Browsing by Subject "SEQUESTRATION"

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  • Abbott, Benjamin W.; Jones, Jeremy B.; Schuur, Edward A. G.; Chapin, F. Stuart; Bowden, William B.; Bret-Harte, M. Syndonia; Epstein, Howard E.; Flannigan, Michael D.; Harms, Tamara K.; Hollingsworth, Teresa N.; Mack, Michelle C.; McGuire, A. David; Natali, Susan M.; Rocha, Adrian V.; Tank, Suzanne E.; Turetsky, Merritt R.; Vonk, Jorien E.; Wickland, Kimberly P.; Aiken, George R.; Alexander, Heather D.; Amon, Rainer M. W.; Benscoter, Brian W.; Bergeron, Yves; Bishop, Kevin; Blarquez, Olivier; Bond-Lamberty, Ben; Breen, Amy L.; Buffam, Ishi; Cai, Yihua; Carcaillet, Christopher; Carey, Sean K.; Chen, Jing M.; Chen, Han Y. H.; Christensen, Torben R.; Cooper, Lee W.; Cornelissen, J. Hans C.; de Groot, William J.; DeLuca, Thomas H.; Dorrepaal, Ellen; Fetcher, Ned; Finlay, Jacques C.; Forbes, Bruce C.; French, Nancy H. F.; Gauthier, Sylvie; Girardin, Martin P.; Goetz, Scott J.; Goldammer, Johann G.; Gough, Laura; Grogan, Paul; Guo, Laodong; Higuera, Philip E.; Hinzman, Larry; Hu, Feng Sheng; Hugelius, Gustaf; Jafarov, Elchin E.; Jandt, Randi; Johnstone, Jill F.; Karlsson, Jan; Kasischke, Eric S.; Kattner, Gerhard; Kelly, Ryan; Keuper, Frida; Kling, George W.; Kortelainen, Pirkko; Kouki, Jari; Kuhry, Peter; Laudon, Hjalmar; Laurion, Isabelle; Macdonald, Robie W.; Mann, Paul J.; Martikainen, Pertti J.; McClelland, James W.; Molau, Ulf; Oberbauer, Steven F.; Olefeldt, David; Pare, David; Parisien, Marc-Andre; Payette, Serge; Peng, Changhui; Pokrovsky, Oleg S.; Rastetter, Edward B.; Raymond, Peter A.; Raynolds, Martha K.; Rein, Guillermo; Reynolds, James F.; Robards, Martin; Rogers, Brendan M.; Schaedel, Christina; Schaefer, Kevin; Schmidt, Inger K.; Shvidenko, Anatoly; Sky, Jasper; Spencer, Robert G. M.; Starr, Gregory; Striegl, Robert G.; Teisserenc, Roman; Tranvik, Lars J.; Virtanen, Tarmo; Welker, Jeffrey M.; Zimov, Sergei (2016)
    As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release will be offset by increased production of Arctic and boreal biomass; however, the lack of robust estimates of net carbon balance increases the risk of further overshooting international emissions targets. Precise empirical or model-based assessments of the critical factors driving carbon balance are unlikely in the near future, so to address this gap, we present estimates from 98 permafrost-region experts of the response of biomass, wildfire, and hydrologic carbon flux to climate change. Results suggest that contrary to model projections, total permafrost-region biomass could decrease due to water stress and disturbance, factors that are not adequately incorporated in current models. Assessments indicate that end-of-the-century organic carbon release from Arctic rivers and collapsing coastlines could increase by 75% while carbon loss via burning could increase four-fold. Experts identified water balance, shifts in vegetation community, and permafrost degradation as the key sources of uncertainty in predicting future system response. In combination with previous findings, results suggest the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario but that 65%-85% of permafrost carbon release can still be avoided if human emissions are actively reduced.
  • Waldén, Pirjetta; Ollikainen, Markku; Kahiluoto, Helena (2020)
    The impact of carbon revenue on the profitability of agroforestry systems in comparison to monocultures is unexplored in regard to Sub-Saharan Africa. This study creates a multivariate model to evaluate the impact of carbon revenue on the profitability of agroforestry relative to the dominant monocultures in Ethiopia by using stylized plots. Yields and carbon stock changes of eight agroforestry systems were modeled based on data from agroforestry plots in the Ethiopian Central Rift Valley. According to our model, agroforestry was, on average, four times more profitable than the main monoculture systems (wheat, barley, maize, teff, sorghum, sugarcane and lentil) even when carbon revenues were excluded, primarily due to the higher prices of fruit produce. Carbon revenues were estimated using a plausible carbon price ranging from US$8/tCO2e to $40/tCO2e and carbon sequestration rates of 0.59 to 17.2 Mg C ha−1 year−1. The possibility of receiving carbon revenue increased the profitability of agroforestry by 0.5% when using the lowest utilized carbon price and carbon sequestration rate, by 20% when using the carbon price of $20 and the average carbon sequestration rate, and by 70% when using the highest price and highest sequestration rate of carbon. On average, carbon revenue increased the profitability of agroforestry by 150% in comparison to monoculture farming. We conclude that carbon income may have significant potential to motivate smallholders to convert to agroforestry when there is a proper management system, a sufficiently high carbon price and effective institutional support to mitigate the transition and transaction costs.
  • Larjavaara, Markku; Kanninen, Markku Tapani; Alam, Syed Ashraful; Mäkinen, Antti; Poeplau, Christopher (2017)
    Land use directly impacts ecosystem carbon and indirectly influences atmospheric carbon. Computing ecosystem carbon for an area experiencing changes in land use is not trivial, as carbon densities change slowly after land-use changes. We developed a tool, CarboScen, to estimate ecosystem carbon in landscapes. It is a simple tool typically used with an annual time step, and is based on carbon pools and densities. It assumes that carbon density asymptotically approaches a value, which is set for the land-use type in question. We recommend CarboScen for landscapes with spatially relatively homogenous soils and climate, multiple land uses, and changes between these leading to slow changes in carbon densities because either soil organic carbon is included in the analysis or afforestation occurs. Thanks to its simplicity, it is particularly suitable for participatory planning, rapid assessment of REDD+ project potential, and educational use.
  • Tammeorg, Priit; Soronen, Päivi Anneli; Riikonen, Anu; Salo, Esko; Tikka, Suvi Maria; Koivunen, Minja; Salonen, Anna-Reetta; Kopakkala, Topi Pietari; Jalas, Mikko (2021)
    In order to achieve the goals of carbon (C) neutrality within next 20 year, municipalities worldwide need to increasingly apply negative emission technologies. We focus on the main principles of urban demonstration areas using biochars for C sequestration and explore the lessons learned from a co-creation process of one such park, Hyvantoivonpuisto in Helsinki, Finland. Demonstration sites of urban C sinks in public parks must be safe, visible and scientifically sound for reliable and cost-effective verification of carbon sequestration. We find that different interests can be arbitrated and that synergy that emerges from co-creation of urban C sink parks between stakeholders (scientists, city officials, companies, and citizens) can result in demo areas with maximized potential for impact, dissemination and consideration of principles of scientific experimentation.
  • Mattila, Anniina L. K.; Jiggins, Chris D.; Saastamoinen, Marjo (2022)
    Aposematic animals advertise their toxicity or unpalatability with bright warning coloration. However, acquiring and maintaining chemical defenses can be energetically costly, and consequent associations with other important traits could shape chemical defense evolution. Here, we have tested whether chemical defenses are involved in energetic trade-offs with other traits, or whether the levels of chemical defenses are condition dependent, by studying associations between biosynthesized cyanogenic toxicity and a suite of key life-history and fitness traits in a Heliconius butterfly under a controlled laboratory setting. Heliconius butterflies are well known for the diversity of their warning color patterns and widespread mimicry and can both sequester the cyanogenic glucosides of their Passiflora host plants and biosynthesize these toxins de novo. We find energetically costly life-history traits to be either unassociated or to show a general positive association with biosynthesized cyanogenic toxicity. More toxic individuals developed faster and had higher mass as adults and a tendency for increased lifespan and fecundity. These results thus indicate that toxicity level of adult butterflies may be dependent on individual condition, influenced by genetic background or earlier conditions, with maternal effects as one strong candidate mechanism. Additionally, toxicity was higher in older individuals, consistent with previous studies indicating accumulation of toxins with age. As toxicity level at death was independent of lifespan, cyanogenic glucoside compounds may have been recycled to release resources relevant for longevity in these long-living butterflies. Understanding the origins and maintenance of variation in defenses is necessary in building a more complete picture of factors shaping the evolution of aposematic and mimetic systems.
  • Assmuth, Aino; Ramo, Janne; Tahvonen, Olli (2018)
    We study the economics of carbon storage using a model that includes forest size structure and determines the choice between rotation forestry and continuous cover forestry. Optimal harvests may rely solely on thinning, implying infinite rotation and continuous cover forestry, or both thinning and clearcuts, implying finite rotation periods. Given several carbon prices and interest rates, we optimize the timing and intensity of thinnings along with the choice of management regime. In addition to the carbon storage in living trees, we include the carbon dynamics of dead trees and timber products. Forest growth is specified by an empirically validated transition matrix model for Norway spruce (Picea abies (L.) Karst.). The optimization problem is solved in its general dynamic form by applying bilevel optimization with gradient-based interior point methods and a genetic algorithm. Carbon pricing postpones thinnings, increases stand density by directing harvests to larger trees, and typically yields a regime shift from rotation forestry to continuous cover forestry. In continuous cover solutions, the steady-state harvesting interval and the diameter distribution of standing and harvested trees are sensitive to carbon price, implying that carbon pricing increases the sawlog ratio of timber yields. Additionally, we obtain relatively inexpensive stand-level marginal costs of carbon storage.
  • Seeber, Julia; Tasser, Erich; Rubatscher, Dagmar; Loacker, Ingrid; Lavorel, Sandra; Robson, T. Matthew; Balzarolo, Manuela; Altimir, Nuria; Droesler, Matthias; Vescovo, Loris; Gamper, Sonja; Barancok, Peter; Staszewski, Tomasz; Wohlfahrt, Georg; Cernusca, Alexander; Sebastia, M-Teresa; Tappeiner, Ulrike; Bahn, Michael (2022)
    European mountain grasslands are increasingly affected by land-use changes and climate, which have been suggested to exert important controls on grassland carbon (C) and nitrogen (N) pools. However, so far there has been no synthetic study on whether and how land-use changes and climate interactively affect the partitioning of these pools amongst the different grassland compartments. We analyzed the partitioning of C and N pools of 36 European mountain grasslands differing in land-use and climate with respect to above- and belowground phytomass, litter and topsoil (top 23 cm). We found that a reduction of management intensity and the abandonment of hay meadows and pastures increased above-ground phytomass, root mass and litter as well as their respective C and N pools, concurrently decreasing the fractional contribution of the topsoil to the total organic carbon pool. These changes were strongly driven by the cessation of cutting and grazing, a shift in plant functional groups and a related reduction in litter quality. Across all grasslands studied, variation in the impact of land management on the topsoil N pool and C/N-ratio were mainly explained by soil clay content combined with pH. Across the grasslands, below-ground phytomass as well as phytomass- and litter C concentrations were inversely related to the mean annual temperature; furthermore, C/N- ratios of phytomass and litter increased with decreasing mean annual precipitation. Within the topsoil compartment, C concentrations decreased from colder to warmer sites, and increased with increasing precipitation. Climate generally influenced effects of land use on C and N pools mainly through mean annual temperature and less through mean an- nual precipitation. We conclude that site-specific conditions need to be considered for understanding the effects of land use and of current and future climate changes on grassland C and N pools.
  • Kuittinen, Matti; Hautamaki, Ranja; Tuhkanen, Eeva-Maria; Riikonen, Anu; Ariluoma, Mari (2021)
    Purpose Currently, no clear guidance exists for ISO and EN standards of calculating, verifying, and reporting the climate impacts of plants, mulches, and soils used in landscape design and construction. In order to optimise the potential of ecosystem services in the mitigation of greenhouse gas emissions in the built environment, we unequivocally propose their inclusion when assessing sustainability. Methods We analysed the life cycle phases of plants, soils, and mulches from the viewpoint of compiling standard-based Environmental Product Declarations. In comparison to other construction products, the differences of both mass and carbon flows were identified in these products. Results Living and organic products of green infrastructure require an LCA approach of their own. Most importantly, if conventional life cycle guidance for Environmental Product Declarations were to be followed, over time, the asymmetric mass and carbon flows would lead to skewed conclusions. Moreover, the ability of plants to reproduce raises additional questions for allocating environmental impacts. Conclusions We present a set of recommendations that are required for compiling Environmental Product Declarations for the studied products of green infrastructure. In order to enable the quantification of the climate change mitigation potential of these products, it is essential that work for further development of LCA guidance be mandated.
  • Mattila, Anniina L. K.; Jiggins, Chris D.; Opedal, Øystein H.; Montejo-Kovacevich, Gabriela; de Castro, Érika; McMillan, William O.; Bacquet, Caroline; Saastamoinen, Marjo (2021)
    Chemical defences against predators underlie the evolution of aposematic coloration and mimicry, which are classic examples of adaptive evolution. Surprisingly little is known about the roles of ecological and evolutionary processes maintaining defence variation, and how they may feedback to shape the evolutionary dynamics of species. Cyanogenic Heliconius butterflies exhibit diverse warning color patterns and mimicry, thus providing a useful framework for investigating these questions. We studied intraspecific variation in de novo biosynthesized cyanogenic toxicity and its potential ecological and evolutionary sources in wild populations of Heliconius erato along environmental gradients, in common-garden broods and with feeding treatments. Our results demonstrate substantial intraspecific variation, including detectable variation among broods reared in a common garden. The latter estimate suggests considerable evolutionary potential in this trait, although predicting the response to selection is likely complicated due to the observed skewed distribution of toxicity values and the signatures of maternal contributions to the inheritance of toxicity. Larval diet contributed little to toxicity variation. Furthermore, toxicity profiles were similar along steep rainfall and altitudinal gradients, providing little evidence for these factors explaining variation in biosynthesized toxicity in natural populations. In contrast, there were striking differences in the chemical profiles of H. erato from geographically distant populations, implying potential local adaptation in the acquisition mechanisms and levels of defensive compounds. The results highlight the extensive variation and potential for adaptive evolution in defense traits for aposematic and mimetic species, which may contribute to the high diversity often found in these systems.
  • Arvola, Anne M; Ha, Ho Thanh; Kanninen, Markku; Malkamäki, Arttu; Simola, Noora (2021)
    In Vietnam, fast-growing Acacia hybrid dominates commercial smallholdings and is largely managed in short rotations for pulpwood. However, increasing demand for logwood implies growing Acacia hybrid in longer rotations. One way of encouraging smallholders to prolong the rotation would be payments for aboveground carbon storage. Thus, this study evaluated the financial attractiveness of shifting from pulpwood to logwood production, with and without hypothetical carbon payments of $5, $10 and $20 tCO(2)e ha(-1). The data were drawn from smallholder interviews, a plantation inventory and a market study. The growth models for a 5-year pulpwood regime and various logwood regimes used for financial modelling were developed in CO2FIX simulation software. With a financially optimal rotation length of 9-10 years, the study finds that growing Acacia hybrid for logwood is much more profitable than growing it for pulpwood. However, due to thinning in logwood regime, a financially optimal logwood regime stores only 15-16% more carbon than a 5-year pulpwood regime. Consequently, carbon payments at any of the three price levels would not shift the financially optimal rotation length. The study concluded that carbon payments alone are unlikely to be an effective means to encourage smallholders in central Vietnam to prolong the rotation.
  • Karppinen, Heimo; Hänninen, Maria; Valsta, Lauri Tapani (2018)
    Given the high percentage of private forest ownership in Finland, family forest owners have an important role in mitigating climate change. The study aims to explore Finnish family forest owners' perceptions on climate change and their opinions on increasing carbon storage in their forests through new kinds of management activities and policy instruments. The data consists of thematic face-to-face interviews among Helsinki metropolitan area forest owners (n = 15). These city-dwellers were expected to be more aware of and more interested in climate change mitigation than forest owners at large. Forests as carbon fluxes appear to be a familiar concept to most of the forest owners, but carbon storage in their own forests was a new idea. Four types concerning forest owners' view on storing carbon in their forests could be identified. The Pioneer utilizes forestland versatilely and has already adopted practices to mitigate climate change. The Potential is concerned about climate change, but this is not seen in forest practices applied. The Resistant is generally aware of climate change but sees a fundamental contradiction between carbon storing and wood production. The Indifferent Owner believes that climate change is taking place but does not acknowledge a relation between climate change and the owner's forests.
  • Zhao, Peng; Chi, Jinshu; Nilsson, Mats B.; Lofvenius, Mikaell Ottosson; Hogberg, Peter; Jocher, Georg; Lim, Hyungwoo; Mäkelä, Annikki; Marshall, John; Ratcliffe, Joshua; Tian, Xianglin; Nasholm, Torgny; Lundmark, Tomas; Linder, Sune; Peichl, Matthias (2022)
    The boreal forest is an important global carbon (C) sink. Since low soil nitrogen (N) availability is commonly a key constraint on forest productivity, the prevalent view is that increased N input enhances its C sink-strength. This understanding however relies primarily on observations of increased aboveground tree biomass and soil C stock following N fertilization, whereas empirical data evaluating the effects on the whole ecosystem-scale C balance are lacking. Here we use a unique long-term experiment consisting of paired forest stands with eddy covariance measurements to explore the effect of ecosystem-scale N fertilization on the C balance of a managed boreal pine forest. We find that the annual C uptake (i.e. net ecosystem production, NEP) at the fertilized stand was 16 +/- 2% greater relative to the control stand by the end of the first decade of N addition. Subsequently, the ratio of NEP between the fertilized and control stand remained at a stable level during the following five years with an average NEP to N response of 7 & PLUSMN; 1 g C per g N. Our study reveals that this non-linear response of NEP to long-term N fertilization was the result of a cross-seasonal feedback between the N-induced increases in both growing-season C uptake and subsequent winter C emission. We further find that one decade of N addition altered the sensitivity of ecosystem C fluxes to key environmental drivers resulting in divergent responses to weather patterns. Thus, our study highlights the need to account for ecosystem-scale responses to perturbations to improve our understanding of nitrogen-carbon-climate feedbacks in boreal forests.
  • Peltomaa, Elina; Johnson, Matthew D. (2017)
    The marine ciliate Mesodinium rubrum is known to form large non-toxic red water blooms in estuarine and coastal upwelling regions worldwide. This ciliate relies predominantly upon photosynthesis by using plastids and other organelles it acquires from cryptophyte prey. Although M. rubrum is capable of ingesting different species of cryptophytes, mainly Teleaulax amphioxeia plastids have been detected from wild M. rubrum populations. These observations suggest that either M. rubrum is a selective feeder, or T. amphioxeia are taken up because of higher availability. To test these hypotheses, we determined whether the ciliate showed different grazing rates, growth responses, or plastid retention dynamics when offered Storeatula major, T. amphioxeia, T. acuta, or a mix. When M. rubrum was offered the cryptophyte S. major as prey, no evidence was found for ingestion. In contrast, M. rubrum grazed both Teleaulax spp. equally, was able to easily switch plastid type between them, and the ratio of each in the ciliate reflected the abundance of free-living prey in the culture. M. rubrum grew equally well when acclimated to each plastid type or when having mixed plastids. However, when offered single prey, T. amphioxeia could sustain higher M. rubrum growth rates (mu) over longer periods. Compared to other M. rubrum strains, this culture had higher grazing rates, greater ingestion requirements for reaching mu(max), and appeared to rely more on plastid sequestration than de novo division of cryptophyte organelles. Our results suggest that while M. rubrum may prefer Teleaulax-like cryptophytes, they do not select among the species used here.
  • Karhu, Kristiina; Alaei, Saeed; Li, Jian; Merilä, Päivi; Ostonen, Ivika; Bengtson, Per (2022)
    During the last decade it has been increasingly acknowledged that carbon (C) contained in root exudates can accelerate decomposition of soil organic matter (SOM), a phenomenon known as rhizosphere priming effect (RPE). However, the controlling factors and the role of different soil microorganisms in RPE are not yet well understood. There are some indications that the response of the soil microbial decomposers to labile C input in the rhizosphere depends on microbial demand of nutrients for growth and maintenance, especially that of C and nitrogen (N). To test this hypothesis, we assessed SOM decomposition induced by 13C-glucose additions during one week in forest soils with different C:N ratios (11.5–22.2). We estimated SOM respiration, the potential activity (concentration) of a range of extracellular enzymes, and incorporation of 13C and deuterium (D) in microbial phospholipid fatty acids (PLFAs). Glucose additions induced positive priming (a 12–52% increase in SOM respiration) in all soil types, but there was no linear relationship between priming and the soil C:N ratio. Instead, priming of SOM respiration was positively linked to the C:N imbalance, where a higher C:N imbalance implies stronger microbial N limitation. The total oxidative enzyme activity and the ratio between the activities of C and N acquiring enzymes were lower in soil with higher C:N ratios, but these findings could not be quantitatively linked to the observed priming rates. It appears as if glucose addition resulted in priming by stimulating the activity rather than the concentration of oxidative enzymes. Microbial incorporation of D and 13C into in PLFAs demonstrated that glucose additions stimulated both fungal and bacterial growth. The increased growth was mainly supported by glucose assimilation in fungi, while the increase in bacterial growth partly was a result of increased availability of C or N released from SOM. Taken together, the findings suggest that the soil C:N ratio is a poor predictor of priming and that priming is more dependent on the C:N imbalance, which reflects both microbial nutrient demand and nutrient provision.
  • Chen, Zhijie; Setala, Heikki; Geng, Shicong; Han, Shijie; Wang, Shuqi; Dai, Guanhua; Zhang, Junhui (2017)
    Purpose Anthropogenic-induced greenhouse gas (GHG) emission rates derived from the soil are influenced by long-term nitrogen (N) deposition and N fertilization. However, our understanding of the interplay between increased N load and GHG emissions among soil aggregates is incomplete. Materials and methods Here, we conducted an incubation experiment to explore the effects of soil aggregate size and N addition on GHG emissions. The soil aggregate samples (0-10 cm) were collected from two 6-year N addition experiment sites with different vegetation types (mixed Korean pine forest vs. broad-leaved forest) in Northeast China. Carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) production were quantified from the soil samples in the laboratory using gas chromatography with 24-h intervals during the incubation (at 20 degrees C for 168 h with 80 % field water capacity). Results and discussion The results showed that the GHG emission/uptake rates were significantly higher in the micro-aggregates than in the macro-aggregates due to the higher concentration of soil bio-chemical properties (DOC, MBC, NO3-, NH4+, SOC and TN) in smaller aggregates. For the N addition treatments, the emission/uptake rates of GHG decreased after N addition across aggregate sizes especially in mixed Korean pine forest where CO2 emission was decreased about 30 %. Similar patterns in GHG emission/uptake rates expressed by per soil organic matter basis were observed in response to N addition treatments, indicating that N addition might decrease the decomposability of SOM in mixed Korean pine forest. The global warming potential (GWP) which was mainly contributed by CO2 emission (>98 %) decreased in mixed Korean pine forest after N addition but no changes in broad-leaved forest. Conclusions These findings suggest that soil aggregate size is an important factor controlling GHG emissions through mediating the content of substrate resources in temperate forest ecosystems. The inhibitory effect of N addition on the GHG emission/uptake rates depends on the forest type.
  • Suorsa, V.; Otaki, M.; Virkanen, J.; Koivula, R. (2022)
  • Qu, Zhao-Lei; Santalahti, Minna; Köster, Kajar; Berninger, Frank; Pumpanen, Jukka; Heinonsalo, Jussi; Sun, Hui (2021)
    The boreal forest environment plays an important role in the global C cycle due to its high carbon storage capacity. However, relatively little is known about the forest fungal community at a regional scale in boreal forests. In the present study, we have re-analyzed the data from our previous studies and highlighted the core fungal community composition and potential functional groups in three forests dominated by Scots pine (Pinus sylvestris L.) in Finland, and identified the fungal generalists that appear across geographic locations despite differences in local conditions. The three forests represent subarctic, northern and southern boreal forest, and are all in an un-managed state without human interference or management. The subarctic and northern areas are subject to reindeer grazing. The results showed that the three locations formed distinct fungal community structures (P < 0.05). Compared to the two northern locations, the southern boreal forest harbored a greater abundance of Zygomycota, Lactarius, Mortierella Umbelopsis, and Tylospora, in which aspect there were no differences between the two northern forests. Cortinarius, Piloderma, and Suillus were the core fungal genera in the boreal Scots pine forest. Functionally, the southern boreal forest harbored a greater abundance of saprotroph, endophytes and fungal parasite-lichen, whereas a greater abundance of ectomycorrhizal fungi was observed in the northern boreal forests. Moreover, the pathotroph and wood saprotrophs were commonly present in these three regions. The three locations formed two distinct fungal community functional structures, by which the southern forest was clearly separated from the two northern forests, suggesting a distance-decay relationship via geographic location. This study provides useful information for better understanding the common fungal communities and functions in boreal forests in different geographical locations.
  • Wang, Sichu; Wang, Zhiqiang; Heinonsalo, Jussi; Zhang, Yuanxia; Liu, Gang (2022)
    Mollisols are globally distributed in grain-producing regions, and soil organic carbon (SOC) dynamics in mollisol regions are closely related to food security. Regional climate, land use and cover, and field management practice have massively changed since the 1980s in mollisol region in Northeast China, however, the dynamics of topsoil and profile SOC stocks and their distribution have not updated. To explore the dynamics of SOC stocks and their horizontal and vertical distributions in the 1980s-2010s, we took the mollisol region in Northeast China as an example location to conduct profile-scale soil surveys. The in situ surveys indicated that the topsoil SOC stock (0-20 cm) remained relatively stable throughout the 1980s, 2000s, and 2010s, and was 57.3 +/- 5.5, 58.2 +/- 3.3, and 57.4 +/- 4.4 t C ha(-1), respectively. The average profile SOC stock (1 m) increased from 148.9 +/- 18.5 t C ha(-1) in the 1980s to 162.0 +/- 14.0 t C ha(-1) in the 2010s. A slowdown in land reclamation and implementation of conservation tillage helped maintain and restore SOC stocks. Although the overall SOC stock tended to accumulate, the study area suffered an increasingly unbalanced redistribution of SOC related to severe soil erosion. Soil particles and SOC at erosional positions such as backslope were stripped from the soil surface, leading to attenuated soil thickness and SOC stock; SOC-rich sediment accumulated and was buried at depositional positions, especially at the foot-slope, increasing the soil thickness and SOC stock. These results confirmed that not only the total SOC stock, but also changes in SOC spatial distribution deserve great attention. This study provides a platform to examine and modify the simulation effectiveness of carbon-cycling models, as well as solid foundations for optimal global mollisols management. (C) 2021 The Authors. Published by Elsevier B.V.