Sub-boreal Forests Research Articles

The relationships between modern pollen rain assemblages and vegetation from Sougna Mountain (Rif Mountains-Northern Morocco)

This study discovers the distribution of vegetation in the Sougna Mountain and its modern pollen representation and investigates the relationships with environment and land use variables. A total of 31 moss polsters were collected between 138 and 1364 m above sea-level from wooded to open areas (e.g. cork oak forest, pine reforestation, and shrubland). At each sampling site land use and environment variables were collected. The vegetation in the Sougna Mountain is scattered in a mosaic along three vegetation belts which are displayed in distinct pollen assemblages dominated by the pollen equivalents of the vegetation types (Quercus suber forest, matorrals of Erica spp. and Cistus spp. and Pinus pinaster reforestation). The variation between the variables and pollen data was performed using CCA analysis. The anthropogenic variables such as grazing, and cultivation, contribute to discrimination of the degraded and grazed areas. High precipitation and altitude have a rather good correlation to wooded communities and consequently a good relation to the tree cover. Our results show that the pollen types of Poaceae, Cannabis, Plantago, Nicotiana, Asteraceae, and Urtica are related mostly to human practice and distinguish the disrupted communities. The presence of those taxa in the pollen diagram must be interpreted carefully. A high taxonomic resolution is recommended to prevent the overestimation of the abundance of some taxa. Our results contribute to the advancement of palynological reconstructions of past vegetation and land use in Sougna Mountain and generally in the Rif landscape.

Fragmentation and Connectivity in dehesa Ecosystems Associated with Cerambyx spp. Dispersion and Control: A Graph-Theory Approach

Xylophagous insects play a crucial role in forest ecosystems, contributing to population dynamics. The “Cerambyx complex” (CC) constitutes an emerging pest in Mediterranean oak woodlands. We studied the fragmentation and connectivity of holm and cork oak stands in Andalusia (Spain), and the relationships with the current dispersion of CC, as well as the effect on the connectivity and dispersion patterns with the implementation of nests of a predator bird (Garrulus glandarius) to reduce insect populations in highly connected areas. The Kernel Density Estimation (KDE) was used to assess the spatial distribution of CC. Connectivity was assessed using graphs theory (Graphab 2.6) to characterize the importance of patches and linkages for contributing to dispersal. We selected the Eurasian jay (G. glandarius) as a reference bird species to generate “barriers” to the dispersion of the CC. We used the probability of connectivity (PC) and the flux (F) to compare the effect of the introduction of Eurasian jay nets. Results showed an increasing trend in the distribution and incidence of CC during the period 2001–2016, resulting in 7.3% and 13.1% mortality rates for Q. ilex and Q. suber, respectively. The connectivity model using only Q. ilex and Q. suber forests as reference habitats was not enough to explain the distribution of CC. The value of PC and F metrics decreased by 38.09% and 20.59% by introducing 300 nests of Eurasian jay. Our methodology provides a pest management tool using connectivity metrics, which can be integrated with other variables to control pest outbreaks and pest dispersion.

CO2 at introduction of fallow into circulation on gray forest soil

The work is devoted to research of CO2 emission dynamics on fallow lands of 5-10 years of age. The purpose was to study the amount of CO2 emission from gray forest soil at different technologies of fallow land introduction into agricultural turnover in the sub-boreal forest of Western Siberia. Technologies of fallow land introduction into turnover have a significant influence on CO2 emission. Spring wheat was cultivated on experimental plots under 2 technologies (methods) of fallow land introduction into turnover. In comparison with fallow land, CO2 emission increased by 1.35 times at agrotechnical technology (with pre-sowing tillage). At combined technology (direct sowing) - 1.18 times. The agrotechnical technology of fallow land restoration contributed to higher CO2 emission (than the combined technology), probably due to higher intensity of soil tillage during fallow land restoration with this technology and increased aeration and microbiological activity in the soil layer. On the basis of the data obtained on carbon dioxide emission from gray forest soils in the sub-boreal forest, models of soil CO2 emission depending on the applied technology of fallow land conversion were developed.

Revising the role of belowground fungi in pentachlorophenol pollution management: insights from Tunisian cork oak forests

This summarizes the doctoral thesis “Belowground fungi are key sentinels in forest soils vulnerable to pentachlorophenol pollution: a mechanistic study in Quercus suber forests”. The PhD degree was awarded by ITQB NOVA in March 2018. It comprises a revision of the major issues, objectives, methodology and results, as well as a few possible recommendations for future work on bioremediation of halogenated aromatic pollutants. The working hypothesis of the thesis proposed that soils in Tunisian cork oak forests are likely contaminated with pentachlorophenol (PCP), a persistent organic pollutant (POP). This hypothesis is based on frequent reports of cork contamination with pentachloroanisole (PCA), which is likely formed through microbial conversion of PCP. Furthermore, PCP was considered a suitable model for investigating the role of soil mycobiota in pollution management due to its ability to travel long distances in the atmosphere, partition favourably into the soil layer, and moderate abiotic resistance, besides its life-threatening toxicity. Finally, fungi play a key role in colonizing soil in cork oak forests. These concepts have been applied in the "Preventive and remediation strategies for continuous elimination of polychlorinated phenols from forest soil" project (SfP-NATO 981674, 2006-2011). Overall the major findings of the study include the demonstration of the prevalence of PCP in the soils of Tunisian cork oak forests. Additionally, the study elucidated both the significance and impact of fungal activity in the mitigation and dispersion of PCP.

Dietary niche overlap in an understudied Mustelidae community in the subboreal forests of western North America: does body size differentiate dietary niche?

Dietary niche overlap in an understudied Mustelidae community in the subboreal forests of western North America: does body size differentiate dietary niche?

Usnea jezoformosana Y. Ohmura & P. Clerc, sp. nov. (Parmeliaceae, lichenized Ascomycota) from East Asia


 
 
 Usnea jezoformosana is described as a new species from East Asia. The morphology of this taxon is very similar to Usnea fragilescens but differs by the presence of granular soredia (instead of farinose soredia). It differs furthermore chemically by the presence of protocetraric acid (major) and barbatic acid (major to trace). The monophyly and independence of the newly described species from U. fragilescens and related taxa were inferred by a molecular phylogenetic tree based on ITS rDNA sequences. Usnea jezoformosana was collected in subboreal forests of Hokkaido (Japan) and in Taiwan where it grew on tree barks, building wood or cliffs.
 
 

Distribution patterns of lianas from subtropical to subboreal zones of the Japanese archipelago and the difference between climbing types

Several factors related to liana abundance have been shown at broad scales, however, the information on factors affecting liana distribution in temperate zones is limited. Climbing types of lianas appear to be associated with interspecific variations of lianas and may be related to the broad-scale distribution and functions of lianas. We aimed to assess the environmental factors related to the abundance of all lianas and those of each climbing type from subtropical to subboreal forests in the Japanese archipelago to better understand the geographical gradient of the liana community.We established six 400 m2 subplots within each of 19 forest plots and recorded the species, stem diameter, and climbing types of lianas with stem diameters ≥ 1 cm. We used generalised linear mixed effects models and model selection based on Akaike's information criterion to examine the effects of climate, soil, and forest structural attributes on liana stem density and basal area.Liana abundance varied substantially among the 19 plots and some forests were characterized by abundant lianas in temperate zones. Twining and root climbers were the major climbing types. Mean annual temperature positively affected the stem density of twining climbers and negatively affected the basal area of root climbers. Maximum snow depth positively affected the stem density of root climbers and negatively affected the basal area of twining climbers. Carbon:nitrogen ratio and dry mass of the soil organic layer had negative effects on the abundance of twining climbers and stem density of both climbers, respectively. Tree basal area positively affected the basal area of root climbers.This study demonstrated the effects of environmental factors, including unique factors such as snow accumulation, on liana distribution at a broad scale from the subtropical to the subboreal zone. Furthermore, the difference between climbing types in distribution may contribute to the gradient of forest ecosystem functions along the environmental factors.

Динамика структуры популяции ели под пологом березняков южной тайги и смешанных лесов в европейской части России

A comparative study of a restoration process is conducted in combinational forests of birch and spruce, as a population under the canopy, in the conditions of coniferousdeciduous or subboreal (Moscow region, Mozhayskiy district), and southern taiga or boreal forests (Yaroslavl region, Rybinskiy district) of European Russia. The relevance of investigations in this field is determined by the controversies over the outcomes from the natural course of successional processes in small-leaved forests with spruce growth under the canopy. The permanent trial plots, which were used for examinations, are characterized by the high-density birch forests of the oxalis-blueberry group with a first-class growth quality at the maturity stage, between 60 and 80 years old. The dynamics of age and vertical layers are investigated for the spruce under the canopy and the parcel structure of stand with ages within the 20-year period. It is determined that the main part of the spruce population under the canopy is represented by the generation, which was established in the birch forests until they reach the age of 30. The age composition of the spruce population, the arrangement of renewal periods, and the process of tree falling at the beginning and the end of the birch forests maturity stage are practically similar. In the zone of subboreal forests the vertical structure of the second layer of the spruce population develops earlier, compared to the boreal forests. In the boreal area, the formation of the under canopy second layer of spruce and its development to the first one begins at the aging stage, which is reached by birch trees around 90 years old. It was concluded that there are no fundamental differences in parcel structure of the stand or its fragmentation. In the mixed birch forests under the age of 60–80 years old the following properties are observed: an increase in the monoparcellarity of phytocenoses, in the areas with a closed second layer of spruce rises the occurrence of parcels, the amount of parcel plots declines, while their areas expand. If the birch forests are older than 90 years, monoparcellarity of the phytocenosis structure destroys, the number of parcels increases due to the appearance of gaps in the canopy, spruce renews in the areas the birche group-fall or after the snowfall and gusts of strong wind. For citation: Deryugin A.A., Rybakova N.A., Glazunov Y.B. Dynamics of the Spruce Population Structure Under the Canopy of Birch in Coniferous-Deciduous and Southern Taiga Forests of European Russia. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 2, pp. 15–25. (In Russ.). https://doi.org/10.37482/0536-1036-2023-2-15-25

Influence of Earlier Snowmelt on the Seedling Growth of Six Subboreal Tree Species in the Spring

Climate warming is advancing snowmelt timing in the spring at high latitudes. To predict tree growth in subboreal forests under warmer climates based on mechanistic understanding, it is important to assess how advancing snowmelt influences tree growth in the spring via ecophysiological changes in subboreal forests. In this study, we conducted a field manipulation experiment of snowmelt timing and investigated the response of tree growth, leaf functional traits, and bud-burst phenology in the spring for the seedlings of six dominant tree species in subboreal forests. We found that the spring growth of only one species (Kalopanax septemlobus) out of six species responded positively to advancing snowmelt. Among the leaf functional traits (leaf mass per area, leaf nitrogen content, leaf δ13C value, leaf dry matter content, and leaf area) and bud-burst phenology, only the increase in leaf area was linked to the enhanced shoot growth of K. septemlobus. The significant change in K. septemlobus might be associated with its ecological characteristics to prefer regeneration in canopy gaps. These results indicate that advancing snowmelt under warmer winters can be beneficial for tree species that can plastically develop leaf area in Japanese subboreal forests.

Fire severity and the legacy of mountain pine beetle outbreak: high-severity fire peaks with mixed live and dead vegetation

Bark beetle outbreaks and wildfires are two of the most prevalent disturbances that influence tree mortality, regeneration, and successional trajectories in western North American forests. Subboreal forests have experienced broad overlaps in these disturbances, and recent wildfires have burned through landscapes with substantial tree mortality from prior outbreaks. This study investigated how fuel conditions associated with mountain pine beetle outbreaks influence the probability of high burn severity (i.e. stand-replacing fire) across a range of fire weather conditions in subboreal forests of central interior British Columbia, Canada. We focused on three large fires that occurred in 2012, 2013, and 2014. We characterized outbreak severity, outbreak-influenced prefire vegetation, and subsequent burn severity using Landsat spectral vegetation indices, high-resolution imagery, and field observations. Substantial portions of the prefire landscape contained mixtures of live and dead vegetation created by variable beetle damage and vegetation response—spatial patterns that are related to, but distinct from, peak outbreak severity. We evaluated drivers—fuels, weather, and topography—of high-severity fire under ‘extreme,’ ‘moderate,’ and ‘benign’ fire weather conditions (i.e. burning conditions) using Boosted Regression Trees. While fire weather was a primary driver in most cases, prefire vegetation was an influential predictor variable across all burning conditions, and the probability of high-severity fire was highest when prefire vegetation was a mixture of tree mortality from bark beetles and live vegetation. Thus, while weather and drought are important drivers of wildfires in subboreal forests, bottom-up drivers of elevation and vegetation, including the fuel legacies of bark beetle outbreaks, are crucial factors influencing high-severity burning. The legacy of recent bark beetle outbreaks will continue for decades on these landscapes, affecting fuel structures, future wildfires, forest dynamics, and the broader social-ecological systems of the region.

Canopy height impacts on the growing season and monthly microclimate in a burned forest of British Columbia, Canada

Forest canopies can buffer seedlings from extreme climate conditions. Yet, how disturbed forest canopies influence microclimate is not well understood, despite the important implications of microclimate for seedling establishment and post-disturbance successional trajectories. Better understanding of the relationship between a forest canopy and sub-canopy temperature and moisture conditions requires easily acquired and continuous forest canopy data, which is increasingly available due to new technology. Here, we measured canopy height using a remotely piloted aircraft (RPA) and monitored microclimate with low-cost temperature and soil moisture sensors in a sub-boreal forest impacted by fires of variable severity. We used regression models to investigate how differences in canopy height influenced microclimate variables. Mean growing season temperatures at -8 cm (soil), 0 cm (surface), and 15 cm (near-surface) relative to the ground surface were higher under shorter more disturbed canopies. Soil temperature was most sensitive to canopy height differences: linear models for the observed data range predicted a 2.0 °C increase in mean growing season soil temperature with every 10 m decrease in canopy height. We observed a weak negative relationship between canopy height and mean growing season soil moisture. We found that canopy height summarized at moderate resolution (15 m) better explained differences in temperature in our disturbed landscape. This work informs future methods to produce gridded microclimate datasets and outlines the impact of disturbed forest structure on microclimate variables. Our results show that the characteristics of the forest canopy remaining after a burn impact microclimates, which has important implications for post-fire ecosystems.

Contrasting climate signals across a Scots pine (Pinus sylvestris L.) tree-ring network in the Middle Volga (European Russia)

Since the late-19th century, the Middle Volga has played a major role in the supplying grains and other agricultural products to European Russia. The study area is located in the south of sub-boreal forest in the north and in the forest-steppe in the south. Due to large seasonal differences in rainfall, agriculture in the region, especially in its southern part, strongly depends on hydroclimate variability. According to climate model forecasts, the frequency and intensity of droughts in the Middle Volga are expected to increase due to ongoing warming. Here we introduce 16 new Scots pine tree ring width (TRW) chronologies (Pinus sylvestris L.) from the region and use a dendroclimatological approach to determine what climatic factors drive radial growth. Our analysis revealed contrasting climate signals across the network of sites with chronologies from the north showing weak correlation with May temperature and precipitation (r = −0.27 and r = 0.28, respectively), while the southern sites demonstrated stronger relationships with climate in the first half of the vegetation season (May to July temperature, r = −0.26 to −0.43; May and July precipitation, r = 0.29–0.35). The northern sites did not demonstrate a strong growth response to the self-calibrated Palmer drought severity index (scPDSI) whereas the southern group was more drought sensitive had a strong drought response and positively correlates with scPDSI for the period from previous July to the current October (r = 0.27–0.56). Based on this strong relationship between southern TRW and scPDSI we reconstruct June-September scPDSI using the most sensitive sites (T04S, T06S, T08S) for the period from 1830 to 2014. The model explains 31% of variance. Our reconstruction shows droughts in 19th century: in 1831–33, 1851, 1853, 1859, 1863–65, 1880, 1891–92, 1897–98 and in 20–21th centuries: in 1906, 1921, 1936, 1939, 1967, 1975, 1996, 2010.

Evaluating the rhizospheric and endophytic bacterial microbiome of pioneering pines in an aggregate mining ecosystem post-disturbance

AimsDespite little soil development and organic matter accumulation, lodgepole pine (Pinus contorta var. latifolia) consistently shows vigorous growth on bare gravel substrate of aggregate mining pits in parts of Canadian sub-boreal forests. This study aimed to investigate the bacterial microbiome of lodgepole pine trees growing at an unreclaimed gravel pit in central British Columbia and suggest their potential role in tree growth and survival following mining activity.MethodsWe characterized the diversity, taxonomic composition, and relative abundance of bacterial communities in rhizosphere and endosphere niches of pine trees regenerating at the gravel pit along with comparing them with a nearby undisturbed forested site using 16S rRNA high-throughput sequencing. Additionally, the soil and plant nutrient contents at both sites were also analyzed.ResultsAlthough soil N-content at the gravel pit was drastically lower than the forest site, pine tissue N-levels at both sites were identical. Beta-diversity was affected by site and niche-type, signifying that the diversity of bacterial communities harboured by pine trees was different between both sites and among various plant-niches. Bacterial alpha-diversity was comparable at both sites but differed significantly between belowground and aboveground plant-niches. In terms of composition, pine trees predominantly associated with taxa that appear plant-beneficial including phylotypes of Rhizobiaceae, Acetobacteraceae, and Beijerinckiaceae at the gravel pit and Xanthobacteraceae, Acetobacteraceae, Beijerinckiaceae and Acidobacteriaceae at the forest site.ConclusionsOur results suggest that, following mining activity, regenerating pine trees recruit bacterial communities that could be plant-beneficial and support pine growth in an otherwise severely N-limited disturbed environment.

Frequent new particle formation at remote sites in the subboreal forest of North America

Abstract. The frequency and intensity of new particle formation (NPF) over remote forest regions in the temperate and boreal zones, and thus the importance of NPF for the aerosol budget and life cycle in the pristine atmosphere, remains controversial. Whereas NPF has been shown to occur relatively frequently at several sites in Scandinavia, it was found to be nearly absent at a mid-continental site in Siberia. To explore this issue further, we made measurements of aerosol size distributions between 10 and 420 nm diameter at two remote sites in the transition region between temperate and boreal forest in British Columbia, Canada. The measurements covered 23 d during the month of June 2019, at the time when NPF typically reaches its seasonal maximum in remote midlatitude regions. These are the first such measurements in a near-pristine region on the North American continent. Although the sites were only 150 km apart, there were clear differences in NPF frequency and intensity between them. At the Eagle Lake site, NPF occurred daily, and nucleation-mode particle concentrations reached above 5000 cm−3. In contrast, at the Nazko River site, there were only six NPF events in 11 d, and the nucleation-mode particle concentrations only reached about 800 cm−3. The reasons for this difference could not be conclusively resolved with the available data; they may include air mass origins, preexisting aerosols, and the density and type of forest cover in the surrounding regions. In contrast to observations in other temperate and boreal environments, we found that NPF at our sites occurred at nighttime just as frequently as during daytime. Together with the lack of identifiable sources of sulfuric acid precursor species in the fetch region of our sites, this suggests that nucleation of extremely low volatility organics was the predominant NPF mechanism. Our results indicate that extended measurement campaigns with a more comprehensive set of instrumentation to investigate the role of NPF in the remote forest regions of North America are essential for a deeper scientific understanding of this important process and its role in the global aerosol budget.

Pacific ocean mega ecotone of Northern Eruasia as the belt of the origin of the modern continental biosphere

The Pacific Ocean margin of Eurasia includes the age row (at the geologic time scale) of geoecotone objects which can be imagined by certain nodal stages of the evolutionary trajectory of exogenous landscape genesis in the continental biosphere. The reported strategy of scientific research is aimed at the establishment of zonal-regional and local regularities of landscape organization of insular and marginal-continental land in different morphotectonic and macroclimatic sectors of the Pacific Ocean mega-ecotone of Northern Eurasia, which is considered as a natural laboratory for studying the modern stage of development of the geographical envelope The empirical statistical models of the island-arc stage of continental biosphere development in the North-West Pacific have been created by the example of experimental test ground of the active Mendeleev volcano on the Kunashir Island (the South Kuril Ridge). It was shown that on this initial stage local geomorphological and hydro-edaphic conditions created the centers of origin of diverse phytocoenological structures. An exceptionally high percentage of green mass in the structure of production results in the acceleration of the biological cycle as a factor of stability of forest community under unfavorable conditions of “cold” oceanicity. Geothermal energy induces rearrangement of the plant cover towards the increase in its flora- and phytocoenotic diversity to the detriment of biomass formation rate. The “climatically unjustified” but sufficiently stable sub-boreal forest ecosystems were formed, as well as the early stages of buffer forest communities. The multidimensional empirical-statistical modeling of landscape connections in the marginal-continental sector of the Pacific Ocean mega ecotone has been performed based on an experimental site in the Lower By-Amur Region. The ecology of the boreal-forest landscape of the continental margin characterizes the mature stage of evolution of the continental biosphere. The regularities and causal mechanisms of the formation of buffer forest communities typical of ecotone systems have been represented more integrally. Forests of this phenomenal buffer flora are distinguished by extremely high parameters of structural and functional development and have reached the state approaching the evolutionary climax. The previously advanced concepts of the Pacific ecotone of Northern Eurasia as a focus of evolutionary processes in the continental biosphere have been confirmed.

Landscape-scale population connectivity in two parasitoid species associated with the spruce budworm: Testing the birdfeeder effect using genetic data.

Periodic and spatially synchronous outbreaks of insect pests have dramatic consequences for boreal and sub-boreal forests. Within these multitrophic systems, parasitoids can be stabilizing agents by dispersing toward patches containing higher host density (the so-called birdfeeder effect). However, we know little about the dispersal abilities of parasitoids in continuous forested landscapes, limiting our understanding of the spatiotemporal dynamics of host-parasitoid systems, and constraining our ability to predict forest resilience in the context of global changes. In this study, we investigate the spatial genetic structure and spatial variation in genetic diversity of two important species of spruce budworm larval parasitoids during outbreaks: Apanteles fumiferanae Viereck (Braconidae) and Glypta fumiferanae (Viereck) (Ichneumonidae). Using parasitoids sampled in 2014 from 26 and 29locations across a study area of 350,000km2 , we identified 1,012 and 992 neutral SNP loci for A. fumiferanae (N=279 individuals) and G.fumiferanae (N=382), respectively. Using DAPC, PCA, AMOVA, and IBD analyses, we found evidence for panmixia and high genetic connectivity for both species, matching the previously described genetic structure of the spruce budworm within the same context, suggesting similar effective dispersal during outbreaks and high parasitoid population densities between outbreaks. We also found a significant negative relationship between genetic diversity and latitude for A. fumiferanae but not for G. fumiferanae, suggesting that northern range limits may vary by species within the spruce budworm parasitoid community. These spatial dynamics should be considered when predicting future insect outbreak severities in boreal landscapes.

Trade-Offs among Release Treatments in Jack Pine Plantations: Twenty-Five Year Responses

We assessed 27 indicators of plant diversity, stand yield and individual crop tree responses 25 years post-treatment to determine long-term trade-offs among conifer release treatments in boreal and sub-boreal forests. This research addresses the lack of longer-term data needed by forest managers to implement more integrated vegetation management programs, supporting more informed decisions about release treatment choice. Four treatments (untreated control, motor-manual brushsaw, single aerial spray, and complete competition removal) were established at two jack pine (Pinus banksiana Lamb.) sites in Ontario, Canada. Our results suggest that plant diversity and productivity in boreal jack pine forests are significantly influenced by vegetation management treatments. Overall, release treatments did not cause a loss of diversity but benefitted stand-scale yield and individual crop tree growth, with maximum benefits occurring in more intensive release treatments. However, none of the treatments maximized all 27 indicators studied; thus, forest managers are faced with trade-offs when choosing treatments. Research on longer term effects, ideally through at least one rotation, is essential to fully understand outcomes of different vegetation management on forest diversity, stand yield, and individual crop tree responses.

Specialized mycorrhizal association between a partially mycoheterotrophic orchid Oreorchis indica and a Tomentella taxon.

The evolution of full mycoheterotrophy in orchids likely occurs through intermediate stages (i.e., partial mycoheterotrophy or mixotrophy), in which adult plants obtain nutrition through both autotrophy and mycoheterotrophy. However, because of its cryptic manifestation, partial mycoheterotrophy has only been confirmed in slightly more than 20 orchid species. Here, we hypothesized that Oreorchis indica is partially mycoheterotrophic, since (i) Oreorchis is closely related to leafless Corallorhiza, and (ii) it possesses clustered, multi-branched rhizomes that are often found in fully mycoheterotrophic orchids. Accordingly, we investigated the nutritional modes of O. indica in a Japanese subboreal forest by measuring the 13C and 15N abundances and by community profiling of its mycorrhizal fungi. We found that O. indica mycorrhizal samples (all 12 samples from four individuals) were predominantly colonized by a single OTU of the obligate ectomycorrhizal Tomentella (Thelephoraceae). In addition, the leaves of O. indica were highly enriched in both 13C and 15N compared with those of co-occurring autotrophic plants. It was estimated that O. indica obtained 44.4±6.2% of its carbon from fungal sources. These results strongly suggest that in the Oreorchis-Corallorhiza clade, full mycoheterotrophy evolved after the establishment of partial mycoheterotrophy, rather than through direct shifts from autotrophy.

Change in Tree Spatial Pattern After Severe Wind Disturbance in Four North American Northern Hardwood and Sub-Boreal Forests

Growing appreciation for the importance of forest structural features to forest functioning has led to increased focus on tree spatial patterns. While the influence of disturbances on composition and diversity has been well-studied, understanding of how disturbances influence spatial pattern is still far from complete. In particular, very few studies have examined the change in spatial pattern as a result of wind disturbance. Here results are presented for change in spatial pattern after severe wind disturbance in four eastern North American forests. It is hypothesized that, as in other types of disturbances, severe wind will cause an increase in aggregation among survivors, and aggregated distribution of mortality. These trends were indeed observed; at very small distances (e.g. 5-10 m), all four sites showed significantly greater aggregation after wind disturbance. Mortality was also significantly aggregated at three of the four sites, but at different distances. Unexpectedly, at slightly larger distances (e.g. 30-50m), all four sites showed significant decreases in aggregation; it is suggested that this second trend may generalize across disturbance types. A hypothesis proposed by Davis et al. (2005) is that intermediate disturbance severity produces the greatest aggregation; this hypothesis is tested in the four sites reported here, and the hypothesis is rejected. Two refinements to this hypothesis are proposed for further testing in future research.

СУББОРЕАЛЬНЫЕ ЭЛЕМЕНТЫ В ЛЕПИДОПТЕРОФАУНЕ (LEPIDOPTERA) ЕВРОПЕЙСКОГО СЕВЕР О-ВОСТОКА РОССИИ

Based on the material of Macrolepidoptera, high percentage of in the taiga and tundra biota of subboreal geographical elements – one of the main biogeographic features of the European North-East of Russia – is considered. It is shown that over 50 species of Lepidoptera from 11 families have peripheral area covers in various extent taiga zone and the southern parts of Hypoarctic zone, and the area of their ecological optimum situated in the subboreal forest and steppe zones. In consideration of peculiarities of the natural process, the analysis of the landscape-zonal distribution of Lepidoptera species suggests that the penetration of subboreal species was began and gradually took place during the warm periods of Holocene. A few groups of Holocene climatic relicts have been preserved in various areas of the taiga and the foresttundra zones. At the present time the most of subboreal species of Lepidoptera in the European North- East of Russia are new and actively distributing in anthropogenic habitats.