Sukachev Institute of Forest

Wildfires are an increasingly important factor in boreal forest biome. The fire cycle have significant effects on the cycling of nutrients within and through an ecosystem. Past research shows that major elements, nutrients, and organic matter in stream water can be altered for decades after a wildfire. Here we examine how stream chemistry might be used to characterize biogeochemical effects of fire across the continuous permafrost taiga of the Central Siberia. By comparing the results of laboratory combustion of organic horizons, soil solution chemistry in burned and unburned watersheds, and stream chemistry in a chronosequence of watersheds with a well-described fire history, we assess possible proxies in stream water chemistry for wildfire severity and timing in this landscape. Our results suggest that the time since last wildfire can be estimated by sulfates (SO 4 2− ) and nitrates (NO 3 − ) concentrations, and that the soil active layer thickness (ALT, the soil depth at which soil thaws annually) increase by wildfires is reflected in bicarbonates (HCO 3 − ) concentrations. Phosphate (PO 4 3− ), although it is released from organic matter by combustion, is unchanged in stream water following fire. Chloride (Cl − ) produces a useful marker for hydrologic conditions at the time of sampling, allowing a relatively small number of stream water samples to be used to characterize past fire regime. Concentrations of SO 4 2− , NO 3 − and HCO 3 − in stream runoff can thus be used as a specific fingerprint of fire history in the northern taiga larch and birch forests of the Central Siberia, since an increase in their concentrations in stream runoff reflects fire occurrence in the catchment area. • Wildfires increase concentrations of major ions in pyrogenic organic layers, topsoil and streams. • Phosphorus is liberated by organic matter combustion, but retained in subsoil. • Wildfires affect stream HCO 3 − , SO 4 2− , Cl − and NO 3 − concentrations at decadal scales. • Stream bicarbonate can serve as a proxy for the active layer depth and wildfire timing • Sulfate in stream water is the most reliable indicator of time since fire disturbance in the catchments.

The Siberian moth, Dendrolimus sibiricus Tschetverikov, is one of the most destructive conifer pests in Northern Asia, causing severe ecological and economic losses. In Russia, its range overlaps with that of the closely related pine-tree lappet Dendrolimus pini (L.), and this raises the potential for hybridization and complicates accurate identification, particularly in the context of the potential westward expansion of D. sibiricus. Here, we present the first comprehensive morphometric analysis of male genitalia aimed at distinguishing these two major forest pests and their hybrids. The study was based on D. sibiricus and D. pini specimens collected during the last 130 years (1894-2024) across Europe and Asia, including their hybrids reared indoors by crossing D. pini females with D. sibiricus males in 1956 and preserved in the collection of the Zoological Institute of the Russian Academy of Sciences (St. Petersburg, Russia). Overall, 70 permanent genitalia slides were prepared (33 D. sibiricus, 33 D. pini, and 4 hybrids), and the following genital structures were measured: valva and harpe length, aedeagus width and length, and cornuti length. Dendrolimus sibiricus had significantly larger genital structures compared to D. pini: 74% longer harpe, 32% longer valva, and a 28% wider and longer aedeagus. In contrast, in D. sibiricus cornuti were 21% shorter than in D. pini. Hybrids displayed intermediate values for valva, harpe, and aedeagus lengths, and for these parameters, they significantly differed from both parental species. The following diagnostic indices were suggested to distinguish between the two species and their hybrids: Harpe Length/Valva Length Index (HL/VL) and Cornuti Length/Aedeagus Length Index (CL/AL). Decision-tree analysis identified HL/VL as the strongest predictor for separating the parental species and the Combined Genital Proportion Index (CGPI), which integrates harpe, valva, aedeagus, and cornuti lengths, as the strongest predictor for identifying hybrids. The morphometric criteria developed here have practical applications for monitoring programs and quarantine diagnostics, particularly in sympatric zones and regions at risk of D. sibiricus expansion.

Abstract The results of aerosol condensation activity obtained at the Siberian ZOTTO background station (60.8° N, 89.35° E) are presented. The measurements were carried out during the growing season from June 18 to July 6, 2021. The condensation activity of aerosol particles was estimated from cloud activation spectra measured depending on the supersaturation of water vapor and the aerosol particles size. Based on these data, the size distributions of activated particles, the critical diameters of cloud activation, and the hygroscopicity parameter of aerosol particles are calculated. The obtained cloud activation parameters are compared with similar data obtained at background stations in the Amazon rainforest and boreal forests of Northern Europe.

Prospects for the forestry of young pine stands, naturally regenerated on abandoned arable land in the subtaiga-forest-steppe zone of Central Siberia have been evaluated. For the period 2007-2021, the inventory characteristics of the young stand formed in 2000 have been established. In 2007-2021, the average diameter increased from 1.8 to 8.0 cm, and the average height increased from 2.3 to 10.3 m. The studies carried out prove the necessity to include such promising young stand, regenerated on abandoned fields, in the forest fund.

A new trophic association between the leaf-rolling weevil Cycnotrachelodes cyanopterus (Motschulsky, 1861) and the North American woody plant Robinia pseudoacacia L. used in landscaping of populated areas of the region has been documented in the Primorsky Territory (south of the Russian Far East) for the first time. In the towns of Artem, Bolshoy Kamen, and Spassk-Dalny, isolated damage by the leaf-rolling weevil (fine leaflets rolled into tubes with larvae feeding inside) was found. The paper gives a brief overview of biology and ecology of the leaf-rolling weevil and illustrates the leaf damage as well as male and female adults reared from two leaf tubes. If the plant lacks resistance to this new consumer, an increase in the population density of C. cyanopterus can be expected in the Primorsky Territory. Further research is needed to monitor the spread of C. cyanopterus and to assess its potential impact on the new host plant.

The results of the study of the Holocene carbon accumulation in four peatlands of different genesis and landscape position in the area of Smidovich Mordovian State Nature Reserve, located on the southern border of the coniferous-broadleaved forests of the East European Plain, are presented. The analysis of the carbon content in the peat deposits showed that in the mineratrophic peat dominated by remains of peat-forming vascular plants, the Corg content is 46.9‒60.9% (the average is 54.6%) and these values are generally higher than the Corg content in transitional woody-Eriophorum-Sphagnum and Eriophorum-Sphagnum peats, 43.6‒50.1% (the average is 47.8%). Low values of Corg (39.2%) are found for grass and woody-grass highly inundated and weakly decomposed peat in a karst bog. The carbon accumulation rate in the peatlands ranges from 5.2 to 84.9 g C/m2 per year, with an average value for the entire Holocene of 22.5 g C/m2 per year. The analysis of the distribution of carbon accumulation rate (CAR) in the peat deposits by depth and age has shown similar patterns of carbon deposition in the four peatlands studied: an increase in CAR during the period of 10 500‒7500 cal. yr BP (calendar years before present) and a decrease in the intensity of carbon accumulation during the period of 7500‒3500 cal. yr BP, which partly coincides with the Holocene Thermal Maximum, when the climate was warmer and drier than at present. The formation of the upper horizons of the peat deposits of the bogs and the carbon accumulation during the late Holocene showed individual specific features in different peatlands, with a general trend of CAR growth.

The influence of the local environmental conditions on invasive small spruce bark beetle Ips amitinus (Eichhoff) (Coleoptera: Curculionidae: Scolytinae) populations and on the vitality of Siberian stone pine (Pinus sibirica Du Tour) trees has been investigated. The field measurements were carried out in the Siberian stone pine forests near settlements (semi-artificial high-productive stands) of Tomsk region damaged by I. amitinus outbreaks. On eleven plots, the population characteristics and reproductive success of the bark beetle, Siberian stone pine vitality, attributes of the stand (e.g, age, height, and diameter), presence of rot and canker diseases, phytosociological characteristics (as a proxy of soil moisture and fertility), and dendrochronological features (as a proxy of weather impact) were measured. By principal component analysis for mixed data and by linear regression with or without mixed effects, we have analyzed the structure of relationships between the measured features. It was found that I. amitinus populations and Siberian stone pine vitality during the bark beetle outbreak were influenced by several parallel processes. The long-term decrease in the resistance of Siberian stone pine stands is provoked by aging and low soil fertility. This decrease leads both to more frequent small spruce bark beetles attacks and to higher attack density (nuptial chambers per dm–2). Another cause of an increase in attack density is high variance of Siberian stone pine height along with short-term stresses triggered by a deficit of precipitation early in the growing season. In such a situation, the number of suitable microstations of I. amitinus, i.e., stressed trees with a well-lit crown, increased. The abundance of the trees attacked by the small spruce bark beetle (m3 ha–1) is positively related to the total volume of Siberian stone pine per hectare. The review of the literature about natural Siberian stone pine forests in the taiga zone allow us to propose a low likelihood of I. amitinus outbreaks under these conditions. Such forests in the taiga have a lot of differences from P. sibirica semi-artificial forests near settlements, and these differences are unfavorable for the small spruce bark beetle. In the native south- and middle-taiga forests, the risk of bark beetle outbreaks is high with the correspondence of several criteria. First, the Siberian stone pine stands must be old-grown with a high variance of age. This is possible only if the stand is undisturbed. Second, the soil must be moderately dry. The possible exception is forests under acute stress, like defoliation or fire. I. amitinus may impact the undisturbed Siberian stone pine stands as a consequence of migration from such stressed forests.

Abstract Hylurgus ligniperda (F.) is a highly successful invader among bark beetles (Scolytinae) and forest insects in general. Native to the western Palearctic region, it has become established in every continent where its host plants ( Pinus spp.) occur. Especially in southern hemisphere regions with large pine plantations, it is often highly abundant. As a repeat invader with a wealth of information on various aspects relevant for biological invasions, it is highly suitable as a model organism for studying the role of international trade, the planting of non-native trees, and the potential occurrence of bridgehead invasions (where abundant non-native populations precipitate further invasions). In the present study, our specific objectives were to reconstruct the worldwide invasions of H. ligniperda and the pathways involved by using a multi-pronged approach including population genetics, analysis of historic interception data generated from inspections of imports, and records of establishments in the literature. Our review of the native and non-native ranges of H. ligniperda and the chronology of establishments revealed at least 13 separate invasions of non-native regions, beginning with Madeira (Portugal) before 1850, and, most recently, eastern China in 2019. We compared the population genetics of 464 specimens from eight countries in the native range and eight countries in the non-native range. Sequencing of the mitochondrial COI gene revealed the presence of 29 haplotypes in six well-supported clades, based on a Bayesian analysis. Non-native populations had significantly lower haplotype diversity (mean h = 0.219) than populations in the native range (mean h = 0.691). Countries in the non-native range had an average of about two haplotypes compared with about four haplotypes in native countries. In the non-native range, only one or two haplotypes were dominant, and these differed among invaded regions except for haplotype HL-H3 which occurred in Australia, New Zealand and China as well as in four countries in southern Europe, and HL-H4 which was dominant in New Zealand, California, New York State, and eastern China as well as two countries in southern Europe. Analyses of interceptions of H. ligniperda with imports arriving in five countries revealed that between 74% and 99% of interceptions originated from other non-native regions while in the USA, most interceptions were linked to imports from the native range beginning in the 1970s. Based on the combined evidence of the chronology of invasions, interception data, and analysis of haplotype distribution, we conclude that the early invasions (before 1950) probably all originated from the native range, while several of the more recent invasions probably originated from parts of the non-native range (suggestive of a bridgehead effect). However, it cannot be determined with certainty what the original sources of each of the invading populations were.