scholarly journals The biogeophysical climatic impacts of anthropogenic land use change during the Holocene

2015 ◽  
Vol 11 (5) ◽  
pp. 4601-4641
Author(s):  
M. C. Smith ◽  
J. S. Singarayer ◽  
P. J. Valdes ◽  
J. O. Kaplan ◽  
N. P. Branch
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Large Scale ◽  
Wave Train ◽  
Global Climate Model ◽  
Storm Track ◽  
Temperature Changes ◽  
Land Disturbance ◽  
Early Land ◽  
Anthropogenic Land Use

Abstract. The first agricultural societies were established around 10 ka BP and had spread across much of Europe and southern Asia by 5.5 ka BP with resultant anthropogenic deforestation for crop and pasture land. Various studies have attempted to assess the biogeochemical implications for Holocene climate in terms of increased carbon dioxide and methane emissions. However, less work has been done to examine the biogeophysical impacts of this early land use change. In this study, global climate model simulations with HadCM3 were used to examine the biogeophysical effects of Holocene land cover change on climate, both globally and regionally, from the early Holocene (8 ka BP) to the early industrial era (1850 CE). Two experiments were performed with alternative descriptions of past vegetation: (i) potential natural vegetation simulated by TRIFFID but no land-use changes, and (ii) where the anthropogenic land use model, KK10 (Kaplan et al., 2009, 2011) has been used to set the HadCM3 crop regions. Snapshot simulations have been run at 1000 year intervals to examine when the first signature of anthropogenic climate change can be detected both regionally, in the areas of land use change, and globally. Results indicate that in regions of early land disturbance such as Europe and S.E. Asia detectable temperature changes, outside the normal range of variability, are encountered in the model as early as 7 ka BP in the June/July/August (JJA) season and throughout the entire annual cycle by 2–3 ka BP. Areas outside the regions of land disturbance are also affected, with virtually the whole globe experiencing significant temperature changes (predominantly cooling) by the early industrial period. Large-scale precipitation features such as the Indian monsoon, the intertropical convergence zone (ITCZ), and the North Atlantic storm track are also impacted by local land use and remote teleconnections. We investigated how advection by surface winds, mean sea level pressure (MSLP) anomalies, and tropospheric stationary wave train disturbances in the mid- to high-latitudes led to remote teleconnections.

scholarly journals The biogeophysical climatic impacts of anthropogenic land use change during the Holocene

2016 ◽  
Vol 12 (4) ◽  
pp. 923-941 ◽  
Author(s):  
M. Clare Smith ◽  
Joy S. Singarayer ◽  
Paul J. Valdes ◽  
Jed O. Kaplan ◽  
Nicholas P. Branch
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Large Scale ◽  
Global Climate Model ◽  
Storm Track ◽  
Temperature Changes ◽  
Model Simulations ◽  
Land Disturbance ◽  
Early Land ◽  
Anthropogenic Land Use

Abstract. The first agricultural societies were established around 10 ka BP and had spread across much of Europe and southern Asia by 5.5 ka BP with resultant anthropogenic deforestation for crop and pasture land. Various studies (e.g. Joos et al., 2004; Kaplan et al., 2011; Mitchell et al., 2013) have attempted to assess the biogeochemical implications for Holocene climate in terms of increased carbon dioxide and methane emissions. However, less work has been done to examine the biogeophysical impacts of this early land use change. In this study, global climate model simulations with Hadley Centre Coupled Model version 3 (HadCM3) were used to examine the biogeophysical effects of Holocene land cover change on climate, both globally and regionally, from the early Holocene (8 ka BP) to the early industrial era (1850 CE). Two experiments were performed with alternative descriptions of past vegetation: (i) one in which potential natural vegetation was simulated by Top-down Representation of Interactive Foliage and Flora Including Dynamics (TRIFFID) but without land use changes and (ii) one where the anthropogenic land use model Kaplan and Krumhardt 2010 (KK10; Kaplan et al., 2009, 2011) was used to set the HadCM3 crop regions. Snapshot simulations were run at 1000-year intervals to examine when the first signature of anthropogenic climate change can be detected both regionally, in the areas of land use change, and globally. Results from our model simulations indicate that in regions of early land disturbance such as Europe and south-east Asia detectable temperature changes, outside the normal range of variability, are encountered in the model as early as 7 ka BP in the June–July–August (JJA) season and throughout the entire annual cycle by 2–3 ka BP. Areas outside the regions of land disturbance are also affected, with virtually the whole globe experiencing significant temperature changes (predominantly cooling) by the early industrial period. The global annual mean temperature anomalies found in our single model simulations were −0.22 at 1850 CE, −0.11 at 2 ka BP, and −0.03 °C at 7 ka BP. Regionally, the largest temperature changes were in Europe with anomalies of −0.83 at 1850 CE, −0.58 at 2 ka BP, and −0.24 °C at 7 ka BP. Large-scale precipitation features such as the Indian monsoon, the Intertropical Convergence Zone (ITCZ), and the North Atlantic storm track are also impacted by local land use and remote teleconnections. We investigated how advection by surface winds, mean sea level pressure (MSLP) anomalies, and tropospheric stationary wave train disturbances in the mid- to high latitudes led to remote teleconnections.

scholarly journals Soil Denitrifier Community Size Changes with Land Use Change to Perennial Bioenergy Cropping Systems

2016 ◽  
Author(s):  
Karen A. Thompson ◽  
Bill Deen ◽  
Kari E. Dunfield
Keyword(s):  
Land Use ◽  
16S Rrna ◽  
Land Use Change ◽  
Crop Production ◽  
Large Scale ◽  
Perennial Grasses ◽  
N2o Emissions ◽  
Research Station ◽  
N2o Production ◽  
Nirs Gene

Abstract. Dedicated biomass crops are required for future bioenergy production. However, the effects of large-scale land use change (LUC) from traditional annual crops, such as corn-soybean rotations to the perennial grasses (PGs) switchgrass and miscanthus on soil microbial community functioning is largely unknown. Specifically, ecologically significant denitrifying communities, which regulate N2O production and consumption in soils, may respond differently to LUC due to differences in carbon (C) and nitrogen (N) inputs between crop types and management systems. Our objective was to quantify bacterial denitrifying gene abundances as influenced by corn-soybean crop production compared to PG biomass production. A field trial was established in 2008 at the Elora Research Station in Ontario, Canada (n = 30), with miscanthus and switchgrass grown alongside corn-soybean rotations at different N rates (0 and 160 kg N ha-1) and biomass harvest dates within PG plots. Soil was collected on four dates from 2011–2012 and quantitative PCR was used to enumerate the total bacterial community (16S rRNA), and communities of bacterial denitrifiers by targeting nitrite reductase (nirS) and N2O reductase (nosZ) genes. Miscanthus produced significantly larger yields and supported larger nosZ denitrifying communities than corn-soybean rotations regardless of management, indicating large-scale LUC from corn-soybean to miscanthus may be suitable in variable Ontario conditions while potentially mitigating soil N2O emissions. Harvesting switchgrass in the spring decreased yields in N-fertilized plots, but did not affect gene abundances. Standing miscanthus overwinter resulted in higher 16S rRNA and nirS gene copies than in fall-harvested crops. However, the size of the total (16S rRA) and denitrifying communities changed differently over time and in response to LUC, indicating varying controls on these communities.

scholarly journals Impacts of changes in land use and land cover on atmospheric chemistry and air quality over the 21st century

2011 ◽  
Vol 11 (5) ◽  
pp. 15469-15495 ◽  
Author(s):  
S. Wu ◽  
L. J. Mickley ◽  
J. O. Kaplan ◽  
D. J. Jacob
Keyword(s):  
Land Use ◽  
Air Quality ◽  
Land Use Change ◽  
Land Cover ◽  
21St Century ◽  
Secondary Organic Aerosols ◽  
Surface Ozone ◽  
Organic Aerosols ◽  
Ozone Concentrations ◽  
Anthropogenic Land Use

Abstract. The effects of future land use and land cover change on the chemical composition of the atmosphere and air quality are largely unknown. To investigate the potential effects associated with future changes in vegetation driven by atmospheric CO2 concentrations, climate, and anthropogenic land use over the 21st century, we performed a series of model experiments combining a general circulation model with a dynamic global vegetation model and an atmospheric chemical-transport model. Our results indicate that climate- and CO2-induced changes in vegetation composition and density could lead to decreases in summer afternoon surface ozone of up to 10 ppb over large areas of the northern mid-latitudes. This is largely driven by the substantial increases in ozone dry deposition associated with changes in the composition of temperate and boreal forests where conifer forests are replaced by those dominated by broadleaf tree types, as well as a CO2-driven increase in vegetation density. Climate-driven vegetation changes over the period 2000–2100 lead to general increases in isoprene emissions, globally by 15 % in 2050 and 36 % in 2100. These increases in isoprene emissions result in decreases in surface ozone concentrations where the NOx levels are low, such as in remote tropical rainforests. However, over polluted regions, such as the northeastern United States, ozone concentrations are calculated to increase with higher isoprene emissions in the future. Increases in biogenic emissions also lead to higher concentrations of secondary organic aerosols, which increase globally by 10 % in 2050 and 20 % in 2100. Surface concentrations of secondary organic aerosols are calculated to increase by up to 1 μg m−3 for large areas in Eurasia. When we use a scenario of future anthropogenic land use change, we find less increase in global isoprene emissions due to replacement of higher-emitting forests by lower-emitting cropland. The global atmospheric burden of secondary organic aerosols changes little by 2100 when we account for future land use change, but both secondary organic aerosols and ozone show large regional changes at the surface.

scholarly journals Potential Changes of Annual-Averaged Nutrient Export in the South Saskatchewan River Basin under Climate and Land-Use Change Scenarios

Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1438 ◽  
Author(s):  
Luis Morales-Marín ◽  
Howard Wheater ◽  
Karl-Erich Lindenschmidt
Keyword(s):  
Water Quality ◽  
Land Use ◽  
Land Use Change ◽  
General Circulation ◽  
Large Scale ◽  
Land Use Changes ◽  
General Circulation Models ◽  
Nutrient Export ◽  
The South ◽  
South Saskatchewan River

Climate and land-use changes modify the physical functioning of river basins and, in particular, influence the transport of nutrients from land to water. In large-scale basins, where a variety of climates, topographies, soil types and land uses co-exist to form a highly heterogeneous environment, a more complex nutrient dynamic is imposed by climate and land-use changes. This is the case of the South Saskatchewan River (SSR) that, along with the North Saskatchewan River, forms one of the largest river systems in western Canada. The SPAtially Referenced Regression On Watershed (SPARROW) model is therefore implemented to assess water quality in the basin, in order to describe spatial and temporal patterns and identify those factors and processes that affect water quality. Forty-five climate and land-use change scenarios comprehended by five General Circulation Models (GCMs) and three Representative Concentration Pathways (RCPs) were incorporated into the model to explain how total nitrogen (TN) and total phosphorus (TP) export could vary across the basin in 30, 60 and 90 years from now. According to model results, annual averages of TN and TP export in the SSR are going to increase in the range 0.9–1.28 kg km − 2 year − 1 and 0.12–0.17 kg km − 2 year − 1 , respectively, by the end of the century, due to climate and land-use changes. Higher increases of TP compared to TN are expected since TP and TN are going to increase ∼36% and ∼21%, respectively, by the end of the century. This research will support management plans in order to mitigate nutrient export under future changes of climate and land use.

scholarly journals Nitrogen isotopic signatures and fluxes of N2O in response to land-use change on naturally occurring saline–alkaline soil

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Arbindra Timilsina ◽  
Wenxu Dong ◽  
Jiafa Luo ◽  
Stuart Lindsey ◽  
Yuying Wang ◽  
...  
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Large Scale ◽  
N Availability ◽  
Alkaline Soil ◽  
Isotopic Signatures ◽  
Naturally Occurring ◽  
Artificial Ecosystems ◽  
The Impact ◽  
Natural Grassland

AbstractThe conversion of natural grassland to semi-natural or artificial ecosystems is a large-scale land-use change (LUC) commonly occurring to saline–alkaline land. Conversion of natural to artificial ecosystems, with addition of anthropogenic nitrogen (N) fertilizer, influences N availability in the soil that may result in higher N2O emission along with depletion of 15N, while converting from natural to semi-natural the influence may be small. So, this study assesses the impact of LUC on N2O emission and 15N in N2O emitted from naturally occurring saline–alkaline soil when changing from natural grassland (Phragmites australis) to semi-natural [Tamarix chinensis (Tamarix)] and to cropland (Gossypium spp.). The grassland and Tamarix ecosystems were not subject to any management practice, while the cropland received fertilizer and irrigation. Overall, median N2O flux was significantly different among the ecosystems with the highest from the cropland (25.3 N2O-N µg m−2 h−1), intermediate (8.2 N2O-N µg m−2 h−1) from the Tamarix and the lowest (4.0 N2O-N µg m−2 h−1) from the grassland ecosystem. The 15N isotopic signatures in N2O emitted from the soil were also significantly affected by the LUC with more depleted from cropland (− 25.3 ‰) and less depleted from grassland (− 0.18 ‰). Our results suggested that the conversion of native saline–alkaline grassland with low N to Tamarix or cropland is likely to result in increased soil N2O emission and also contributes significantly to the depletion of the 15N in atmospheric N2O, and the contribution of anthropogenic N addition was found more significant than any other processes.

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