Carbon variation of dry grasslands in Central Asia in response to climate controls and grazing appropriation

AbstractQuantification of grassland carbon (C) variations is necessary for understanding how grazing and climate change interact to regulate carbon capture and release. Central Asia (CA) has the largest temperate grassland belt in the world and unique temperate dryland ecosystems, which experienced severe climate change and grazing-induced disturbances. However, the impact of grazing on C dynamics is highly uncertain owing to climate variations. Here, an arid ecosystem model (AEM) supplemented with a grazing module that specifically addressed physiological and ecological characteristics of dryland vegetation was developed to quantitatively simulate grassland C dynamics in response to changes in precipitation, temperature, grazing intensity, and CO2 level in the past decades. The regional simulation results showed that net primary productivity (NPP) was affected mainly by precipitation (in 59% of the studied area). Grazing had a negative effect on NPP and C stocks, whereas overcompensation occurred in 25.71% of the studied area, mainly in the dry western parts. The complex interaction effects of climate, CO2, and grazing negatively affected productivity, with a grassland NPP decrease of − 1.14 g C/m2/a and high interannual variability. We found that the temporal pattern of cumulative C sequestration, especially total C and vegetation C (VEGC), closely followed the annual fluctuations of precipitation. VEGC stocks decreased from 182.22 to 177.82 g C/m2, with a very low value between 1998 and 2008, when precipitation significantly decreased. The results indicate that southern Xinjiang and the Turgay Plateau of Kazakhstan are ecologically fragile areas due to grassland degradation.

Download Full-text

Impact of grazing intensity on seasonal variations in soil organic carbon and soil CO 2 efflux in two semiarid grasslands in southern Botswana

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2012.0102 ◽

2012 ◽

Vol 367 (1606) ◽

pp. 3076-3086 ◽

Cited By ~ 53

Author(s):

Andrew D. Thomas

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Seasonal Variations ◽

Field Experiments ◽

Grazing Intensity ◽

C Sequestration ◽

Ecosystem Functions ◽

Semiarid Environments ◽

The Impact ◽

And Storage

Biological soil crusts (BSCs) are an important source of organic carbon, and affect a range of ecosystem functions in arid and semiarid environments. Yet the impact of grazing disturbance on crust properties and soil CO 2 efflux remain poorly studied, particularly in African ecosystems. The effects of burial under wind-blown sand, disaggregation and removal of BSCs on seasonal variations in soil CO 2 efflux, soil organic carbon, chlorophyll a and scytonemin were investigated at two sites in the Kalahari of southern Botswana. Field experiments were employed to isolate CO 2 efflux originating from BSCs in order to estimate the C exchange within the crust. Organic carbon was not evenly distributed through the soil profile but concentrated in the BSC. Soil CO 2 efflux was higher in Kalahari Sand than in calcrete soils, but rates varied significantly with seasonal changes in moisture and temperature. BSCs at both sites were a small net sink of C to the soil. Soil CO 2 efflux was significantly higher in sand soils where the BSC was removed, and on calcrete where the BSC was buried under sand. The BSC removal and burial under sand also significantly reduced chlorophyll a , organic carbon and scytonemin . Disaggregation of the soil crust, however, led to increases in chlorophyll a and organic carbon. The data confirm the importance of BSCs for C cycling in drylands and indicate intensive grazing, which destroys BSCs through trampling and burial, will adversely affect C sequestration and storage. Managed grazing, where soil surfaces are only lightly disturbed, would help maintain a positive carbon balance in African drylands.

Download Full-text

Critical Analysis and Evaluation of the Technology Pathways for Carbon Capture and Utilization

Clean Technologies ◽

10.3390/cleantechnol2040031 ◽

2020 ◽

Vol 2 (4) ◽

pp. 492-512

Author(s):

Simon P. Philbin

Keyword(s):

Climate Change ◽

Carbon Dioxide ◽

Circular Economy ◽

Critical Analysis ◽

Carbon Capture ◽

Research Study ◽

Carbon Dioxide Emission ◽

Analysis And Evaluation ◽

Carbon Capture And Utilization ◽

The Impact

Carbon capture and utilization (CCU) is the process of capturing unwanted carbon dioxide (CO2) and utilizing for further use. CCU offers significant potential as part of a sustainable circular economy solution to help mitigate the impact of climate change resulting from the burning of hydrocarbons and alongside adoption of other renewable energy technologies. However, implementation of CCU technologies faces a number of challenges, including identifying optimal pathways, technology maturity, economic viability, environmental considerations as well as regulatory and public perception issues. Consequently, this research study provides a critical analysis and evaluation of the technology pathways for CCU in order to explore the potential from a circular economy perspective of this emerging area of clean technology. This includes a bibliographic study on CCU, evaluation of carbon utilization processes, trend estimation of CO2 usage as well as evaluation of methane and methanol production. A value chain analysis is provided to support the development of CCU technologies. The research study aims to inform policy-makers engaged in developing strategies to mitigate climate change through reduced carbon dioxide emission levels and improve our understanding of the circular economy considerations of CCU in regard to production of alternative products. The study will also be of use to researchers concerned with pursuing empirical investigations of this important area of sustainability.

Download Full-text

Climate change mitigation and adaptation by biochar: mechanisms and regulatory trend in the rhizosphere

10.5194/egusphere-egu2020-22654 ◽

2020 ◽

Author(s):

Ali Feizi ◽

Bahar Razavi

Keyword(s):

Climate Change ◽

Climate Change Mitigation ◽

High Efficiency ◽

C Sequestration ◽

Alkaline Soil ◽

Mitigation And Adaptation ◽

The Impact ◽

Change Mitigation ◽

Biochar Amendment ◽

Impacts Of Climate Change

Climate change represents a key challenge to the sustainability of global ecosystems and human prosperity in the twenty-first century. The impacts of climate change combined with natural climate variability are predominantly adverse, and often exacerbate other environmental challenges such as degradation of ecosystems, loss of biodiversity, and air, water and land pollution. Besides, rapid industrialization and increasing adaption of agrochemical based crop production practices since green revolution have considerably increased the heavy metal contaminations in the environment.Assessing the impacts of climate change on our planet and addressing risks and opportunities is essential for taking decisions that will remain robust under future conditions, when many climate change impacts are expected to become more significant.Here, we established a review survey to assess the impact of biochar amendment and agroforstry system on CO2 sequestration and methaloid remediation.Our data base showed that Agroforestry-based solutions for carbon dioxide capture and sequestration for climate change mitigation and adaptation in long-term is more practical and realistic options for a sustainable ecosystem and decreasing negative effect of climate change. This was more supported in arid and semi-arid regions as well as area with saline and alkaline soil (20%).From a soil remediation standpoint, the general trend has been shifting from reduction of the total concentration to reduction of the physic-chemically and/or biologically available fractions of metals. This regulatory shift represents a tremendous saving in remediation cost. While metals are not degradable, their speciation and binding with soil through biochar amending reduced their solubility, mobility, and bioavailability. While agroforestry showed high efficiency in C sequestration (32%), biochar amendment raveled significant mitigation in heavymetals bioavailability (42%). However, studies which coupled both approaches are limited. Thus, we conclude that combined Agroforestry and biochar amendment regulates C sequestration and metalloids remediation more efficiently.

Download Full-text

Environmental assessment of amending the Amager Bakke incineration plant in Copenhagen with carbon capture and storage

Waste Management & Research ◽

10.1177/0734242x211048125 ◽

2021 ◽

pp. 0734242X2110481

Author(s):

V. Bisinella ◽

J. Nedenskov ◽

Christian Riber ◽

Tore Hulgaard ◽

Thomas H. Christensen

Keyword(s):

Climate Change ◽

Carbon Capture ◽

Carbon Capture And Storage ◽

Climate Change Impacts ◽

Waste Incineration ◽

Heat Output ◽

Net Energy ◽

District Heating System ◽

The Impact ◽

And Storage

Amending municipal solid waste incineration with carbon capture and storage (CCS) is a new approach that can reduce the climate change impacts of waste incineration. This study provides a detailed analysis of the consequences of amending the new Amager Bakke incinerator in Copenhagen (capacity: 600,000 tonnes waste per year) with CCS as a post-combustion technology. Emphasis is on the changes in the energy flows and outputs as well as the environmental performance of the plant; the latter is assessed by life cycle assessment. Amending Amager Bakke with CCS of the chosen configuration reduces the electricity output by 50% due to steam use by the capture unit, but introducing post-capture flue gas condensation increases the heat output utilized in the Copenhagen district heating system by 20%. Thus, the overall net energy efficiency is not affected. The CCS amendment reduces the fossil CO2 emissions to 40 kg CO2 per tonne of incinerated waste and stores 530 kg biogenic CO2 per tonne of incinerated waste. Potential developments in the composition of the residual waste incinerated or in the energy systems that Amager Bakke interacts with, do not question the benefits of the CCS amendment. In terms of climate change impacts, considering different waste composition and energy system scenarios, introducing CCS reduces in average the impact of Amager Bakke by 850 kg CO2-equivalents per tonne of incinerated waste. CCS increases the environmental impacts in other categories, but not in the same order of magnitude as the savings introduced within climate change.

Download Full-text

How Can Litter Modify the Fluxes of CO2 and CH4 from Forest Soils? A Mini-Review

Forests ◽

10.3390/f12091276 ◽

2021 ◽

Vol 12 (9) ◽

pp. 1276

Author(s):

Anna Walkiewicz ◽

Adrianna Rafalska ◽

Piotr Bulak ◽

Andrzej Bieganowski ◽

Bruce Osborne

Keyword(s):

Climate Change ◽

Forest Soils ◽

Tree Species ◽

Water Movement ◽

C Sequestration ◽

Climatic Conditions ◽

Tree Species Composition ◽

Clear Cutting ◽

And Shifts ◽

The Impact

Forests contribute strongly to global carbon (C) sequestration and the exchange of greenhouse gases (GHG) between the soil and the atmosphere. Whilst the microbial activity of forest soils is a major determinant of net GHG exchange, this may be modified by the presence of litter through a range of mechanisms. Litter may act as a physical barrier modifying gas exchange, water movement/retention and temperature/irradiance fluctuations; provide a source of nutrients for microbes; enhance any priming effects, and facilitate macro-aggregate formation. Moreover, any effects are influenced by litter quality and regulated by tree species, climatic conditions (rainfall, temperature), and forest management (clear-cutting, fertilization, extensive deforestation). Based on climate change projections, the importance of the litter layer is likely to increase due to an litter increase and changes in quality. Future studies will therefore have to take into account the effects of litter on soil CO2 and CH4 fluxes for various types of forests globally, including the impact of climate change, insect infestation, and shifts in tree species composition, as well as a better understanding of its role in monoterpene production, which requires the integration of microbiological studies conducted on soils in different climatic zones.

Download Full-text

Comprehensive Assessment of the Effect of Urban Built-Up Land Expansion and Climate Change on Net Primary Productivity

Complexity ◽

10.1155/2020/8489025 ◽

2020 ◽

Vol 2020 ◽

pp. 1-12 ◽

Cited By ~ 5

Author(s):

Pengyan Zhang ◽

Yanyan Li ◽

Wenlong Jing ◽

Dan Yang ◽

Yu Zhang ◽

...

Keyword(s):

Climate Change ◽

Land Use ◽

Land Use Change ◽

Primary Productivity ◽

Net Primary Productivity ◽

Urban Expansion ◽

Ecosystem Functions ◽

Rapid Urbanization ◽

Important Indicator ◽

The Impact

Urbanization is causing profound changes in ecosystem functions at local and regional scales. The net primary productivity (NPP) is an important indicator of global change, rapid urbanization and climate change will have a significant impact on NPP, and urban expansion and climate change in different regions have different impacts on NPP, especially in densely populated areas. However, to date, efforts to quantify urban expansion and climate change have been limited, and the impact of long-term continuous changes in NPP has not been well understood. Based on land use data, night light data, NPP data, climate data, and a series of social and economic data, we performed a comprehensive analysis of land use change in terms of type and intensity and explored the pattern of urban expansion and its relationship with NPP and climate change for the period of 2000–2015, taking Zhengzhou, China, as an example. The results show that the major form of land use change was cropland to built-up land during the 2000–2015 period, with a total area of 367.51 km2 converted. The NPP exhibited a generally increasing trend in the study area except for built-up land and water area. The average correlation coefficients between temperature and NPP and precipitation and NPP were 0.267 and 0.020, respectively, indicating that an increase in temperature and precipitation can promote NPP despite significant spatial differences. During the examined period, most expansion areas exhibited an increasing NPP trend, indicating that the influence of urban expansion on NPP is mainly characterized by an evident influence of the expansion area. The study can provide a reference for Zhengzhou and even the world's practical research to improve land use efficiency, increase agricultural productivity and natural carbon sinks, and maintain low-carbon development.

Download Full-text

Dynamic forest vegetation models for predicting impacts of climate change on forests: An Indian perspective

Indian Journal of Forestry ◽

10.54207/bsmps1000-2018-f7l9y5 ◽

2018 ◽

Vol 41 (1) ◽

pp. 1-12

Author(s):

Manoj Kumar ◽

◽

S.P.S. Rawat ◽

Hukum Singh ◽

N.H. Ravindranath ◽

...

Keyword(s):

Climate Change ◽

Environmental Variables ◽

Net Primary Productivity ◽

Climate Change Impacts ◽

Forest Vegetation ◽

Elevated Concentration ◽

Impact Prediction ◽

Vegetation Models ◽

Ibis Model ◽

The Impact

Understanding climate change vulnerability of Indian forests has received wider attention in recent years and a number of assessments with different approaches have emerged over time. These assessments have mostly used climate-sensitive vegetation models to explain the climate change impacts. In these studies, trees constituting a particular forest are often clubbed together into small number of groups having similar functional traits referred as Plant Functional Types (PFTs). Most of the Forest Vegetation Models (FVMs) are still in their developmental stage and there have been attempts at various levels to develop more versatile and precise models. Several developing countries, including India, still lag behind in developing dynamic vegetation models (DVMs), which could be appropriate for the local applications to predict the impact on forests at regional level. This is restrained mainly because of the lack of long-term observations with respect to various interacting biotic, abiotic and climatic (or environmental) variables in a forest ecosystem, like water and nitrogen use efficiency, response to elevated concentration of CO2, nutrient cycling, net primary productivity, etc. The observations on influence of the environmental variables on forest ecosystems are available in discrete form. Existing FVMs integrate observations more appropriately for their place of origin for which they have been developed. Different types of forests in different climatic zones are supposed to respond differently to climatic changes. Hence, it is imperative that models are developed for the specific biogeographic regions in order to predict the influences more accurately. It may not be wise to use existing FVMs in their pristine form for all of the region without considering the regional influences. Various challenges associated with the usage of the generic models of external origin with special reference to Integrated Biosphere Simulator (IBIS) model - being widely used and accepted in Indian policy documents- is presented in this paper. We also discuss on the need for developing a regional FVM for climate change impact studies, so that the impact prediction is more precise and reliable.

Download Full-text

Climate–Carbon Cycle Feedback Analysis: Results from the C4MIP Model Intercomparison

Journal of Climate ◽

10.1175/jcli3800.1 ◽

2006 ◽

Vol 19 (14) ◽

pp. 3337-3353 ◽

Cited By ~ 2085

Author(s):

P. Friedlingstein ◽

P. Cox ◽

R. Betts ◽

L. Bopp ◽

W. von Bloh ◽

...

Keyword(s):

Climate Change ◽

Carbon Cycle ◽

Net Primary Productivity ◽

Future Climate ◽

Climate Feedback ◽

Future Climate Change ◽

Ocean Carbon Cycle ◽

Intergovernmental Panel ◽

Ocean Carbon ◽

The Impact

Abstract Eleven coupled climate–carbon cycle models used a common protocol to study the coupling between climate change and the carbon cycle. The models were forced by historical emissions and the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) A2 anthropogenic emissions of CO2 for the 1850–2100 time period. For each model, two simulations were performed in order to isolate the impact of climate change on the land and ocean carbon cycle, and therefore the climate feedback on the atmospheric CO2 concentration growth rate. There was unanimous agreement among the models that future climate change will reduce the efficiency of the earth system to absorb the anthropogenic carbon perturbation. A larger fraction of anthropogenic CO2 will stay airborne if climate change is accounted for. By the end of the twenty-first century, this additional CO2 varied between 20 and 200 ppm for the two extreme models, the majority of the models lying between 50 and 100 ppm. The higher CO2 levels led to an additional climate warming ranging between 0.1° and 1.5°C. All models simulated a negative sensitivity for both the land and the ocean carbon cycle to future climate. However, there was still a large uncertainty on the magnitude of these sensitivities. Eight models attributed most of the changes to the land, while three attributed it to the ocean. Also, a majority of the models located the reduction of land carbon uptake in the Tropics. However, the attribution of the land sensitivity to changes in net primary productivity versus changes in respiration is still subject to debate; no consensus emerged among the models.

Download Full-text

Constraining carbon allocation in a terrestrial ecosystem model using long-term forest biomass time series

10.5194/egusphere-egu2020-10523 ◽

2020 ◽

Author(s):

Simon Besnard ◽

Sujan Koirala ◽

Maurizio Santoro ◽

Shanning Bao ◽

Oliver Cartus ◽

...

Keyword(s):

Time Series ◽

Forest Biomass ◽

Terrestrial Ecosystem ◽

Ecosystem Model ◽

Dynamic Allocation ◽

Terrestrial Ecosystem Model ◽

C Dynamics ◽

C Cycling ◽

C Stocks

Forests cover about 30% of the terrestrial surface of our planet and store a large part of the terrestrial carbon (C), indicating their fundamental role in terrestrial C dynamics. In recent years, significant advances have been made in understanding terrestrial C cycling across scales, albeit uncertainties remain about fundamental processes, such as photosynthesis, allocation, and mortality, which exert dominant controls on vegetation C dynamics. Allocation plays a critical role in forest ecosystem C cycling by partitioning the products of net photosynthesis into leaves, wood, and below-ground components but is still poorly represented mostly given limitations in process understanding as well as in both suitable and commensurate observations.Here, we explore different approaches in constraining C allocation alongside processes driving assimilation and out fluxes in a terrestrial ecosystem model based on novel forest biomass datasets. More specifically, we use a series of temporally changing above-ground biomass (AGB) data from local (i.e. in-situ forest inventory data) to global (i.e. long-term C-band satellite retrievals from 1992 to 2018) scales, in a multi-constraint approach. We explore the information contained in a novel AGB time series to diagnose the potential of using changes in vegetation C stocks, jointly with C and water fluxes, to constrain and parameterize different C allocation modeling approaches. Both at FLUXNET site level and global scale, we will: i) present these novel AGB datasets, their strengths and limitations, ii) demonstrate the relevance of constraining C allocation with such temporally changing AGB estimates, and iii) provide a comparison of different C allocation approaches (i.e. fixed versus dynamic allocation, and an hybrid modeling approach) and their implications in representing ecosystem dynamics.

Download Full-text

Risk and vulnerability of Mongolian grasslands to climate change and grazing

10.5194/egusphere-egu2020-4335 ◽

2020 ◽

Author(s):

Banzragch Nandintsetseg ◽

Bazartsersen Boldgiv ◽

Jinfeng Chang ◽

Philippe Ciais ◽

Masato Shinoda ◽

...

Keyword(s):

Climate Change ◽

Ecosystem Services ◽

National Level ◽

Grazing Intensity ◽

Ecosystem Model ◽

Dust Storms ◽

Cold Climate ◽

Economic Consequences ◽

Climatic Hazards ◽

The Future

Robust changes in climatic hazards, including droughts, heatwaves and dust storms, are evident in many parts of the world and they are expected to increase in magnitude and frequency in the future. At the same time, socio-ecological damage from climate-related disasters has increased worldwide, including the Eurasian steppes, notably Mongolian grasslands (MGs), which occur in arid and harsh cold climate and still support traditional nomadic livelihood and culture through the food supply, and agricultural and ecosystem services. In the 2000s, increasing climate disasters (droughts combined with anomalously harsh winters (dzuds in Mongolian), and dust storms) resulted in massive livestock deaths, causing socioeconomic stagnation. In this context, assessments of risk and vulnerability of MGs to climate change and grazing may support disaster risk management by helping to identify hazard risk hotspots, allowing herders in risky areas to be prepared for events, and to mitigate the future potential impacts. Here, we examine the risk and vulnerability of the MG ecosystem to droughts at the national-level during a 40-year (1976&#8211;2015) using simulations of a gridded process-based ecosystem model by contrasting the recent (1996&#8211;2015) and past (1976&#8211;1995) 20-years. In general, the model realistically simulates temporal and spatial variations of vegetation biomass and soil moisture that were captured by field and satellite observations during 2000&#8211;2015 over MGs. We apply a probabilistic risk analysis in which risk is the product of the probability of hazardous drought during June-August and ecosystem vulnerability. Results reveal that during 1976&#8211;2015, increases in droughts with rapid warming and slight drying occurred over MGs, particularly in the recent 20-year, accompanied by ever-increasing grazing intensity, which together resulted in declining trends in grassland productivity. During the recent 20-year, the risk of drought to productivity slightly increased over extended areas in MGs compared to the past 20-year. The increase in the risk to MGs predominantly caused by the climate change-induced increase in the probability of hazardous drought, and less by the vulnerability. Regionally, recent droughts modify the risk to grasslands particularly in northcentral and northeast Mongolia. Given the benefits of MGs for both ecosystem services and socio-economic consequences, recent increases in drought hazards and associated risk to MGs signal an urgent need to implement drought management policies that sustain MGs.

Download Full-text