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We integrate a carbon net sink and stand-level wood production to analyze their simultaneous optimization as an economic problem. Carbon is included in living trees, wood products, and forest soil. Forestry is specified by a size-structured model for optimizing thinning timing and intensity, rotation period, and the optimal choice of rotation versus continuous cover forestry. The optimal inclusion of a carbon net sink increases the carbon pool mainly in living trees and forest soil, while the effect on the product carbon pool remains minor. With a 3% interest rate, increasing the C[O.sub.2] price to 40 [euro] per tC[O.sub.2] increases the total steady-state carbon pool by 131% and the soil carbon accounts for ca. 60% of the increased carbon storage. Omitting soil carbon, as in previous studies, leads to underestimates of the carbon sink, significantly decreasing the optimal total C[O.sub.2] net sink and achievable economic net gain from joint wood production and carbon management. The inclusion of soil carbon suggests that, in contrast to previous results, a higher C[O.sub.2] price does not necessarily favor continuous cover forestry. Key words: carbon sequestration, economic profitability, soil carbon, continuous cover forestry, rotation forestry, optimal rotation, 1. Introduction Climate change and the aim of limiting global warming have strongly increased the attention given to forests as carbon sinks (Shukla et al. 2019). Compared with the tropics, [...]

The control of the production of ozone-depleting substances through the Montreal Protocol means that the stratospheric ozone layer is recovering.sup.1 and that consequent increases in harmful surface ultraviolet radiation are being avoided.sup.2,3. The Montreal Protocol has co-benefits for climate change mitigation, because ozone-depleting substances are potent greenhouse gases.sup.4-7. The avoided ultraviolet radiation and climate change also have co-benefits for plants and their capacity to store carbon through photosynthesis.sup.8, but this has not previously been investigated. Here, using a modelling framework that couples ozone depletion, climate change, damage to plants by ultraviolet radiation and the carbon cycle, we explore the benefits of avoided increases in ultraviolet radiation and changes in climate on the terrestrial biosphere and its capacity as a carbon sink. Considering a range of strengths for the effect of ultraviolet radiation on plant growth.sup.8-12, we estimate that there could have been 325-690 billion tonnes less carbon held in plants and soils by the end of this century (2080-2099) without the Montreal Protocol (as compared to climate projections with controls on ozone-depleting substances). This change could have resulted in an additional 115-235 parts per million of atmospheric carbon dioxide, which might have led to additional warming of global-mean surface temperature by 0.50-1.0 degrees. Our findings suggest that the Montreal Protocol may also be helping to mitigate climate change through avoided decreases in the land carbon sink. Modelling suggests that the Montreal Protocol may be mitigating climate change by protecting the land carbon sink, as well as by protecting the ozone layer and reducing greenhouse gas emissions., Author(s): Paul J. Young [sup.1] [sup.2] [sup.3] , Anna B. Harper [sup.4] [sup.5] , Chris Huntingford [sup.6] , Nigel D. Paul [sup.1] [sup.7] , Olaf Morgenstern [sup.8] , Paul A. [...]

Author(s): Per Gundersen [sup.1] , Emil E. Thybring [sup.1] , Thomas Nord-Larsen [sup.1] , Lars Vesterdal [sup.1] , Knute J. Nadelhoffer [sup.2] , Vivian K. Johannsen [sup.1] Author Affiliations: (1) [...]

Author(s): Sebastiaan Luyssaert [sup.1] , E.-Detlef Schulze [sup.2] , Alexander Knohl [sup.3] , Beverly E. Law [sup.4] , Philippe Ciais [sup.5] , John Grace [sup.6] Author Affiliations: (1) Faculty of [...]

As the Earth's climate continues to warm, scientists are searching for ways to reduce greenhouse gases in the atmosphere. Ecosystem ecologist and biogeochemist Ariana Sutton-Grier says that it will take [...]

The long-term record of atmospheric carbon dioxide growth rate shows that the sensitivity of this growth rate to tropical temperature variability has increased by a factor of about two in the past five decades, and was greater when tropical land regions experienced drier conditions, implying that moisture regulates this sensitivity. Sensitivity of tropical carbon flux to temperature Global warming and increasing drought conditions are thought likely to reduce the capacity of the tropical land carbon sink during this century, causing a positive climate feedback, but limited data are available to test the Earth system models making such predictions. This study makes use of long-term records of atmospheric CO.sub.2 growth rate and from Mauna Loa and the South Pole to demonstrate that the sensitivity of the tropical terrestrial carbon cycle to temperature fluctuations has increased by a factor of two during the past 50 years -- most probably in response to changes in humidity. The analysis also suggests that current models do not capture the observed increase in sensitivity and that a better understanding of the factors driving the response of tropical ecosystems to drought and warming is needed. Earth system models project that the tropical land carbon sink will decrease in size in response to an increase in warming and drought during this century, probably causing a positive climate feedback.sup.1,2. But available data.sup.3,4,5 are too limited at present to test the predicted changes in the tropical carbon balance in response to climate change. Long-term atmospheric carbon dioxide data provide a global record that integrates the interannual variability of the global carbon balance. Multiple lines of evidence.sup.6,7,8 demonstrate that most of this variability originates in the terrestrial biosphere. In particular, the year-to-year variations in the atmospheric carbon dioxide growth rate (CGR) are thought to be the result of fluctuations in the carbon fluxes of tropical land areas.sup.6,9,10. Recently, the response of CGR to tropical climate interannual variability was used to put a constraint on the sensitivity of tropical land carbon to climate change.sup.10. Here we use the long-term CGR record from Mauna Loa and the South Pole to show that the sensitivity of CGR to tropical temperature interannual variability has increased by a factor of 1.9 [plus or minus] 0.3 in the past five decades. We find that this sensitivity was greater when tropical land regions experienced drier conditions. This suggests that the sensitivity of CGR to interannual temperature variations is regulated by moisture conditions, even though the direct correlation between CGR and tropical precipitation is weak.sup.9. We also find that present terrestrial carbon cycle models do not capture the observed enhancement in CGR sensitivity in the past five decades. More realistic model predictions of future carbon cycle and climate feedbacks require a better understanding of the processes driving the response of tropical ecosystems to drought and warming., Author(s): Xuhui Wang [sup.1] , Shilong Piao [sup.1] [sup.2] , Philippe Ciais [sup.1] [sup.3] , Pierre Friedlingstein [sup.4] , Ranga B. Myneni [sup.5] , Peter Cox [sup.4] , Martin Heimann [...]

PROBLEM: Because its daunting size, long winters, and harsh conditions limit critical in-situ observations, the Southern Ocean poses special scientific uncertainties. One of those data-starved challenges has been understanding the [...]

Fertilization of the ocean by adding iron compounds has induced diatom-dominated phytoplankton blooms accompanied by considerable carbon dioxide drawdown in the ocean surface layer. However, because the fate of bloom biomass could not be adequately resolved in these experiments, the timescales of carbon sequestration from the atmosphere are uncertain. Here we report the results of a five-week experiment carried out in the closed core of a vertically coherent, mesoscale eddy of the Antarctic Circumpolar Current, during which we tracked sinking particles from the surface to the deep-sea floor. A large diatom bloom peaked in the fourth week after fertilization. This was followed by mass mortality of several diatom species that formed rapidly sinking, mucilaginous aggregates of entangled cells and chains. Taken together, multiple lines of evidence--although each with important uncertainties--lead us to conclude that at least half the bloom biomass sank far below a depth of 1,000 metres and that a substantial portion is likely to have reached the sea floor. Thus, iron-fertilized diatom blooms may sequester carbon for timescales of centuries in ocean bottom water and for longer in the sediments. The study of an iron-fertilized phytoplankton bloom dominated by diatoms, which takes up carbon dioxide from the atmosphere, shows that a substantial proportion of the bloom eventually sinks to the deep-sea floor, sequestering the carbon for timescales of centuries or more. Greening the seas The iron hypothesis proposes that the supply of iron-bearing dust to certain oceanic regions stimulates phytoplankton blooms that, by sinking out to the deep ocean when the organisms die, sequester carbon absorbed from exchange with the atmosphere. Experiments carried out to test the idea have provided clear evidence that iron addition generates phytoplankton blooms in waters with high -nutrient but low -chlorophyll concentrations, as proposed. But the fate of phytoplankton blooms and hence the extent of any carbon sequestration to the deep ocean has remained uncertain. This paper presents multiple lines of evidence, collected by aboard RV Polarstern in 2004 during the European Iron Fertilization Experiment (EIFEX), that suggest carbon is exported to the deep ocean as a result of iron fertilization, with at least half of the bloom biomass sinking to below 1,000 metres., Author(s): Victor Smetacek [sup.1] [sup.2] , Christine Klaas [sup.1] , Volker H. Strass [sup.1] , Philipp Assmy [sup.1] [sup.3] , Marina Montresor [sup.4] , Boris Cisewski [sup.1] [sup.5] , Nicolas [...]

This study quantified new biomass production of algae and bacteria in both benthic and pelagic habitats of clear-water lakes to contrast how carbon from the atmosphere and terrestrial sources regulates whole-lake metabolism. We studied four small unproductive lakes in subarctic northern Sweden during one summer season. The production of new biomass in both benthic and pelagic habitats was calculated as the sum of autotrophic production by algae and heterotrophic production by bacteria using allochthonous organic carbon (OC). Whole-lake production of new biomass was dominated by the benthic habitat (86% [+ or -] 4% [mean [+ or -] SD]) and by primary production (77% [+ or -] 9%). Still, heterotrophic bacteria fueled by allochthonous OC constituted a significant portion of the new biomass production in both benthic (19% [+ or -] 11%) and pelagic habitats (51% [+ or -] 24%). In addition, overall net production (primary production minus respiration) was close to zero in the benthic habitats but highly negative (-163 [+ or -] 81 mg C x [m.sup.-2] x [d.sup.1]) in pelagic regions of all lakes. We conclude (1) that allochthonous OC supported a significant part of total production of new biomass in both pelagic and benthic habitats, (2) that benthic habitats dominated the wholelake production of new biomass, and (3) that respiration and net C[O.sub.2] production dominated the carbon flux of the pelagic habitats and biomass production dominated the benthic carbon flux. Taken together, these findings suggest that previous investigations have greatly underestimated the productivity of clear-water lakes when benthic autotrophic production and metabolism of allochthonous OC have not been measured. Key words: allochthonous organic carbon; autotrophy; bacterial production; benthic; clear-water lakes; heterotrophy; metabolism; net ecosystem production; pelagic; primary production; respiration

Byline: Krister Andersson (1), Tom P. Evans (2), Kenneth R. Richards (3) Abstract: Previous research has identified the importance of the role of land cover in the global carbon cycle. In particular, forests have been identified as a significant carbon sink that can mitigate the rate of global climate change. Policy makers are faced with complex and difficult challenges in getting timely and useful information in monitoring global forest resources. Recent advances in the tools and methods of forest carbon accounting have produced new, innovative approaches to forest-based carbon inventories. But it is important as new tools are developed that scientists understand the needs of policy makers and that policy makers understand the capabilities and limitations of forest inventory methods. This paper explores four different policy applications that rely, or could benefit from, national carbon inventories. The goal is to help build a bridge between the communities of climate policy makers and scientists specialized in forest carbon inventories. To this end, we pursue three specific objectives: First we provide an overview for policy makers about approaches to forest carbon inventories, paying particular attention to the contributions of remote sensing technologies. Second, we outline the issues particularly relevant to forest inventory scientists who are interested in responding to public policy needs. We then discuss the tradeoffs between information cost, accuracy, precision, transparency and timeliness that need to be balanced in long-term monitoring of forest carbon. Finally, the article concludes with a series of observations and recommendations for the implementation of forest carbon inventories as increasingly central components of global climate change policy. Author Affiliation: (1) University of Colorado, Boulder, CO, USA (2) Indiana University, Bloomington, IN, USA (3) School of Public and Environmental Affairs, Indiana University, Bloomington, IN, 47405, USA Article History: Registration Date: 14/10/2008 Received Date: 06/02/2006 Accepted Date: 22/09/2008 Online Date: 21/11/2008

A forest model with an endogenous growth description and age-class structure is applied to study the impacts of potential climate policy instruments on the carbon services of privately owned and managed forests. The model describes the behaviour of a utility-maximizing private nonindustrial landowner who optimizes consumption flow, harvest timing, and the intertemporal allocation of silvicultural investments. Two policy options, one in which the landowner is granted periodic carbon rental payments and one in which the government subsidizes the costs of silvicultural investments, are studied. The rules for when the policy measures have both intended and unintended effects are derived. Using numerical examples, we demonstrate that the effectiveness of both policy options depends on the age-class structure of forests when future carbon benefits are discounted. In that case, carbon rental payments are more effective for forests with old age-class structures, while silvicultural subsidies are more effective for forests with young age-class structures. Un modele forestier, comportant des modules endogenes pour la croissance et la structure des classes d'age, est utilise afin d'etudier les impacts d'instruments potentiels consideres dans le cadre d'une politique climatique au sujet des services environnementaux que l'amenagement de forets privees pourrait procurer en terme de carbone. Le modele decrit le comportement d'un proprietaire non industriel qui maximise son utilite tout en optimisant sa consommation, la programmation des coupes et l'allocation intertemporelle des intrants sylvicoles. L'objet de l'etude concerne une politique prevoyant le paiement d'une rente periodique au proprietaire en echange du carbone immobilise et une autre selon laquelle le gouvernement subventionne le coht des investissements sylvicoles. Nous derivons des regles selon que les mesures appliquames ont les effets attendus ou non. Nous montrons, a l'aide d'exemples chiffres, que l'efficacite; de ces mesures depend de la structure d'age des forets quand les benefices futurs associes au carbone sont escomptes. Par exemple, les rentes payees pour la retention du carbone sont plus efficaces quand la foret presente une structure agee. A l'inverse, les subventions a la sylviculture sont plus efficaces quand la foret comporte une structure d'age plus jeune. [Traduit par la Redaction], Introduction The potential of forests has been widely recognized in climate policies (Adams et al. 1999; IPCC 2001). The role of forest management in abating climate change includes establishing plantations, [...]

We quantified and compared carbon (C) pools at a Missouri Ozark experimental forest 8 years after different harvest treatments. Total C pools were 182, 170, and 130 Mg C * [ha.sup.-1] for the control (no-harvest management; NHM), singletree, uneven-age management (UAM), and clearcut even-age management (EAM) stands, respectively. Harvesting reduced the live tree C pool by 31% in the UAM, 93% in EAM stands, and increased the coarse woody debris (CWD) C pool by 50% in UAM and 176% for EAM, compared with NHM stands. UAM significantly (p = 0.02) increased the mineral soil C pool by 14%, whereas EAM had no effect. More interestingly, the distribution of C among various components (i.e., live, dead wood, CWD, litter, and soil) ranged from 0.7% to 29% on NHM stands and from 0.1% to 43% on EAM stands. Soil nitrogen (N) (%) was significantly correlated with soil C (%) in the UAM stands, whereas soil temperature was negatively related to live tree C. Soil N (%) and canopy cover were significantly correlated with live tree and soil C (%) pools at EAM stands. Our results revealed that the largest C pool in these forests was living trees. The soil and CWD C pool sizes suggest the importance of dynamics of decaying harvest debris, which influences N retention. Nous avons quantifie et compart; les reservoirs de carbone (C) dans une foret experimentale situtie dans les monts Ozark au Missouri huit ans apres que differents traitements de recolte eurent ete appliques. La quantite totale de carbone dans les differents reservoirs de carbone atteignait respectivement 182, 170 et 130 Mg C * [ha.sup.-1] dans le traitement temoin (amenagement sans recolte), avec un amenagement inequienne par pied d'arbre (AIPA) et avec un amenagement equienne et une coupe a blanc (AECB). La recolte a reduit le reservoir de C des arbres vivants de 31% dans le systeme AIPA et de 93% dans le systeme AECB et augmente le reservoir de C dans les debris ligneux grossiers (DLG) de 31% dans le systeme AIPA et de 176% dans le systeme AECB comparativement aux peuplements non recoltes. Le systeme AIPA a significativement (p = 0,02) augmente le reservoir de C du sol mineral de 14% tandis que le systeme AECB n'a eu aucun effet. Il etait plus interessant de constater que la distribution de C parmi les diverses composantes (c.-a-d. le bois vivant, le bois mort, les DLG, la litiere et le sol) variait de 0,7% a 29% dans les peuplements non coupes et de 0,1% a 43% dans les peuplements coupes a blanc. L'azote (N) (%) dans le sol etait significativement correle avec le C (%) dans le sol dans le systeme AIPA. Nos resultats revelent que le plus important reservoir de C dans ces forets est constitue des arbres vivants. La dimension des reservoirs de C du sol et des DLG montre l'importance de la dynamique de la decomposition des dechets de coupe qui influence la retention de N. [Traduit par la Redaction], Introduction Carbon (C) pools in terrestrial ecosystems are receiving increasing attention partly because terrestrial ecosystems have some potential to store C and, thus, help offset increases in atmospheric carbon dioxide [...]

Carbon uptake by forestation is one method proposed (1) to reduce net carbon dioxide emissions to the atmosphere and so limit the radiative forcing of climate change (2). But the overall impact of forestation on climate will also depend on other effects associated with the creation of new forests. In particular, the albedo of a forested landscape is generally lower than that of cultivated land, especially when snow is lying (3,9), and decreasing albedo exerts a positive radiative forcing on climate. Here I simulate the radiative forcings associated with changes in surface albedo as a result of forestation in temperate and boreal forest areas, and translate these forcings into equivalent changes in local carbon stock for comparison with estimated carbon sequestration potentials (10,12). I suggest that in many boreal forest areas, the positive forcing induced by decreases in albedo can offset the negative forcing that is expected from carbon sequestration. Some high-latitude forestation activities may therefore increase climate change, rather than mitigating it as intended., Perturbations to the balance between radiation absorbed and emitted by the Earth ('radiative forcing') can result from changes in atmospheric chemistry and planetary albedo. A positive 'greenhouse' forcing results from [...]

GLOBAL Human-caused climate change is a reality, so, evidence that a major carbon sink has been long-overlooked is a big deal. Mangrove swamps are ecologically critical intertidal wetlands (above water [...]

Organic particle behaviour may predict less carbon stored in the sea bed. Organic particle behaviour may predict less carbon stored in the sea bed, Author Affiliations: Plug pulled on ocean carbon sink The ocean's biological carbon pump may be shuttling less carbon from the surface to the depths than is assumed in most climate [...]

The extent to which coastal-ocean regions act as a sink for carbon dioxide has been enigmatic. An estimate based on more than 3 million observations suggests a smaller sink than [...]