Effects of site preparation methods on soil physical properties and outplanting success of coniferous seedlings in boreal forests

This study assessed the effect of patch scarification and mounding on the physical properties of the root layer and the success of tree planting in various types of forests.This study was conducted on 12 forest sites in taiga forests of the European part of Russia.A total of 54 plots were set up to assess seedling survival;root collar diameter,height,and heigh increment were measured for 240 seedlings to assess growth.In the rooting layer,240 soil samples were taken to determine physical properties.The study showed that soil treatment methods had no effect on bulk density and total porosity in Cladina sites.However,reduced soil moisture was noted,particularly in mounds,resulting in increased aeration.In Myrtillus sites,there were increased bulk density,reduced soil moisture,and total porosity in the mounds.Mounding treatment in Polytrichum sites resulted in reduced soil moisture and increased aeration porosity.In the Myrtillus and Polytrichum sites,patch scarification had no effects on physical properties.In Polytrichum sites,survival rates,heights,and heigh increments of bareroot Norway spruce seedlings in mounds were higher than in patches;however,the same did not apply to diameter.In Cladina and Myrtillus sites,there was no difference in growth for bareroot and containerised seedlings with different soil treatments.Growing conditions and soil types should be considered when applying different soil treatment methods to ensure high survival rates and successful seedling growth.

The impact of climate change on forest fire danger rating in China’s boreal forest

The Great Xing＇an Mountains boreal forests were focused on in the northeastern China.The simulated future climate scenarios of IPCC SRES A2a and B2a for both the baseline period of 1961-1990 and the future scenario periods were downscaled by the Delta Method and the Weather Generator to produce daily weather data.After the verification with local weather and fire data,the Canadian Forest Fire Weather Index System was used to assess the forest fire weather situation under climate change in the study region.An increasing trend of fire weather severity was found over the 21st century in the study region under the both future climate change scenarios,compared to the 1961-1990 baseline period.The annual mean/maximum fire weather index was predicted to rise continuously during 2010-2099,and by the end of the 21st century it is predicted to rise by 22%-52% across much of China＇s boreal forest.The significant increases were predicted in the spring from of April to June and in the summer from July to August.In the summer,the fire weather index was predicted to be higher than the current index by as much as 148% by the end of the 21st century.Under the scenarios of SRES A2a and B2a,both the chance of extremely high fire danger occurrence and the number of days of extremely high fire danger occurrence was predicted to increase in the study region.It is anticipated that the number of extremely high fire danger days would increase from 44 days in 1980s to 53-75 days by the end of the 21st century.

Effect of species composition on ecosystem services in European boreal forest

Forest management in several boreal countries is strongly focused on conifers because they are more productive,the technical quality of their stems is better,and their wood fibers are longer as compared to broadleaves.Favoring conifers in forest management leads to simple forest structures with low resilience and diversity.Such forests are risky in the face of climate change and fluctuating timber prices.Climate change increases the vitality of many forest pests and pathogens such as Heterobasidion spp.and Ips typographus L.which attack mainly spruce.Wind damages are also increasing because of a shorter period of frozen soil to provide a firm anchorage against storms.Wind-thrown trees serve as starting points for bark beetle outbreaks.Increasing the proportion of broadleaved species might alleviate some of these problems.This study predicts the long-term(150 years) consequences of current conifer-oriented forest management in two forest areas,and compared this management with silvicultural strategies that promote mixed forests and broadleaved species.The results show that,in the absence of damages,conifer-oriented forestry would lead to 5–10% higher timber yields and carbon sequestration.The somewhat lower carbon sequestration of broadleaved forests was counteracted by their higher albedo(reflectance).Mixed and broadleafforests were better providers of recreational amenities.Species diversity was much higher in mixed stand and broadleaf-oriented silviculture at stand and forest levels.The analysis indicates that conifer-oriented forest management produces rather small and uncertain economic benefits at a high cost in resilience and diversity.

Dead standing pine trees in a boreal forest landscape in the Kalevala National Park,northern Fennoscandia: amount,population characteristics and spatial pattern

Background： After their death, Scots pine trees can remain standing for decades and sometimes up to 200 years,forming long-lasting and ecologically important structures in boreal forest landscapes. Standing dead pines decay very slowly and with time develop into ‘kelo＇ trees, which are characterized by hard wood with silvery-colored appearance. These kelo trees represent an ecologically important, long lasting and visually striking element of the structure of natural pine-dominated forests in boreal Fennoscandia that is nowadays virtually absent from managed forest landscapes.Methods： We examined and mapped the amount, structural features, site characteristics and spatial distribution of dead standing pine trees over a ten hectare area in an unmanaged boreal forest landscape in the Kalevala National Park in Russian Viena Karelia.Results： The mean basal area of dead standing pine trees in the forested part of the landscape was 1.7 m^2·ha^-1 and the estimated volume 12.7 m^3·ha^-1. From the total number of standing dead pine trees 65% were kelo trees, with a basal area of 1.1 m^2·ha^-1 and volume of 8.0 m^3·ha^-1, the remainder consisting of standing dead pines along the continuum between a recently dead tree and a kelo tree. Overall, standing dead pines were distributed throughout the study area, but there was a tendency towards spatial clustering up to 〈100 m distances. Standing dead pines were most commonly situated on flat ground or in the mid slope in the local topography.In addition, standing dead pines contributed to substrate diversity also by commonly having charred wood and broken tops. Based on the presence of dead pine snags in different stage of transition from a recently dead pine to a kelo with silvery surface, it seems evident that the process of kelo recruitment was continuously in action in the studied landscape.Conclusions： Kelo trees are an omnipresent feature in natural pine-dominated forest landscapes with important contribution to forest structural and substrate diversity. Because of their longevity and extremely slow turnover dynamics and importance for biodiversity, protection of vulnerable kelo tree populations, and ensuring their continuous recruitment, should be of high priority in forest restoration and sustainable management.

Does variable stand structure associated with multi-cohort forests support diversity of ground beetle (Coleoptera, Carabidae) communities in the central Nearctic boreal forest？

Multi-cohort management （MCM） that retains a range of stand structures （age and size class） has been proposed to emulate natural disturbance and improve management in the Nearctic boreal forest. Although MCM forests contain both single- and multi-aged stands of mixed tree sizes, little is known about how variable stand structure affects associated fauna and biodiversity. Here, we examine the relationship between ground beetle （Coleoptera, Carabidae） communities and stand characteristics across a range of forest structure （=cohort classes）. Given that MCM classes are defined by the distribution of their tree-stem diameters, we ask whether parameters associated with these distributions （Weibull） could explain observed variation in carabid communities, and if so, how this compares to traditional habitat variables such as stand age, foliage complexity or volume of downed woody debris. We sampled carabids using weekly pitfall collections and compared these with structural habitat variables across a range of cohort classes （stand structure and age since disturbance） in 18 sites of upland mixed boreal forests from central Canada. Results showed that richness and diversity of carabid communities were similar among cohort classes. Weibull parameters from the diameter distribution of all stems were the strongest predictors of variation in carabid communities among sites, but vertical foliage complexity, understory thickness, and percentage of deciduous composition were also significant. The abundance of several carabid forest specialists was strongly correlated with tree canopy height, the presence of large trees, and high vertical foliage complexity. Our results demonstrate that variable forest structure, as expected under MCM, may be useful in retaining the natural range of ground beetle species across the central Nearctic boreal forest.

Response of saproxylic insect communities to logging history, tree species, stage of decay, and wood posture in the central Nearctic boreal forest

Saproxylic insect assemblages are essential functional components of forest ecosystems that can be affected by forest management.We used a split-plot ANOVA design to analyze differences in selected saproxylic insects（all arthropod orders and dipteran and parasitic hymenopteran families） emerging from dead wood of sites with different logging histories（horse-logged,mechanically-logged and unlogged）,tree species（Populus and Picea）,stage of decay（early-and late-decay stages） and posture（standing and downed logs） in the boreal forest of central Canada.No clear effects of logging history were seen for the studied taxa; however,interaction between logging history and other dead wood features was apparent.Cecidomyiidae consistently emerged more from Populus than from Picea dead wood.Most of the studied saproxylic families were more abundant in late-decay than in early-decay wood.Dipterans of the Cecidomyiidae,Ceratopogonidae,Empididae,Mycetophilidae and Sciaridae families,and hymenopterans of the Diapriidae and Ichneumonidae families were significantly more abundant in downed than in standing dead wood.In contrast,Mymaridae was most abundant in standing dead wood.Our study provides evidence that some insects at high taxonomic levels respond differently to dead wood quality,and this could inform future management strategies in the boreal forest for the conservation of saproxylic fauna and their ecological functions.

Holocene variations of wildfire occurrence as a guide for sustainable management of the northeastern Canadian boreal forest

Background: Cumulative impacts of wildfires and forest harvesting can cause shifts from closed-crown forest to open woodland in boreal ecosystems. To lower the probability of occurrence of such catastrophic regime shifts,forest logging must decrease when fire frequency increases, so that the combined disturbance rate does not exceed the Holocene maximum. Knowing how climate warming will affect fire regimes is thus crucial to sustainably manage the forest. This study aimed to provide a guide to determine sustainable forest harvesting levels, by reconstructing the Holocene fire history at the northern limit of commercial forestry in Quebec using charcoal particles preserved in lake sediments.Methods: Sediment cores were sampled from four lakes located close to the northern limit of commercial forestry in Quebec. The cores were sliced into consecutive 0.5 cm thick subsamples from which 1 cm3 was extracted to count and measure charcoal particles larger than 150 microns. Age-depth models were obtained for each core based on accelerator mass spectroscopy(AMS) radiocarbon dates. Holocene fire histories were reconstructed by combining charcoal counts and age-depth models to obtain charcoal accumulation rates and, after statistical treatment,long-term trends in fire occurrence(expressed as number of fires per 1000 years).Results: Fire occurrence varied between the four studied sites, but fires generally occurred more often during warm and dry periods of the Holocene, especially during the Holocene Thermal Maximum(7000–3500 cal. BP), when fire occurrence was twice as high as at present.Conclusions: The current fire regime in the study area is still within the natural range of variability observed over the Holocene. However, climatic conditions comparable to the Holocene Thermal Maximum could be reached within the next few decades, thus substantially reducing the amount of wood available to the forest industry.

Identifying Possible Climate Change Signals Using Meteorological Parameters in Short-Term Fire Weather Variability for Russian Boreal Forest in the Republic of Sakha (Yakutia)

The Boreal forest is a terrestrial ecosystem highly vulnerable to the impacts of short-term climate and weather variabilities. Detecting abrupt, rapid climate-induced changes in fire weather and related changes in fire seasonality can provide important insights to assessing impacts of climate change on forestry. This paper, taking the Sakha Republic of Russia as study area, aims to suggest an approach for detecting signals indicating climate-induced changes in fire weather to express recent fire weather variability by using short-term ranks of major meteorological parameters such as air temperature and atmospheric precipitation. Climate data from the “Global Summary of the Day Product” of NOAA (the United States National Oceanic and Atmospheric Administration) for 1996 to 2018 were used to investigate meteorological parameters that drive fire activity. The detection of the climate change signals is made through a 4-step analysis. First, we used descriptive statistics to grasp monthly, annual, seasonal and peak fire period characteristics of fire weather. Then we computed historical normals for WMO reference period, 1961-1990, and the most recent 30-year period for comparison with the current means. The variability of fire weather is analyzed using standard deviation, coefficient of variation, percentage departures from historical normals, percentage departures from the mean, and precipitation concentration index. Inconsistency and abrupt changes in the evolution of fire weather are assessed using homogeneity analysis whilst a Mann-Kendall test is used to detect significant trends in the time series. The results indicate a significant increase of temperature during spring and fall months, which extends the fire season and potentially contributes to increase of burned areas. We again detected a significant rainfall shortage in September which extended the fire season. Furthermore, this study suggests a new approach in statistical methods appropriate for the detection of climate change signals on fire weather variability using short-term climate ranks and evaluation of its impact on fire seasonality and activity.

Stand age structural dynamics of conifer, mixedwood, and hardwood stands in the boreal forest of central Canada

To study the effects of stand development and overstory composition on stand age structure, we sampled 32 stands representing conifer, mixedwood, and hardwood stand types, ranging in ages from 72 to 201 years on upland mesic sites in northwestern Ontario. We defined the stages of stand development as: stem exclusion/canopy transition, canopy transition, canopy transition/gap dynamics, and gap dynamics. Stand age structure of conifer stands changed from bimodal, bimodal, reverse-J, and bimodal, respectively, through the stages of stand development. Mixedwood and hardwood stands revealed similar trends, with the exception of missing the canopy transition/gap dynamic stage in mixedwoods. Canopy transition/gap dynamic stage in hardwoods showed a weaker reverse-J distribution than their conifer counterparts. The results suggest that forest management activities such as partial and selection harvesting and seed-tree systems may diversify standard landscape-level age structures and benefit wildlife, hasten the onset of old-growth, and create desired stand age structures. We also recommend that the determination of old-growth using the following criteria in the boreal forest: 1) canopy breakdown of pioneering cohort is complete and stand is dominated by later successional tree species, and 2) stand age structure is bimodal, with dominating canopy trees that fall within a relatively narrow range of age and height classes and a significant amount of understory regeneration.

Quantitative Evaluation of Bitterlich Sampling for Estimating Basal Area in Sparse Boreal Forests and Dense Tropical Forests

Bitterlich sampling is an extensively used technique in worldwide forest inventories. Although it has been proved that estimates of basal area from Bitterlich sampling are mathematically unbiased, its precision for individual forest stands may be fairly poor. An extension of validation efforts to different forest biomes could therefore provide more comprehensive assessment and understanding of the Bitterlich sampling technique. In this study, this technique was quantitatively evaluated by using simulated sparse boreal forests and dense tropical forests from an empirical forest structure model (EFSM). Theoretical estimation of basal areas and practical estimation influenced by the hidden-tree effect were both compared with true basal areas of the simulated forests. The evaluation results indicated that: 1) Bitterlich sampling can yield acceptable accuracy and precision when the count number (CN) of trees was set to 10 for the studied boreal and tropical forests with distinct characteristics, 2) the theoretical estimation of basal area can be improved by increasing the CN values for both forests, and 3) when the hidden-tree effect is encountered, the accuracy for tropical forests will be decreased by increasing the CN values, whereas the accuracy for boreal forests can still be improved. Accordingly, a relatively high CN, at a reasonable cost, is recommended for sparse boreal forests to improve the accuracy of basal area estimation. In contrast, for dense tropical forests, a CN of ten is appropriate to mitigate the hidden-tree effect.

Long-term monitoring of cycles in Clethrionomys rutilus in the Yukon boreal forest

Baseline studies of small rodent populations in undisturbed ecosystems are rare.We report here 50 years of mon-itoring and experimentation in Yukon of a dominant rodent species in the North American boreal forest,the red-backed vole Clethrionomys rutilus.These voles breed in summer,weigh 20–25 g,and reach a maximum density of 20 to 25 per ha.Their populations have shown consistent 3–4-year cycles for the last 50 years with the only change being that peak densities averaged 8/ha until 2000 and 18/ha since that year.During the last 25 years,we have measured food resources,predator numbers,and winter weather,and for 1-year social interactions,to estimate their contribution to changes in the rate of summer increase and the rate of overwinter decline.All these potential limiting factors could contribute to changes in density,and we measured their relative contributions statistically with multiple regressions.The rate of winter decline in density was related to both food supply and winter severity.The rate of summer increase was related to summer berry crops and white spruce cone production.No measure of predator numbers was related to winter or summer changes in vole abundance.There was a large signal of climate change effects in these populations.There is no density dependence in summer population growth and only a weak one in winter population declines.None of our results provide a clear understanding of what generates 3–4-year cycles in these voles,and the major missing piece may be an understanding of social interactions at high density.

Response of soil bacterial community to biochar application in a boreal pine forest

Boreal forests commonly suff er from nitrogen defi ciency due to low rate of nitrogen mineralization.Biochar may promote soil organic matter decomposition and accelerate nitrogen mineralization.In this study,Illumina NovaSeq sequencing combined with functional annotation of prokaryotic taxa(FAPROTAX)analysis was used to investigate the eff ect of biochar pyrolysis temperatures,the amount of applied biochar,and the period since the biochar application(2-and 3-year)on soil bacterial communities.The results show that biochar pyrolysis temperatures(500℃ and 650℃)and the amount of applied biochar(0.5 kg m^(−2)and 1.0 kg m^(−2))did not change soil properties.Nevertheless,the interaction of biochar pyrolysis temperature and the amount had signifi cant eff ects on bacterial species richness and evenness(P<0.05).The application of biochar produced at 500℃ had a lower abundance of Actinobacteria and Verrucomicrobia,while that produced at 650℃ had a higher abundance of Conexibacter and Phenylobacterium.When biochar produced at 650℃ was applied,applying 0.5 kg m^(−2)had a higher abundance of Cyanobacteria,Conexibacter,and Phenylobacterium than that of 1.0 kg m^(−2)(P<0.05).Functionally,the abundance of the aromatic compound degradation group increased with the extension of application time and increase of pyrolysis temperature.The time since application played an important role in the formation of soil bacterial communities and their functional structure.Long-term studies are necessary to understand the consequence of biochar on bacterial communities in boreal forests.

Historic distribution and driving factors of human-caused fires in the Chinese boreal forest between 1972 and 2005

Aims The pattern and driving factors of forest fires are of interest for fire occurrence prediction and forest fire management.The aims of the study were:(i)to describe the history of human-caused fires by season and size of burned area over time;(ii)to identify the spatial patterns of human-caused fires and test for the existence of‘hotspots’to determine their exact locations in the Daxing’an mountains;(iii)to determine the driving factors that determine the spatial distribution and the possibility of human-caused fire occurrence.Methods In this study,K-function and Kernel density estimation were used to analyze the spatial pattern of human-caused fires.The analysis was conducted in s-plus and arcgIs environments,respectively.The analysis of driving factors was performed in SPSS 19.0 based on a logistic regression model.The variables used to identify factors that influence fire occurrence included vegetation types,meteorological conditions,socioeconomic factors,topography and infrastructure factors,which were extracted and collected through the spatial analysis mode of arcgIs and from official statistics,respectively.Important Findings The annual number of human-caused fires and the area burnt have declined since 1987 due to the implementation of a forest fire protection act.There were significant spatial heterogeneity and seasonal variations in the distribution of human-caused fires in the Daxing’an mountains.The heterogeneity was caused by elevation,distance to the nearest railway,forest type and temperature.a logistic regression model was developed to predict the likelihood of human-caused fire occurrence in the Daxing’an mountains;its global accuracy attained 64.8%.The model was thus comparable to other relevant studies.

Young and old forest in the boreal:critical stages of ecosystem dynamics and management under global change

The circumboreal forest encompasses diverse landscape structures, dynamics and forest age distributions determined by their physical setting, and historical and current disturbance regimes. However, due to intensifying forest utilisation, and in certain areas due to increasing natural disturbances, boreal forest age-class structures have changed rapidly, so that the proportion of old forest has substantially declined, while that of young post-harvest and post-natural-disturbance forest proportions have increased. In the future, with a warming climate in certain boreal regions, this trend may further be enhanced due to an increase in natural disturbances and large-scale use of forest biomass to replace fossil-based fuels and products.The major drivers of change of forest age class distributions and structures include the use of clearcut shortrotation harvesting, more frequent and severe natural disturbances due to climate warming in certain regions. The decline in old forest area, and increase in managed young forest lacking natural post-disturbance structural legacies,represent a major transformation in the ecological conditions of the boreal forest beyond historical limits of variability.This may introduce a threat to biodiversity, ecosystem resilience and long-term adaptive capacity of the forest ecosystem.To safeguard boreal forest biodiversity and ecosystem functioning, and to maintain the multiple services provided to societies by this forest biome, it is pivotal to maintain an adequate share and the ecological qualities of young postdisturbance stages, along with mature forest stages with old-growth characteristics. This requires management for natural post-disturbance legacy structures, and innovative use of diverse uneven-aged and continuous cover management approaches to maintain critical late-successional forest structures in landscapes.

A MESO-β SCALE SIMULATION OF THE EFFECTS OF BOREAL FOREST ECOSYSTEM ON THE LOWER ATMOSPHERE

Based on the Intensive Field Campaign(IFC-1)data of Boreal Ecosystem-Atmosphere Study (BOREAS).a three-dimensional meso-β scale model is used to simulate the effect of boreal forests on the lower atmosphere.A fine horizontal resolution of 2 km×2 km is used in order to distinguish the vegetative heterogeneity in the boreal region.A total of 20×25 grid points cover the entire sub- modeling area in BOREAS' South Study Area(SSA).The ecosystem types and their coverage in each grid square are extracted from the North American Land Cover Characteristics Data Base (NALCCD)generated by the U.S.Geographical Survey(USGS)and the University of Nebraska- Lincoln(UNL).The topography of the study area is taken from the Digital Elevation Map(DEM) of USGS.The model outputs include the components of the energy balance budget within the canopy and at the ground.the turbulence parameters in the atmospheric boundary layer and the wind. temperature and humidity profiles extending up to a height of 1500 m.In addition to the fine time and spatial step,the unique feature of the present model is the incorporation of both dynamic and biological effects of the Boreal forest into the model parameterization scheme.The model results compare favorably with BOREAS' IFC-1 data in 1994 when the forest was in the luxuriant growing period.

Winter soil respiration during soilfreezing process in a boreal forest in Northeast China

Aims Boreal forest is the largest and contains the most soil carbon among global terrestrial biomes.Soil respiration during the prolonged winter period may play an important role in the carbon cycles in boreal forests.This study aims to explore the characteristics of winter soil respiration in the boreal forest and to show how it is regulated by environmental factors,such as soil temperature,soil moisture and snowpack.Methods Soil respiration in an old-growth larch forest(Larix gmelinii Ruppr.)in Northeast China was intensively measured during the winter soilfreezing process in 2011 using an automated soil CO_(2) flux system.The effects of soil temperature,soil moisture and thin snowpack on soil respiration and its temperature sensitivity were investigated.Important Findings Total soil respiration and heterotrophic respiration both showed a declining trend during the observation period,and no significant difference was found between soil respiration and heterotrophic respiration until the snowpack exceeded 20cm.Soil respiration was exponentially correlated with soil temperature and its temperature sensitivity(Q10 value)for the entire measurement duration was 10.5.Snow depth and soil moisture both showed positive effects on the temperature sensitivity of soil respiration.Based on the change in the Q10 value,we proposed a‘freeze–thaw critical point’hypothesis,which states that the Q10 value above freeze–thaw critical point is much higher than that below it(16.0 vs.3.5),and this was probably regulated by the abrupt change in soil water availability during the soil-freezing process.Our findings suggest interactive effects of multiple environmental factors on winter soil respiration and recommend adopting the freeze–thaw critical point to model soil respiration in a changing winter climate.

Assessing the impacts of vegetation heterogeneity on energy fluxes and snowmelt in boreal forests

Aims In the mid-and high-latitude regions,three quarters of the land surface is covered by boreal conifer forests,and snow lasts for 6–8 months of the year.Correctly modeling surface energy balance and snowmelt at mid-and high-latitudes has a significant influence on climate and hydrological processes.However,the heterogeneous and clumped forest structure exerts important control over the radiative energy at the forest floor,which results in large variations of underneath snow cover and snowmelt rate.The goal of this study is to investigate the impact of hierarchically clumped vegetation structure in boreal forest on snowmelt and exchanges of energy and water.Methods We used a simple Clumped Canopy Scheme(CCS)for canopy radiation transfer to characterize the impact of the clumped forest structure on net radiation at the snow surface underneath forests.The CCS was integrated with the Variable Infiltration Capacity macroscale hydrological model(herein referred to as VIC-CCS)to characterize the impact of clumped vegetation structure on surface energy balance and snowmelt during the snow season.A twin simulation,VICCCS and the standard VIC model,was performed to isolate the impact of CCS on the energy and water fluxes and snowmelt rates.The simulation results were compared to in situ measurements at four different forest stands:old aspen forest in the Southern Study Area(SOA),black spruce forests in the Southern and Northern Study Areas(SOBS and NOBS)and fen wetland in the Northern Study Area(NFEN)within the Boreal Ecosystem–Atmosphere Study(BOREAS)region in central Canada during 1994 to1996.Important Findings Simulations showed that the implementation of CCS has reduced incoming long-wave radiation at the underlying snow surface and,thereby,lowered the snowmelt rate.Comparison against ground observations of net radiation and surface flux rates showed a reasonable agreement while demonstrating implementation of CCS can markedly improve model surface energy budget and energy inputs computation for snowmelt.The modeled snowmelt matches reasonably well with observations with root mean square error(RMSE)ranging from 16.51 to 19.81 mm using VIC-CCS versus 29.86 to 32.61 mm for VIC only in the four forest sites.The improvement is the most significant for the deciduous forest(old aspen)site,reducing RMSE by16 mm.This study demonstrates that taking into account the effect of the clumped forest structure in land surface parameterization schemes is critical for snowmelt prediction in the boreal regions.

Characterization of spatial relationships between three remotely sensed indirect indicators of biodiversity and climate:a 21years’data series review across the Canadian boreal forest

Climate drives ecosystem processes and impacts biodiversity.Biodiversity patterns over large areas,such as Canada’s boreal,can be monitored using indirect indicators derived from remotely sensed imagery.In this paper,we characterized the historical space–time relationships between climate and a suite of indirect indicators of biodiversity,known as the Dynamic Habitat Index(DHI)to identify where climate variability is co-occurring with changes in biodiversity indicators.We represented biodiversity using three indirect indicators generated from 1987 to 2007 National Oceanic and Atmospheric Administration Advanced Very High Resolution Radiometer images.By quantifying and clustering temporal variability in climate data,we defined eight homogeneous climate variability zones,where we then analyzed the DHI.Results identified unique areas of change in climate,such as the Hudson Plains,that explain significant variations in DHI.Past variability in temperatures and growing season index had a strong influence on observed vegetation productivity and seasonality changes throughout Canada’s boreal.Variation in precipitation,for most of the area,was not associated with DHI changes.The methodology presented here enables assessment of spatial–temporal relationships between biodiversity and climate variability and characterizes distinctive zones of variation that may be used for prioritization and planning to ensure long-term biodiversity conservation in Canada.

Increasing loss of mature boreal forests around protected areas with red-listed forest species

Background:Protected areas(PA)are central to biodiversity,but their efficiency is challenged by human‑induced habitat loss and fragmentation.In the Fennoscandian boreal region,forestry with clearcutting is a threat to biodiversity causing the loss of mature forest elements and deterioration of ecological processes in forest landscapes,ultimately affecting PAs via declined structural connectivity.This paper aims to(1)determine PAs with high,red‑listed species concentrations;(2)estimate the change in forest habitat around these PAs on different spatial scales;and(3)determine if forest management intensity is higher around biologically most valuable PAs.Occurrences of red‑listed forest‑dwelling species in Finland were used to identify PAs harbouring these species and to produce site‑specific importance indices.CORINE landcover data was used as a baseline for the distribution of forests to assess the cover of clear‑cuttings from 2001 to 2019 with the Global Forest Change(GFC)data set in three buffer areas around the PAs with occurrences of red‑listed species.Results:The largest proportion of clear‑cuts occurred in 1 km and 10 km buffers around the PAs in the southern and middle boreal zones,being ca.20%.This indicates that the forest habitat is degrading fast at regional and landscape levels.On the positive side,the change in forest cover was lower around the biologically most important PAs compared to other PAs with red‑listed species.Conclusions:Open and free satellite‑data based assessments of the cover and change of forests provide reliable estimates about the rates at which mature and old‑growth forests are being converted into young managed ones in Finland mainly via clear‑cuts on different scales around PAs.The rate of clear‑cuts was lowest in adjacent buffer areas next to the most species‑rich PAs,which provides opportunities for biodiversity conservation efforts to be targeted to the remaining mature and old‑growth forests found in the vicinity of these areas.

Effects of long-term nitrogen addition on theδ^(15)N andδ^(13)C of Larix gmelinii and soil in a boreal forest

Background:Natural abundance of carbon(C)and nitrogen(N)stable isotope ratios(δ^(13)C andδ^(15)N)has been used to indicate the state and cycle of ecosystem C and N.However,it is still unclear how C and N cycle of boreal forests respond to the N deposition.Results:We conducted an 8-year continuous N addition field experiment in a Larix gmelinii forest in Greater Khingan Mountains,Northeast China.Four N treatments(0,25,50,75 kg N ha^(−1)year^(−1))were built.The effects of N addition on theδ^(13)C andδ^(15)N of needle,branch,bark,and fine root of Larix gmelinii and soil were studied.The result of the balance between the N input and output flux showed that N addition significantly increased theδ^(15)N in each organ of Larix gmelinii,but did not change theδ^(15)N of soil.We also found that the N absorption by needles of Larix gmelinii could increase the needle photosynthesis rate andδ^(13)C by increasing carboxylation,but N addition had no significant effect on theδ^(13)C of soil and other organs.In addition,both the soilδ^(15)N andδ^(13)C increased with the soil depth.Conclusions:Long-term N addition may lead to more open C and N cycles and further affect plant nutrient acquisition strategies in boreal forest ecosystems.