Browsing by Subject "NORWAY SPRUCE"

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  • Virjamo, Virpi; Fyhrquist, Pia; Koskinen, Akseli; Lavola, Anu; Nissinen, Katri; Julkunen-Tiitto, Riitta (2020)
    Knowledge about the defensive chemistry of coniferous trees has increased in recent years regarding a number of alkaloid compounds; in addition to phenolics and terpenes. Here, we show that Norway spruce (Picea abies (L.) H. Karst.), an important boreal zone tree species; accumulates 1,6-dehydropinidine (2-methyl-6-(2-propenyl)-1,6-piperideine) in its needles and bark. We reanalyzed previously published GC-MS data to obtain a full picture of 1,6-dehydropinidine in P. abies. 1,6-dehydropinidine appeared to especially accumulate in developing spring shoots. We used solid-phase partitioning to collect the alkaloid fraction of the sprouts and thin-layer chromatography to purify 1,6-dehydropinidine. The antibacterial properties of the 1,6-dehydropinidine fraction were tested using a broth microdilution method; with Streptococcus equi subsp. equi as a model organism. Based on our results 1,6-dehydropinidine is common in alkaloid extractions from P. abies (0.4 +/- 0.03 mg g(-1) dw in mature needles) and it is especially abundant in young spruce shoots (2.7 +/- 0.5 mg g(-1) dw). Moreover; 1,6-dehydropinidine extracted from P. abies sprouts showed mild antibacterial potential against Streptococcus equi subsp. equi (MIC 55 mu g mL(-1)). The antibacterial activity of a plant compound thought of as an intermediate rather than an end-product of biosynthesis calls for more detailed studies regarding the biological function of these coniferous alkaloids
  • Hu, Man; Pitkanen, Timo P.; Minunno, Francesco; Tian, Xianglin; Lehtonen, Aleksi; Makela, Annikki (2021)
    Background and Aims Branch biomass and other attributes are important for estimating the carbon budget of forest stands and characterizing crown structure. As destructive measuring is time-consuming and labour-intensive, terrestrial laser scanning (TLS) as a solution has been used to estimate branch biomass quickly and non-destructively. However, branch information extraction from TLS data alone is challenging due to occlusion and other defects, especially for estimating individual branch attributes in coniferous trees. Methods This study presents a method, entitled TSMtls, to estimate individual branch biomass non-destructively and accurately by combining tree structure models and TLS data. The TSMtls method constructs the stem-taper curve from TLS data, then uses tree structure models to determine the number, basal area and biomass of individual branches at whorl level. We estimated the tree structural model parameters from 122 destructively measured Scots pine (Pinus sylvestris) trees and tested the method on six Scots pine trees that were first TLS-scanned and later destructively measured. Additionally, we estimated the branch biomass using other TLS-based approaches for comparison. Key Results Tree-level branch biomass estimates derived from TSMtls showed the best agreement with the destructive measurements [coefficient of variation of root mean square error (CV-RMSE) = 9.66 % and concordance correlation coefficient (CCC) = 0.99], outperforming the other TLS-based approaches (CV-RMSE 12.97-57.45 % and CCC 0.43-0.98 ). Whorl-level individual branch attributes estimates produced from TSMtls showed more accurate results than those produced from TLS data directly. Conclusions The results showed that the TSMtls method proposed in this study holds promise for extension to more species and larger areas.
  • Zhang-Turpeinen, Huizhong; Kivimäenpää, Minna; Berninger, Frank; Köster, Kajar; Zhao, Peng; Zhou, Xuan; Pumpanen, Jukka (2021)
    The amplification of global warming in the Northern regions results in a higher probability of wildfires in boreal forests. On the forest floor, wildfires have long-term effects on vegetation composition as well as soil and its microbial communities. A large variety of biogenic volatile organic compounds (BVOCs) such as isoprene, monoterpenes, sesquiterpenes have been observed to be emitted from soil and understory vegetation of boreal forest floor. Ultimately, the fire-induced changes in the forest floor affect its BVOC fluxes, and the recovery of the forest floor determines the quantity and quality of BVOC fluxes. However, the effects of wildfires on forest floor BVOC fluxes are rarely studied. Here we conducted a study of the impacts of post-fire succession on forest floor BVOC fluxes along a 158-year fire chronosequence in boreal Scots pine stands near the northern timberline in north-eastern Finland throughout a growing season. We determined the forest floor BVOC fluxes and investigated how the environmental and ground vegetation characteristics, soil respiration rates, and soil microbial and fungal biomass are associated with the BVOC fluxes during the post-fire succession. The forest floor was a source of diverse BVOCs. Monoterpenes (MTs) were the largest group of emitted BVOCs. We observed forest age-related differences in the forest floor BVOC fluxes along the fire chronosequence. The forest floor BVOC fluxes decreased with the reduction in ground vegetation coverage resulted from wildfire, and the decreased fluxes were also connected to a decrease in microbial activity as a result of the loss of plant roots and soil organic matter. The increase in BVOC fluxes was associated with the recovery of aboveground plant coverage and soils. Our results suggested taking into consideration the implications of BVOC flux variations on the atmospheric chemistry and climate feedbacks.
  • Heinaro, Einari; Tanhuanpaa, Topi; Yrttimaa, Tuomas; Holopainen, Markus; Vastaranta, Mikko (2021)
    Fallen trees decompose on the forest floor and create habitats for many species. Thus, mapping fallen trees allows identifying the most valuable areas regarding biodiversity, especially in boreal forests, enabling well-focused conservation and restoration actions. Airborne laser scanning (ALS) is capable of characterizing forests and the underlying topography. However, its potential for detecting and characterizing fallen trees under varying boreal forest conditions is not yet well understood. ALS-based fallen tree detection methods could improve our understanding regarding the spatiotemporal characteristics of dead wood over large landscapes. We developed and tested an automatic method for mapping individual fallen trees from an ALS point cloud with a point density of 15 points/m2. The presented method detects fallen trees using iterative Hough line detection and delineates the trees around the detected lines using region growing. Furthermore, we conducted a detailed evaluation of how the performance of ALS-based fallen tree detection is impacted by characteristics of fallen trees and the structure of vegetation around them. The results of this study showed that large fallen trees can be detected with a high accuracy in old-growth forests. In contrast, the detection of fallen trees in young managed stands proved challenging. The presented method was able to detect 78% of the largest fallen trees (diameter at breast height, DBH > 300 mm), whereas 30% of all trees with a DBH over 100 mm were detected. The performance of the detection method was positively correlated with both the size of fallen trees and the size of living trees surrounding them. In contrast, the performance was negatively correlated with the amount of undergrowth, ground vegetation, and the state of decay of fallen trees. Especially undergrowth and ground vegetation impacted the performance negatively, as they covered some of the fallen trees and lead to false fallen tree detections. Based on the results of this study, ALS-based collection of fallen tree information should be focused on old-growth forests and mature managed forests, at least with the current operative point densities.
  • Tanhuanpää, Topi; Kankare, Ville; Setälä, Heikki; Yli-Pelkonen, Vesa; Vastaranta, Mikko; Niemi, Mikko T.; Raisio, Juha; Holopainen, Markus (2017)
    Assessment of the amount of carbon sequestered and the value of ecosystem services provided by urban trees requires reliable data. Predicting the proportions and allometric relationships of individual urban trees with models developed for trees in rural forests may result in significant errors in biomass calculations. To better understand the differences in biomass accumulation and allocation between urban and rural trees, two existing biomass models for silver birch (Betula pendula Roth) were tested for their performance in assessing the above-ground biomass (AGB) of 12 urban trees. In addition, the performance of a volume-based method utilizing accurate terrestrial laser scanning (TLS) data and stem density was evaluated in assessing urban tree AGB. Both tested models underestimated the total AGB of single trees, which was mainly due to a substantial underestimation of branch biomass. The volume-based method produced the most accurate estimates of stem biomass. The results suggest that biomass models originally based on sample trees from rural forests should not be used for urban, open-grown trees, and that volume-based methods utilizing TLS data are a promising alternative for non-destructive assessment of urban tree AGB. (C) 2017 Elsevier GmbH. All rights reserved.
  • Pyorala, Jiri; Liang, Xinlian; Saarinen, Ninni; Kankare, Ville; Wang, Yunsheng; Holopainen, Markus; Hyyppa, Juha; Vastaranta, Mikko (2018)
    Terrestrial laser scanning (TLS) accompanied by quantitative tree-modeling algorithms can potentially acquire branching data non-destructively from a forest environment and aid the development and calibration of allometric crown biomass and wood quality equations for species and geographical regions with inadequate models. However, TLS's coverage in capturing individual branches still lacks evaluation. We acquired TLS data from 158 Scots pine (Pinus sylvestris L.) trees and investigated the performance of a quantitative branch detection and modeling approach for extracting key branching parameters, namely the number of branches, branch diameter (b(d)) and branch insertion angle (b) in various crown sections. We used manual point cloud measurements as references. The accuracy of quantitative branch detections decreased significantly above the live crown base height, principally due to the increasing scanner distance as opposed to occlusion effects caused by the foliage. b(d) was generally underestimated, when comparing to the manual reference, while b was estimated accurately: tree-specific biases were 0.89cm and 1.98 degrees, respectively. Our results indicate that full branching structure remains challenging to capture by TLS alone. Nevertheless, the retrievable branching parameters are potential inputs into allometric biomass and wood quality equations.
  • Saarinen, Ninni; Kankare, Ville; Pyorala, Jiri; Yrttimaa, Tuomas; Liang, Xinlian; Wulder, Michael A.; Holopainen, Markus; Hyyppa, Juha; Vastaranta, Mikko (2019)
    Large and comprehensive datasets, traditionally based on destructive stem analysis or other labor-intensive approaches, are commonly considered as a necessity in developing stem-volume equations. The aim here was to investigate how a decreasing number of sample trees affects parametrizing an existing taper curve equation and resultant stem-volume estimates. Furthermore, the potential of terrestrial laser scanning (TLS) in producing taper curves was examined. A TLS-based taper curve was derived for 246 Scots pines (Pinus sylvestris L.) from southern Finland to parametrize an existing taper curve equation. To assess sensitivity of the parametrization regarding sample size, the number of Scots pines included in the parametrization varied between full census and 1 Scots pine at a time. Root mean square error of stem-volume estimates remained = 46 Scots pines. Thus, it can be concluded that, with a rather small sample size, a taper curve equation can be re-parametrized for local conditions using point clouds from TLS to produce consistent stem-volume estimates.
  • Saarinen, Ninni; Kankare, Ville; Yrttimaa, Tuomas; Viljanen, Niko; Honkavaara, Eija; Holopainen, Markus; Hyyppä, Juha; Huuskonen, Saija; Hynynen, Jari; Vastaranta, Mikko (2020)
    Forest management alters the growing conditions and thus further development of trees. However, quantitative assessment of forest management on tree growth has been demanding as methodologies for capturing changes comprehensively in space and time have been lacking. Terrestrial laser scanning (TLS) has shown to be capable of providing three-dimensional (3D) tree stem reconstructions required for revealing differences between stem shapes and sizes. In this study, we used 3D reconstructions of tree stems from TLS and an unmanned aerial vehicle (UAV) to investigate how varying thinning treatments and the following growth effects affected stem shape and size of Scots pine (Pinus sylvestris L.) trees. The results showed that intensive thinning resulted in more stem volume and therefore total biomass allocation and carbon uptake compared to the moderate thinning.Relationship between tree height and diameter at breast height (i.e. slenderness) varied between both thinning intensity and type (i.e. from below and above) indicating differing response to thinning and allocation of stem growth of Scots pine trees. Furthermore, intensive thinning, especially from below, produced less variation in relative stem attributes characterizing stem shape and size. Thus, it can be concluded that thinning intensity,type, and the following growth effects have an impact on post-thinning stem shape and size of Scots pine trees.Our study presented detailed measurements on post-thinning stem growth of Scots pines that have been laborious or impracticable before the emergence of detailed 3D technologies. Moreover, the stem reconstructions from TLS and UAV provided variety of attributes characterizing stem shape and size that have not traditionally been feasible to obtain. The study demonstrated that detailed 3D technologies, such as TLS and UAV, provide information that can be used to generate new knowledge for supporting forest management and silviculture as well as improving ecological understanding of boreal forests.1
  • Ren, Wenzi; Penttilä, Reijo; Kasanen, Risto; Asiegbu, Fred (2022)
    The microbiome of Heterobasidion-induced wood decay of living trees has been previously studied; however, less is known about the bacteria biota of its perennial fruiting body and the adhering wood tissue. In this study, we investigated the bacteria biota of the Heterobasidion fruiting body and its adhering deadwood. Out of 7,462 operational taxonomic units (OTUs), about 5,918 OTUs were obtained from the fruiting body and 5,469 OTUs were obtained from the associated dead wood. Interestingly, an average of 52.6% of bacteria biota in the fruiting body was shared with the associated dead wood. The overall and unique OTUs had trends of decreasing from decay classes 1 to 3 but increasing in decay class 4. The fruiting body had the highest overall and unique OTUs number in the fourth decay class, whereas wood had the highest OTU in decay class 1. Sphingomonas spp. was significantly higher in the fruiting body, and phylum Firmicutes was more dominant in wood tissue. The FAPROTAX functional structure analysis revealed nutrition, energy, degradation, and plant-pathogen-related functions of the communities. Our results also showed that bacteria communities in both substrates experienced a process of a new community reconstruction through the various decay stages. The process was not synchronic in the two substrates, but the community structures and functions were well-differentiated in the final decay class. The bacteria community was highly dynamic; the microbiota activeness, community stability, and functions changed with the decay process. The third decay class was an important turning point for community restructuring. Host properties, environmental factors, and microbial interactions jointly influenced the final community structure. Bacteria community in the fruiting body attached to the living standing tree was suppressed compared with those associated with dead wood. Bacteria appear to spread from wood tissue of the standing living tree to the fruiting body, but after the tree is killed, bacteria moved from fruiting body to wood. It is most likely that some of the resident endophytic bacteria within the fruiting body are either parasitic, depending on it for their nutrition, or are mutualistic symbionts.
  • Minunno, Francesco; Peltoniemi, Mikko; Harkonen, Sanna; Kalliokoski, Tuomo; Makinen, Harri; Makela, Annikki (2019)
    Policy-relevant forest models must be environment and management sensitive and provide unbiased estimates of predicted variables over their intended areas of application. While empirical models derive their structure and parameters from representative data sets, process-based model (PBM) parameters should be evaluated in ranges that have a biological meaning independently of output data. At the same time PBMs should be calibrated against observations in order to obtain unbiased estimates and an understanding of their predictive capability. By means of model data assimilation, we Bayesian calibrated a forest model (PREBAS) using an extensive dataset that covered a wide range of climatic conditions, species composition and management practices. PREBAS was calibrated for three species in Finland: Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies [L.] H. Karst.) and Silver birch (Betula pendula L.). Data assimilation was strongly effective in reducing the uncertainty of PREBAS parameters and predictions. A country-generic calibration showed robust performances in predicting forest variables and the results were consistent with yield tables and national forest statistics. The posterior predictive uncertainty of the model was mainly influenced by the uncertainty of the structural and measurement error.
  • Palviainen, Marjo; Aaltonen, Heidi; Laurén, Ari; Köster, Kajar; Berninger, Frank; Ojala, Anne; Pumpanen, Jukka (2020)
    Biochar is charred material formed by the pyrolysis of organic matter. The addition of biochar to soil may offer a chance to mitigate climate change by increasing soil carbon stocks, improving soil fertility and enhancing plant growth. Vast majority of biochar studies are conducted in agricultural soils, and field experiments studying the effect of biochar on tree growth in boreal forests are lacking. We applied spruce biochar amendments of 5 and 10 Mg ha(-1) to the soil surface in young boreal Scots pine (Pinus sylvestris L.) forests in Southern Finland and studied the responses in tree growth and needle nitrogen (N) and N-15 concentrations during the first three years after treatment. The biochar amendment of 10 Mg ha(-1) increased the diameter growth of dominant trees significantly, on average by 1 mm year(-1), which corresponded to 25% increase compared to control during the three years study period. The positive growth responses were less pronounced in height than in diameter growth. The biochar amendment of 5 Mg ha(-1) increased the height growth of dominant trees by 0.16 m or 12% compared to the control during three years. Biochar amendments did not affect N and N-15 concentrations in needles. The results suggest that wood biochar amendment can be a climate-friendly method to increase tree biomass production in nutrient poor, xeric, young Scots pine forests.
  • Palviainen, Marjo; Aaltonen, Heidi; Laurén, Ari; Köster, Kajar; Berninger, Frank; Ojala, Anne; Pumpanen, Jukka (2020)
    Biochar is charred material formed by the pyrolysis of organic matter. The addition of biochar to soil may offer a chance to mitigate climate change by increasing soil carbon stocks, improving soil fertility and enhancing plant growth. Vast majority of biochar studies are conducted in agricultural soils, and field experiments studying the effect of biochar on tree growth in boreal forests are lacking. We applied spruce biochar amendments of 5 and 10 Mg ha(-1) to the soil surface in young boreal Scots pine (Pinus sylvestris L.) forests in Southern Finland and studied the responses in tree growth and needle nitrogen (N) and N-15 concentrations during the first three years after treatment. The biochar amendment of 10 Mg ha(-1) increased the diameter growth of dominant trees significantly, on average by 1 mm year(-1), which corresponded to 25% increase compared to control during the three years study period. The positive growth responses were less pronounced in height than in diameter growth. The biochar amendment of 5 Mg ha(-1) increased the height growth of dominant trees by 0.16 m or 12% compared to the control during three years. Biochar amendments did not affect N and N-15 concentrations in needles. The results suggest that wood biochar amendment can be a climate-friendly method to increase tree biomass production in nutrient poor, xeric, young Scots pine forests.
  • Palviainen, Marjo; Aaltonen, Heidi; Laurén, Ari; Köster, Kajar; Berninger, Frank; Ojala, Anne; Pumpanen, Jukka (2020)
    Biochar is charred material formed by the pyrolysis of organic matter. The addition of biochar to soil may offer a chance to mitigate climate change by increasing soil carbon stocks, improving soil fertility and enhancing plant growth. Vast majority of biochar studies are conducted in agricultural soils, and field experiments studying the effect of biochar on tree growth in boreal forests are lacking. We applied spruce biochar amendments of 5 and 10 Mg ha(-1) to the soil surface in young boreal Scots pine (Pinus sylvestris L.) forests in Southern Finland and studied the responses in tree growth and needle nitrogen (N) and N-15 concentrations during the first three years after treatment. The biochar amendment of 10 Mg ha(-1) increased the diameter growth of dominant trees significantly, on average by 1 mm year(-1), which corresponded to 25% increase compared to control during the three years study period. The positive growth responses were less pronounced in height than in diameter growth. The biochar amendment of 5 Mg ha(-1) increased the height growth of dominant trees by 0.16 m or 12% compared to the control during three years. Biochar amendments did not affect N and N-15 concentrations in needles. The results suggest that wood biochar amendment can be a climate-friendly method to increase tree biomass production in nutrient poor, xeric, young Scots pine forests.
  • Lintunen, Anna; Lindfors, Lauri; Kolari, Pasi; Juurola, Eija; Nikinmaa, Eero; Hölttä, Tuomo (2014)
  • Köster, Egle; Köster, Kajar; Berninger, Frank; Prokushkin, Anatoly; Aaltonen, Heidi; Zhou, Xuan; Pumpanen, Jukka (2018)
    Rising air temperatures and changes in precipitation patterns in boreal ecosystems are changing the fire occurrence regimes (intervals, severity, intensity, etc.). The main impacts of fires are reported to be changes in soil physical and chemical characteristics, vegetation stress, degradation of permafrost, and increased depth of the active layer. Changes in these characteristics influence the dynamics of carbon dioxide (CO2) and methane (CH4) fluxes. We have studied the changes in CO2 and CH4 fluxes from the soil in boreal forest areas in central Siberia underlain by continuous permafrost and the possible impacts of the aforementioned environmental factors on the emissions of these greenhouse gases. We have used a fire chronosequence of areas, with the last fire occurring 1, 23, 56, and more than 100 years ago. The soils in our study acted as a source of CO2. Emissions of CO2 were lowest at the most recently burned area and increased with forest age throughout the fire chronosequence. The CO2 flux was influenced by the pH of the top 5cm of the soil, the biomass of the birch (Betula) and alder (Duschekia) trees, and by the biomass of vascular plants in the ground vegetation. Soils were found to be a CH4 sink in all our study areas. The uptake of CH4 was highest in the most recently burned area (forest fire one year ago) and the lowest in the area burned 56 years ago, but the difference between fire chronosequence areas was not significant. According to the linear mixed effect model, none of the tested factors explained the CH4 flux. The results confirm that the impact of a forest fire on CO2 flux is long-lasting in Siberian boreal forests, continuing for more than 50 years, but the impact of forest fire on CH4 flux is minimal.
  • Zamorano, Juan Gallego; Hokkanen, Tatu; Lehikoinen, Aleksi (2018)
    Aims Understanding fluctuations in plant reproductive investment can constitute a key challenge in ecology, conservation and management. Masting events of trees (i.e. the intermittent and synchronous production of abundant seeding material) is an extreme example of such fluctuations. Our objective was to establish the degree of spatial and temporal synchrony in common four masting tree species in boreal Finland and account for potential causal drivers of these patterns. Methods We investigated the spatial intraspecific and temporal interspecific fluctuations in annual seed production of four tree species in Finland, silver birch Betula pendula Roth, downy birch Betula pubescens Ehrh., Norway spruce Picea abies (L.) H.Karst. and rowanberry Sorbus aucuparia L. We also tested to see whether variations in seed production were linked to annual weather conditions. Seeding abundance data were derived from tens of stands per species across large spatial scales within Finland during 1979 to 2014 (for rowanberries only 1986 to 2014). Important Findings All species showed spatial synchrony in seed production at scales up to 1000 km. Annual estimates of seed production were strongly correlated between species. Spring and summer temperatures explained most variation in crop sizes of tree species with 0-to 2-year time lags, whereas rainfall had relatively little influence. Warm weather during flowering (May temperature) in the flowering year (Year t) and 2 years before (t-2) were correlated with seed production. However, high May temperatures during the previous year (t-1) adversely affected seed production. Summer temperatures in Year t-1 was positively correlated with seed production, likely because this parameter enhances the development of flower primordials, but the effect was negative with a time lag of 2 years. The negative feedback in temperature coefficients is also likely due to patterns of resource allocation, as abundant flowering and seed production in these species is thought to reduce the subsequent initiation of potential new flower buds. Since the most important weather variables also showed spatial correlation up to 1000 km, weather parameters likely explain much of the spatial and temporal synchrony in seed production of these four studied tree species.
  • Peltoniemi, Mikko; Markkanen, Tiina; Härkönen, Sanna; Muukkonen, Petteri; Thum, Tea; Aalto, Tuula; Mäkelä, Annikki (2015)
    We simulated Gross Primary Production (GPP) of Finnish forests using a landsurface model (LSM), JSBACH, and a semi-empirical stand-flux model PRELES, and compared their predictions with the MODIS GPP product. JSBACH used information about plant functional type fractions in 0.167 degrees pixels. PRELES applied inventory-scaled information about forest structure at high resolution. There was little difference between the models in the results aggregated to national level. Temporal trends in annual GPPs were also parallel. Spatial differences could be partially related to differences in model input data on soils and leaf area. Differences were detected in the seasonal pattern of GPP but they contributed moderately to the annual totals. Both models predicted lower GPPs than MODIS, but MODIS still showed similar south north distribution of GPP. Convergent results for the national total GPP between JSBACH and PRELES, and those derived for comparison from the forest ghg-inventory, implied that modelled GPP estimates can be realistically up-scaled to larger region in spite of the fact that model calibrations may not originate from the study region, or that a limited number of sites was used in the calibration of a model.
  • Moose, Ryan A.; Schigel, Dmitry; Kirby, Lucas J.; Shumskaya, Maria (2019)
    Saproxylic fungi act as keystone species in forest ecosystems because they colonise and decompose dead wood, facilitating colonisation by later species. Here, we review the importance of intact forest ecosystems to dead wood fungi, as well as trends in their diversity research and challenges in conservation. Saproxylic communities are sensitive to transition from virgin forests to managed ecosystems, since the latter often results in reduced tree diversity and the removal of their natural habitat dead wood. The impact of dead wood management can be quite significant since many saproxylic fungi are host-specific. The significance of citizen science and educational programmes for saproxylic mycology is discussed with the emphasis on the North American region. We intend to raise the awareness of the role that dead wood fungi play in forest health in order to support development of corresponding conservational programmes.
  • Palviainen, Marjo; Laurén, Ari; Pumpanen, Jukka; Bergeron, Yves; Bond-Lamberty, Ben; Larjavaara, Markku; Kashian, Daniel; Köster, Kajar; Prokushkin, Anatoly; Chen, Han; Seedre, Meelis; Wardle, David; Gundale, Michael; Nilsson, Marie-Charlotte; Wang, Chuankuan; Berninger, Frank (2020)
    Boreal forests store 30% of the world's terrestrial carbon (C). Consequently, climate change mediated alterations in the boreal forest fire regime can have a significant impact on the global C budget. Here we synthesize the effects of forest fires on the stocks and recovery rates of C in boreal forests using 368 plots from 16 long-term (>= 100 year) fire chronosequences distributed throughout the boreal zone. Forest fires led to a decrease in total C stocks (excluding mineral soil) by an average of 60% (range from 80%), which was primarily a result of C stock declines in the living trees and soil organic layer. Total C stocks increased with time since fire largely following a sigmoidal shape Gompertz function, with an average asymptote of 8.1 kg C m(-2). Total C stocks accumulated at a rate of 2-60 g m(-2) yr(-1)during the first 100 years. Potential evapotranspiration (PET) was identified as a significant driver of C stocks and their post-fire recovery, likely because it integrates temperature, radiation, and the length of the growing season. If the fire return interval shortens to