Global pattern of ecosystem respiration tendencies and its implications on terrestrial carbon sink potential

As the largest component of carbon export from terrestrial ecosystems, ecosystem respiration (RECO) determines the carbon stock changes in terrestrial ecosystems. It is essential to accurately simulate the response of RECO to climate change. In this study, by constructing an optimal deep learning model for simulating global-scale RECO, we found that there is a 1–2 years' lagged response of RECO to changes in water conditions and an inconsistency in carbon input (NPP) and output (RECO) trends. The NPP growth trend in global terrestrial ecosystems is greater than that of RECO, with a trend showing increasing carbon sinks, particularly in the northern extra-tropics; while the carbon sink capacity of tropical regions has gradually saturated, showing that the changing trend of RECO is close to that of NPP, which poses a potential risk to the sustainable carbon sink capacity of global ecosystems in the future.

Siberian 2020 heatwave increased spring CO2 uptake but not annual CO2 uptake

Siberia experienced an unprecedented strong and persistent heatwave in winter to spring of 2020. Using bottom-up and top-down approaches, we evaluated seasonal and annual CO2 fluxes of 2020 in the northern hemisphere (north of 30ºN), focusing on Siberia where the pronounced heatwave occurred. We found that over Siberia, CO2 respiration loss in response to the pronounced positive winter temperature anomaly was greater than in previous years. However, continued warming in spring enhanced photosynthetic CO2 uptake, resulting in the largest seasonal transition in NEE, that is, the largest magnitude of the switch from the net CO2 loss in winter to net CO2 uptake in spring until June. However, this exceptional transition was followed by the largest reduction in CO2 uptake in late summer, due to multiple environmental constraints, including a soil moisture deficit. Despite a substantial increase of CO2 uptake by 22 ± 9 gC m-2 in spring in response to the heatwave, the mean annual CO2 uptake over Siberia was slightly lower (3 ± 13 gC m-2 year-1) than the average of the previous five years. These results highlight the highly dynamic response of seasonal carbon fluxes to extreme temperature anomalies at high latitudes, indicating a seasonal compensation between abnormal uptake and release of CO2 in response to extreme warmth that may limit carbon sink capacity in high northern latitudes.

Comparative analysis of means to control the thermal regime of a cooling thermoelement while minimizing the set of basic parameters

This paper reports a comparative analysis of the thermal regime control means while minimizing a set of basic parameters in various combinations with the indicators of reliability and dynamics of the functioning of a single-stage thermoelectric cooler. The connection has been established between the optimal relative operating current corresponding to the minimum of the set on the relative temperature difference and heat sink capacity of the radiator. The results of calculating the main parameters, reliability indicators, time of entering the stationary mode of operation for various current modes of operation at a fixed temperature difference, thermal load at different geometry of the branches of thermoelements are given. A comparative analysis of the main parameters, indicators of the reliability and operational dynamics of a single-stage cooler under various characteristic current modes of operation has been carried out. Minimizing the set of basic parameters in conjunction with the reliability indicators and operational dynamics of the cooling thermoelement provides a decrease in the refrigeration coefficient up to 40 % compared to the maximum cooling capacity mode, as well as the optimal heat sink capacity of the radiator, the amount of energy expended, the time of entering the stationary mode, the relative intensity of failures. The analysis of the influence of the temperature difference at a predefined thermal load on the relative operating current, the time it takes for the cooler to enter the stationary thermal regime, the heat sink capacity of the radiator, the relative intensity of failures has been performed. The devised method of optimal control over the thermal regime of a single-stage thermoelectric cooler based on minimizing the set of basic parameters makes it possible to search for and select compromise solutions, taking into consideration the weight of each of the limiting factors

Greenhouse gas emissions and carbon sink potential in Eastern Africa rangeland ecosystems: A review

Many activities from livestock husbandry contribute to emission and concentration of carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) gases to the atmosphere; activities such as grazing, manure and urine deposited or stored on land as well as crop farming practices such as tilling, burning of biomass or crop residues. A better understanding of the extent of emission sources and carbon sequestration potential for Eastern Africa rangelands is vital for developing mitigation strategies. In this article, we review the sources of emission with a focus on land conversion for crop farming, livestock husbandry, wildfire/burning and biotic processes such as soil biota activity in the ecosystem. The trade-offs of using rangeland with an emphasis on enhancing carbon sequestration potential are also addressed. This review revealed that many practices that enhance carbon capture process show promising benefits with sink capacity of −0.004 to 13 Mg C ha−1 year−1. However, given multiple land-use and environmental dynamics in Eastern African rangelands, it is imperative to generate more data across various land management and climatic zones in order to ascertain varied sink capacity. Improving carbon sequestration in rangelands through appropriate land management is a promising cost-effective strategy to mitigate climate change. Through improved farming or grazing management practice and restoring of degraded areas, there are significant benefits to enhance carbon sequestration. As rangeland resources are multi-faceted, engaging trans-disciplinary approaches is necessary to allow analyses of co-benefits of improved management or trade-offs degrading.

Natural Carbon Sinks Linked to Pastoral Activity in S Spain: A Territorial Evaluation Methodology for Mediterranean Goat Grazing Systems

Exploring and developing new tools for the accounting and management of natural C sinks will provide a closer, more accurate option to remark the importance of such sinks in relation to livestock production, helping to support the persistence of some seriously endangered traditional, environmentally sustainable livestock farming. Following both precision and usability criteria, two main C sink databases covering the Andalusian region (S Spain) were developed from the Spanish Land Parcel Identification System (SIGPAC, coarse resolution) and the Spanish Information System on Land Cover (SIOSE, finer resolution) land use classes. Particular C sink factors based on growth rates for individual plant species were associated with detailed vegetation maps and, further, were linked to Land Use and Covers cartography across the region. In addition, eight ruminant farms were exhaustively studied in situ and used as a control. Results were compared with the obtained through the application of the developed C sink databases, and with the commonly used Petersen methodology. The sink capacity of vegetation associated with farms varied from 0.25 to 1.37 t CO2 ha−1 year−1, depending on the plant species composition and abundance. All the approaches showed significant differences from the control. C sink values were significantly higher when applying SIGPAC-based C sink database to farms, while values from the SIOSE and Petersen methodology approaches provided more moderate values, closer to the control. SIGPAC and Petersen approaches showed higher usability but presented lower precision due to a poor definition of plant cover. SIOSE-based C sink database provided suitable values able to be adapted to reality and used by farmers. In this regard, further research efforts to improve the adjustment of results and ease of use are required. The present approach means a methodological advance in the estimation of the C sink capacity associated with pastoral livestock farms, able to be incorporated into the CF calculation in contrasted areas worldwide, in the frame of the ‘eco-schemes’ being recently under development through the EU CAP.