Northeast Eurasia Research Articles

Expeditionary Studies of the Seas of Northeast Eurasia during Cruise 69 of the R/V Akademik Oparin

Expeditionary Studies of the Seas of Northeast Eurasia during Cruise 69 of the R/V Akademik Oparin

Traditional nature management in the North as a technological culture of the Arctic subcivilization: from past to future

This article examines thehistorical andcurrent state of the subcivilization in the Russiansector of the Arcticand Subarctic, which is rooted in reindeer husbandry and other forms of environmental-based traditional northern environental management.The preservation anddevelopmentof this subcivilization in modern conditionsis closely linked to the organizational and economic modernization, as well as the technological re-equipment, of all sectors of tradi tional Northern Natural Resource Management. Examples include the biotechnological advancement of traditionalenvironmental managementin the North,which enhances the economic viabilityof its industries while improving the quality of life in the region. Another key resource in Northeast Eurasia is the natural cold, which is a unique and fundamental feature of thecoldest inhabited region ontheplanetwith the lowest temperature and most stable permafrost. The development of modern technologies for preserving permafrostin the conditions of climate change and increased economic activity in the Arctic has the potential to significantly impact the development of subcivilization in the Northeast of Russia.

Consideration of Whether a Climatic Regime Shift Has Prevented the Occurrence of a Cold Summer in Northeast Eurasia since 2010

Abstract Does a warming world, where extremely hot summers are becoming more common, mean that cold summers will never again occur? It is crucial to know whether extremely cold summers are still possible, as such knowledge will significantly impact decisions regarding the further adaptation of crops to cold summers. Japan, which has suffered from many extremely cold summers, has managed past agricultural disruptions with emergency rice imports. In this paper, we show that a climate regime shift associated with the positive phase shift of the summer Arctic Oscillation occurred in 2010 in northeast Eurasia, making the occurrence of extremely cold summers highly unlikely as long as this new regime persists. In fact, Japan has not experienced a cold summer since 2010, while extremely hot summers have been frequent. Since 2010, a double-jet structure with subtropical and polar jets has strengthened, and the polar jet has meandered farther north of Japan, resulting in an upper-tropospheric anticyclone. This anticyclone, which extends downward and tilts southward, reaches southern Japan and prevents cold advection of oceanic air over the cold Oyashio. The Okhotsk high, known as the leading cause of cold summers, has occurred frequently in recent years; however, cold summers have not occurred due to the tilting anticyclone. The recent warming of the Oyashio weakens cold advection. The Pacific–Japan pattern, known as a remote tropical influence, has been weakened. A better understanding of the regime shift will help us understand the tilting anticyclone and the associated extreme summers in northeast Eurasia. Significance Statement Extremely cold summers are among the most destructive natural disasters, both socioeconomically and agriculturally. Historically, food shortages due to cold summers have triggered wars. This paper proposes that a hemispheric-scale climate regime shift occurred in or around 2010. This regime shift has included warmings in the North Pacific and East Eurasian land surface temperatures. The regime shift is accompanied by the positive shift of the Arctic Oscillation (AO), a jet meander, and an upper-tropospheric anticyclone, making eastern Eurasia extremely hot. Our results imply that extremely cold summers are unlikely to occur in eastern Eurasia so long as this regime persists. Moving forward, it is important that the link between this regime shift and global warming be explored.

Geocryological Structure of a Giant Spring Aufeis Glade at the Anmangynda River (Northeastern Russia)

Gigantic aufeis fields serve as indicators of water exchange processes within the permafrost zone and are important in assessing the state of the cryosphere in a changing climate. The Anmangynda aufeis, located in the upstream of the Kolyma River basin, is present in the mountainous regions of Northeast Eurasia. Recent decades have witnessed significant changes in aufeis formation patterns, necessitating a comprehensive understanding of cryospheric processes. The objective of the study, conducted in 2021–2022, was to examine the structure of the Anmangynda aufeis and its glade, aiming to understand its genesis and formation processes. The tasks included identifying above- and intra-frozen taliks, mapping groundwater (GW) discharge channels, determining permafrost base depth, and assessing ice thickness distribution. Soundings using ground-penetrating radar (GPR), capacitively coupled electrical resistivity tomography (CCERT), and the transient electromagnetic (TEM) method were employed. GW discharge channels originating from alluvial deposits and extending to the aufeis surface within river channels were identified through GPR and verified through drilling. Deep-seated sources of GW within the bedrock were inferred. CCERT data allowed us to identify large and localized frozen river taliks, from which water is forced onto the ice surface. According to the TEM data, the places of GW outlets spatially coincide with the zones interpreted as faults.

Absence of Large‐Scale Ice Masses in Central Northeast Siberia During the Late Pleistocene

AbstractOngoing speculation regarding the existence of large Late Pleistocene ice masses in Northeast Eurasia reflects the dearth of age constraints on glaciations across this vast region. Here, we report the first dates from the central part of Northeast Siberia, consisting of 22 cosmogenic 10Be exposure ages from boulders deriving from a sequence of three moraines in the Chersky Range. The dated moraine sequence indicates progressive contraction of maximum glacier extent from Marine Isotope Stage 6 to the Last Glacial Maximum, while the remotely‐sensed mapping indicates an older, more expansive glaciation in the region yet undated. Our results show that Late Pleistocene glaciations were limited to the highlands, and Northeast Siberia did not host a large, coalescent ice sheet during the Last Glacial Maximum or Marine Isotope Stage 6.

Effects of large-scale changes in environmental factors on the genesis of Arctic extreme cyclones

The Arctic cyclone is an active weather system in the Arctic, and the Arctic extreme cyclone (AEC) strongly influences polar weather. Thus, many studies have focused on the activity of AEC and its relationship with large-scale circulation in the Arctic. In this study, Arctic cyclones were detected using the ERA5 Reanalysis data from 1979 to 2020, and the AECs of cold and warm semesters were defined using the 5th percentile of sea level pressure. An Arctic cyclone genesis index, GPIArctic, is established by using the least square fitting of absolute vorticity, omega, wind shear, and long-wave radiation with Eady growth rate. Our findings show that wind shear and long-wave radiation strongly influence AECs. In the cold semester, the high value of GPIArctic mainly occurs in the south of Greenland, while in the warm semester, the high value of GPIArctic also occurs in northeast Eurasia. The results of the multi-model integration of CMIP6 show that more AECs will be formed in the Arctic in the future (2021–2050), and their seasonal contrast will be stronger in northeast Eurasia.

Morphological and Genetic Assessment of Sympatric Lenok Species (Brachymystax spp.) in the Onon River, Mongolia

The genus Brachymystax is represented by three putative species that disjointedly inhabit the major river basins of central and northeast Eurasia. Brachymystax lenok and B. tumensis have been regularly misidentified throughout their range, including across sympatric populations in the upper Onon River of Mongolia. This research has focused on Mongolia’s understudied lenok populations by conducting detailed morphometric measurements and genetic analyses to confirm key metrics for accurately distinguishing between these cryptic species. While there are slight differences in colouration and patterns including size and density of their defining black spots, four key metrics were found to be significantly different between the species including gill rakers counts, snout length, lateral line scale counts and body depth. Brachymystax tumensis was also typically heavier than B. lenok at the same length. These results were supported by genetic analyses which clustered the two species into separate clades and displayed unique haplotypes for the Mongolian populations. Initial investigations of diets and gonad maturation indicated an ecological and spatial separation of these sympatric species. The current study is important for these recreationally targeted species which require further research and species-specific management measures to ensure their threatened populations are conserved in Mongolia for the future.

Ancient DNA Reveals Maternal Philopatry of the Northeast Eurasian Brown Bear (Ursus arctos) Population during the Holocene.

Significant palaeoecological and paleoclimatic changes that took place during Late Pleistocene-Early Holocene transition are considered important factors that led to megafauna extinctions. Unlike many other species, the brown bear (Ursus arctos) has survived this geological time. Despite the fact that several mitochondrial DNA clades of brown bears became extinct at the end of the Pleistocene, this species is still widely distributed in Northeast Eurasia. Here, using the ancient DNA analysis of a brown bear individual that inhabited Northeast Asia in the Middle Holocene (3460 ± 40 years BP) and comparative phylogenetic analysis, we show a significant mitochondrial DNA similarity of the studied specimen with modern brown bears inhabiting Yakutia and Chukotka. In this study, we clearly demonstrate the maternal philopatry of the Northeastern Eurasian U. arctos population during the several thousand years of the Holocene.

Multi-year observations reveal a larger than expected autumn respiration signal across northeast Eurasia

Abstract. Site-level observations have shown pervasive cold season CO2 release across Arctic and boreal ecosystems, impacting annual carbon budgets. Still, the seasonality of CO2 emissions are poorly quantified across much of the high latitudes due to the sparse coverage of site-level observations. Space-based observations provide the opportunity to fill some observational gaps for studying these high-latitude ecosystems, particularly across poorly sampled regions of Eurasia. Here, we show that data-driven net ecosystem exchange (NEE) from atmospheric CO2 observations implies strong summer uptake followed by strong autumn release of CO2 over the entire cold northeastern region of Eurasia during the 2015–2019 study period. Combining data-driven NEE with satellite-based estimates of gross primary production (GPP), we show that this seasonality implies less summer heterotrophic respiration (Rh) and greater autumn Rh than would be expected given an exponential relationship between respiration and surface temperature. Furthermore, we show that this seasonality of NEE and Rh over northeastern Eurasia is not captured by the TRENDY v8 ensemble of dynamic global vegetation models (DGVMs), which estimate that 47 %–57 % (interquartile range) of annual Rh occurs during August–April, while the data-driven estimates suggest 59 %–76 % of annual Rh occurs over this period. We explain this seasonal shift in Rh by respiration from soils at depth during the zero-curtain period, when sub-surface soils remain unfrozen up to several months after the surface has frozen. Additional impacts of physical processes related to freeze–thaw dynamics may contribute to the seasonality of Rh. This study confirms a significant and spatially extensive early cold season CO2 efflux in the permafrost-rich region of northeast Eurasia and suggests that autumn Rh from subsurface soils in the northern high latitudes is not well captured by current DGVMs.

Pleistocene mitogenomes reconstructed from the environmental DNA of permafrost sediments

Traditionally, paleontologists have relied on the morphological features of bones and teeth to reconstruct the evolutionary relationships of extinct animals.1 In recent decades, the analysis of ancient DNA recovered from macrofossils has provided a powerful means to evaluate these hypotheses and develop novel phylogenetic models.2 Although a great deal of life history data can be extracted from bones, their scarcity and associated biases limit their information potential. The paleontological record of Beringia3-the unglaciated areas and former land bridge between northeast Eurasia and northwest North America-is relatively robust thanks to its perennially frozen ground favoring fossil preservation.4,5 However, even here, the macrofossil record is significantly lacking in small-bodied fauna (e.g., rodents and birds), whereas questions related to migration and extirpation, even among well-studied taxa, remain crudely resolved. The growing sophistication of ancient environmental DNA (eDNA) methods have allowed for the identification of species within terrestrial/aquatic ecosystems,6-12 in paleodietary reconstructions,13-19 and facilitated genomic reconstructions from cave contexts.8,20-22 Murchie etal.6,23 used a capture enrichment approach to sequence a diverse range of faunal and floral DNA from permafrost silts deposited during the Pleistocene-Holocene transition.24 Here, we expand on their work with the mitogenomic assembly and phylogenetic placement of Equus caballus (caballine horse), Bison priscus (steppe bison), Mammuthus primigenius (woolly mammoth), and Lagopus lagopus (willow ptarmigan) eDNA from multiple permafrost cores spanning the last 40,000 years. We identify a diverse metagenomic spectra of Pleistocene fauna and identify the eDNA co-occurrence of distinct Eurasian and American mitogenomic lineages.

The State of Migratory Landbirds in the East Asian Flyway: Distributions, Threats, and Conservation Needs

With nearly 400 migratory landbird species, the East Asian Flyway is the most diverse of the world’s flyways. This diversity is a consequence of the varied ecological niches provided by biomes ranging from broadleaf forests to arctic tundra and accentuated by complex biogeographic processes. The distribution and migration ecology of East Asian landbirds is still inadequately known, but a recent explosion in the number of studies tracking the migration of raptors, cuckoos, kingfishers and passerines has greatly increased our knowledge about the stopover and wintering ecology of many species, and the migratory routes that link northeast Eurasia and the Asian tropics. Yet the East Asian Flyway also supports the highest number of threatened species among flyways. Strong declines have been detected in buntings (Emberizidae) and other long-distance migrants. While the conservation of migratory landbirds in this region has largely focused on unsustainable hunting, there are other threats, such as habitat loss and increased agro-chemical use driven directly by land cover change and climate-related processes. Important knowledge gaps to be addressed include (1) threats affecting species in different parts of their annual cycle, (2) range-wide population trends, (3) ecological requirements and habitat use during the non-breeding season, and (4) the conservation status of critical wintering sites (including understudied farming landscapes, such as rice fields) and migration bottlenecks along the flyway.

Mitochondrial genome diversity on the Central Siberian Plateau with particular reference to the prehistory of northernmost Eurasia.

The Central Siberian Plateau was the last geographic area in Eurasia to become habitable by modern humans after the Last Glacial Maximum (LGM). Through a comprehensive dataset of mitochondrial DNA (mtDNA) genomes retained in the remnats of earlier (“Old”) Siberians, primarily the Ket, Tofalar, and Todzhi, we explored genetic links between the Yenisei-Sayan region and Northeast Eurasia (best represented by the Yukaghir) over the last 10,000 years. We generated 218 new complete mtDNA sequences and placed them into compound phylogenies with 7 newly obtained and 70 published ancient mitochondrial genomes. We have considerably extended the mtDNA sequence diversity (at the entire mtDNA genome level) of autochthonous Siberians, which remain poorly sampled, and these new data may have a broad impact on the study of human migration. We compared present-day mtDNA diversity in these groups with complete mitochondrial genomes from ancient samples from the region and placed the samples into combined genealogical trees. The resulting components were used to clarify the origins and expansion history of mtDNA lineages that evolved in the refugia of south-central Siberia and beyond, as well as multiple phases of connection between this region and distant parts of Eurasia.

Classical Eurasians on the civilizational identity of Russia

Philosophical and world outlook understanding of the problem of civilizational identity of Russia acquires special relevance in connection with the preservation of the Eurasian civilizational breakdown that arose at the end of the 20th century. To prepare a new civilization project, it is important to use the theoretical legacy of prominent Russian thinkers, including the classics of Eurasianism. The purpose of the article is an objective analysis of classical Eurasianism, the comprehension of its most important provisions, taking into account the modern realities of Russian society. Using historical and philosophical methodology, critical analysis, methodology of civilizational theories, the author of the article substantiates the conclusion about the scientific significance of the Eurasian concept of civilizational identity of Russia. Its components are examined in a systematic form, such as the perception of Russia-Eurasia as a whole civilizational continent of an equal Europe, the idea of a “symphonic personality” in Eurasian culture, the idea of pan-European nationalism, the idea of establishing social justice, the provision on strengthening the religious element to strengthen the spiritual principle, etc. The article provides a critical analysis of some judgments of historical Eurasians, including their idea of absolutizing the role of the state, the theory of “potential Orthodoxy”, etc. An important conclusion of the article is the provision that Eurasianism is not a teaching hostile to the West, but a different non-Western scientific perception of the historical fate and civilizational development of Russia. Concrete examples substantiate the claim that it is necessary to distinguish fair criticism of classical Eurasianism from its simplified and largely biased assessments. The author of the article concludes that understanding the heritage of the classics of Eurasianism is necessary to develop a social project for the cultural and civilizational revival of the Russian Federation and the entire area of Northeast Eurasia.

Why Does a Colder (Warmer) Winter Tend to Be Followed by a Warmer (Cooler) Summer over Northeast Eurasia?

AbstractThis study reveals a pronounced out-of-phase relationship between surface air temperature (SAT) anomalies over northeast Eurasia in boreal winter and the following summer during 1980–2017. A colder (warmer) winter over northeast Eurasia tends to be followed by a warmer (cooler) summer of next year. The processes for the out-of-phase relation of winter and summer SAT involve the Arctic Oscillation (AO), the air–sea interaction in the North Atlantic Ocean, and a Eurasian anomalous atmospheric circulation pattern induced by the North Atlantic sea surface temperature (SST) anomalies. Winter negative AO/North Atlantic Oscillation (NAO)-like atmospheric circulation anomalies lead to continental cooling over Eurasia via anomalous advection and a tripolar SST anomaly pattern in the North Atlantic. The North Atlantic SST anomaly pattern switches to a dipolar pattern in the following summer via air–sea interaction processes and associated surface heat flux changes. The summer North Atlantic dipolar SST anomaly pattern induces a downstream atmospheric wave train, including large-scale positive geopotential height anomalies over northeast Eurasia, which contributes to positive SAT anomalies there via enhancement of downward surface shortwave radiation and anomalous advection. Barotropic model experiments verify the role of the summer North Atlantic SST anomalies in triggering the atmospheric wave train over Eurasia. Through the above processes, a colder winter is followed by a warmer summer over northeast Eurasia. The above processes apply to the years when warmer winters are followed by cooler summers except for opposite signs of SAT, atmospheric circulation, and SST anomalies.

Cold Waves in East China and Their Response to Two Types of Arctic Amplification

Cold waves occur frequently in East China, with their cold air source in the Arctic. Changes in the Arctic are often linked with Arctic amplification. The circulation anomaly associated with Arctic amplification is often represented by Arctic Oscillation (AO). In recent years, storms have frequently invaded the central Arctic region, resulting in dramatic changes in Arctic environment. In this paper, based on correlation studies, composite analysis, and case studies, the remote effects of the old and storm-induced Arctic amplification are compared, especially with regard to their impact on cold waves in East China. The results show that the AO can shed light on the interannual variation of cold events intermittently, although it cannot explain the increasing trend of cold waves in the southern part of East China. However, this long-term trend correlates well with storm activity. Cyclones are becoming more active in the western Arctic and anticyclones are intensifying in the eastern Arctic. In this scenario, the storm-induced warm advection could enhance the ridge over northeast Eurasia, the Siberian High expands southeastward, and cold air accumulates in northeast Asia, which cools the northern part of East China directly. The circulation around the Siberian High leads to a northeast wind in the southern part of East China, which plays a vital role in snowstorms. This study could improve our understanding of the global effects of Arctic changes and could enhance the prediction skill of cold waves.

New Rhynchonellids and Atrypids (Brachiopoda) from the Lower Devonian Deposits of Northeast Eurasia

The rhynchonellid Dogdoa talyndzhensis Baranov, sp. nov. (subfamily Dogdoinae) and the atrypid Vagrania naanchanensis Baranov, sp. nov. (subfamily Vagraninae) are described from the Lower Devonian deposits of Northeast Eurasia. Trails with preserved thin striae and concentric growth lines were found for the first time in the species Vagrania kolymensis (Nalivkin, 1936). The subfamily Punctspinatrypinae Baranov, subfam. nov. includes two genera: Punctspinatrypa Rzhonsnitskaya, and Mishninia Baranov, gen. nov with the reference species М. nodosa Baranov, sp. nov.

Givetian Stringocephalid brachiopods from eastern Yunnan of Southwest China with notes on global distribution of the family Stringocephalidae

Stringocephalid brachiopods are widely known in the Givetian, but little knowledge is obtained concerning their palaeobiogeographical patterns globally, therefore further studies with new updates and details are required. In this paper, we describe two new stringocephalid brachiopod genera: Yangirostra asiatica n. gen. n. sp. (subfamily Stringocephalinae) and Chinellirostra rara n. gen. n. sp. (subfamily Bornhardtininae), and a new species Stringocephalus sinensis n. sp., together with an indeterminate species Parastringocephalus sp., from the Givetian (late Middle Devonian) of eastern Yunnan, Southwest China. Moreover, with information of the stringocephalides from North Africa, Alaska, North America, Europe and Northeast Eurasia, we compile a dataset of family Stringocephalidae containing 32 genera in 7 subfamilies globally. Based on our data, subfamily Stringocephalinae brachiopods show cosmopolitism and considerably wide distribution from Siberia to the northern Gondwana margins (i.e., North Africa and Australia). Nevertheless, the Boreal Realm and Palaeotethyan Realm are depicted in this paper at the subfamily level, which is much different from the previous palaeobiogeographical schemes in the Givetian. Furthermore, palaeobiogeographical links between Siberia, the Urals and western North America (Alaska, Canada, Nevada and Sonora) are confirmed by diversification of the subfamilies Omoloninae and Rensselandiinae. Whereas in Eurasia (i.e., western and eastern Europe, North and South China), many endemic species of the subfamilies Bornhardtininae and Geranocephalinae are present, as well as the Kaplexinae and Leioseptathyridinae.

Growth, Nutrient Assimilation, and Carbohydrate Metabolism in Korean Pine (Pinus koraiensis) Seedlings in Response to Light Spectra

A need is growing to plant superior Korean pine (Pinus koraiensis Siebold & Zucc.) seedlings to cope with the degradation of secondary forests in Northeast Eurasia. The goal of this study was to detect the physiological effect on the quality of Korean pine seedlings exposed to a range of spectra. One-year-old seedlings (n = 6) were cultured in three light-emitting diode (LED) spectra (69‒77 μmol m−2 s−1) of 13.9% red (R) + 77.0% green (G) + 9.2% blue (B) (R1BG5), 26.2% R + 70.2% G + 3.5% B (R2BG3), and 42.3% R + 57.3% G + 0.4% B (R3BG1). The spectrum of high-pressure sodium (HPS) lamps (43.9% R + 54.7% G + 1.5 B) was taken as the reference. Results showed that LED-lighting resulted in shorter seedlings with a greater diameter, shoot biomass, assessed quality, and sturdiness compared to those under the HPS-lighting. The R3BG1 spectrum reduced the shoot nitrogen (N) deficiency induced by the HPS spectrum, while the R1BG5 treatment induced a steady-state uptake of N and phosphorus (P) in whole-plant organs. The R1BG5 spectrum also resulted in a higher soluble sugar concentration and higher activities of glutamine synthetase and acid phosphatase in needles compared to the control. Seedlings in the R2BG3 spectrum had the highest concentrations of chlorophyll and soluble protein in the leaves. Overall, the R-high LED-spectrum could stimulate biomass accumulation in shoot, but meanwhile resulted in a P deficiency. Hence, the LED lighting in the R1BG5 spectrum is recommended to promote the quality of Korean pine seedlings.

Role of soil moisture-atmosphere feedback during high temperature events in 2002 over Northeast Eurasia

In summer 2002, abnormally high-temperature events and associated low soil moisture conditions were observed in Northeast Eurasia. In this study, two regional climate model experiments, one with and the other without soil moisture–atmosphere interaction, were conducted to investigate the role of soil moisture in surface air temperature and precipitation in Northeast Eurasia utilizing the Weather Research and Forecasting (WRF) model. In the experiment without interaction, satellite-based soil moisture was prescribed. Under the persistent mid-tropospheric ridge pattern with prolonged clear skies, both experiments captured the magnitude of the extreme surface air temperature events. A comparison of the model experiments demonstrated that the mid-tropospheric ridge pattern was intensified by dry soil moisture conditions that further increase the surface air temperature. The temporal variability of surface air temperature for the experiments with and without soil moisture–atmosphere interaction reveals the strong coupling of soil moisture to surface air temperature in June–August, raising the possibility that extreme hot temperature events in Northeast Eurasia were strengthened by the soil moisture anomaly. These results also indicate that the impact of soil moisture–atmosphere coupling on surface air temperature varies spatially and temporally, having higher importance for the predictability of extreme high-temperature events in Northeast Eurasia during mid-summer. This also suggests that the performance of the land surface model in simulating appropriate land–atmosphere coupling intensity is a key to evaluating the impact of climate change on extreme heat events in this region.

Effects of simulated nitrogen deposition on ectomycorrhizae community structure in hybrid larch and its parents grown in volcanic ash soil: The role of phosphorous

With the rapid industrial development and modern agricultural practices, increasing nitrogen (N) deposition can cause nutrient imbalance in immature volcanic ash soil commonly found in Japan. Larch species, widely distributed in northeast Eurasia, are associated with ectomycorrhizal (ECM) fungi which play a critical role in nutrient acquisition for their hosts. In this study, we investigated species richness and diversity of ECM fungi associated with a hybrid larch (F1) and its parents, Dahurian larch (Larix gmelinii var. japonica) and Japanese larch (L. kaempferi), under simulated N deposition (0 and 100kgha−1yr−1) with/without phosphorous (P) (0 and 50kgha−1yr−1). Seedlings planted in immature volcanic ash with low nutrient availability were subjected to the N and P treatments for fifteen months. We found that response of ECM community structure to the increased nutrient availability depended on host genotypes. Nutrient addition significantly affected ECM structure in Japanese larch, but no such significant effect was found for Dahurian larch. Effects of the nutrient addition to ECM fungal community in F1 were intermediate. F1 was tolerant to high N loading, which was due to consistent, relatively high association with Suillus sp. and Hebeloma sp. F1 showed heterosis in relative biomass, which was most apparent under high N treatments. This co-variation of ECM fungal community structure and F1 biomass in response to N loading suggest that ECM community structure might play an important role in host growth. The present findings indicate effects of N deposition on ECM fungal community structure can depend on larch species, thus it is challenging to predict general trends.