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The northern boreal forest treeline is usually considered to be the result of climate limiting tree reproduction. Although climate also influences the cycling of nutrients, the effects of nutrient availability on the treeline have largely been ignored. Various animal activities can alter nutrient cycling, creating microsites of highly fertile soil. Red foxes (Vulpes vulpes) act as ecosystem engineers in the nutrient-poor northern boreal woodlands by concentrating soil nutrients through their denning activities, increasing white spruce (Picea glauca) tree growth. Here, we examined how denning activity affects reproduction in white spruce by determining the number cones per tree, seeds per cone (with or without endosperm, i.e., filled or not) and their viability. Overall, seed production in the study region was low, with an average of 3.7 filled seeds and 0.73 viable seeds per cone. Denning activity affected all stages of seed production, with trees on dens producing an average of two times more cones, three times more total seeds, four times more filled seeds, and 18 times more viable seeds than trees growing away from dens. While cone counts per tree were a good predictor of filled seeds per tree, they were less reliable at predicting viable seeds per tree. Additionally, the number of cones on a tree does not predict the number of filled seeds in a cone, making it difficult for granivores like squirrels and birds to assess food availability from cone abundance. Overall, these results suggest that nutrient availability can play a crucial role in tree reproduction at the treeline and denning activities can create hotspots of seed production and seed viability, acting as a potential food source for granivores and locations for tree reproduction. [ABSTRACT FROM AUTHOR]

• Vegetation cover negatively affects activity of the ecological engineer root-rat. • Reciprocally, plant species richness positively affects activity of the giant root-rat. • Livestock grazing modulates the ecological engineering role of the giant root-rat. Subterranean rodents can act as ecosystem engineers by shaping the landscape due to soil perturbation and herbivory. At the same time, their burrow density is affected by environmental conditions, vegetation and anthropogenic factors. Disentangling this complex interplay between subterranean rodents and their environment remains challenging. In our study, we analysed the interplay of abiotic conditions, vegetation patterns and human land-use and the burrow density of the giant root-rat (GRR; Tachyoryctes macrocephalus), a subterranean rodent endemic to the Afroalpine ecosystem of the Bale Mountains in south-east Ethiopia. Specifically, we examined the effects of GRR on plant species richness and vegetation cover and vice-versa , and how these reciprocal effects might be modulated by temperature, habitat wetness and grazing. Our results showed that increasing GRR burrow density led to decreased vegetation cover, and that effects of GRR on vegetation cover were slightly stronger than vice - versa. Considering the reciprocal causation models, we found that increasing plant species richness led to increased GRR burrow density, while GRR burrow density decreased as vegetation cover increased. Increases in habitat wetness and livestock grazing intensity also directly led to increased GRR burrow density. Our results stress the importance of subterranean ecosystem engineers on vegetation and highlight the vulnerability of these complex interactions to human activity. [ABSTRACT FROM AUTHOR]

• Over many decades, red foxes increase nutrient concentrations and affect vegetation diversity on their dens in the boreal woodlands, a nutrient-poor environment. • Denning activity also affects the growth and reproduction of white spruce, a mast-seeding conifer. • White spruce on fox dens are taller and produce more cones in non-mast years than trees off dens. • The effects of denning are subject to the mast-seeding cycle, as cone production in mast years was not elevated on dens. Predators may act as ecosystem engineers by modifying their physical environment through non-trophic interactions. Red foxes (Vulpes vulpes) are ecosystem engineers in the boreal woodlands, a nutrient-poor environment, where their denning activity increases soil nutrient concentrations, affecting the diversity of vegetation around dens. Since dens can persist for many decades and tree growth is enhanced on dens, dens can be used to study the long term impacts of nutrient additions on community and ecosystem processes. We examined the reproductive output of a mast-seeding conifer, white spruce (Picea glauca), on 10 red fox dens and paired control sites at the boreal treeline near Churchill, Manitoba, in July 2019. We estimated cone production in both the current non-mast year (2019) and the previous mast year. The number of cones produced per tree and per hectare was significantly higher on dens than control sites in the non-mast year, but did not differ in the mast year. Higher cone production on dens was partly driven by trees being larger on dens. These results suggest that red fox ecosystem engineering activity affects white spruce reproduction, since increased soil nutrients on dens allow for higher cone production, but the effect of red fox denning is limited by interactions with mast-seeding mechanisms. For example, weather cues may override the effects of denning in mast years, while trees on dens may be able to allocate more resources to reproduction in non-mast years, but store the same amount of resources as trees off dens to produce similarly large cone crops in mast years. Altered resource availability in this nutrient-limited landscape could have additional ecological implications, by affecting the foraging patterns of seed predators and spruce range expansion. [ABSTRACT FROM AUTHOR]

This article argues for the integration of environmental perspectives into historical studies of territorialization. Using the case of the Western Expedition for the Drainage of Marshlands in Polesia (1873-1902), it shows that the transformation of the environment was one of many means by which the government of the Russian Empire sought to integrate the imperial territory and to develop regions that were considered backward. Three factors shaped these territorialization efforts in Polesia: firstly, the desire to foster economic development in rural areas; secondly, the role of the state as landowner; and, thirdly, a widespread consensus regarding the economic uselessness of wetlands. The canal network built by the Western Expedition improved conditions for commercial forestry in Polesia and connected the region to important transport routes. Yet, canal construction and river straightening measures were contested, as they subordinated existing land and water use practices to the interests of the central government. The example of the Western Expedition demonstrates that the concept of the "ecosystem engineer" can help to analytically grasp the ecological dimension of imperial rule. At the same time, the case is symptomatic of a new paradigm in the relationship between state and nature in modern Russia: Environmental change was not a side effect of the state‟s territorialization efforts, but an actively applied means of spatial consolidation. [ABSTRACT FROM AUTHOR]

Tree roots have biogeomorphic engineering effects on epikarst weathering and soil deepening. This is investigated using a system model describing the interactions among biogeomorphic effects of roots, weathering, and soil-epikarst development. The model shows that the system is dynamically unstable when roots are limited by subsurface accommodation space and water availability, and weathering is moisture limited. Instability indicates relatively rapid, unstable growth of epikarst cavities and soil, driven by positive feedbacks. However, when belowground rooting space and moisture are no longer limiting, and weathering is reaction-limited, the system is dynamically stable, indicating steady state or slow growth of epikarst and soils. Results suggest an important role for biogeomorphic ecosystem engineering (BEE) by tree roots in soil and epikarst development, but that BEE is self-limiting. When moisture storage and supply for both plants and dissolution are adequate and sufficient root space is available, BEE effects become negligible. Supportive data and field observations from the Inner Bluegrass region of Kentucky indicate that BEE effects of trees can produce favorable conditions for tree growth, with these effects becoming negligible as soil thickness increases sufficiently. [ABSTRACT FROM AUTHOR]

The boundary between mud flat and coastal wetland ecosystems is highly productive and a haven of considerable biodiversity. It is also embedded in a highly dynamic environment and can be easily destabilised by environmental changes, invasive species, and human activity. Thus, understanding the processes which govern the formation of this ecotone is important both for conservation and economic reasons. In this study we introduce a simple conceptual model for this joint ecosystem, which demonstrates that the interaction between tidal flooding and habitat elevation is able to produce an ecotone with similar characteristics to that observed in empirical studies. In particular, the transition from mud flat to vegetated state is locally abrupt, occurring at a critical threshold elevation, but, on broader spatial scales can occur over a range of elevations determined by the variability in high tide water levels. Additionally, the model shows the potential for regime shifts, resulting from periods of unusual weather or the invasion of a fast growing, or flood resistant, species. [ABSTRACT FROM AUTHOR]

Oncideres albomarginata chamela (Cerambycidae: Lamiinae) is a stem-boring beetle that girdles branches of Spondias purpurea (Anacardiaceae) for oviposition. Many beetles opportunistically oviposit in these branches and larvae create cavities that are abandoned when the adults emerge. Our objective was to evaluate the role of wood-boring beetles in promoting ant nest cavities mediated by a twig-girdler engineer. We collected 120 abandoned branches that had been detached by O. albomarginata chamela , in a tropical dry forest, in Jalisco, Mexico. Sixty abandoned branches were placed in trees from February to April, and another sixty from August to October 2016. In order to test the effects of nest characteristics on ant species, we measured the diameter of each branch and the diameter of the ant nest entrance as explanatory variables, whereas the size of ant species was used as response variable. We found 49 nests of arboreal ants from 14 species. The body size of the ants nesting in the abandoned branches was positively correlated with the diameter of the nest entrance. Ants used abandoned branches mainly as polydomic nests. Our result confirms that ants partitioning resources according to the size of entrance holes made by wood-boring beetles in dead wood. Polydomic nests have been reported as a strategy to promote the colonization of new nesting sites and the reduction of intraspecific competition. We conclude that the ecosystem engineering carried out by the twig-girdler O. albomarginata chamela had extended effects on the arboreal ant community, that takes advantage of the cavities abandoned by wood-boring beetles for nesting, especially for polydomic nests. [ABSTRACT FROM AUTHOR]

Although much research has examined the characteristics of Olympic marmot behavior and habitat, most studies mention the direct bioturbation effects of these marmots incidentally in an effort to examine other phenomena. A better understanding of marmot impacts on soil properties can provide a baseline for examining additional phenomena that are influenced by marmot activity. Soil surface and subsurface temperature, compaction, and moisture were measured in situ on abandoned marmot burrows in northeastern Olympic National Park, Washington. Soil samples were collected to analyze texture, pH, salinity, P, K, and organic matter content. Results indicated that soil compaction and organic matter were significantly reduced on abandoned marmot burrows when compared to undisturbed sites. Surface temperatures were typically warmer on marmot-disturbed soils, and subsurface temperatures were cooler. Soil moisture, texture, pH, salinity, and macronutrients were surprisingly similar on both disturbed and undisturbed soils. Findings suggest that Olympic marmots affect both physical and chemical soil characteristics, but additional research will be needed to evaluate the duration and extent of their impacts. [ABSTRACT FROM AUTHOR]

Abstract: The Ediacaran–Cambrian transition signals a drastic change in both diversity and ecosystem construction. The Ediacara biota (consisting of various metazoan stem lineages in addition to extinct eukaryotic clades) disappears, and is replaced by more familiar Cambrian and Paleozoic metazoan groups. Although metazoans are present in the Ediacaran, their ecological contribution is dwarfed by Ediacaran-type clades of uncertain phylogenetic affinities, while Ediacaran-type morphologies are virtually non-existent in younger assemblages. Three alternative hypotheses have been advanced to explain this dramatic change at, or near, the Ediacaran–Cambrian boundary: 1) mass extinction of most Ediacaran forms; 2) biotic replacement, with early Cambrian organisms eliminating Ediacaran forms; and 3) a Cheshire Cat model, with Ediacaran forms gradually disappearing from the fossil record (but not necessarily going extinct) as a result of the elimination of unique preservational settings, primarily microbial matgrounds, that dominated the Ediacaran. To evaluate these proposed explanations for the biotic changes observed at the Ediacaran–Cambrian transition, environmental drivers leading to global mass extinction are compared to biological factors such as predation and ecosystem engineering. We explore temporal and biogeographic distributions of Ediacaran taxa combined with evaluations of functional guild ranges throughout the Ediacaran. The paucity of temporally-resolved localities with diverse Ediacaran assemblages, combined with difficulties associated with differences in taphonomic regimes before, during, and after the transition hinders this evaluation. Nonetheless, the demonstration of geographic and niche range changes offers a novel means of assessing the downfall of Ediacara-type taxa at the hands of emerging metazoans, which we hypothesize to be most likely due to the indirect ecological impact metazoans had upon the Ediacarans. Ultimately, the combination of studies on ecosystem construction, biostratigraphy, and biogeography showcases the magnitude of the transition at the Ediacaran–Cambrian boundary. [Copyright &y& Elsevier]

The article discusses a research study on activities of 3 macrobenthic species that are differentially affecting the diversity and density of shallow subtidal marine nematodes. Added to sediment from subtidal station in the North Sea near Belgium were single-species treatment of Abra alba, Lanice conchilega and Nepthys hombergii for the multivariate and univariate analyses to determine the correlation of vertical profiles and nematode community composition through the Distance Based Linear Model (DISTLM) and generalized linear model (GLM) analyses. Results showed no significant difference on total nematode density in field control (FC), experimental control (C) and reconstruction control (RC) while macrobenthic groups do not affect depth profiles of silt content and sediment grain size.

The article presents a study on the association between populations of non-native burrowing crustacean Sphaeroma quoianum and lateral erosion rate of saltmarshes in Coos Bay, Oregon. For the study, researchers analyzed erosion in saltmarshes through the measurement of lateral erosion over a year and through the measurement of indicators of bank erosion. After a year of observation, they found increased lateral erosion rates, higher undercutting and increased numbers of calved and slumped marsh sections in marsh locations infested by Sphaeroma quoianum compared to uninfested locations. They concluded that burrowing by Sphaeroma quoianum can boost erosion rates in saltmarshes.

The effect of different sewage concentrations (0, 20, 60 and 100%), vegetation (Bare, Avicennia marina or Rhizophora mucronata) and immersion periods (immersion/emersion period of 12/12 h or 3/3 days just for 100%) conditions were studied for 6 months on survival and growth rates of Terebralia palustris (Linnaeus, 1767). Gastropods' activity and ecosystem engineering preformed at bare and A. marina planted cells and 3 sewage conditions (0, 20 and 60%) were determined. Survival rates were higher than 70% in all treatments. Growth rate decreased significantly with increasing sewage concentrations (mainly at unplanted conditions) and longer immersion periods. A complete shift (from immersion to emersion periods) and a significant decrease in mobility and consequently its engineer potential, due to sewage contamination, lead to a 3–4 fold decrease in the amount of sediment disturbed. Sewage contamination, primary producers' abundance and environmental conditions may have influenced the gastropods survival, growth and its ecosystem engineering potential. [Copyright &y& Elsevier]

• Canopy trees altered forest floor by litter and deadwood production and uprooting. • Deep beech litter accumulations prevented regeneration of spruce, but not of beech. • Deadwood and uprooting mounds were the best microsites for spruce regeneration. • Soil wetness became more limiting for beech regeneration in larger size classes. • Canopy trees of both species showed the ability to support their own regeneration. Natural regeneration of European beech (Fagus sylvatica) and Norway spruce (Picea abies) plays a crucial role in the future of many European mountain forests. It is affected by various soil and stand-related factors whose relative importance, especially in mixed stands, is still not known. In this study, we assessed the importance of stand composition, soil wetness, disturbances and different microsites and seedbeds for regeneration of beech and spruce in a mixed old-growth mountain forest. We also focused on how the effects of these factors change as regeneration gets older. We sampled all regeneration in 563 plots from different microsite types (deadwood, intact soil, treethrow pits and mounds), distinguishing three seedbeds (mosses, beech litter, bare substrate) for seedlings. We used soil survey and tree census data with generalized linear mixed models and variance partitioning to identify the main factors driving tree regeneration and their relative importance. Although beech was slightly less abundant in the canopy than spruce, it strongly outnumbered spruce in regeneration. Beech regeneration showed an affinity for beech litter-rich microsites and drier soils, while spruce was more common on deadwood and moister soils and its response to the seedbed was microsite-specific. The regeneration of both species was positively related to the proportion of their own species in the canopy, but more so in seedlings than in older regeneration cohorts, where soil wetness was more important. The overall pattern of tree regeneration thus resulted from a complex interplay between site conditions and their alterations by current and former generations of canopy trees through the creation of new microsites (deadwood, uprooting mounds) or litter production. Where beech regeneration is not suppressed by excess soil wetness, it is much more successful than spruce due to its shade tolerance and ability to be established in the beech litter that dominates the forest floor. On the other hand, spruce regeneration is mostly restricted to elevated microsites with lower litter accumulation, such as deadwood and treethrow mounds. Our results indicate that both species exhibit an ability to modify their environment in favor of their own regeneration, but under current conditions, beech is more successful than spruce and can be expected to increase its dominance in the future. [ABSTRACT FROM AUTHOR]

• Great longhorn beetles were related to the structure of old-growth holm forests. • Tree cavities were positively associated with past presence of the wood borers. • Other structural parameters of forests appeared related to the wood borers. • Parasitism from wood borers could be important for holm oak forest conservation. Great longhorn beetles (GLBs) may affect forest structure, because their larvae colonize trees and create networks of cavities further exploited by other species, resulting in dead or broken branches and tree mortality. At the same time, tree size, condition and location are known to affect the likelihood of tree colonization by GLBs. Here, we study the relationship between GLBs and the structure of old-growth holm oak Mediterranean forests in Sardinia, Italy. Generalized linear models were used to relate presence of GLBs with structural parameters that can be affected by or can affect these ecosystem engineers. We found a strong positive relationship between GLBs and the number of trees with cavities, while the relationships between GLBs and the number of dead wood decaying classes, amount of coarse woody debris, stand basal area, forest canopy layer complexity were positive but weak. Overall, our results suggest that larval activity of GLBs could be responsible for increased tree cavity and dead wood formation, enhancing forest structure. On the other hand, forests with larger and older trees could be more likely to be colonized by GLBs. While it is not possible with observational studies to disentangle to what extent GLBs affect forest structure or vice versa , it seems likely that reciprocal interactions may enhance the structure of holm oak forests. Therefore, parasitism from native GLBs should be seen and understood more as a key ecological process that enhances the structure of Mediterranean holm oak forest habitats. [ABSTRACT FROM AUTHOR]