Combining livestock production information in a process based vegetation model to reconstruct the history of grassland management

Combining livestock production information in a process-based vegetation model to reconstruct the history of grassland management

Biogeosciences ◽

10.5194/bg-13-3757-2016 ◽

2016 ◽

Vol 13 (12) ◽

pp. 3757-3776 ◽

Cited By ~ 17

Author(s):

Jinfeng Chang ◽

Philippe Ciais ◽

Mario Herrero ◽

Petr Havlik ◽

Matteo Campioli ◽

...

Keyword(s):

Primary Productivity ◽

Net Primary Productivity ◽

Biomass Productivity ◽

Grassland Management ◽

Global Scale ◽

Surface Energy Budget ◽

Greenhouse Gas Balance ◽

Large Spatial Scale ◽

Management Intensity ◽

Grass Biomass

Abstract. Grassland management type (grazed or mown) and intensity (intensive or extensive) play a crucial role in the greenhouse gas balance and surface energy budget of this biome, both at field scale and at large spatial scale. However, global gridded historical information on grassland management intensity is not available. Combining modelled grass-biomass productivity with statistics of the grass-biomass demand by livestock, we reconstruct gridded maps of grassland management intensity from 1901 to 2012. These maps include the minimum area of managed vs. maximum area of unmanaged grasslands and the fraction of mown vs. grazed area at a resolution of 0.5° by 0.5°. The grass-biomass demand is derived from a livestock dataset for 2000, extended to cover the period 1901–2012. The grass-biomass supply (i.e. forage grass from mown grassland and biomass grazed) is simulated by the process-based model ORCHIDEE-GM driven by historical climate change, rising CO2 concentration, and changes in nitrogen fertilization. The global area of managed grassland obtained in this study increases from 6.1  ×  106 km2 in 1901 to 12.3  ×  106 km2 in 2000, although the expansion pathway varies between different regions. ORCHIDEE-GM also simulated augmentation in global mean productivity and herbage-use efficiency over managed grassland during the 20th century, indicating a general intensification of grassland management at global scale but with regional differences. The gridded grassland management intensity maps are model dependent because they depend on modelled productivity. Thus specific attention was given to the evaluation of modelled productivity against a series of observations from site-level net primary productivity (NPP) measurements to two global satellite products of gross primary productivity (GPP) (MODIS-GPP and SIF data). Generally, ORCHIDEE-GM captures the spatial pattern, seasonal cycle, and interannual variability of grassland productivity at global scale well and thus is appropriate for global applications presented here.

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Modelling the response of net primary productivity of the Zambezi teak forests to climate change along a rainfall gradient in Zambia

Biogeosciences ◽

10.5194/bg-16-3853-2019 ◽

2019 ◽

Vol 16 (19) ◽

pp. 3853-3867

Author(s):

Justine Ngoma ◽

Maarten C. Braakhekke ◽

Bart Kruijt ◽

Eddy Moors ◽

Iwan Supit ◽

...

Keyword(s):

Climate Change ◽

21St Century ◽

Primary Productivity ◽

General Circulation ◽

Net Primary Productivity ◽

Co2 Concentration ◽

Annual Rainfall ◽

Rainfall Gradient ◽

Local Soil ◽

Parameter Values

Abstract. Understanding climate change effects on forests is important considering the role forests play in mitigating climate change. We studied the effects of changes in temperature, rainfall, atmospheric carbon dioxide (CO2) concentration, solar radiation, and number of wet days (as a measure of rainfall intensity) on net primary productivity (NPP) of the Zambian Zambezi teak forests along a rainfall gradient. Using 1960–1989 as a baseline, we projected changes in NPP for the end of the 21st century (2070–2099). We adapted the parameters of the dynamic vegetation model, LPJ-GUESS, to simulate the growth of Zambian forests at three sites along a moisture gradient receiving annual rainfall of between 700 and more than 1000 mm. The adjusted plant functional type was tested against measured data. We forced the model with contemporary climate data (1960–2005) and with climatic forecasts of an ensemble of five general circulation models (GCMs) following Representative Concentration Pathways (RCPs) RCP4.5 and RCP8.5. We used local soil parameter values to characterize texture and measured local tree parameter values for maximum crown area, wood density, leaf longevity, and allometry. The results simulated with the LPJ-GUESS model improved when we used these newly generated local parameters, indicating that using local parameter values is essential to obtaining reliable simulations at site level. The adapted model setup provided a baseline for assessing the potential effects of climate change on NPP in the studied Zambezi teak forests. Using this adapted model version, NPP was projected to increase by 1.77 % and 0.69 % at the wetter Kabompo and by 0.44 % and 0.10 % at the intermediate Namwala sites under RCP8.5 and RCP4.5 respectively, especially caused by the increased CO2 concentration by the end of the 21st century. However, at the drier Sesheke site, NPP would respectively decrease by 0.01 % and 0.04 % by the end of the 21st century under RCP8.5 and RCP4.5. The projected decreased NPP under RCP8.5 at the Sesheke site results from the reduced rainfall coupled with increasing temperature. We thus demonstrated that differences in the amount of rainfall received in a site per year influence the way in which climate change will affect forest resources. The projected increase in CO2 concentration would thus have more effects on NPP in high rainfall receiving areas, while in arid regions, NPP would be affected more by the changes in rainfall and temperature. CO2 concentrations would therefore be more important in forests that are generally not temperature- or precipitation-limited; however, precipitation will continue to be the limiting factor in the drier sites.

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Response of Net Primary Productivity of Zambezi teak forests to climate change along a rainfall gradient in Zambia

10.5194/bg-2018-421 ◽

2018 ◽

Author(s):

Justine Ngoma ◽

Maarten C. Braakhekke ◽

Bart Kruijt ◽

Eddy Moors ◽

Iwan Supit ◽

...

Keyword(s):

Climate Change ◽

21St Century ◽

Primary Productivity ◽

Net Primary Productivity ◽

Co2 Concentration ◽

Annual Rainfall ◽

Base Line ◽

Rainfall Gradient ◽

Local Soil ◽

Parameter Values

Abstract. Understanding climate change effects on forests is important considering the role forests play in mitigating climate change. We studied the effects of changes in temperature, rainfall, atmospheric carbon dioxide (CO2) concentration, solar radiation, and number of wet days (as a measure of rainfall intensity) on net primary productivity (NPP) of the Zambian Zambezi teak forests along a rainfall gradient. Using 1960–1989 as base-line, we projected changes in NPP for the end of the 21st century (2070–2099). We adapted the parameters of the dynamic vegetation model, LPJ-GUESS, to simulate the growth of Zambian forests at three sites along a moisture gradient receiving annual rainfall of between 700 mm to more than 1000 mm. The thus adjusted plant functional type was tested against measured data. We forced the model with contemporary climate data (1960–2005) and with climatic forecasts of an ensemble of five General Circulation Models (GCMs) following RCP4.5 and RCP8.5. We used local soil parameter values to characterize texture and measured local tree parameter values for maximum crown area, wood density, leaf longevity, and allometry. While increased CO2 concentration enhances NPP at the wetter Kabompo and the intermediate Namwala sites, NPP decreases at the drier Sesheke site under both scenarios by the end of 21st century. The projected decreased NPP under RCP8.5 at the Sesheke site results from the reduced rainfall. We thus demonstrated that differences in rainfall pattern influence the way in which climate change will affect forests resources. We also showed that using local parameter values is essential to obtaining reasonably reliable simulations.

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Roles of Climate Change and Increasing CO2 in Driving Changes of Net Primary Productivity in China Simulated Using a Dynamic Global Vegetation Model

Sustainability ◽

10.3390/su11154176 ◽

2019 ◽

Vol 11 (15) ◽

pp. 4176 ◽

Cited By ~ 1

Author(s):

Qing Huang ◽

Weimin Ju ◽

Fangyi Zhang ◽

Qian Zhang

Keyword(s):

Climate Change ◽

Interannual Variability ◽

Primary Productivity ◽

Southwest China ◽

Net Primary Productivity ◽

Terrestrial Ecosystem ◽

Co2 Concentration ◽

Series Data ◽

Geographical Regions ◽

The Future

Net primary productivity (NPP) is the key component of the terrestrial carbon cycle, and terrestrial NPP trends under increasing CO2 and climate change in the past and future are of great significance in the study of the global carbon budget. Here, the LPJ-DGVM was employed to simulate the magnitude and pattern of China’s terrestrial NPP using long-term series data to understand the response of terrestrial NPP to increasing CO2 concentration and climate change. The results showed that total NPP of China’s terrestrial ecosystem increased from 2.8 to 3.6 Pg C yr−1 over the period of 1961–2016, with an annual average of 3.1 Pg C yr−1. The average NPP showed a gradient decrease from the southeast to northwest. Southwest China and Northwest China, comprising mostly arid and semi-arid regions, exhibited the largest increase rate in total NPP among the six geographical regions of China. Additionally, large interannual variability around the NPP trends was presented, and NPP anomalies in China’s terrestrial ecosystem are strongly associated with the El Niño-Southern Oscillation (ENSO). Southwest China made the largest contribution to the interannual variability of national total NPP. The total NPP of China’s terrestrial ecosystem continuously increased with the concurrent increase in the CO2 concentration and climate change under different scenarios in the future. During the period from 2091 to 2100, the average total NPP under the A2 and RCP85 scenarios would reach 4.9 and 5.1 Pg C yr−1 respectively, higher than 4.2 and 3.9 Pg C yr−1 under the B1 and RCP45 scenarios. Forests, especially temperate forests, make the largest contribution to the future increase in NPP. The increase in CO2 concentration would play a dominant role in driving further NPP increase in China’s terrestrial ecosystems, and climate change may slightly attenuate the fertilization effect of CO2 on NPP.

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Reaching 1.5 °C and 2.0 °C global surface temperature targets using stratospheric aerosol geoengineering

10.5194/esd-2019-76 ◽

2019 ◽

Cited By ~ 1

Author(s):

Simone Tilmes ◽

Douglas E. MacMartin ◽

Jan T. M. Lenaerts ◽

Leo van Kampenhout ◽

Laura Muntjewerf ◽

...

Keyword(s):

Surface Temperature ◽

Primary Productivity ◽

Net Primary Productivity ◽

Surface Air Temperature ◽

Co2 Concentration ◽

Stratospheric Aerosol ◽

Meridional Overturning Circulation ◽

Baseline Scenario ◽

Surface Mass ◽

Ecosystem Impacts

Abstract. We propose new testbed model experiments for the Geoengineering Model Intercomparison Project (GeoMIP) that are designed to limit global warming to 1.5 °C or 2.0 °C above 1850–1900 conditions using stratospheric aerosol geoengineering (SAG). The new modeling experiments use the overshoot scenario defined in CMIP6 (SSP5-34-OS) as a baseline scenario and are designed to reduce side effects of SAG in reaching three temperature targets: global mean surface temperature, and inter-hemispheric and pole-to-equator surface temperature gradients. We further compare results to another SAG simulation using a high emission scenario (SSP5-85) as a baseline scenario in order to investigate the dependency of impacts using different injection amounts to offset different amounts of warming by SAG. The new testbed simulations are performed with the CESM2(WACCM6). We use a feedback algorithm that identifies the needed amount of sulfur dioxide injections in the stratosphere at four predefined latitudes, 30° N, 15° N, 15° S, and 30° S, to reach the three temperature targets. Here we analyze climate variables and quantities that matter for societal and ecosystem impacts. We find that changes from present day conditions (2015–2025) in some variables depend strongly on the defined temperature target (1.5 °C vs 2.0 °C). These include surface air temperature and related impacts, the Atlantic Meridional Overturning Circulation (AMOC), which impacts ocean net primary productivity, and changes in ice sheet surface mass balance, which impacts sea-level rise. Others, including global precipitation changes and the recovery of the Antarctic ozone hole, depend strongly on the amount of SAG application. Furthermore, land net primary productivity as well as ocean acidification depend mostly on the global atmospheric CO2 concentration and therefore the baseline scenario. Multi-model comparisons of the experiments proposed here would help identify consequences of scenarios that include strong mitigation, carbon dioxide removal with some SAG application, on societal impacts and ecosystems.

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Aspects of productivity and nutrient cycling in an 8-year-old Eucalyptus plantation in a moist plain area adjacent to central Himalaya, India

Canadian Journal of Forest Research ◽

10.1139/x91-193 ◽

1991 ◽

Vol 21 (9) ◽

pp. 1365-1372 ◽

Cited By ~ 12

Author(s):

Surendra S. Bargali ◽

Surendra P. Singh

Keyword(s):

Nutrient Cycling ◽

Nutrient Uptake ◽

Primary Productivity ◽

Net Primary Productivity ◽

Biomass Productivity ◽

Central Himalaya ◽

Natural Forests ◽

Eucalyptus Plantation ◽

Plain Area ◽

Sal Forest

In the present study we describe biomass, productivity, and nutrient cycling in an 8-year-old Eucalyptustereticornis Sm. (Eucalyptus hybrid) plantation and compare them with those of a Populusdeltoides Bartr. plantation of the same age and area, a natural sal (Shorearobusta Gaertn. F.) forest, and other natural forests of the central Himalaya. The total vegetation biomass of the Eucalyptus plantation (126.7 t•ha−1) was lower than that of the P. deltoides plantation (176 t•ha−1) and natural forests (163.4–786.7 t•ha−1). The net primary productivity of the Eucalyptus plantation (23.4 t•ha−1•year−1) was similar to that of the P. deltoides plantation (25 t•ha−1•year−1) and the natural sal forest (22 t•ha−1•year−1). The net nutrient uptake of Eucalyptus was lower than that of Populus plantation and natural forests.

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A simple parameterization of nitrogen limitation on primary productivity for global vegetation models

Biogeosciences Discussions ◽

10.5194/bgd-2-1243-2005 ◽

2005 ◽

Vol 2 (4) ◽

pp. 1243-1282 ◽

Cited By ~ 3

Author(s):

G. Krinner ◽

P. Ciais ◽

N. Viovy ◽

P. Friedlingstein

Keyword(s):

Primary Productivity ◽

Nitrogen Limitation ◽

Net Primary Productivity ◽

Co2 Concentration ◽

C Sequestration ◽

Ecosystem Productivity ◽

Soil Warming ◽

Co2 Fertilization ◽

Vegetation Models ◽

Global Vegetation

Abstract. Nitrogen limitation of ecosystem productivity is ubiquitous, and it is thought that it has and will have a significant impact on net ecosystem productivity, and thus carbon sequestration, in the context of ongoing future increase of atmospheric CO2 concentration and climate change. However, many vegetation models do not represent nitrogen limitation, and might thus overestimate future terrestrial C sequestration. This work presents a simple parameterization of nitrogen limitation that can be easily implemented in vegetation models which do not yet include a complete nitrogen cycle. This parameterization is based on the ratio between heterotrophic respiration (considered a "proxy" of net mineralization rate) and net primary productivity of the ecosystem (considered a "proxy" of nitrogen demand). It is implemented in a global vegetation model and tested against site experiments of CO2 fertilization and soil warming. Furthermore, global simulations of past and future CO2 fertilization are carried out and compared to other model results and available estimates of global C sequestration. It is shown that when N limitation is taken into account using the simple parameterization presented here, the model reproduces fairly realistically the carbon dynamics observed under CO2 fertilization and soil warming.

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