The boreal forest is one of the worlds largest forest biomes and comprises a major portion of the terrestrial carbon (C) sink. Quantifying the net C change in forest ecosystems is an important step in understanding and modeling the global C cycle. The goals of this project were: to estimate and compare the total change in ecosystem C over a 10-year period in two boreal forest stands using biometric and eddy-covariance approaches, and to evaluate the year-to-year changes in C uptake. This study utilized 10 years of eddy-covariance data and ecosys model data from the Old Aspen (OA) and Old Jack Pine (OJP) sites in central Saskatchewan, part of the Boreal Ecosystem Research and Monitoring Sites (BERMS). According to the eddy-covariance and C stock approaches, between 1994 and 2004 the net change in C storage at OA was 15.6 ± 4.0 and 18.2 ± 8.0 Mg C ha-1, respectively. At OJP, the 10-year net change in C storage from eddy-covariance was 5.8 ± 2.0 Mg C ha-1 in comparison to 6.9 ± 1.6 Mg C ha-1 from the carbon stock approach. While both sites were sinks of C between 1994 and 2004, the greatest increase in C occurred in different components - the forest floor at OA (14.6 Mg C ha-1) and in the living vegetation at OJP (8.0 Mg C ha-1). In 2004, total ecosystem C content was greater at OA (180.6 Mg C ha-1) than OJP (78.9 Mg C ha-1), with 50% (OA) and 39% (OJP) of the C in the detritus and mineral soil pools. During the 10-year period of eddy-covariance measurements, there was a positive correlation between both annual and growing season gross ecosystem photosynthesis (GEP) and live stem C biomass increment at OA, whereas no significant relationships were found at OJP. Stem C increment accounted for 30% of total net primary productivity (NPP) at both sites, and NPP/GEP ratios were 0.36 and 0.32 at OA and OJP, respectively. Overall, this study found good agreement between eddy-covariance and biometric estimates of ecosystem C change at OA and OJP between 1994 and 2004. Over that period at OA, eddy-covariance estimates of photosynthesis captured the inter-annual variability in C uptake based on the growth of tree rings.

Global warming and climate change are closely related to the amount of CO2 in the air. Forest ecosystem plays very important role in the global carbon cycle; CO2 from the atmosphere is taken up by vegetation and stored as plant biomass. Therefore, quantifying biomass and carbon sequestration in tropical forests has a significant concern within the United Nations Framework Convention on Climate Change (UNFCC), Kyoto Protocol and Reducing Emission from Deforestation and Forest Degradation (REDD) program for the purpose of the improvement of national carbon accounting as well as for addressing the potential areas for carbon credits, basis for payment for environmental services. The aim of research is to estimate biomass and carbon stocks in tropical forests using remote sensing data for dry forest of central highlands of Vietnam. This result showed that from satellite images of the SPOT, satellites could build the land cover map, carbon map and biomass map of Yok Don National Park, Central Highlands of Vietnam. Through which also the biomass (above ground biomass and below ground biomass) of each type of forest can be calculated. For instance the biomass of the dry forest (Dry Dipterocarp Forest) is 153.49 tones x ha-1, biomass of rich forest is 343.35 tones x ha-1, biomass of medium forest is 210.34 tones x ha-1 and biomass of poor forest & scrub are 33.56 tones x ha-1. / Sự ấm lên toàn cầu và biến đổi khí hậu có liên quan chặt chẽ với tổng lượng CO2 trong không khí. Hệ sinh thái rừng có vai trò rất quan trọng trong chu trình các bon toàn cầu; khí CO2 trong khí quyển được hấp thụ bởi thảm thực vật dưới dạng sinh khối. Vì vậy, việc xác định sinh khối và carbon tích trữ trong rừng nhiệt đới đã có được sự quan tâm đáng kể trong Công ước của Liên hiệp quốc về biến đổi khí hậu (UNFCC), Nghị định thư Kyoto và Chương trình giảm phát thải từ phá rừng và suy thoái rừng (REDD) gần đây, nhằm cho mục đích cải thiện việc tính toán lượng các bon tích trữ cũng như giải quyết các vấn đề tiềm năng cho tín dụng các bon, làm cơ sở cho việc thanh toán cho các dịch vụ môi trường. Mục đích của nghiên cứu này là ước lượng sinh khối và các bon lưu trữ trong các khu rừng nhiệt đới bằng cách sử dụng dữ liệu viễn thám, mà ở nghiên cứu này là cho rừng khộp Tây Nguyên của Việt Nam. Kết quả cho thấy rằng, từ ảnh vệ tinh SPOT có thể xây dựng bản đồ lớp phủ thực vật, bản đồ các bon và bản độ sinh khối của Vườn quốc gia Yok Đôn, Tây Nguyên Việt Nam. Qua đó đã tính toán được sinh khối (bao gồm cả trên mặt đất và dưới mặt đất) như: đối với sinh khối của rừng khô cây họ dầu (Dry Dipterocarp Forest) là 153,59 tấn/ha, sinh khối rừng giàu là 343,35 tấn/ha, sinh khối rừng trung bình là 210,34 tấn/ha và sinh khối rừng nghèo&cây bụi là 33,56 tấn/ha.

After the injection of CO₂ into a subsurface formation, various storage mechanisms help immobilize the CO₂. Injection strategies that promote the buoyant movement of CO₂ during the post-injection period can increase immobilization by the mechanisms of dissolution and residual phase trapping. In this work, we argue that the heterogeneity intrinsic to sedimentary rocks gives rise to another category of trapping, which we call local capillary trapping. In a heterogeneous storage formation where capillary entry pressure of the rock is correlated with other petrophysical properties, numerous local capillary barriers exist and can trap rising CO₂ below them. The size of barriers depends on the correlation length, i.e., the characteristic size of regions having similar values of capillary entry pressure. This dissertation evaluates the dynamics of the local capillary trapping and its effectiveness to add an element of increased capacity and containment security in carbon storage in heterogeneous permeable media. The overall objective is to obtain the rigorous assessment of the amount and extent of local capillary trapping expected to occur in typical storage formations. A series of detailed numerical simulations are used to quantify the amount of local capillary trapping and to study the effect of local capillary barriers on CO₂ leakage from the storage formation. Also, a research code is developed for finding clusters of local capillary trapping from capillary entry pressure field based on the assumption that in post-injection period the viscous forces are negligible and the process is governed solely by capillary forces. The code is used to make a quantitative assessment of an upper bound for local capillary trapping capacity in heterogeneous domains using the geologic data, which is especially useful for field projects since it is very fast compared to flow simulation. The results show that capillary heterogeneity decreases the threshold capacity for non-leakable storage of CO₂. However, in cases where the injected volume is more than threshold capacity, capillary heterogeneity adds an element of security to the structural seal, regardless of how CO₂ is accumulated under the seal, either by injection or by buoyancy. In other words, ignoring heterogeneity gives the worst-case estimate of the risk. Nevertheless, during a potential leakage through failed seals, a range of CO₂ leakage amounts may occur depending on heterogeneity and the location of the leak. In geologic CO₂ storage in typical saline aquifers, the local capillary trapping can result in large volumes that are sufficiently trapped and immobilized. In fact, this behavior has significant implications for estimates of permanence of storage, for assessments of leakage rates, and for predicting ultimate consequences of leakage. / text

Wetlands have been considered throughout millenniums as valuable assets due to the ecosystem services they provide for humans. However, previous research has shown that the value of wetlands has declined over the last 150 years, in parallel to the growth of agriculture. Today, society has realized the value of ecosystem services, through increased knowledge and awareness.This study focuses on the area of Byringe, 20 km southwest of Strängnäs. The aim of this study was to identify changes of wetland areas, wetland classes and ecosystem services over time. This study compared four maps covering the area, between the years 1714 to 2013. The results show that the wetland areas have increased from their initial coverage of 6.5% up to 24.4% today. This 17.9% increase corresponds to 115.3 ha. A closer examination of this 300-year transformation showed variation among the wetland classes. Marshlands showed the largest increase of 44.3ha, followed by fen with 33.5ha and bog 7.6ha. In some areas fen had been converted to bog, which is a change in carbon storage and thus climate regulation. The lakes had developed into marshland, which has caused the disappearance of fish stocks, negatively affecting the generation of food supply. The increased marshland area has also resulted in increased carbon storage and provisioning services such as fiber material from plants and bioenergy production from trees. Furthermore, the recent transformation of agricultural land into fen has generated a loss in food production services such as crops. Instead, other services have appeared in terms of climate regulation, flood protection, increased protection against erosion, water purification and support of biodiversity.

The objectives were to analyze the effect of different cropping systems and plants in succession to corn (Zea mays L.) on carbon storage and nitrogen and the carbon and nitrogen fractions of OM in experiment Long-term driven in a Red-Yellow, and evaluate the decomposition and nutrient release to soil the shoots of plant cover, placed in bags to decompose. We used an experimental system tracks under split plot design with three replications consisting of 12 treatments involving three management of soils (plots) - (CC - conventional tillage, CM - minimum tillage, NT - no-tillage) and four plants (subplots ) - (Commercial: peanut (Arachis hypogeae), bean (Phaseolus vulgaris) cover: (Cajanus cajan) and (Crotalaria juncea). The time of implementation of zero tillage and crop succession promote changes in C stocks and N in the depths. The absence and minimization of soil disturbance in PD and CM systems resulted in higher levels of C and N in humic fractions of OM Alfissol. The PD system was the largest contributor to the release of soil nitrogen, from the decomposing plant residues. The CM system had the highest rates of decomposition of soil carbon. We conclude that the management systems NT and MT may help to improve agricultural sustainability. / Os objetivos deste trabalho foram analisar o efeito de diferentes sistemas de cultivo e plantas em sucessão ao milho doce (Zea mays L.), no estoque de C e N do solo e sobre o teor de carbono e nitrogênio das frações da MO, em experimento de longa duração conduzido em um Argissolo Vermelho-Amarelo; e avaliar a decomposição e a liberação de nutrientes para o solo pela parte aérea de plantas de cobertura, colocadas em bolsas de decomposição. Utilizou-se um sistema de faixas experimentais sob parcelas subdivididas com três repetições, compostos por 12 tratamentos que associam três manejos de solos (parcelas)- (CC cultivo convencional, CM cultivo mínimo, PD plantio direto) e quatro plantas (subparcelas)- (comerciais: amendoim (Arachis hypogeae), feijão (Phaseolus vulgaris); cobertura: guandu (Cajanus cajan) e crotalária (Crotalaria juncea). O tempo de implantação do plantio direto e a sucessão de culturas promoveram alterações nos estoques de C e N nas profundidades avaliadas. A ausência e minimização do revolvimento do solo nos sistemas CM e PD favoreceu os maiores teores de C e N nas frações húmicas da M.O do Argissolo Vermelho Amarelo. O sistema PD foi o que mais contribuiu para a liberação de nitrogênio no solo, proveniente dos restos vegetais em decomposição. O sistema CM apresentou as maiores taxas de decomposição do carbono no solo. Conclui-se que os sistemas de manejo PD e CM podem contribuir para uma melhor sustentabilidade agrícola.

Seagrasses are considered highly important CO2 sinks, with the capacity to store substantial quantities of organic carbon in the living biomass and sediments, and thereby acting as a buffer against climate change. In this thesis, I have studied carbon storage variability in temperate and tropical seagrass habitats and identified factors influencing this variation. In addition, as seagrass areas are decreasing worldwide, I have assessed effects of different anthropogenic disturbances on carbon sequestration processes. The result from this thesis showed that there was a large variation in carbon storage within and among temperate, tropical and subtropical regions. The highest organic carbon stocks were found in temperate Zostera marina meadows, which also showed a larger carbon storage variability than the subtropical and tropical seagrass habitats. The tropical and subtropical seagrass meadows had inorganic carbon pools exceeding the organic carbon accumulation, which could potentially weakens the carbon sink function. The variability in organic carbon stocks was generally strongly related to the sediment characteristics of the seagrass habitats. In Z. marina meadows, the strength of the carbon sink function was mainly driven by the settings of the local environment, which in turn indicates that depositional areas will likely have higher organic carbon stocks than more exposed meadows, while in the tropics seagrass biomass was also influencing sedimentary carbon levels. Furthermore, locations with large areas of seagrass were associated with higher carbon storage in tropical and subtropical regions, which could be related to increased accumulation of both autochthonous and allochthonous carbon. In an in situ experiment, impacts on carbon sequestration processes from two types of disturbances (with two levels of intensity) were tested by simulating reduced water quality (by shading) and high grazing pressure (through removal of shoot biomass). At high disturbance intensity, reductions in the net community production and seagrass biomass carbon were observed, which negatively affected carbon sequestration and could impact the sedimentary organic carbon stocks over time. In the treatments with simulated grazing, erosion was also seen, likely due to an increase in near-bed hydrodynamics. When experimentally testing effects of increased current flow on organic carbon suspension in Z. marina sediment, a ten-fold release of organic carbon with higher current flow velocities was measured, which resulted in an increase in the proportion of suspended organic carbon by three times in relation to other sediment particles. Therefore, periods with enhanced hydrodynamic activity could result in a removal of organic carbon and thereby likely reduce the seagrass meadows’ capacity to store carbon. The findings of this thesis add to the emerging picture that there is a large natural variability in seagrasses’ capacity to store carbon, and highlight how human-induced disturbances could negatively affect the carbon sink function in seagrass meadows. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.</p>

The purpose of this study was to provide a methodological framework for the first estimates of the total carbon storage and its economic valuation in the mangrove forests of Everglades National Park (ENP), Florida. The total carbon storage in the ENP mangroves is estimated to be 7,144 Mg C/ha, much higher than tropical, boreal and temperate forests. The final selection of carbon prices for the valuation was based on the social, economic and political milieu of the study site, the biological attributes influencing the quantity and quality of carbon storage, and the status of the ENP mangroves as a protected area. The carbon storage in ENP mangroves is estimated at $50,000/ha and $614,000/ha based on the U.S. market price and social cost of carbon, respectively. The study also estimates the change in the economic value of the carbon stock in ENP mangroves in response to different scenarios of sea level rise.

Rapid warming in northern latitudes will lead to permafrost thaw and subsequent carbon remobilisa­tion and release to the atmosphere. To incorporate the permafrost carbon climate feedback in globalEarth System Models, it is of importance to know the carbon stored in the circum­Arctic permafrostregion as accurate and precise as possible. Whereas soil, Yedoma and delta carbon stocks are alreadyquantified, deep carbon stocks for vast areas of the current permafrost region are still unaccountedfor. The aim of this Master thesis project is to estimate the deep carbon stock (&gt;3m) for Quaternarydeposits outside the known reservoirs. Therefore, 363 boreholes and exposures were compiled fromthe scientific literature. 244 sites provide profile descriptions (depositional environment, depth andthickness) and another 119 sites contain data to calculate carbon densities (ground ice content, coarsefraction (&gt;1cm and/or &gt;2mm), bulk density and total organic carbon). Data gaps were filled usinglocal, regional and global average facies values from the compiled dataset. For spatial upscaling,key regions are defined using the permafrost zone, overburden thickness and ice content. The fielddata compiled here shows disagreements with the Circum­Arctic Map of Permafrost and Ground­Iceconditions (Brown et al. 2002), which should be updated especially in thin and ice­poor regions. Atotal C stock of 1698 ±255 PgC is estimated for 3­25m in Quaternary deposits of the circum­Arcitcpermafrost region, next to the Yedoma domain (327 ­ 466 PgC, Strauss et al. 2017) and deltas (41 ­151 PgC, Hugelius et al. 2014). About 70% of the carbon is stored within 3­10m (1200 ±238 PgC).Due to a publication bias towards thick and organic­rich sediments in the literature, C stocks calcualtedhere might be overestimated. Additional to the Yedoma domain, 309 ±99 PgC are stored in ice­richdeposits of the continuous permafrost zone, a regions especially prone to thermokarst and deep carbonremobilisation. Thermokarst, thermo­fluvial erosion along rivers and coasts as well as carbon releasethrough inland water systems presents possible release mechanisms for stored carbon. The permafrostcarbon estimate determined here doubles the known carbon reservoir in the permafrost region and em­phasises the importance for possible deep carbon release with future permafrost thawing.

Amidst the global climate action movement, geologic carbon storage (GCS) has emerged as a pivotal strategy for mitigating atmospheric CO2 levels, offering environmental and economic opportunities. This thesis targets the Bunter Sandstone Formation within the Rødby structures in Denmark, focusing on seismic Profile 1. Profile 1 is chosen as it crosses over the existing domal structure, and this will enable to investigate the closure or the extension of the domal structure, and also to evaluate its capacity for CO2 sequestration. Utilizing 2D Reflection Seismic Imaging and collaborating with the Geological Survey of Denmark and Greenland (GEUS), the study employs advanced seismic techniques to analyse the Triassic period sandstone formation.  The seismic data for Profile 1 was acquired during June-July 2023 as part of GEUS's national GCS projects by Uppsala University’s Geophysics Program, utilizing the SeisMoveTM dual-element recording system. A total of 991 shots were recorded by 1030 wireless recorders in a fixed geometry, enhancing the signal-to-noise ratio through vertical stacking of repeated shot records. The data acquisition parameters were carefully selected based on similar projects involving pilot and upscaling work conducted in Denmark prior to the Rødby survey. These parameters were influenced by experiences gained during previous successful applications in Denmark and similar environments, ensuring the retrieval of high-resolution seismic reflection images across a wide depth range. The results reveal the presence of a potential new domal structure within the Rødby region, which could substantially influence the area's capacity for carbon storage. The new possible domal structure extend toward east of the survey area and this discovery suggests the need for further investigations to comprehensively assess the extent of this new structure. Therefore, this study enhances the understanding of the Rødby region's subsurface geology; and by advancing the application of carbon capture and storage technologies, this study aligns with Denmark's climate initiatives and contributes to global climate change mitigation efforts. / Mitt i den globala klimatrörelsen har geologisk kollagring (GCS) dykt upp som en viktig strategi för att minska atmosfärens CO2-nivåer, vilket erbjuder miljömässiga och ekonomiska möjligheter. Denna avhandling är inriktad på Bunter-sandstensformationen i Rødby-strukturerna i Danmark, med fokus på seismisk profil 1. Profil 1 valdes eftersom den korsar den befintliga konvexa strukturen, och detta gördet möjligt att undersöka formationens omfattning, och detta i sin tur gör det möjligt att undersöka stängningen eller utvidgningen av domalstrukturen och att utvärdera dess kapacitet för CO2-bindning. Att använda och Isamarbete med Danmarks och Grönlands geologiska undersökning (GEUS) använder studien avancerade seismiska tekniker för att analysera sandstensformationen från triasperioden.  Seismiska data för Profil 1 samlades in under juni-juli 2023 som en del av GEUSs nationella GCSprojekt av Uppsala universitets Geofysikprogram, med hjälp av SeisMoveTM inspelningssystem med dubbla element. Totalt 991 bilder spelades in av 1030 trådlösa inspelare i en bestämd geometri, vilket förbättrade signal-brusförhållandet genom vertikal stapling av upprepade tagningar. Datainsamlingsparametrarna valdes noggrant ut baserat på liknande projekt med pilot- och uppskalningsarbete som genomfördes i Danmark före Rødby-undersökningen. Dessa parametrar valdes baserat på erfarenheter från tidigare framgångsrika tillämpningar i Danmark och liknande miljöer, vilket säkerställde registreringen av högupplösta seismiska reflektionsbilder över ett brett djupområde. Resultaten visar att det finns en potentiell ny struktur i Rødbyregionen, vilket skulle kunna påverka områdets kapacitet för koldioxidlagring avsevärt. Den nya möjliga konvexa strukturen sträcker sig öster om undersökningsområdet och denna upptäckt tyder på behovet av ytterligare undersökningar för att göra en omfattande bedömning av kunna bedöma omfattningen av denna nya struktur. Därför ökar denna studie förståelsen för Rødbyregionens underjordiska geologi. Genom att främja tillämpningen av teknik för avskiljning och lagring av koldioxid är denna studie i linje med Danmarks klimatinitiativ och bidrar till de globala insatserna för att begränsa klimatförändringarna.

Global warming and climate change are closely related to the amount of CO2 in the air. Forest ecosystem plays very important role in the global carbon cycle; CO2 from the atmosphere is taken up by vegetation and stored as plant biomass. Therefore, quantifying biomass and carbon sequestration in tropical forests has a significant concern within the United Nations Framework Convention on Climate Change (UNFCC), Kyoto Protocol and Reducing Emission from Deforestation and Forest Degradation (REDD) program for the purpose of the improvement of national carbon accounting as well as for addressing the potential areas for carbon credits, basis for payment for environmental services. The aim of research is to estimate biomass and carbon stocks in tropical forests using remote sensing data for dry forest of central highlands of Vietnam. This result showed that from satellite images of the SPOT, satellites could build the land cover map, carbon map and biomass map of Yok Don National Park, Central Highlands of Vietnam. Through which also the biomass (above ground biomass and below ground biomass) of each type of forest can be calculated. For instance the biomass of the dry forest (Dry Dipterocarp Forest) is 153.49 tones x ha-1, biomass of rich forest is 343.35 tones x ha-1, biomass of medium forest is 210.34 tones x ha-1 and biomass of poor forest & scrub are 33.56 tones x ha-1. / Sự ấm lên toàn cầu và biến đổi khí hậu có liên quan chặt chẽ với tổng lượng CO2 trong không khí. Hệ sinh thái rừng có vai trò rất quan trọng trong chu trình các bon toàn cầu; khí CO2 trong khí quyển được hấp thụ bởi thảm thực vật dưới dạng sinh khối. Vì vậy, việc xác định sinh khối và carbon tích trữ trong rừng nhiệt đới đã có được sự quan tâm đáng kể trong Công ước của Liên hiệp quốc về biến đổi khí hậu (UNFCC), Nghị định thư Kyoto và Chương trình giảm phát thải từ phá rừng và suy thoái rừng (REDD) gần đây, nhằm cho mục đích cải thiện việc tính toán lượng các bon tích trữ cũng như giải quyết các vấn đề tiềm năng cho tín dụng các bon, làm cơ sở cho việc thanh toán cho các dịch vụ môi trường. Mục đích của nghiên cứu này là ước lượng sinh khối và các bon lưu trữ trong các khu rừng nhiệt đới bằng cách sử dụng dữ liệu viễn thám, mà ở nghiên cứu này là cho rừng khộp Tây Nguyên của Việt Nam. Kết quả cho thấy rằng, từ ảnh vệ tinh SPOT có thể xây dựng bản đồ lớp phủ thực vật, bản đồ các bon và bản độ sinh khối của Vườn quốc gia Yok Đôn, Tây Nguyên Việt Nam. Qua đó đã tính toán được sinh khối (bao gồm cả trên mặt đất và dưới mặt đất) như: đối với sinh khối của rừng khô cây họ dầu (Dry Dipterocarp Forest) là 153,59 tấn/ha, sinh khối rừng giàu là 343,35 tấn/ha, sinh khối rừng trung bình là 210,34 tấn/ha và sinh khối rừng nghèo&cây bụi là 33,56 tấn/ha.