scholarly journals Sensitivity of the global carbonate weathering carbon-sink flux to climate and land-use changes

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Sibo Zeng ◽  
Zaihua Liu ◽  
Georg Kaufmann
Keyword(s):  
Land Use ◽  
Carbon Cycle ◽  
Negative Impact ◽  
Carbon Sink ◽  
Land Use Changes ◽  
Global Scale ◽  
Environmental Drivers ◽  
Carbonate Weathering ◽  
Consistent Increase ◽  
Increasing Temperature

AbstractThe response of carbonate weathering carbon-sink flux (CCSF) to its environmental drivers is still not well understood on the global scale. This hinders understanding of the terrestrial carbon cycle. Here, we show that there is likely to be a widespread and consistent increase in the global CCSF (ranging from + 9.8% (RCP4.5) to + 17.1% (RCP8.5)) over the period 1950–2100. In the coming years the increasing temperature might be expected to have a negative impact on carbonate weathering. However, the increasing rainfall and anticipated land-use changes will counteract this, leading to a greater CCSF. This finding has been obtained by using long-term historical (1950–2005) and modeled future (2006–2100) data for two scenarios (RCP4.5 and RCP8.5) for climate and land-use change in our CCSF equilibrium model. This study stresses the potential role that carbonate weathering may play in the evolution of the global carbon cycle over this century.

scholarly journals China’s Terrestrial Ecosystem Carbon Balance During The 20th Century: An Analysis With A Process-Based Biogeochemistry Model

2021 ◽  
Author(s):  
Yanyu Lu ◽  
Yao Huang ◽  
Qianlai Zhuang ◽  
Wei Sun ◽  
Shutao Chen ◽  
...  
Keyword(s):  
Land Use ◽  
Carbon Cycle ◽  
Carbon Balance ◽  
Net Primary Production ◽  
Carbon Sink ◽  
Land Use Changes ◽  
Terrestrial Ecosystem ◽  
Terrestrial Ecosystems ◽  
Sink Strength ◽  
Temperature And Precipitation

Abstract China’s terrestrial ecosystems play a pronounced role in the global carbon cycle. Here we combine spatially-explicit information on vegetation, soil, topography, climate and land use change with a process-based biogeochemistry model to quantify the responses of terrestrial carbon cycle in China during the 20th century. We find that that the regional soil thermal and moisture regimes have dramatically changed. Specifically, evapotranspiration increased due to rising temperature and soils were drying in the last two decades of the 20th century. At a century scale, China’s terrestrial ecosystems have acted as a carbon sink averaging at 0.09 Pg C yr-1, with large inter-annual and decadal variabilities. The regional sink has been enhanced due to the rising temperature and CO2 concentration, with a slight increase trend in carbon sink strength along with the enhanced net primary production in the century. Meanwhile, the heterotrophic respiration increased in response to warming. The spatial and temporal variabilities of carbon balance in China are due to multiple controlling factors including temperature and precipitation and changing atmospheric CO2 concentrations. Land-use changes including reforestation and afforestation during the late 20th century partially contributed to the increase in carbon sink at the national scale.

scholarly journals Terrestrial Carbon Cycle Variability

F1000Research ◽  
2016 ◽  
Vol 5 ◽  
pp. 2371 ◽  
Author(s):  
Dennis Baldocchi ◽  
Youngryel Ryu ◽  
Trevor Keenan
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Carbon Cycle ◽  
Primary Productivity ◽  
Carbon Sink ◽  
Global Scale ◽  
Gross Primary Productivity ◽  
Arid Ecosystems ◽  
Terrestrial Carbon ◽  
Terrestrial Carbon Cycle

A growing literature is reporting on how the terrestrial carbon cycle is experiencing year-to-year variability because of climate anomalies and trends caused by global change. As CO2 concentration records in the atmosphere exceed 50 years and as satellite records reach over 30 years in length, we are becoming better able to address carbon cycle variability and trends. Here we review how variable the carbon cycle is, how large the trends in its gross and net fluxes are, and how well the signal can be separated from noise. We explore mechanisms that explain year-to-year variability and trends by deconstructing the global carbon budget. The CO2 concentration record is detecting a significant increase in the seasonal amplitude between 1958 and now. Inferential methods provide a variety of explanations for this result, but a conclusive attribution remains elusive. Scientists have reported that this trend is a consequence of the greening of the biosphere, stronger northern latitude photosynthesis, more photosynthesis by semi-arid ecosystems, agriculture and the green revolution, tropical temperature anomalies, or increased winter respiration. At the global scale, variability in the terrestrial carbon cycle can be due to changes in constituent fluxes, gross primary productivity, plant respiration and heterotrophic (microbial) respiration, and losses due to fire, land use change, soil erosion, or harvesting. It remains controversial whether or not there is a significant trend in global primary productivity (due to rising CO2, temperature, nitrogen deposition, changing land use, and preponderance of wet and dry regions). The degree to which year-to-year variability in temperature and precipitation anomalies affect global primary productivity also remains uncertain. For perspective, interannual variability in global gross primary productivity is relatively small (on the order of 2 Pg-C y-1) with respect to a large and uncertain background (123 +/- 4 Pg-C y-1), and detected trends in global primary productivity are even smaller (33 Tg-C y-2). Yet residual carbon balance methods infer that the terrestrial biosphere is experiencing a significant and growing carbon sink. Possible explanations for this large and growing net land sink include roles of land use change and greening of the land, regional enhancement of photosynthesis, and down regulation of plant and soil respiration with warming temperatures. Longer time series of variables needed to provide top-down and bottom-up assessments of the carbon cycle are needed to resolve these pressing and unresolved issues regarding how, why, and at what rates gross and net carbon fluxes are changing.

Mistletoes in a changing world: a premonition of a non-analog future?

Botany ◽  
2020 ◽  
Vol 98 (9) ◽  
pp. 479-488
Author(s):  
Francisco E. Fontúrbel
Keyword(s):  
Land Use ◽  
Land Use Changes ◽  
Biodiversity Loss ◽  
Global Scale ◽  
Ecological Interactions ◽  
Human Disturbances ◽  
Climate Change Effects ◽  
Long Run ◽  
Plant Animal Interactions ◽  
Changing World

Mistletoes are a group of flowering plants that have developed a parasitic lifeform through complex eco-evolutionary processes. Despite being considered a pest, mistletoes represent a keystone forest resource and are involved in complex plant–plant and plant–animal interactions. Their parasitic lifeform and specialized ecological interactions make mistletoes an ideal model with which to understand the effects of anthropogenic disturbances in a changing world. The accelerated growth of the human population has altered all ecosystems on Earth, leading to biodiversity loss. Land-use changes (involving habitat loss, fragmentation, degradation, and transformation processes) can alter the ecological scenario for mistletoe by altering hosts, mutualists, and nutrient cycling. Those changes may have large consequences at the community level, changing the spatial structure of mistletoes, as well as interaction effectiveness, facilitation process, interaction disruption, and novel interactions with invasive species, leading to non-analog communities in the long run. Furthermore, climate change effects operate on a global scale, enhancing the effects of land-use changes. As temperatures increase, many species would alter their distribution and phenology, potentially causing spatial and temporal mismatches. But more critical is the fact that water stress is likely to disrupt key ecological interactions. Thus, mistletoes can provide valuable insights for what we can expect in the future, as a result of human disturbances.

scholarly journals Effect of Land Use on Soil Quality in Afaka Forest Northern Guinea Savannah of Nigeria

2019 ◽  
pp. 1-12
Author(s):  
H. Haruna
Keyword(s):  
Land Use ◽  
Soil Fertility ◽  
Bulk Density ◽  
Soil Quality ◽  
Negative Impact ◽  
Land Use Changes ◽  
Chemical Properties ◽  
Available Phosphorus ◽  
Cultivated Land ◽  
Soil Fertility Management

Land use changes from forest into cultivated ecosystems result in negative impact on soil structure and quality. The purpose of this study was to determine effect of land use on soil quality in Afaka forest northern guinea savannah of Nigeria. Land use systems, including natural forest and cultivated land were identified. Eighteen (18) composite disturbed and undisturbed samples were collected from depth of 0-5 and 5-10 cm for analysis of pertinent soil properties in the laboratory using grid procedure. Most physical and chemical properties show relative variations in response to land use types and geomorphic positions. Results  indicate  that the soils had  high degree of weathering potentials, low  to moderate  bulk density at 0-5cm depth values between 1.42 to 1.49 Mg m-3 in  forest and  cultivated land, bulk density of  1.34 and 1.46 1.Mg m-3at 5 -1ocm depth   for forest and  cultivated land respectively. The soil water at 0-5cm depth is from 4.20 to 2.63 cm3/cm3, while at 5-10 cm depth these values vary from 4.32 to 2.13 cm3/cm3 under forest and cultivation land use. The pH (H2O) is 6.9 to 7.16 with low electrical conductivity of 0.13 dS/m(forest) and 0.12 dS/m (cultivation). The CEC of soils is recorded as 8.60 cmol kg-1 (forest) to 8.54 cmol kg-1 (cultivated)whereas  total nitrogen content of 1.21 g kg-1 and 1.11 g kg-1 and available phosphorus of 8.78 mg kg-1 (cultivated) and 5.47 mg kg-1 (forest).. Results indicate that soil fertility parameters were moderate to low for cultivated land and at all slope positions, suggesting that soil fertility management is required in order to make agriculture sustainable on Afaka area.

scholarly journals LAND USE CHANGE OF AGRICULTURAL LAND IN A SPATIAL POLITICAL APPROACH

2021 ◽  
Vol 3 (1) ◽  
pp. 25
Author(s):  
Rizca Yunike Putri
Keyword(s):  
Land Use ◽  
Environmental Sustainability ◽  
Agricultural Land ◽  
Negative Impact ◽  
Land Use Changes ◽  
Point Of View ◽  
Agricultural Activity ◽  
Spatial Politics ◽  
Community Activities ◽  
Political Approach

The effort to meet the community's need for space is to change the function of land which was originally used as agricultural activity to become a space for other community activities and is non-agricultural in nature, which we will later call the conversion of agricultural land. Generally, uncontrolled conversion of agricultural land functions, if not addressed, can lead to serious problems, among others, can threaten the capacity of food supply and environmental sustainability. The trend of increasing demand for land makes conversion of agricultural land difficult to avoid. The loss of agricultural land and the conversion of agricultural land to non-agricultural functions regardless of its form are indicators for the development of modern cities. The modern city which is synonymous with industrialization and the splendor of buildings will gradually remove agricultural areas and change the environmental ecosystem further. If viewed from an ecological point of view, of course this problem causes environmental imbalance which will have a negative impact on food security. But what about the conversion of agricultural land from the viewpoint of spatial politics?Keywords: Agricultural land, land use changes, political spatial

scholarly journals Si cycling in transition zones: a study of Si isotopes and biogenic silica accumulation in the Chesapeake Bay through the Holocene

2019 ◽  
Vol 146 (2) ◽  
pp. 145-170
Author(s):  
Carla K. M. Nantke ◽  
Patrick J. Frings ◽  
Johanna Stadmark ◽  
Markus Czymzik ◽  
Daniel J. Conley
Keyword(s):  
Land Use ◽  
Chesapeake Bay ◽  
Biogenic Silica ◽  
Environmental Changes ◽  
Land Use Changes ◽  
Sediment Cores ◽  
Global Scale ◽  
Silicon Isotope ◽  
Coastal Zones ◽  
Local Climate

AbstractSi fluxes from the continents to the ocean are a key element of the global Si cycle. Due to the ability of coastal ecosystems to process and retain Si, the ‘coastal filter’ has the potential to alter Si fluxes at a global scale. Coastal zones are diverse systems, sensitive to local environmental changes, where Si cycling is currently poorly understood. Here, we present the first palaeoenvironmental study of estuarine biogenic silica (BSi) fluxes and silicon isotope ratios in diatoms (δ30Sidiatom) using hand-picked diatom frustules in two sediment cores (CBdist and CBprox) from the Chesapeake Bay covering the last 12000 and 8000 years, respectively. Constrained by the well-understood Holocene evolution of the Chesapeake Bay, we interpret variations in Si cycling in the context of local climate, vegetation and land use changes. δ30Sidiatom varies between + 0.8 and + 1.7‰ in both sediment cores. A Si mass balance for the Chesapeake Bay suggests much higher rates of Si retention (~ 90%) within the system than seen in other coastal systems. BSi fluxes for both sediment cores co-vary with periods of sea level rise (between 9500 and 7500 a BP) and enhanced erosion due to deforestation (between 250 and 50 a BP). However, differences in δ30Sidiatom and BSi flux between the sites emphasize the importance of the seawater/freshwater mixing ratios and locally variable Si inputs from the catchment. Further, we interpret variations in δ30Sidiatom and the increase in BSi fluxes observed since European settlement (~ 250 a BP) to reflect a growing human influence on the Si cycle in the Chesapeake Bay. Thereby, land use change, especially deforestation, in the catchment is likely the major mechanism.

Environmental carrying capacity for sustainable shrimp farming.

2020 ◽  
Author(s):  
Md. Zakir Hossain ◽  
Nitin K. Tripathi ◽  
Michael J. Phillips
Keyword(s):  
Land Use ◽  
Carrying Capacity ◽  
Geographical Information Systems ◽  
Negative Impact ◽  
Land Use Changes ◽  
Shrimp Farming ◽  
Geographical Information ◽  
Land Use Patterns ◽  
Use Patterns ◽  
Creek Water

Abstract Aquaculture, particularly shrimp farming in the Kandaleru creek area, has shown spectacular growth within the last two decades. However, economic prosperity which was the driving force for shrimp farming expansion, has also had a significant negative impact on land use changes and creek water quality causing shrimp health hazards. Using a hypothesis that the discharge of shrimp farming effluents may have exceeded the carrying capacity (CC) of the creek water, the environmental CC of Kandaleru creek was assessed based on total nitrogen (TN) input. Remote sensing (RS) and image enhancement techniques integrated with geographical information systems (GIS) were applied to quantify and determine the changes in land use patterns in the creek area. GIS and a numeric model were used to compute the TN load in three different salinity zones to determine the CC status. The study revealed that exceeding the CC of the creek along with increasing shrimp farms, decreasing natural resources and changes in land use patterns.

scholarly journals Forest management in southern China generates short term extensive carbon sequestration

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Xiaowei Tong ◽  
Martin Brandt ◽  
Yuemin Yue ◽  
Philippe Ciais ◽  
Martin Rudbeck Jepsen ◽  
...  
Keyword(s):  
Land Use ◽  
Forest Cover ◽  
Southern China ◽  
Carbon Sink ◽  
Land Use Changes ◽  
Timber Harvest ◽  
Forest Growth ◽  
Carbon Equivalent ◽  
Forest Regions ◽  
Intensively Managed

AbstractLand use policies have turned southern China into one of the most intensively managed forest regions in the world, with actions maximizing forest cover on soils with marginal agricultural potential while concurrently increasing livelihoods and mitigating climate change. Based on satellite observations, here we show that diverse land use changes in southern China have increased standing aboveground carbon stocks by 0.11 ± 0.05 Pg C y−1 during 2002–2017. Most of this regional carbon sink was contributed by newly established forests (32%), while forests already existing contributed 24%. Forest growth in harvested forest areas contributed 16% and non-forest areas contributed 28% to the carbon sink, while timber harvest was tripled. Soil moisture declined significantly in 8% of the area. We demonstrate that land management in southern China has been removing an amount of carbon equivalent to 33% of regional fossil CO2 emissions during the last 6 years, but forest growth saturation, land competition for food production and soil-water depletion challenge the longevity of this carbon sink service.

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