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Carbon budget

Florian A Busch, Rowan F Sage
The biochemical model of C3 photosynthesis by Farquhar, von Caemmerer and Berry (FvCB) assumes that photosynthetic CO2 assimilation is limited by one of three biochemical processes that are not always easily discerned. This leads to improper assessments of biochemical limitations that limit the accuracy of the model predictions. We use the sensitivity of rates of CO2 assimilation and photosynthetic electron transport to changes in O2 and CO2 concentration in the chloroplast to evaluate photosynthetic limitations...
October 21, 2016: New Phytologist
Yadvinder Malhi, Cécile A J Girardin, Gregory R Goldsmith, Christopher E Doughty, Norma Salinas, Daniel B Metcalfe, Walter Huaraca Huasco, Javier E Silva-Espejo, Jhon Del Aguilla-Pasquell, Filio Farfán Amézquita, Luiz E O C Aragão, Rossella Guerrieri, Françoise Yoko Ishida, Nur H A Bahar, William Farfan-Rios, Oliver L Phillips, Patrick Meir, Miles Silman
Why do forest productivity and biomass decline with elevation? To address this question, research to date generally has focused on correlative approaches describing changes in woody growth and biomass with elevation. We present a novel, mechanistic approach to this question by quantifying the autotrophic carbon budget in 16 forest plots along a 3300 m elevation transect in Peru. Low growth rates at high elevations appear primarily driven by low gross primary productivity (GPP), with little shift in either carbon use efficiency (CUE) or allocation of net primary productivity (NPP) between wood, fine roots and canopy...
October 21, 2016: New Phytologist
Guohua Shi, Changhui Peng, Meng Wang, Shengwei Shi, Yanzheng Yang, Junyao Chu, Junjun Zhang, Guanghui Lin, Yan Shen, Qiuan Zhu
The lateral transport of dissolved organic carbon (DOC) plays an important role in linking the carbon cycles of terrestrial and aquatic ecosystems. Neglecting the lateral flow of dissolved organic carbon can lead to an underestimation of the organic carbon budget of terrestrial ecosystems. It is thus necessary to integrate DOC concentrations and flux into carbon cycle models, particularly with regard to the development of models that are intended to directly link terrestrial and ocean carbon cycles. However, to achieve this goal, more accurate information is needed to better understand and predict DOC dynamics...
2016: PloS One
Dennis Baldocchi, Youngryel Ryu, Trevor Keenan
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 CO 2 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...
2016: F1000Research
Alexandra Garzon-Garcia, J Patrick Laceby, Jon M Olley, Stuart E Bunn
Understanding the sources of sediment, organic matter and nitrogen (N) transferred from terrestrial to aquatic environments is important for managing the deleterious off-site impacts of soil erosion. In particular, investigating the sources of organic matter associated with fine sediment may also provide insight into carbon (C) and N budgets. Accordingly, the main sources of fine sediment, organic matter (indicated by total organic carbon), and N are determined for three nested catchments (2.5km(2), 75km(2), and 3076km(2)) in subtropical Australia...
October 5, 2016: Science of the Total Environment
Daijun Liu, Joan Llusia, Romà Ogaya, Marc Estiarte, Laura Llorens, Xiaohong Yang, Josep Peñuelas
Warmer temperatures and extended drought in the Mediterranean Basin are becoming increasingly important in determining plant physiological processes and affecting the regional carbon budget. The responses of plant physiological variables such as shoot water potential (Ψ), carbon-assimilation rates (A), stomatal conductance (gs) and intrinsic water-use efficiency (iWUE) to these climatic regimes, however, are not well understood. We conducted long-term (16 years) field experiments with mild nocturnal warming (+0...
November 2016: Plant Science: An International Journal of Experimental Plant Biology
Robert M Cirocco, José M Facelli, Jennifer R Watling
Associations between plants and nitrogen (N)-fixing rhizobia intensify with decreasing N supply and come at a carbon cost to the host. However, what additional impact parasitic plants have on their leguminous hosts' carbon budget in terms of effects on host physiology and growth is unknown. Under glasshouse conditions, Ulex europaeus and Acacia paradoxa either uninfected or infected with the hemiparasite Cassytha pubescens were supplied (high nitrogen (HN)) or not (low nitrogen (LN)) with extra N. The photosynthetic performance and growth of the association were measured...
September 22, 2016: New Phytologist
Stefan Schwietzke, Owen A Sherwood, Lori M P Bruhwiler, John B Miller, Giuseppe Etiope, Edward J Dlugokencky, Sylvia Englund Michel, Victoria A Arling, Bruce H Vaughn, James W C White, Pieter P Tans
Methane has the second-largest global radiative forcing impact of anthropogenic greenhouse gases after carbon dioxide, but our understanding of the global atmospheric methane budget is incomplete. The global fossil fuel industry (production and usage of natural gas, oil and coal) is thought to contribute 15 to 22 per cent of methane emissions to the total atmospheric methane budget. However, questions remain regarding methane emission trends as a result of fossil fuel industrial activity and the contribution to total methane emissions of sources from the fossil fuel industry and from natural geological seepage, which are often co-located...
October 5, 2016: Nature
Elyn Remy, Rainer Gasche, Ralf Kiese, Karen Wuyts, Kris Verheyen, Pascal Boeckx
Forest ecosystems may act as sinks or sources of nitrogen (N) and carbon (C) compounds, such as the climate relevant trace gases nitrous oxide (N2O), nitric oxide (NO) and methane (CH4). Forest edges, which catch more atmospheric deposition, have become important features in European landscapes and elsewhere. Here, we implemented a fully automated measuring system, comprising static and dynamic measuring chambers determining N2O, NO and CH4 fluxes along an edge-to-interior transect in an oak (Q. robur) and a pine (P...
October 1, 2016: Science of the Total Environment
Gerard F Ricardo, Ross J Jones, Peta L Clode, Andrew P Negri
Suspended sediments produced from dredging activities, or added to the sediment budget via river runoff, are a concern for marine resource managers. Understanding the impact of suspended sediments on critical life history stages of keystone species like corals is fundamental to effective management of coastlines and reefs. Coral embryos (Acropora tenuis and A. millepora) and larvae (A. tenuis, A. millepora and Pocillopora acuta) were subjected to a range of suspended sediment concentrations of different sediment types (siliciclastic and carbonate) to assess concentration-response relationships on ecologically relevant endpoints, including survivorship and ability to metamorphose...
2016: PloS One
Roberto Pilli, Giacomo Grassi, Werner A Kurz, Jose V Moris, Raúl Abad Viñas
BACKGROUND: Forests and the forest sector may play an important role in mitigating climate change. The Paris Agreement and the recent legislative proposal to include the land use sector in the EU 2030 climate targets reflect this expectation. However, greater confidence on estimates from national greenhouse gas inventories (GHGI) and more comprehensive analyses of mitigation options are needed to seize this mitigation potential. The aim of this paper is to provide a tool at EU level for verifying the EU GHGI and for simulating specific policy and forest management scenarios...
December 2016: Carbon Balance and Management
Hong-Tao Liu, Yan-Wen Wang, Xiao-Jie Liu, Ding Gao, Guo-di Zheng, Mei Lei, Guang-Hui Guo, Hai-Xia Zheng, Xiang-Juan Kong
Sludge is an important source of greenhouse gas (GHG) emissions, both in the form of direct process emissions and as a result of indirect carbon-derived energy consumption during processing. In this study, the carbon budgets of two sludge disposal processes at two well-known sludge disposal sites in China (bio-drying and heat drying pre-treatments, both followed by mono-incineration) were quantified and compared. Total GHG emissions from heat drying combined with mono-incineration were 0.1731 tCO2e∙t(-1), while 0...
September 14, 2016: Journal of the Air & Waste Management Association
Ling Luo, Ji-Dong Gu
Bioturbation and bioirrigation induced by burrowing macrofauna are recognized as important processes in aquatic sediment since macrofaunal activities lead to the alteration of sediment characteristics. However, there is a lack of information on how macrofauna influence microbial abundance and extracellular enzyme activity in mangrove sediment. In this study, the environmental parameters, extracellular enzyme activities, and microbial abundance were determined and their relationships were explored. Sediment samples were taken from the surface (S) and lower layer (L) without burrow, as well as crab burrow wall (W) and bottom of crab burrow (B) located at the Mai Po Nature Reserve, Hong Kong...
September 13, 2016: Microbial Ecology
Ming Xu, Hua Shang
Soil respiration (Rs) is the second largest carbon flux next to GPP between the terrestrial ecosystem (the largest organic carbon pool) and the atmosphere at a global scale. Given their critical role in the global carbon cycle, Rs measurement and modeling issues have been well reviewed in previous studies. In this paper, we briefly review advances in soil organic carbon (SOC) decomposition processes and the factors affecting Rs. We examine the spatial and temporal distribution of Rs measurements available in the literature and found that most of the measurements were conducted in North America, Europe, and East Asia, with major gaps in Africa, East Europe, North Asia, Southeast Asia, and Australia, especially in dry ecosystems...
September 20, 2016: Journal of Plant Physiology
Adéyèmi Chabi, Sven Lautenbach, Vincent Oladokoun Agnila Orekan, Nicholas Kyei-Baffour
BACKGROUND: The estimation of forest biomass changes due to land-use change is of significant importance for estimates of the global carbon budget. The accuracy of biomass density maps depends on the availability of reliable allometric models used in combination with data derived from satellites images and forest inventory data. To reduce the uncertainty in estimates of carbon emissions resulting from deforestation and forest degradation, better information on allometric equations and the spatial distribution of aboveground biomass stocks in each land use/land cover (LULC) class is needed for the different ecological zones...
December 2016: Carbon Balance and Management
Jesús Rodríguez-Calcerrada, Meng Li, Rosana López, Francisco Javier Cano, Jacek Oleksyn, Owen K Atkin, Pilar Pita, Ismael Aranda, Luis Gil
Combining hydraulic- and carbon-related measurements helps to understand drought-induced plant mortality. Here, we investigated the role that plant respiration (R) plays in determining carbon budgets under drought. We measured the hydraulic conductivity of stems and roots, and gas exchange and nonstructural carbohydrate (NSC) concentrations of leaves, stems and roots of seedlings of two resprouting species exposed to drought or well-watered conditions: Ulmus minor (riparian tree) and Quercus ilex (dryland tree)...
August 30, 2016: New Phytologist
Stefania Gilardoni, Paola Massoli, Marco Paglione, Lara Giulianelli, Claudio Carbone, Matteo Rinaldi, Stefano Decesari, Silvia Sandrini, Francesca Costabile, Gian Paolo Gobbi, Maria Chiara Pietrogrande, Marco Visentin, Fabiana Scotto, Sandro Fuzzi, Maria Cristina Facchini
The mechanisms leading to the formation of secondary organic aerosol (SOA) are an important subject of ongoing research for both air quality and climate. Recent laboratory experiments suggest that reactions taking place in the atmospheric liquid phase represent a potentially significant source of SOA mass. Here, we report direct ambient observations of SOA mass formation from processing of biomass-burning emissions in the aqueous phase. Aqueous SOA (aqSOA) formation is observed both in fog water and in wet aerosol...
September 6, 2016: Proceedings of the National Academy of Sciences of the United States of America
Renata Slavíková, David Püschel, Martina Janoušková, Martina Hujslová, Tereza Konvalinková, Hana Gryndlerová, Milan Gryndler, Martin Weiser, Jan Jansa
Quantification of carbon (C) fluxes in mycorrhizal plants is one of the important yet little explored tasks of mycorrhizal physiology and ecology. (13)CO2 pulse-chase labelling experiments are increasingly being used to track the fate of C in these plant-microbial symbioses. Nevertheless, continuous monitoring of both the below- and aboveground CO2 emissions remains a challenge, although it is necessary to establish the full C budget of mycorrhizal plants. Here, a novel CO2 collection system is presented which allows assessment of gaseous CO2 emissions (including isotopic composition of their C) from both belowground and shoot compartments...
August 22, 2016: Mycorrhiza
Sean T Michaletz, Michael D Weiser, Nate G McDowell, Jizhong Zhou, Michael Kaspari, Brent R Helliker, Brian J Enquist
Leaf thermoregulation has been documented in a handful of studies, but the generality and origins of this pattern are unclear. We suggest that leaf thermoregulation is widespread in both space and time, and originates from the optimization of leaf traits to maximize leaf carbon gain across and within variable environments. Here we use global data for leaf temperatures, traits and photosynthesis to evaluate predictions from a novel theory of thermoregulation that synthesizes energy budget and carbon economics theories...
2016: Nature Plants
Hao Wang, Lingfei Yu, Zhenhua Zhang, Wei Liu, Litong Chen, Guangmin Cao, Haowei Yue, Jizhong Zhou, Yunfeng Yang, Yanhong Tang, Jin-Sheng He
Rapid climate change and intensified human activities have resulted in water table lowering (WTL) and enhanced nitrogen (N) deposition in Tibetan alpine wetlands. These changes may alter the magnitude and direction of greenhouse gas (GHG) emissions, affecting the climate impact of these fragile ecosystems. We conducted a mesocosm experiment combined with a metagenomics approach (GeoChip 5.0) to elucidate the effects of WTL (-20 cm relative to control) and N deposition (30 kg N ha(-1) yr(-1) ) on carbon dioxide (CO2 ), methane (CH4 ) and nitrous oxide (N2 O) fluxes as well as the underlying mechanisms...
August 18, 2016: Global Change Biology
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