Soil microarthropods and macrofauna in monsoon tropical forests of Cat Tien and Bi Dup-Nui Ba National Parks,southern Vietnam

The abundance, biomass, vertical distribution, and taxonomic composition of soil invertebrates (springtails, macrofauna, and termites) were studied in forest formations differing in edaphic and climatic conditions: lowland forests dominated by Lagerstroemia spp. or Dipterocarpus spp. in the Cat Tien National Park and in a mountain pine (Pinus kesiya) forest on the Da Lat Plateau, southern Vietnam. In the lowland forests, springtails had a relatively low density (10000–12000 ind./m²), but their diversity was high (41–43 species in each forest). The density of large soil invertebrates (without ants and termites) reached 500–700 ind./m² at a biomass of approximately 30 g/m² (with earthworms accounting for up to 230 ind./m² and 19–28 g/m²). Among termites, species of the genera Macrotermes and Odontotermes were dominant. Their total biomass in some areas exceeded 15–20 g/m². In the mountain pine forest, the total biomass of soil macrofauna was approximately 11 g/m², the abundance and diversity of springtails were low (7500 ind./m², 28 species), and wood-destroying species of the genera Schedorhinotermes sp. and Coptotermes sp. dominated among termites.     

Pine wilt disease and possible causes of its incidence in Russia

Surveys of forests and stockpiled timber of pine, spruce, larch, and silver fir in 14 administrative subjects of the Russian Federation revealed widespread occurrence of the coniferous wood parasitic nematode Bursaphelenchus mucronatus. Twenty species of bacteria belonging to 13 genera have been detected in 25 B. mucronatus isolates, and their identity has been determined by direct sequencing of the 16S RNA gene. The most frequently occurring were bacteria from the genera Pseudomonas, Stenotrophomonas, Pantoea, Bacillus, Burkholderia, and Serratia. Prevalence of Pseudomonas brenneri and P. fluorescence, which were also found in the nematode dauer larva (L_IV) isolated from the fir sawyer beetle Monochamus urussovi, have also been assessed. Two nematode B. xylophilus isolates from Portugal and one isolate from the United States have been examined, and 10 symbiotic bacteria species have been isolated, including Agrobacterium tumefacience, P. fluorescens, P. brenneri, Rahnella aquatilis, Stenotrophomonas maltophilia, S. rhizophila, and Yersinia mollaretii.     

Karyological and cytogenetic studies of conifers from West Siberia and Far East

The results summarize many years of karyological and cytogenetic studies of conifers from the boreal zone, done at the Sukachev Forest Institute. The species under study belong to four genera of the family Pinaceae: Larix (larch), Pinus (pine), Picea (spruce), and Abies (fir). Overall, the research covers more than 100 populations and habitats of the species from these genera. The study concerns species growing under both optimal and marginal conditions. The studies of the family Cupressaceae have been initiated. A special attention is given to conifers growing on bogs and in planted forests.     

Tracking an invasion: community changes in hardwood forests following the arrival of <Emphasis Type="Italic">Amynthas agrestis</Emphasis> and <Emphasis Type="Italic">Amynthas tokioensis</Emphasis> in Wisconsin

Because Upper Midwest temperate forests lack native earthworms, the invasions of European and Asian earthworms can significantly alter soils and understory vegetation. Earthworms’ ability to increase leaf litter decay, alter nutrient cycling by mixing the organic layer with mineral soil, and decrease plant species richness leads to concern about the Asian ‘jumping earthworm’ (Amynthas agrestis and A. tokioensis) species that were recorded in the University of Wisconsin—Madison Arboretum in 2013. In 2015, we found A. agrestis and A. tokioensis in a distinct 8-ha region of a 23-ha hardwood forest surveyed in the Arboretum; by 2016 A. agrestis and A. tokioensis had spread over an additional 7 ha. Plots also contained the European earthworm species Lumbricus terrestris, L. rubellus, and Apporectodea spp., whose distributions decreased from 2015 to 2016. While leaf litter, plant species richness, and tree and shrub seedling abundance were generally reduced in areas with European earthworms, they were typically slightly increased in areas with A. agrestis and A. tokioensis versus those without. Although our results do not show substantial impacts of A. agrestis and A. tokioensis on vegetation in the initial years of invasion, the rapid replacement of European earthworms by A. agrestis and A. tokioensis suggests continued monitoring of these new invasive species is important to better understand their potential to change the Upper Midwest’s forests.     

Earthworm Communities in the Bamboo Plantations of West Tripura (India)

Present study revealed the presence of 16 earthworm species belonging to 11 genera and four families viz. Megascolecidae (Amynthus alexandri, Metaphire houlleti, Lampito mauritii, Kanchuria sp1, Perionyx excavatus), Octochaetidae (Eutyphoeus gigas, Eutyphoeus comillahnus, Eutyphoeus orientalis, Octochaetona beatrix, Dichogaster bolaui, Lennogaster chittagongensis, Lennogaster yeicus), Moniligastridae (Drawida papillifer papillifer, Drawida assamensis, Drawida nepalensis) and Glossoscolecidae (Pontoscolex corethrurus) in the soils of five bamboo species [Bambusa balcooa (Sil Barak), Melocanna baccifera (Muli), Bambusa polumorpha (Bari), Bambus cacharensis (Bom) and Bambus bambus (Katabarak)] of West-Tripura. While four earthworm species viz. Metaphire houlleti, Drawida assamensis, Drawida papillifer papillifer and Pontoscolex corethrurus were common to all species of bamboo plantations, the rest showed restricted distribution. Among the earthworm species 4 were exotic (Amynthus alexandri, Metaphire houlleti, Dichogaster bolaui and Pontoscolex corethrurus) and the others were native to the Indian sub-continent. In general, earthworms under the bamboo plantations occurred within temperature range of 21.6 °C–28.0 °C, pH 4.0–7.0, organic matter 0.56–5.99 %, moisture 9.6–31.7 %, water holding capacity 14.6–43.9 % and bulk density 0.7–1.8 g cm^?3. The average density and biomass of the earthworms in the studied places were 108 ind m^?2 and 44 g m^?2 respectively. Earthworm diversity, dominance and evenness indices showed the values 1.00, 0.47 and 0.70 respectively. Earthworm density and biomass showed a negative correlation with temperature whereas those had a strong positive correlation with pH, moisture and organic matter of the soils.     

Morphophysiologic traits of spruce trees in conditions of Izhevsk

Data on the condition of Picea genus (spruce) representatives in an urban environment have been analyzed. The viability under different environmental conditions and stand types is evaluated. The relative viability of forest stands is evaluated. Morphogenic traits of conifers are examined for the annual increment development. The photosynthetic pigments dynamics is tracked for two coniferous plants across various forest types, including park forests, roadside hedgerows, and plantings in the residential area. The specific responses of pigment system to the urban environment have been revealed for the two coniferous plant species. We have found an increased concentration of carotinoids and higher resilience of blue spruce (Picea pungens Engelm.) in an urban environment.     

Inter-species interactions and ecosystem effects of non-indigenous invasive and native tree-killing bark beetles

Frequent bark beetle outbreaks cause biome-scale impacts in boreal and temperate forests worldwide. Despite frequent interceptions at ports of entry, the most aggressive bark beetle species of Ips and Dendroctonus in North America and Eurasia have failed to establish outside their original home continents. Our experiments showed that Ips typographus can breed in six North American spruce species: Engelmann spruce, white spruce¸ Sitka spruce, Lutz spruce, black spruce and red spruce. This suggests that differences between the Eurasian historical host and North American spruce species are not an insurmountable barrier to establishment of this tree-killing species in North America. However, slightly diminished quality of offspring beetles emerged from the North American spruces could reduce the chance of establishment through an Allee effect. The probabilistic nature of invasion dynamics suggests that successful establishments can occur when the import practice allows frequent arrivals of non-indigenous bark beetles (increased propagule load). Model simulations of hypothetical interactions of Dendroctonus rufipennis and I. typographus indicated that inter-species facilitations could result in more frequent and severe outbreaks than those caused by I. typographus alone. The potential effects of such new dynamics on coniferous ecosystems may be dramatic and extensive, including major shifts in forest structure and species composition, increased carbon emissions and stream flow, direct and indirect impacts on wildlife and invertebrate communities, and loss of biodiversity.     

Spatial and temporal variation in moss-associated dinitrogen fixation in coniferous- and deciduous-dominated Alaskan boreal forests

Dominant canopy tree species have strong effects on the composition and function of understory species, particularly bryophytes. In boreal forests, bryophytes and their associated microbes are a primary source of ecosystem nitrogen (N) inputs, and an important process regulating ecosystem productivity. We investigated how feather moss-associated N₂-fixation rates and contribution to N budgets vary in time and space among coniferous and broadleaf deciduous forests. We measured N₂-fixation rates using stable isotope (¹⁵N₂) labeling in two moss species (Pleurozium schreberi and Hylocomium splendens) in broadleaf deciduous (Alaska paper birch—Betula neoalaskana) and coniferous (black spruce—Picea mariana) stands near Fairbanks, interior Alaska, from 2013 to 2015. N₂-fixation rates showed substantial inter-annual variation among the 3 years. High N₂-fixation was more strongly associated with high precipitation than air temperature or light availability. Overall, contribution of N₂-fixation to N budgets was greater in spruce than in birch stands. Our results enhance the knowledge of the processes that drive N₂-fixation in boreal forests, which is important for predicting ecosystem consequences of changing forest composition.     

Seasonal variability in habitat structure may have shaped acoustic signals and repertoires in the black-capped and boreal chickadees

Many songbird species have evolved multiple vocalizations, or repertoires, that function to communicate various biological signals. More diverse repertoires may have evolved in response to the effects of seasonal variation in habitat structure on signal transmission. Such changes in habitat necessarily occur for migrating species, but they also occur for resident species that occupy deciduous forests. The black-capped chickadee (Poecile atricapillus) possesses a chick-a-dee call and a fee-bee song, but the closely related boreal chickadee (P. borealis) lacks a song. Consistent with the habitat variability hypothesis, the black-capped chickadee possesses a larger repertoire and primarily occupies deciduous forests, whereas the songless boreal chickadee occurs more often in coniferous forests. We explored the ecological basis of this hypothesis by recording audio playbacks of two species in two habitat types during two seasons. Specifically, we played both songs and calls of the black-capped chickadee and calls of the boreal chickadee in deciduous and coniferous habitats, prior to and after leaf-out. We measured attenuation and degradation in re-recorded vocalizations. For black-capped chickadees, the song was less degraded than the call in post-leaf, deciduous forests. The boreal chickadee call attenuated more quickly in all treatments, but maintained its acoustic structure better than both black-capped chickadee vocalizations in coniferous forests. Our results support the hypothesis that variable habitats provided a seasonal transmission benefit for both song and call in the black-capped chickadee, but that the transmission benefit of song is lost in the less variant coniferous forests, which may underlie the absence of a song in the boreal chickadee.     

Changes in the structural parameters of the summer zooplankton in the pelagic zone of Lake Sevan (Armenia) during an increase in fish abundance and biomass

Features of the composition and structure of the summer zooplankton in the pelagic zone of Lake Sevan in years that were characterized by different abundances and biomasses of fish are described. It is shown that the species diversity of the community and the specific number of species of zooplankteurs, the quantity of Copepods in the total abundance and biomass of zooplankton, as well as the value of the Shannon index and the trophic coefficient, increased upon an increase in the fish abundance. At the same time, the total biomass of zooplankton and biomass of cladocerans decreased, among which the density and biomass of the larger and more colored Daphnia (Ctenodaphnia) magna Straus decreased, but the density and biomass of D. (Daphnia) hyalina Leydig and Diaphаnosoma brachyurum Lievin increased.     

Extrinsic environmental factors,not resident diversity itself,lead to invasion of <Emphasis Type="Italic">Ageratum conyzoides</Emphasis> L. in diverse communities

The relationship between diversity and invasibility might be confounded by extrinsic environmental factors and the evolutionary structure of the resident community. To examine the role of extrinsic environmental factors, species and phylogenetic diversity in regulating community susceptibility to invasion, we established 109 plots either with or without Ageratum conyzoides L. in Liandu, China. We identified all the species in our samples, weighed the aboveground biomass of each species, and measured environmental variables. For all species recorded in our survey, we constructed a community phylogeny using PhytoPhylo mega-phylogeny as a backbone. We selected the best-fit environment model based on the minimum corrected Akaike information criteria score to examine the effect of extrinsic environmental variables on the relative abundance of A. conyzoides. Relationship between biodiversity and invasion of A. conyzoides was examined by a multiple regression, in which extrinsic ecological factors and biodiversity were combined to predict the relative abundance of A. conyzoides. To reduce the number of extrinsic variables, the first six components produced by a principal component analysis of environmental variables were used as predictive variables in the multiple regression. The best-fit environment model indicated that the relative abundance of A. conyzoides was higher in summer and in communities with lower total organic matter and higher total nitrogen in the soil. The multiple regression indicated that only the positive relationship between the Shannon–Wiener diversity of exotics and the relative abundance of A. conyzoides was significant. This result challenges the importance of diversity–resistance to plant invasion. Generalist facilitation might exist between A. conyzoides and other exotic species, although mechanisms for such facilitation are unclear. Overall, our finding suggests the extrinsic factors covarying with diversity are more important than diversity itself in regulating community susceptibility to invasion.     

Seasonal and altitude effects on the structure of arthropod communities associated with <Emphasis Type="Italic">Tillandsia violacea</Emphasis> Baker (Bromeliaceae) in a temperate forest of Mexico

The canopy of forests has been considered “the last biotic frontier,” and study of its elements is very important in explaining the global functionality in ecosystems. Epiphytic plants and arthropods are essential elements in canopy habitats, and their relationships have been studied in order to understand the high diversity in tropical forests. Nevertheless, there are few studies on this development in temperate forests. The arthropod community was studied during the rainy and dry seasons at two altitudes, and a total of 240 T. violacea plants of three sizes were collected from Abies religiosa and Quercus spp. host trees. A total of 163,043 arthropods were collected and about 200 morphospecies identified. The highest abundance was obtained during the dry season, while high diversity was found during the rainy season. There was a significant effect of plant size, host trees and collecting season on abundance and diversity, and there were seasonal variations in community composition. The community hosted on A. religiosa epiphytes showed higher abundance and density than that of Quercus.     

Yeast population of the Kindo Peninsula lichens

Yeast abundance and species diversity in the lichens collected at the Kindo Peninsula (Karelia) were studied. A total of 14 lichen species analyzed belonged to the genera Bryoria, Cladonia, Hypogymnia, Icmadophila, Nephroma, Peltigera, and Ramalina. Abundance of cultured yeasts in lichens was intermediate between soil and phyllosphere. The average yeast number on lichens was ~2.5 × 10³ CFU/g, while it exceeded 8 × 10³ CFU/g on plants and reached only 1 × 10³ CFU/g in soil. Yeast population of different parts of Cladonia lichens was found to vary significantly in abundance, species diversity, and community structure. The highest yeast abundance and diversity were revealed in the growth zone. Fifteen yeast species were isolated from lichens, including 6 basidiomycetous and 9 ascomycetous ones. Unlike soils and plants, yeast population of lichens consisted mainly of ascomycetous species, with predominance of Candida sphagnicola and anamorphous yeasts of the genus Dothiora. These results show that yeasts from different taxonomic and ecological groups are a necessary component of lichens; conditions favoring the preservation and development of specific yeast communities differing from the typical soil and phyllosphere yeast complexes are formed in the lichens of northern taiga forests.     

Effect of the vital activity products of beaver (<Emphasis Type="Italic">Castor fiber</Emphasis> L.) on the formation of zooplankton structure: Changes in the quantitative parameters of two cladocera species of different sizes in a beaver pound (in situ experiment)

The experiments were performed in microcosms situated on a control site and on a site regulated by beavers. Two cladoceran species of different sizes were placed in microcosms in different proportions. It was found that the vital activity products of Castor fiber L. promote an increase in the concentration of total phosphorus (P), a decrease in the N/P ratio in water, and an increase in the chlorophyll a concentration and the abundance and biomass of bacterioplankton. In such conditions, the abundance and biomass of the large species Daphnia (Ctenodaphnia) magna Straus was increased to the greatest extent when compared with background values when it was placed in combination with Ceriodaphnia dubia Richard or without it. Moreover, in the case of the combination of two crustacean species in microcosms, the abundance of C. dubia was lower when compared with the control site, while the abundance of D. magna was higher. The results of a bioassay showed that the productivity of C. dubia decreases in waters where D. magna is most abundant. We concluded that the formation of zooplankton in beaver ponds with specific features determined by the presence of large cladoceran species is provided by changes in the quantitative and qualitative parameters of food resources. This contributes to the massive distribution of large D. magna and its competitive relations with small C. dubia. According to the results of a bioassay, the vital activity products of D. magna can inhibit the fecundity of C. dubia.     

Macrocharcoal-Based Chronosequences Reveal Shifting Dominance of Conifer Boreal Forests Under Changing Fire Regime

Balsam fir (Abies balsamea) and black spruce (Picea mariana) forests are the main conifer forest types in the North American boreal zone. The coexistence of the two species as well as their respective canopy dominance in distinct stands raises questions about the long-term evolution from one forest type to the other in relation to environmental factors including climate and stand disturbance. We tested the hypothesis that repetitive fire events promote the succession of balsam fir forest to black spruce forest and vice versa. Postfire chronosequences of one black spruce (BSP) and one balsam fir (BFI) sites were reconstructed based on the botanical composition and ¹⁴C-dated soil macrocharcoals. The results support the hypothesis of a successional dynamics. The BSP site has been affected by fires for the last 7600 years, whereas the BFI site, after having been impacted by several fires during the first half of the Holocene, evolved in a fire-free environment for the last 4400 years. Periods of fire activity facilitated the dominance of black spruce forests. The cessation of fires around 4400 cal. years BP on BFI site marks the beginning of the transition from black spruce to balsam fir stands. This succession is a long process, due to the ability of black spruce to regenerate by layering in the absence of fire. The resulting balsam fir stands are ancient and precarious ecosystems, since fire generally leads to the return of black spruce. The increase in balsam fir to the detriment of black spruce in boreal forests is a response to a decrease in fire frequency.     

Human-mediated introduction of geoengineering earthworms in the Fennoscandian arctic

It is now well established that European earthworms are re-shaping formerly glaciated forests in North America with dramatic ecological consequences. However, few have considered the potential invasiveness of this species assemblage in the European arctic. Here we argue that some earthworm species (Lumbricus rubellus, Lumbricus terrestris and Aporrectodea sp.) with great geomorphological impact (geoengineering species) are non-native and invasive in the Fennoscandian arctic birch forests, where they have been introduced by agrarian settlers and most recently through recreational fishing and gardening. Our exploratory surveys indicate no obvious historical dispersal mechanism that can explain early arrival of these earthworms into the Fennoscandian arctic: that is, these species do not appear to establish naturally along coastlines mimicking conditions following deglaciation in Fennoscandia, nor were they spread by early native (Sami) cultures. The importance of anthropogenic sources and the invasive characteristics of L. rubellus and Aporrectodea sp. in the arctic is evident from their radiation outwards from abandoned farms and modern cabin lawns into adjacent arctic birch forests. They appear to outcompete previously established litter-dwelling earthworm species (i.e. Dendrobaena octaedra) that likely colonized the Fennoscandian landscape rapidly following deglaciation via hydrochory and/or dispersal by early Sami settlements. The high geoengineering earthworm biomasses, their recognized ecological impact in other formerly glaciated environments, and their persistence once established leads us to suggest that geoengineering earthworms may pose a potent threat to some of the most remote and protected arctic environments in northern Europe.     

The Seasonal Dynamics of the Abundance and Species Composition of Nekton in the Upper Epipelagic Layer of the Western Bering Sea

The western Bering Sea is an important region that is used by many nekton species for feeding. From the seasonal aspect, these waters are characterized by pronounced dynamics of the abundance and structure of the nekton community. The pattern of seasonal variations in the total biomass, composition, and structure of nekton in the upper epipelagic layer (0–50 m) of this region are considered based on the data of the complex studies conducted by the Pacific Research Fisheries Center (TINRO Center) in the deep-sea basins of the western Bering Sea and the Navarin area in June–October, 2003–2015. During June–October, the total nekton biomass changed by more than an order of magnitude: from 100 kg/km² in early June it increased to a maximum of 2700 kg/km² in the middle of August and then declined significantly, to 200 kg/km², in late October. The major contribution to the nekton biomass was made by Pacific salmon (Oncorhynchus spp.), mainly O. keta, as well as by the boreopacific gonate squid (Boreoteuthis borealis) and the shortarm gonate squid (Gonatus kamtschaticus). As well, walleye pollock (Theragra chalcogramma), Pacific herring (Clupea pallasii), and capelin (Mallotus villosus) were abundant in waters near the shelf. The dynamics of the species structure can be divided into three periods: (1) early summer, from June to the second 10 days of July, when pre-anadromous pink (O. gorbuscha) and chum salmon predominate and the species diversity is at a medium level (the polydominance index is 3.5–4.0); (2) summer, from the third 10 days of July to the second 10 days of September, when chum salmon becomes dominant (more than 70% of the biomass) and the species diversity is at a minimum (1.5–2.0); and (3) autumn, from the third 10 days of September to October, when common species such as chum salmon, sockeye salmon, and boreopacific gonate squid have relatively equal proportions, the proportion of pink salmon underyearlings is also high, and the species diversity is at a maximum (4.5). The pattern of the spatial distribution in the early summer period is characterized by active formation of the nekton community due to the large-scale migrations from the central and eastern Bering Sea and from the Pacific Ocean. In the summer period, the concentration of the nekton in the western Bering Sea, particularly in the Aleutian Basin, reaches the maximum level and the migratory activity decreases. Reverse migration processes are observed in the autumn period: a major portion of the nekton biomass redistributes to the southeastern Commander Basin for further movement to the ocean and the central Bering Sea.     

On the biology of anthocorid bugs (Heteroptera,Anthocoridae), predators of grass aphids in the forest-steppe zone of West Siberia

Four species of the heteropteran family Anthocoridae, Orius niger Wolff., O. majusculus Reut., O. minutus L., and Anthocoris confusus Reut., feeding on grass aphids on grains and bird cherry occur in the foreststeppe zone of Western Siberia. Orius niger and O. majusculus possess the greatest population numbers, with 98% of all the bugs collected in 1987 and 1988 belonging to these species. In 1998–2000, O. niger was predominant (97–100%). Data on the bionomics, seasonal abundance, feeding intensity, and role of anthocorids in the control of aphids are reported. Density of Orius bugs on wheat has been shown to be independent of the preceding culture. Permanent wheat is a preferable habitat of the predatory anthocorids. Mass reproduction of Orius bugs on pea-oat and alfalfa has been recorded.     

Dynamics of the Abundance and Community Structure of Small Mammals in the Saratov Trans-Volga Region

A typical feature of the populations of small mammals in different areas of the Saratov Trans-Volga region is the long-term and constantly increasing abundance of Sylvaemus uralensis and its wide distribution in a variety of habitats. The maximal abundance of S. uralensis is 72.0 individuals per 100 trap-days, and its share in catches is 73.0%. The abundance of Microtus arvalis tends to increase. It was shown that Lagurus lagurus has been found again in the steppe zone, on fallow lands and fields, after a prolonged depression in 2012–2013, the average density of species being 4.0 individuals per 100 trap-days. A high abundance of other typical steppe inhabitants (Allocricetulus eversmanni and Ellobius talpinus) was noted as well. The highest indices of species diversity (H = 1.18) are typical of fallow lands.