  
Subtropical Climate ◽  
Northern Spain ◽  
Near Surface ◽  
Hydrus 1D

Abstract. The sensitivity of groundwater recharge to different climate conditions was simulated using the approach of climatic analogue stations, i.e. stations presently experiencing climatic conditions corresponding to a possible future climate state. The study was conducted in the context of a safety assessment of a future near-surface disposal facility for low and intermediate level short-lived radioactive waste in Belgium; this includes estimation of groundwater recharge for the next millennia. Groundwater recharge was simulated using the Richards based soil water balance model HYDRUS-1D and meteorological time series from analogue stations. This study used four analogue stations for a warmer subtropical climate with changes of average annual precipitation and potential evapotranspiration from −42% to +5% and from +8% to +82%, respectively, compared to the present-day climate. Resulting water balance calculations yielded a change in groundwater recharge ranging from a decrease of 72% to an increase of 3% for the four different analogue stations. The Gijon analogue station (Northern Spain), considered as the most representative for the near future climate state in the study area, shows an increase of 3% of groundwater recharge for a 5% increase of annual precipitation. Calculations for a colder (tundra) climate showed a change in groundwater recharge ranging from a decrease of 97% to an increase of 32% for four different analogue stations, with an annual precipitation change from −69% to −14% compared to the present-day climate.

Seed size influences the promoting activity of rhizobia on plant growth, nodulation and N fixation in lima bean

2021 ◽  
Vol 51 (3) ◽  
Author(s):  
Claudyanne do Nascimento Costa ◽  
Jadson Emanuel Lopes Antunes ◽  
João Pedro Alves de Aquino ◽  
Ingrid Sthephanie da Costa Silva ◽  
Angela Celis de Almeida Lopes ◽  
...  
Keyword(s):  
Plant Growth ◽  
Seed Size ◽  
Reference Strain ◽  
Dry Weight ◽  
Lima Bean ◽  
N Fixation ◽  
Nodule Number ◽  
Root Dry Weight ◽  
Biological N Fixation

ABSTRACT: This study evaluated the activity of rhizobia isolates inoculated in large (18 mm) and small (11 mm) seeds on lima bean growth, nodulation and N fixation. Selected rhizobia isolates were compared with a reference strain CIAT899 and two controls without inoculation. Large seeds contributed for highest plant growth, nodulation and N fixation than small seeds. The isolates UFPI-59, UFPI-18 and UFPI-38 promoted the highest values of shoot and root dry weight, respectively. The isolates UFPI-32 promoted the highest values of nodule number, while UFPI-59 promoted the highest values of nodule dry weight. The isolates UFPI-38 and UFPI-59 promoted the highest accumulation of N. This study showed that seed size really influences lima bean growth, nodulation and BNF. Considering rhizobia isolates, UFPI-59, UFPI-38, and UFPI-18 contributed for plant growth, promoted better nodulation and effectiveness on biological N fixation.

Derivation Mathematical Equations for Future Calculation of Potential Evapotranspiration in Iraq, A Review of Application of Thornthwaite Evapotranspiration

2019 ◽  
Vol 60 (5) ◽  
pp. 1037-1048
Author(s):  
Hussein Ilaibi Zamil Al-Sudani
Keyword(s):  
Water Balance ◽  
Potential Evapotranspiration ◽  
Coefficient Of Determination ◽  
Research Review ◽  
Climate Conditions ◽  
Average Temperature ◽  
Mean Temperature ◽  
Mathematical Equations ◽  
Two Parameters ◽  
The Relationship

     In any natural area or water body, evapotranspiration is one of the important outcomes in the water balance equation. As a significant method and depending on monthly average temperature, estimating of potential Evapotranspiration depending on Thornthwaite method was adopted in this research review. Estimate and discuss evapotranspiration by using Thornthwaite method is the main objectives of this research review with considerable details as well as compute potential evapotranspiration based on climatologically data obtained in Iraq. Temperature - evapotranspiration relationship can be estimated between those two parameters to reduce cost and time and facilitate calculation of water balance in lakes, river, and hydrogeological basins. The relationship was obtained using Thornthwaite method in Iraq by dividing the area into seven sectors according to geographic latitude. Each sector has multi meteorological stations where thirty two stations were used with different periods of records. A mathematical relationship was obtained between mean temperature and corrected potential evapotranspiration with (97.45) to (99.84) coefficient of determination. The mean temperature has a decreasing pattern from southern east towards northern west of Iraq affected by Mediterranean Sea climate conditions, while corrected potential evapotranspiration has the opposite direction regarding increased value because of a direct relationship with temperature.

The impact of biomass harvesting on phosphorus uptake by wetland plants

2001 ◽  
Vol 44 (11-12) ◽  
pp. 61-67 ◽  
Author(s):  
S-Y. Kim ◽  
P.M. Geary
Keyword(s):  
Plant Biomass ◽  
Phosphorus Uptake ◽  
P Uptake ◽  
Plant Parts ◽  
Biomass Harvesting ◽  
Below Ground ◽  
The Impact ◽  
Total P ◽  
Better Than ◽  
P Removal

Two species of macrophytes, Baumea articulata and Schoenoplectus mucronatus, were examined for their capacity to remove phosphorus under nutrient-rich conditions. Forty large bucket systems with the two different species growing in two types of substrate received artificial wastewaters for nine months, simulating a constructed wetland (CW) under high loading conditions. Half of the plants growing in the topsoil and gravel substrates were periodically harvested whereas the other half remained intact. Plant tissue and substrate samples were regularly analysed to determine their phosphorus concentrations. With respect to phosphorus uptake and removal, the Schoenoplectus in the topsoil medium performed better than the Baumea. Biomass harvesting enhanced P uptake in the Schoenoplectus, however the effect was not significant enough to make an improvement on the overall P removal, due to the slow recovery of plants and regrowth of biomass after harvesting. From P partitioning, it was found that the topsoil medium was the major P pool, storing most of total P present in the system. Plant parts contributed only minor storage with approximately half of that P stored below ground in the plant roots. The overall net effect of harvesting plant biomass was to only remove less than 5% of total phosphorus present in the system.

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