Transitional Habitats Research Articles

Pogonoloma macrorhizum (Basidiomycota, Agaricales) in Slovak landscape: a distinct fungus of Quercus cerris stands transitional in space and time

The lack of precise data on the environmental requirements of the conspicuous fungus with a northern distribution limit in Slovakia, Pogonoloma macrorhizum, initiated our study. Its identity was verified by sequencing of ITS and 28 S nrDNA regions. The analysis of trophic status by stable-isotope ratio of carbon and nitrogen suggested that the species is probably ectomycorrhizal. For the seventeen sampling sites, environmental data were obtained and information on landscape development and management were retrieved from historical maps and aerial orthophotographs. All these parameters were analysed by multivariate ordination methods. In Slovakia, P. macrorhizum is found in thermophilous to mesophilous stands on acidic soils with a pH ranging from 4.1 to 6.2. These habitats are dominated by Quercus cerris, with non-frequent tree taxa of Carpinus betulus and Quercus petraea agg. The key environmental drivers shaping the habitat of P. macrorhizum were identified as time since deforestation, with the presence of old Q. cerris individuals (former solitary trees of pastures) and soil characteristics. The fungus appears to be a species of transitional habitats historically affected by grazing. These transitions occur between thermophilic and mesophilic sites, including oak forest communities, dry steppic grasslands and forest edges, as well as spontaneously overgrown pastures and forests with a closed canopy. It is regrettable that the Q. cerris stands in Slovakia are under threat, particularly because of felling and the lack of grazing in forests. Furthermore, recent silvicultural practices have resulted in the replacement of oaks (Quercus spp.) by hornbeam (Carpinus betulus) and the formation of closed stands.

The spatial pattern of Populus euphratica competition based on competitive exclusion theory.

Population-level competition and spatial patterns may explain the role of competitive exclusion in communities, which is important for vegetation restoration and biodiversity conservation. We analyzed the competitive intensity, spatial patterns, and renewal of Populus euphratica Oliv. forests in the Tarim River Basin using the Hegyi competition index and spatial point pattern analysis in a completely random model with different habitats and different forest ages. The greatest competitive distance for P. euphratica was 10 m, and the intensity of competition steadily decreased as the diameter increased. The intensity of intraspecific and interspecific competition in young, mature, and old P. euphratica forests was as follows: riverside habitat > transitional habitat > desert margin habitat. The Simpson index values for the three habitats decreased as follows: transitional > riverside > desert margin, and the Shannon-Wiener index and Pielou index values decreased as follows: riverside > transitional > desert margin. In the riverside habitat, the young P. euphratica forest experienced the greatest competitive intensity, the mature forest in the transitional habitat was the largest, and the forest in the desert margin habitat was the oldest. Competitive intensity was greatest in the young riverside P. euphratica forest, mature P. euphratica forest in the transitional habitat, and old forest in the desert margin. Riverside P. euphratica experienced strong competition from Populus pruinosa. Competitive exclusion caused P. pruinosa to disappear from the transitional and desert margin habitats. Young, mature, and old P. euphratica forests were randomly distributed along the riverside and in the transitional habitat, while mature and old P. euphratica forests were randomly distributed in the desert margin. Populus pruinosa, Tamarix ramosissima, and Tamarix hispida were mainly randomly distributed, and T. ramosissima and T. hispida were clustered at small scales. In the riverside habitat, young, mature, and old P. euphratica had no spatial correlation, and there was a significant negative correlation at small scales in the transitional habitat. The density of P. euphratica seedlings in the riverside habitat was greater than that in the transitional habitat, and greater competitive pressures on P. euphratica tree seedlings caused a lower renewal density. When planting P. euphratica forests, spacing greater than 10 m can effectively reduce stand competition and thus promote seedling regeneration.

Bacterial diversity in a continuum from supraglacial habitats to a proglacial lake on the Tibetan Plateau.

Mountain glaciers are frequently assessed for their hydrological connectivity from glaciers to proglacial lakes. Ecological process on glacier surfaces and downstream ecosystems have often been investigated separately, but few studies have focused on the connectivity between the different glacial habitats. Therefore, it remains a limited understanding of bacterial community assembly across different habitats along the glacier hydrological continuum. In this study, we sampled along a glacial catchment from supraglacial snow, cryoconite holes, supraglacial runoff, ice-marginal moraine and proglacial lake on the Tibetan Plateau. The bacterial communities in these habitats were analyzed using high-throughput DNA sequencing of the 16S rRNA gene to determine the bacterial composition and assembly. Our results showed that each habitat hosted unique bacterial communities, with higher bacterial α-diversity in transitional habitats (e.g. runoff and ice-marginal moraine). Null model analysis indicated that deterministic processes predominantly shaped bacterial assembly in snow, cryoconite holes and lake, while stochastic process dominantly governed bacterial community in transitional habitats. Collectively, our findings suggest that local environment play a critical role in filtering bacterial community composition within glacier habitats. This study enhances our understanding of microbial assembly process in glacier environments and provides valuable insights into the factors governing bacterial community compositions across different habitats along the glacial hydrological continuum.

Stable isotopes reveal sargassum rafts provide a trophic subsidy to juvenile pelagic fishes

Floating macroalgal rafts can form extensive habitat in coastal waters and support abundant and diverse communities of juvenile fishes. Rafts comprised predominantly of Sargassum spp. are common within the Ningaloo Coast World Heritage Area, Western Australia, and may be an important transitional habitat for pre-settlement coastal fishes. We had three aims: 1) to quantify the diversity and abundance of fishes associated with Sargassum rafts; 2) to use stable isotopes to determine whether fishes associating with rafts preyed on nearby plankton or on prey associated with Sargassum; and 3) to determine whether the food web fishes relied upon was ultimately supported by primary production of Sargassum or planktonic phytoplankton (measured as seston). Fishes and macroinvertebrates associating with Sargassum rafts, zooplankton, and seston were collected at six sites in the Ningaloo Marine Park and analysed for δ15N and δ13C, and the diets of the most common fishes were analysed using MixSIAR. Fishes were more abundant around macroalgal rafts than in open water. Eleven species of juvenile fishes associated with Sargassum rafts, with one species (Histrio histrio (Antennariidae)) represented by juveniles and adults. Four of the five fishes most sampled around Sargassum spp. rafts, (Abudefduf vaigiensis (Pomacentridae), Helotes sexlineatus (Terapontidae), Colurodontis paxmani (Monacanthidae) and Petroscirtes breviceps (Blenniidae)) had generalist diets whose food webs were ultimately supported by greater contributions of primary production from Sargassum spp. (55–72%) than planktonic seston. H. histrio was predominantly piscivorous but still derived most (64%) of its organic matter indirectly from Sargassum spp. Our results reveal the importance of Sargassum rafts as habitat that provides shelter and food for juvenile fishes and adult H. histrio. Moreover, the prevalence of juvenile fishes associating with Sargassum rafts highlights a bidirectional form of benthic-pelagic coupling whereby macroalgae that detach from the benthos provide habitat and a trophic subsidy for pelagic juvenile fishes before they the transition into benthic coastal habitats.

Beach morphodynamics modulate the effects of multidirectional habitat loss on population density and size structure of the Atlantic ghost crab Ocypode quadrata

Sandy beaches are land-sea transitional habitats experiencing ‘multidirectional’ habitat loss due to coastal developments (e.g. armoring and/or conversion of natural vegetation into manmade structures) and beach erosion. This ‘coastal squeeze’ is a chronic and progressive process; however, its impacts on beach biodiversity across morphodynamic gradients are still to be unveiled. We hypothesized that the effects of multidirectional habitat loss would be more severe on dissipative than on reflective beaches, due to the higher elevation, amount of built up sediment, and width of the backshore compartment of the latter. We, thus, examined the effects of coastal developments and erosion on density and size structure of the Atlantic ghost crab, Ocypode quadrata, on beaches with different morphodynamics. Given that the living area of ghost crabs spans all cross-shore compartments and the whole dissipative-to-reflective morphodynamic gradient, they are appropriate organisms to access the synergic effects of coastal developments and beach erosion under different morphodynamic regimes. On dissipative beaches, density and mean crab size increased with moderate erosion, attributed to the effects of space loss, which might increase territorial competition, favoring the remaining larger individuals. However, mean size and density decreased with high erosion given the more intense reduction in the abundance of large-sized crabs living in up-shore habitats. Mean crab size also decreased in the presence of coastal development while crab density did not vary with loss of backshore habitats occupied by larger individuals. On reflective beaches, both density and crab size decreased with coastal development; the crab size decrease recorded under moderate erosion was more evident in the presence of coastal development. Under high erosion, mean crab sizes declined, reflecting those under low erosion conditions. Overall, populations on reflective beaches appeared more resilient to extreme erosion. Notwithstanding, coastal developments affected population structure across all beach types, and especially in areas subjected to high erosion, exhibiting a synergic effect. We predict that, in combination, these stressors may lead to functionally extinct populations where conditions necessary for individuals to reach sexual maturity (i.e. occurrence of only small-sized and immature individuals) are not met. Thus, the connectivity between water, beach compartments and dunes/coastal plain, on both local and regional scales, may be essential to maintain viable and connected populations of ghost crabs. Further, our results strongly suggest that both size and density (complemented with crab abundance) must be considered equally important and in combination in future efforts to assess anthropogenic stressors on ghost crab populations and when guiding conservation strategies and policies to prevent their local and regional extinctions.

Unravelling the influence of annual weather conditions and Mediterranean habitat types on acorn production, availability and predation

Seed production and survival are critical steps in the life cycle of plants, and could become bottlenecks for plant regeneration in case of failure. During regeneration many factors, both abiotic and biotic, intervene and interact with each other. After dispersal, environmental variation affects the success of the plant population, so seedling recruitment can display spatial variability. However, few studies of seed production and availability cover a range of habitat conditions (e.g. mature, transitional and post-fire habitats), which makes it difficult to evaluate the potential of site-production relationships. We study how the heterogeneity of habitat structure and composition affects the phenology, production and availability of acorns, mainly holm oak, in a Mediterranean Natural Park. Our results show that meteorological variables determine the phenology of acorn fall. Habitat types present temporal mismatches in falls since, for example, shrublands required a longer period of time for all seeds to fall. Furthermore, habitats with greater tree density and low understory complexity had higher production but smaller acorns. Lower densities promote higher acorn volume (seedling size) as a consequence of less intraspecific competition and more reserves for germination. The proportion of viable acorns available on the ground also decreased substantially in winter, when the proportion of infested acorns increase because the selective consumption of sound acorns by predators. Acorns from mixed forests and shrublands had less pre-dispersal predation by arthropods and post-dispersal predation by wild boar as a result of oak isolation and understory complexity. Conversely, rodents are more abundant in shrublands, where they find a greater diversity of anti-predator refuges and large nutritious acorns available in autumn and winter. Understanding the reproductive constraints imposed by time and space allows us to infer the consequences of environmental changes on population recruitment and persistence. We thus show that habitats with a high density of oak trees, less plant diversity and understory cover had a greater prevalence of infested acorns, thereby reducing recruitment viability. These habitats also had more available acorns on the ground for seed predators. Therefore, habitat type is an important factor affecting acorn production and should be taken into account in future studies.

Evaluation of Earth System Models outputs over the continental Portuguese coast: A historical comparison between CMIP5 and CMIP6

In the last decades, climate change has been accelerating, affecting, directly and indirectly, the environment, animal habitats, and daily human life. Earth System Models (ESMs) are valuable tools for studying these impacts, and their performance over coastal regions is critical for understanding how physical and biogeochemical processes are evolving through time and how they may change in the future. The continental Portuguese coast, characterized by an important upwelling system, hosts highly productive and nutrient-rich regions with a large diversity of transitional habitats and systems. Therefore, this study aims to evaluate and score the ESMs from the 5th and 6th phases of the Coupled Model Intercomparison Project that better reproduce, simultaneously, physical and biogeochemical ocean properties along the continental Portuguese coast. The analysis was carried out through the computation of a score (SR) between CMIP historical outputs and data from the Iberian-Biscay-Ireland ocean reanalysis system at four selected locations along the coast, considering two physical and four biochemical variables. Results reveal that ESMs perform better for the physical properties than for the biochemical ones, as well as lower differences and variance between CMIP6 models, reflecting an improvement from CMIP5. The Max Planck Institute (MPI) models obtained the best overall classification by delivering a consistently good performance for all variables.

Autumn outmigrants in brown trout (Salmo trutta) are not a demographic dead-end.

Genetic identity analysis and PIT (Passive Integrated Transponder) tagging were used to examine the freshwater return rates and phenotypic characteristics of n=1791 downstream migrating juvenile Salmo trutta in the Burrishoole catchment (northwest Ireland) across the period September 2017 to December 2020. In this system, juveniles out-migrate (move from freshwater into brackish or marine habitats) in every month of the year, with distinct seasonal peaks in spring (March through June; mostly silvered smolts) and autumn (September through December; mostly younger, unsilvered fry or parr). Both types exhibited a sex-bias towards females, which was stronger in spring (78% females) than in autumn outmigrants (67%). Sixty-nine returning fish were matched back to previous juvenile outmigrants and similar return rates were found for spring outmigrants (5.0%), autumn outmigrants (3.3%) and fish that outmigrated outside of spring or autumn (2.8%). Spring and autumn outmigrants returned at similar dates (typically mid to late July) but autumn fish were away for longer (median=612 days; spring outmigrants=104 days). Autumn outmigrants were 25% smaller than spring outmigrants at outmigration and 6% smaller on their return, and within both groups smaller/younger outmigrants spent longer away than larger/older outmigrants. Autumn outmigrants were more likely to return unsilvered as 'slob' trout (84%) than spring outmigrants (31%), suggesting they make greater use of brackish habitats that might be safer, but less productive, than fully marine habitats. However, both types also produced silvered 'sea trout' (≥1+ sea-age), implying neither is locked into a single life-history strategy. Our findings emphasise that autumn outmigrants and the transitional habitats that support their persistence should not be overlooked in salmonid management and conservation. This article is protected by copyright. All rights reserved.

A synthesis of a coastal northern pike (Esox lucius) fishery and its social-ecological environment in the southern Baltic Sea: Implications for the management of mixed commercial-recreational fisheries

We synthesize a large body of literature involving peer-reviewed work, grey literature and novel data analyses about the small-scale northern pike (Esox lucius) fishery in lagoon ecosystems in the southern Baltic Sea. Based on our comprehensive review that synthesizes ecological as well as social, economic and governance-related literature we derive implications for the management of mixed commercial-recreational fisheries in coastal areas. The interconnected shallow and biologically highly productive meso- to polytrophic lagoons (extension about 2000 km²) bordered by the peninsula of Fischland-Darß and the islands of Hiddensee, Rügen and Usedom in the southern Baltic Sea of Germany constitute an oligo- to mesohaline transitional habitat suitable for colonization by a range of freshwater fishes, including pike. In the Rügen area, pike successfully recruits in the mesohaline lagoons, but anadromous subpopulations and freshwater residents also exist in tributaries, forming a connected meta-population. The stock is co-exploited by a small-scale commercial fishery and a largely tourism-dominated recreational fishing sector that, depending on the angler type, values the pike for both consumption as well as for its trophy size. The recreational sector has risen in economic and social relevance since the German reunification in 1990 and today removes similar amounts of biomass than commercial fisheries. Pike is a prime target species of anglers, and recreational pike angling in the lagoons today generates a larger economic impact in terms of jobs created compared to the commercial pike fishing, where pike is typically one target among many freshwater fish. Stock assessments and stakeholder reports have revealed that the stock size and size of pike in the catch have been falling since 2010, fueling conflicts among fishers and anglers for space and fish. Reasons for the current decline of the pike stock involve multiple pressures operating jointly and possibly synergistically, such as local overharvest, loss of stock structure through past blocking of freshwater streams, eutrophication and macrophyte loss, predation mortality by natural predators, reduced availability of marine prey through declines of western Baltic spring-spawning herring (Clupea harengus), and poorly understood impacts of climate change. The assessment of current fishing mortality suggests a the stock stock is size/quality-overfished from the perspective of anglers, and fully exploited to slightly growth-overfished when judged against the reference point of maximum sustainable yield. The current biomass trend is negative. The current instantaneous fishing mortality rate, F, is estimated to range between 0.2 and 0.4 yr-1. Hence, fishing cannot be the sole culprit of the current stock decline because the current fishing mortality rates are too high for the underlying productivity, but not excessive. Because the current fishery no longer meets the expectations of recreational anglers, and angler numbers have recently declined, if the aim is to also suit anglers, reductions of fishing mortality would be useful in recovering the stock and fishing quality, coupled with restoration of access to flooded wetlands as spawning and nursery grounds, and control of other mortality sources of pike (e.g., cormorants). However, whether such actions indeed rebuild the fishery remains uncertain because of the potential for compensatory natural and fisheries mortality and other environmental changes affecting recruitment and abundance negatively. Policy makers may want to solve the allocation problem among commercial and recreational fisheries, install a robust monitoring system and a management framework that is inclusive of multiple perspectives and objectives and adaptive to novel productivity regimes and further structural changes in the mixed fishery. Further research on climate change impacts, food web changes, impacts of natural predators such as seals, cormorants or stickleback, and the behavioral and socio-economic aspects of commercial and recreational fisheries is warranted.

A new species of Endangered giant trapdoor spider (Mygalomorphae: Idiopidae: Euoplos) from the Brigalow Belt of inland Queensland, Australia

A new species of giant trapdoor spider, Euoplos dignitas sp. nov. (family Idiopidae), is described from the Brigalow Belt of inland Queensland, Australia. Phylogenetic analysis of a six gene molecular dataset for the tribe Euoplini reveals that this species is sister to the spinnipes-group from eastern Queensland, and unrelated to a morphologically similar congener (E. grandis Wilson & Rix, 2019) that occurs further south in the Brigalow Belt. Both E. dignitas sp. nov. and E. grandis are very large, scopulate, plug door-building trapdoor spiders from transitional woodland habitats on vertosols (‘black soils’), with superficially similar females and strongly sexually-dimorphic ‘honey-red’ males. Information on the known biology and distribution of E. dignitas sp. nov. is summarized, and a conservation assessment is provided under the International Union for Conservation of Nature’s (IUCN) Red List Criteria, indicating that this species is likely Endangered.

American Burying Beetle (Coleoptera: Silphidae) Occurrence at Reservoir Shoreline and Hand-Planted Forest at the Western Limit of Their Range

The largest North American Silphidae, the American burying beetle (ABB), Nicrophorus americanus Olivier, has been extirpated from ∼90% of its historic range and is federally threatened. Two distinct populations in the Southern (Oklahoma and Arkansas) and North-Central United States (Nebraska and South Dakota) persist at the western edge of the ABB's former range. In Nebraska, the western limits of occurrence are associated with Merritt Reservoir and linked irrigation canals. ABBs are also found at the nearby hand-planted McKelvie National Forest. While habitat alteration and fragmentation are likely the primary reasons for ABB decline, few studies have examined their response to human habitat modifications unrelated to urbanization or agricultural conversion. Through five-day sampling periods with carrion-baited pitfall traps, ABB were captured and recorded in June and August from 2015 to 2017 at Merritt Reservoir and McKelvie National Forest in Cherry County, Nebraska. Traps were placed in transects (N = 4) at each location with reservoir traps set at the shoreline, transition, and upland habitats and forest traps set in the prairie, transition zone, and pine forest. At Merritt Reservoir, 651 ABB were captured, with significantly more collected at the shoreline. Concurrently, 23 ABB were captured at McKelvie Forest, with more ABB found within the forest compared to nearby prairie. These findings support previous suggestions that the western distribution of ABB is limited by moisture. Further investigation may indicate that reliable soil moisture associated with altered habitats in Nebraska could support ABB and potentially allow western range expansion.

Acoustic observations of nekton and zooplankton along the Northeast continental shelf break

Observations of fish and squid (nekton) and crustacean and gelatinous animals (zooplankton) at the shelf break using active acoustic systems (e.g., echosounders) have been made along the United States shelf break from the mid-Atlantic to New England since the early 2000s as part of a biennial bottom trawl survey (NOAA’s Northeast Fisheries Science Center), since 2012 as part of the Atlantic Marine Assessment Program for Protected Species (AMAPPS), and recently as part of the Task Force Ocean New England Shelf Break Acoustic project. The shelf break can be a boundary between seabed-oriented species on the continental shelf and pelagic species in the open ocean, as well as transitional habitat for some species to exploit. These data have been collected using multifrequency, narrowband (e.g., 18, 38, 70, 120, and 200 kHz) and wideband (18–250 kHz) scientific echosounders with hull-mounted transducers to primarily map the prey species of mid- to upper-trophic level foragers and predators. Classification of acoustic data to biologically meaningful metrics and how these can be integrated with oceanographic features and spatial and temporal distributions of predators will be explored in relation to the broader goals of developing ocean acoustic networks. [Work supported by the Office of Naval Research.]

The Lesser-Known Transitions: Organismal Form and Function across Abiotic Gradients.

From minute-to-minute changes, or across daily, seasonal, or geological timescales, animals are forced to navigate dynamic surroundings. Their abiotic environment is continually changing. These changes could include alterations to the substrates animals locomote on, flow dynamics of the microhabitats they feed in, or even altitudinal shifts over migration routes. The only constancy in any organism's day-to-day existence is the heterogeneity of the habitats they move through and the gradients in the physical media (e.g., air and water) they live in. We explored a broad range of organismal transitions across abiotic gradients and investigated how these organisms modify their form, function, and behavior to accommodate their surrounding media. We asked the following questions: (1) What are some challenges common to animals in changing media or moving between media? (2) What are common solutions to these recurring problems? (3) How often are these common solutions instances of either convergence or parallelism? Our symposium speakers explored these questions through critical analysis of numerous datasets spanning multiple taxa, timescales, and levels of analysis. After discussions with our speakers, we suggest that the role of physical principles (e.g., drag, gravity, buoyancy, and viscosity) in constraining morphology and shaping the realized niche has been underappreciated. We recommend that investigations of these transitions and corresponding adaptations should include comparisons at multiple levels of biological organization and timescale. Relatedly, studies of organisms that undergo habitat and substrate changes over ontogeny would be worthwhile to include in comparisons. Future researchers should ideally complement lab-based morphological and kinematic studies with observational and experimental approaches in the field. Synthesis of the findings of our speakers across multiple study systems, timescales, and transitional habitats suggests that behavioral modification and exaptation of morphology play key roles in modulating novel transitions between substrates.

Longitudinal habitat gradient affects diet and body condition of riverine fish: A case study of Pelteobagrus catfishes in the Three Gorges Reservoir, China

AbstractTo understand how riverine fish respond to longitudinally different habitats created by impoundment, we selected three congeneric yellow catfish species (Pelteobagrus spp.) as a model system to assess changes in diet, prey selectivity, and body condition among the lotic, transitional, and lentic habitats along the Three Gorges Reservoir. Our results add to previous findings highlighting a shift in fish diets from diverse zoobenthos to shrimp‐dominated as the river becomes lentic by showing spatial segregation in the size of shrimp prey consumed. Relative to the available shrimp populations, catfish populations selected smaller shrimp in the upper (lotic) section and larger shrimp in the middle (transitional) and lower (lentic) sections. Complementary body condition indices exhibited a consistent spatial pattern, where populations in the lotic zone were healthier than those in the transitional and lentic zones. This pattern seems to result from a greater nutrient value of zoobenthos, the dominant food in the lotic zone, relative to shrimps. Our results suggest that these generalist fish species have adapted to the spatial habitat gradient and maintained their populations, but the impoundment has deeply influenced their energy acquisition and allocation.

Microsite Habitat, Species Associations, and Habitat Suitability Model of a Globally Imperiled Shrub

Miller's witch-alder (Fothergilla milleri, Hamamelidaceae) is a newly described globally imperiled shrub that is known from disjunct populations in coastal Alabama, the panhandle of Florida, and one location in Georgia. Little is currently known about the natural history or ecology of the species. We conducted inventories of three populations of F. milleri in Alabama and Florida. A total of 3060 ramets were found; 45% were in one subpopulation ≤0.5 ha in area and 79% were in one population within an area of 4.5 ha. Low ramet counts in few locations makes the species particularly vulnerable to extinction due to stochastic events. Also, all seed capsules found within the surveys were infected by an aphid, which is possibly preventing sexual reproduction within the populations. Microsite habitat data indicated F. milleri grows in a unique transitional habitat between upland conifer forest and wetlands. The sites where extant populations of F. milleri inhabit tend to have acidic and well-drained soils with a high sand content. Further, many populations were under thick midstory vegetation. Thus, fire or other forms of removal may be needed to release those subpopulations before they may become shaded out. Lastly, a habitat suitability model was developed to better facilitate conservation efforts. However, only 0.5% of the study area was within the highest level of suitability. Fothergilla milleri is facing multiple threats that could lead to its extirpation from the wild, and direct and intense conservation action may be necessary to ensure F. milleri remains on the landscape.

Quantifying restoration success via natural recovery in forested areas following pipeline construction

Natural recovery is a restoration technique that relies on natural ecological processes to reestablish native ecosystems. This “minimal intervention” approach is typically more cost‐effective, less labor intensive, and can result in more diverse communities than more intensive restoration techniques. The purpose of this study was to determine if boreal forest vegetation can reestablish naturally after pipeline construction, and whether a site can be identified as similar to adjacent undisturbed areas within 10 years of pipeline construction. Four naturally recovered pipeline segments (1, 3, 5, and 10 years postreclamation) in west‐central Alberta were assessed. Plots were established on and off each pipeline segment right‐of‐way (ROW) in upland, transitional, and wetland habitats. Vegetation percent cover, vigor, and tree seedling density data were used to determine characteristic and indicator species, regulated weeds and agronomic species, richness, diversity, evenness, and tree establishment for each pipeline segment, habitat type, and site type (on‐ vs. off‐ROW). Threshold values for species richness and community diversity were determined using data collected from sites off‐ROW. Sites which fell within established thresholds were identified as on a trajectory toward restoration within 10 years postconstruction. Metrics for the older pipeline segments, including species richness, diversity, evenness, and seedling count were typically closer to threshold values, and sometimes exceeded them. Only the youngest pipeline segment had tree establishment values below calculated thresholds. This study is the first to provide empirical evidence and a method for identifying successful restoration trajectories for natural recovery of pipeline ROWs in boreal forest.

Morphological and Molecular Identification of Culicoides (Diptera: Ceratopogonidae) Species of the Southern California Desert.

Culicoides Latreille (Diptera: Ceratopogonidae) biting midges are vectors of important animal pathogens including bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV). While some Culicoides species present in the southern California desert are implicated in the transmission of these viruses to ruminant animals, these species have not been extensively studied due in part to the challenge of identifying Culicoides to species and to the lack of published gene sequences for these species to support their molecular identification. In this study, Culicoides were captured using suction traps baited with either carbon dioxide or UV light from transitional habitat between the southern California peninsular mountain ranges and the Colorado desert of southeastern California. Captured midges were initially identified using traditional morphological methods, with species identification subsequently confirmed by sequence analysis of COI and 28S rDNA genes. Phylogenetic analyses support that some Culicoides subgenera are not monophyletic. Two recognized species (C. sitiens Wirth and Hubert and C. bakeri Vargas) shared the same COI and 28S sequences. An additional cryptic species may be present within C. sitiens. Two additional recognized species (C. cacticola Wirth and Hubert and C. torridus Wirth and Hubert) may be conspecific or cryptic to each other. In total, 19 Culicoides species (or species aggregate) were collected in this study, with genetic sequences published for the first time for 16 of them. Published genetic sequences will support future research on these species, including studies on the ecology and habits of their immature stages which are often tedious to identify using morphology.

Importance of peatlands to maintain avian diversity in the Bolivian High Andes

The High Andean peatlands are peat-accumulating wetlands dominated by cushion-forming plants and are embedded in a matrix of puna grasslands above 4,000 m. These ecosystems are an essential source of water and evergreen vegetation for wild and domestic animals and are considered sensitive to environmental alterations. We studied the birds' habitat and microhabitat preference in peatlands and their surrounding grasslands in the Cordillera Real, Bolivia. We established 3 parallel transects around 12 peatlands: (1) in peatland, (2) at 100–200 m from the peatland edge, considered as the transition habitat between peatlands and grasslands, and (3) in puna grasslands at >500 m from the peatland edge. We quantified bird abundance, species richness, and the availability of 8 microhabitats along 36 transects. We recorded 934 individuals of 34 species and found higher bird species richness and abundance in peatlands than in surrounding grasslands and transition habitats. We found that 26% of bird species were exclusive to peatlands. While most bird species common in peatlands were almost nonexistent in other habitats, most species associated with grasslands were also found in proximity to peatlands. A canonical correspondence analysis showed that bird species were associated with one or more microhabitats. The high abundance, bird species richness, and diet types in peatlands is probably related to the high primary productivity of peatlands and year-round availability of water. Degradation of these peatlands may reduce the abundance of regional bird communities, not only peatland specialists but also species in surrounding habitats.

Biodiversity and Ecosystem Functions Across an Afro-Tropical Forest Biodiversity Hotspot

Ecosystem functions are important for the resilience of ecosystems and for human livelihood quality. Intact habitats and heterogeneous environments are known to provide a large variety of ecosystem functions. Natural and near natural ecosystems surrounding agroecosystems may positively support crop growing conditions and thus facilitate crop yields. In contrast, monocultures of crops and trees as well as degraded landscapes are known to provide less ecosystem functions. The Taita Hills in southern Kenya are part of the Eastern Afromontane biodiversity hotspot, and represent a habitat mosaic consisting of largely intact cloud forests, agroecosystems and plantations of exotic trees. In this region, subsistence farmers rely on ecosystem functions provided by natural ecosystems. In this study, we analyze three proxies of biodiversity and ecosystem functions, namely pollination activity, predation rates, and arthropod diversity in tree canopies. We set study plots along forest-agroecosystem-gradients, covering cloud forest, forest edge and agricultural fields, as well as plantations of exotic trees. We assessed environmental conditions, to evaluate the extent to which local environmental factors influence ecosystem functions. Based on these data we investigate potential spill over of ecosystem functions from forest into adjoining agroecosystems. For predation rates we found trends of spill over effects from forest interior into the agroecosystem. The expression of ecosystem functions differed among habitat types, with comparatively high predation rates in the forest, high pollinator activity in the open agricultural areas, and highest arthropod diversity along the forest edge. Eucalyptus plantations showed reduced ecosystem functions and lowest arthropod diversity. Local factors such as vegetation cover and flower supply positively influence pollinator activity. Our study show that natural ecosystems may positively contribute ecosystem functions such as predation, while the homogenization of biota through planting of invasive exotic tree species significantly reduce biodiversity and ecosystem functions. Transition habitats such as forest margins, and small-scale ecological enhancement positively influences biodiversity and ecosystem functions.

Transitional and small aquatic cave habitats diversification based on protist assemblages in the Veternica cave (Medvednica Mt., Croatia)

Protists in caves are scarcely researched. Most cave studies address the diversity of protists, but very little is known about their habitats and spatio-temporal dynamics. The aim of this study was to investigate the diversity and abundance of protists in the Veternica cave in the Medvednica mountain in Croatia on hygropetric and sinter and clay pools during six months. During this study, 47 protists taxa were distinguished belonging to the groups of heterotrophic flagellates, ciliates, heliozoans, stramenopiles and testate and naked amoebae. The highest taxon richness was found at the sinter pool site richest in bats guano (36 taxa). Most diverse were testate amoebae and ciliates. The number of taxa and their abundance differed significantly between the sampling sites. The prospected habitats supported different protist assemblages, proved by ordination analysis. The most distinctive habitat was the hygropetric. Habitat heterogeneity could be attributed to the presence of inorganic and organic sediments at the sites and habitat microhydrology (lotic or lentic system). Kendall’s concordance coefficient showed a good synchronicity between the habitats in the Veternica cave, based on taxon richness and abundance of protists indicating similar seasonal trends. Seasonality in the studied habitats is attributed to the hydro-meteorological conditions in the Veternica cave drainage area. This study is one of the few studies of spatio-temporal diversity and abundance of protists in caves. Despite the similar appearance of small transitional and aquatic habitats in caves, an example of this study showed specific habitat diversification.