Species Density Research Articles

Variation in energy density of northwest Atlantic forage species: Ontogenetic, seasonal, annual, and spatial patterns

AbstractObjectiveEnergy density (ED) estimates for marine forage species have been limited, impeding our understanding of this important trophic level. We studied the EDs of eight key forage species: Alewife Alosa pseudoharengus, Atlantic Herring Clupea harengus, Silver Hake Merluccius bilinearis, Northern Sand Lance Ammodytes dubius, Atlantic Mackerel Scomber scombrus, Butterfish Peprilus triacanthus, northern shortfin squid Illex illecebrosus, and longfin inshore squid Doryteuthis pealeii (also known as Loligo pealeii).MethodsSamples were obtained during spring and fall bottom trawl surveys across five regions (Gulf of Maine, Georges Bank, southern New England, northern Middle Atlantic Bight, and southern Middle Atlantic Bight) from 2017 to 2019. In the laboratory, we developed predictive relations between the percent dry weight (%DW) and ED (kJ/g wet weight) determined by proximate composition analysis (n = 606; r2 = 0.76–0.98) to estimate the ED of additional samples (n = 4583). For each species, we modeled ED as a function of size, depth, season, and year (as factors) as well as location (latitude, longitude) using generalized additive models (GAMs).ResultAlewife, Atlantic Herring, Northern Sand Lance, Atlantic Mackerel, and Butterfish were classified as high‐quality prey (ED > 6 kJ/g), although Atlantic Herring ED was nearly half the values reported in earlier studies. Silver Hake, northern shortfin squid, and longfin inshore squid were classified as moderate‐quality prey (4 kJ/g < ED < 6 kJ/g). Most species had higher EDs in the fall following summer feeding than in the spring after spawning and/or reduced winter feeding. The best‐fitting GAMs included weight, depth (by season), season, and year effects for most species. Location (by season) explained significant amounts of variation.ConclusionObserved variation in ED across regions, species, seasons, and years provides the empirical data necessary to consider hypotheses related to “upstream” regulation of ED (via environmental drivers and productivity) and “downstream” effects on recruitment for these forage species as well the species that prey on them.

Investigation of O atom kinetics in O2 plasma and its afterglow

We have developed a comprehensive kinetic model to study the O atom kinetics in an O2 plasma and its afterglow. By adopting a pseudo-1D plug-flow formalism within the kinetic model, our aim is to assess how far the O atoms travel in the plasma afterglow, evaluating its potential as a source of O atoms for post-plasma gas conversion applications. Since we could not find experimental data for pure O2 plasma at atmospheric pressure, we first validated our model at low pressure (1–10 Torr) where very good experimental data are available. Good agreement between our model and experiments was achieved for the reduced electric field, gas temperature and the densities of the dominant neutral species, i.e. O2(a), O2(b) and O. Subsequently, we confirmed that the chemistry set is consistent with thermodynamic equilibrium calculations at atmospheric pressure. Finally, we investigated the O atom densities in the O2 plasma and its afterglow, for which we considered a microwave O2 plasma torch, operating at a pressure between 0.1 and 1 atm, for a flow rate of 20 slm and an specific energy input of 1656 kJ mol−1. Our results show that for both pressure conditions, a high dissociation degree of ca. 92% is reached within the discharge. However, the O atoms travel much further in the plasma afterglow for p = 0.1 atm (9.7 cm) than for p = 1 atm (1.4 cm), attributed to the longer lifetime (3.8 ms at 0.1 atm vs 1.8 ms at 1 atm) resulting from slower three-body recombination kinetics, as well as a higher volumetric flow rate.

Using density surface models to assess the ecological effectiveness of a protected area network in Tanzania

AbstractGiven recent global endeavors to increase protected area coverage, it is crucial to comprehensively evaluate the efficacy of various area‐based conservation strategies in effectively reducing biodiversity loss. Here, we investigated the responses of wildlife populations to different protection levels and environmental variables at the landscape scale in the Katavi–Rukwa Ecosystem, western Tanzania. To this end, we conducted line distance sampling surveys and counted the dung of six target mammal species (elephant, giraffe, buffalo, zebra, topi, and hartebeest) along foot transects within areas differing in protection levels (from strict to less‐strictly protected: national park, game reserve, forest reserve, game‐controlled area, and unprotected areas). Based on these dung counts, we modeled the spatial distribution of these six mammal species using a species‐specific density surface modeling framework. We found consistent effects of protection level and land use variables on the spatial distribution of the target mammal species: dung densities were highest in the national park and game reserves, intermediate in less‐strictly protected areas, and lowest in unprotected areas. Beyond species‐specific environmental predictors for dung densities, our results highlight consistent negative associations between dung densities of the target species and distance to cropland and avoidance of areas in proximity to houses. Our findings underpin differences in ecological effectiveness of protected areas within one ecosystem. Protection level and land use play crucial roles in moderating the spatial distribution of all considered mammal species. Our findings suggest that a landscape approach needs to guide effective conservation across the entire protection gradient of the Katavi–Rukwa Ecosystem.

Ecological potential of giant clams in Ambon Island waters, Eastern Indonesia

Giant clams are protected marine organisms universally, thus information on giant clams is important for management purposes. This research was conducted in July to August 2021 in Morella and Suli, Ambon Island Maluku Province to get information on ecological potential which consist of species composition, density, occurrence frequency and diversity of giant clams. Sample was collected by using linear quadrat transect line. As many as 25 quadrants (10x10m) were used in both locations. Every individual of giant clams found in the quadrant was identified, photographed and counted. There were three species of giant clams found in Morella namely Tridacna crocea, T. maxima, and T. squamosa while four species were found in Suli i.e. those three species mentions earlier and Hippopus Hippopus. Totally, T. crocea had more individuals followed by T. squamosa and then T. maxima while the lesser belonged to H. Hippopus with one individual. Density of giant clams in Morella (428 ind./ha) was much higher than density of giant clams in Suli (48 ind./ha). Giant clams in Morella can be found in 16 - 19 quadrants of 25 quadrants used while in Suli only found in 1 - 6 quadrants. Ecological indexes for diversity, evenness and dominance showed that giant clams in Morella and Suli had moderate diversity, high evenness and low dominance.

Long-Term Volumetric Change Estimation of Red Ash Quarry Sites in the Afro-Alpine Ecosystem of Bale Mountains National Park in Ethiopia

The Bale Mountains National Park (BMNP) in Ethiopia comprises the largest fraction of the Afro-Alpine ecosystem in Africa, which provides vital mountain ecosystem services at local, regional, and global levels. However, the BMNP has been severely threatened by natural and anthropogenic disturbances in recent decades. In particular, landscape alteration due to human activities such as red ash quarrying has become a common practice in the BMNP, which poses a major environmental challenge by severely degrading the Afro-Alpine ecosystem. This study aims to quantify the long-term volumetric changes of two red ash quarry sites in the BMNP using historical aerial photographs and in situ data, and to assess their impact on the Afro-Alpine ecosystem. The Structure-from-Motion multi-view stereo photogrammetry algorithm was used to reconstruct the three-dimensional landscape for the year 1967 and 1984 while spatial interpolation techniques were applied to generate the current digital elevation models for 2023. To quantify the volumetric changes and landscape alteration of the quarry sites, differences in digital elevation models were computed. The result showed that the volume of resources extracted from the BMNP quarry sites increased significantly over the study period from 1984 to 2023 compared with the period from 1967 to 1984. In general, between 1967 and 2023, the total net surface volume of the quarry sites decreased by 503,721 ± 27,970 m3 and 368,523 ± 30,003 m3, respectively. The extent of the excavated area increased by 53,147 m2 and 45,297 m2 for Site 1 and 2, respectively. In terms of habitat loss, major gravel road construction inside the BMNP resulted in the reduction of Afro-Alpine vegetation by 476,860 m2, ericaceous vegetation by 403,806 m2 and Afromontane forest by 493,222 m2 with associated decline in species diversity and density. The excavation and gravel road construction have contributed to the degradation of the Afro-Alpine ecosystem, especially the endemic Lobelia rhynchopetalum on the quarry sites and roads. If excavation continues at the same rate as in the last half century, it can threaten the whole mountain ecosystem of the National Park and beyond, highlighting the importance of preventing these anthropogenic changes and conserving the remaining Afro-Alpine ecosystem.

Wave-breaking limit of electrostatic waves in two-temperature electron-positron plasmas

Wave-breaking limit of high frequency electrostatic waves in a four-component two-temperature electron-positron (EP) plasma has been studied. Using Sagdeevs pseudopotential approach, the wave-breaking limit in such plasmas has been derived, taking into account the dynamics of both the hot and cool species. It is observed that the value of the limit is diminished in a two temperature EP plasma in comparison to a single-temperature one. The analysis also reveals that the wave-breaking limit is greatly influenced by the ratio of the equilibrium density of the hot species to the equilibrium density of the cool species, and the temperatures of the two species of the plasma. The results of this investigation is expected to have applications in astrophysical and space-plasma environments.

Variations in macrofaunal communities along sand physico-chemical gradient across the intertidal zones on island beaches

Island beaches, once mistakenly considered as 'ecological deserts', are actually unique ecosystems that support abundant macrofaunal communities. However, limited studies have examined the variations and determinants of macrofaunal communities across the intertidal zones on island beaches, which is crucial for shedding light on the underlying ecological processes and enhancing biodiversity conservation efforts. Here, we explored the variations in macrofaunal communities along sand physico-chemical gradient across four intertidal zones on nine representative beaches, within the largest land-bridge archipelago in eastern China. Our findings revealed that species richness, density, and Shannon-Wiener diversity of macrofaunal communities were notably higher in the lower intertidal zones, exhibiting a positive correlation with elevated levels of sand moisture (M), electrical conductivity (EC), available potassium (AK), and grain size (GS). Conversely, macrofaunal Simpson diversity displayed an inverse pattern, with heightened values observed in the vegetation zone. The Saprophagous, Predaceous, and Omnivorous groups of macrofaunal communities demonstrated an increase with higher levels of EC, AK, and M in the lower intertidal zones. Furthermore, Phytophagous group of macrofaunal communities tended to inhabit the vegetation zones characterized by elevated levels of sand total phosphorus (TP), total nitrogen (TN), and organic carbon (OC). Primarily, our findings indicate that sand nutrition, moisture, and salinity play pivotal roles in shaping the variations of macrofaunal communities on island beaches. These insights offer valuable perspectives into the holistic responses of macrofauna on island beaches to changes in sand physico-chemical properties, serving as a crucial theoretical foundation for the assessment, conservation, and restoration of island beaches.

Evaluating Relationship between Surface Water Quality and Zooplankton Diversity in Coastal Areas of Tien Giang Province, Vietnam

The zooplankton diversity is the most important ecological parameter for water quality assessment, as these small creatures are sensitive to any changes in water quality, hence the objective of this study as to evaluate the relationship between surface water quality and zooplankton diversity in the coastal areas of Tien Giang province, Vietnam using appropriate standard methods. The results showed that the coastal water quality had high concentrations of suspended solids, ammonium and coliforms. A total of 71 zooplankton species with a total density ranging from 3,219,383 to 24,993,634 individuals/m3 were identified. Among the zooplankton species, Copepoda nauplius appeared at all monitoring stations, predominating with a density ranging from 740,800 to 7,555,250 individuals/m3. The values of the Shannon-Wiener diversity index (H') ranged from 1.54 to 2.37, reflecting the coastal water quality in the study area from polluted to mildly polluted. The coastal water variables of pH, salinity, DO, NH4+-N and coliform were closely correlated with the density of zooplankton species. The relationship between surface water quality and zooplankton diversity could be a basis for selecting biological indicators to monitor coastal water quality.

Streamer propagation characteristics of nanosecond pulsed discharge plasma on fluidized particles surface: experimental investigation and numerical simulation

Plasma fluidized-bed contributes to strengthening the interaction between active species in plasma and fluidized powder particles, resulting in higher active species utilization efficiency and superior powders processing/modification performance. However, the plasma streamer dynamics on the fluidized powder particles are still unclear due to the intricacy of plasma fluidized-bed. In this work, the time-resolved evolution behavior of plasma streamers on fluidized powder particles surfaces has been explored in plasma fluidized-bed system based on a simplified pin-cylinder configuration. The results reveal that the entire streamer propagation process includes volume discharge and surface discharge. The maximum electron density generated by surface discharge is one order of magnitude higher than that produced by volume discharge, indicating that surface discharge plays a dominant role in powder particles modification. The presence of fluidized particle will cause streamer branching, and the main streamer splits into two independent sub-streamers for propagation in a ‘parabola-like’ shape. Compared with large-size fluidized particles (1000 µm), streamer wraps a larger area on micron-size fluidized particles (200 µm), with a 78% increase in the coverage area, which is favorable to the modification of powder particles. Furthermore, the evolution of active species on fluidized particle surface is analyzed. The active species (N, O, O2 −) are mainly distributed around the north pole, and N2 + is mainly distributed between 25° and 50° of the particles. With the decrease of fluidized particle size, the polarization effect between particles is significantly enhanced, and the maxima of the number densities of active species increase. These findings help to get a better understanding of the interaction between plasma and fluidized particles in fluidized systems.

Increased density of conspecifics caused niche contraction in a multispecific passerine assemblage.

Competition is a prominent mechanism driving population dynamics and structuring community assemblage, which can be investigated by linking shifts in species' ecological niche and the densities of sympatric species because the ecological release from competitive constraints is a density-dependent process. In this work we determine how a steppe passerine community segregates their ecological niches and evaluate the role of competition in inducing changes in the ecological niche of species. We built multidimensional ecological niches (with Gaussian kernel density estimators) using data on the habitat features used by 10 bird species collected from seven sites in the natural steppes of Central Spain over 2 consecutive years. We computed distance and niche similarity metrics to explore the ecological niche partitioning of the bird community. Next, we ran multivariate linear regression models to evaluate the effects of conspecific and heterospecific density (as proxies of intraspecific and interspecific competition, respectively) on niche breadth and/or position of the three most abundant species. We found low niche overlap in the community assemblage but varying levels of niche similarity among pairs of species, which could increase the likelihood of current competition operating in the community. However, we found no effect of heterospecific density on niche breadth or position, although conspecific density was negatively related to niche breadth. Contrary to predictions of competition theory, increased density of conspecifics caused niche contraction. Our results from a multispecies system contribute to advanced knowledge of the biotic mechanisms structuring wildlife communities within the framework of ecological niche theory.

Seagrass Meadow Conditions in Coastal Waters of Siwak Bay Central Lombok

Seagrass is a flowering plant thriving in shallow sea waters and estuaries. Seagrass ecosystems are essential in supporting life in shallow seas as primary producers, biota habitats, sediment trappers, and nutrient trappers. Environmental factors affecting seagrass growth include temperature, salinity, pH, and substrate. The study was conducted in March-June 2023. This study aimed to determine the type and condition of seagrass beds in the waters of Siwak Bay. The method used in this study is the quadrant transect method at three research stations. There are seven types of seagrass identified, namely Thalassia hemprichii, Halophila ovalis, Cymodocea rotundata, Cymodocea serrulata, Halodule pinifolia, Halodule uninervis, and Syringodium isoetifolium. The percentage of total seagrass cover is at a value of 37%-61%, indicating that the condition of seagrass beds in the waters of Siwak Bay is included in the unhealthy category. The highest species density found at station III in Halodule pinifolia was 483.5 stands/m², and the lowest was found at stations II and III in Thalassia hemprichii and Cymodocea serrulata with 0 stands/m². The average density value of seagrass beds in the waters of Siwak Bay is very dense. The highest type frequency was found in Cymodocea rotundata, with a value of 2.53. The tallest species diversity and diversity index was found at station II with values of 1.56 and 0.8, respectively. In contrast, the highest dominance index was found at station I, with a value of 0.44.

Macrobenthic fauna and the ecological status of a shellfish farm in the Mediterranean Sea (Algeria)

A faunistic and ecological study on the benthic macrofauna was carried out in the shellfish farm in Ain Chorb (Ain Taya), central Algeria. This study aims to characterise the composition, structure, and functioning of the benthic community to establish the reference state and ecological quality of the shellfish farm and to monitor its evolution through an adapted sampling and observation methodology adapted and used by the scientific community at the international level. Benthic fauna samples were collected in two different periods (warm and cold season) between February 2020 and June 2021; six grab samples were carried out at three sampling stations. Different indices were evaluated based on the benthic community characteristics (species richness, abundance, density, ecological and trophic groups, and the biotic index) and indicator species. An inventory of the macrobenthic fauna of the farm allowed us to identify 6 phyla, 10 classes, 48 families, 106 genera, and 138 species, with a total of 45960 ind/m2. The benthic assemblage is characterised by the dominance of the species Abra alba, Salvatoria clavata, Caecum spp., and Bittium spp. The results of the four benthic indices (the Shannon-Weaver diversity index [H′], the AZTI Marine Biotic Index [AMBI], the multivariate AZTI Marine Biotic Index [M-AMBI], and the BENTIX) indicated that that the sampling stations have a moderate and good ecological status. These results were confirmed by the abundance/biomass comparison curves and geometric abundance class methods. This study provides the first inventory and represents the reference state of the soft-bottom communities of the aquaculture farm. The findings also indicate that the macrobenthic assemblage is excellent indicator of the ecological status.

Stereo-video landers can rapidly assess marine fish diversity and community assemblages

Climate change and anthropogenic stressors affect the distribution, abundance, and diversity of fish communities across the world. To understand rapidly changing biotic communities, resource managers need a method to quickly and efficiently document temporal and spatial changes in community assemblages across various spatial scales. In this study, we describe the use of new video lander tools to survey fish communities in rocky marine habitats on the continental shelf and slope in California, USA. We evaluate how fish diversity metrics determined by video surveys vary among geographically distinct areas. Our results demonstrate that species diversity, evenness, and richness vary spatially across the coast. Furthermore, community assemblages differ at both broad and fine spatial scales because of differences among habitats. Length frequencies and densities of species in this study were similar to those reported in previous studies. As community assemblages and biodiversity metrics shift in response to changing stressors, it is increasingly important to develop tools and methodologies to detect and rapidly monitor these changes.

Biodiversity of intertidal mollusks in Surigao City, Philippines

Intertidal zones are crucial ecological interfaces, but there is a lack of comprehensive studies on mollusk communities in Surigao City, Philippines. This research aimed to assess intertidal mollusk profiles, including species density, diversity, evenness, and richness, addressing a knowledge gap in regional mollusk biodiversity. Using a belt transect quadrat method in three sampling areas during 2021, the study employed a descriptive correlation design to investigate relationships between mollusk profiles and seawater physico-chemical parameters (conductivity, dissolved oxygen, pH, salinity, and temperature). In Surigao City's Day-asan, Hikdop Island, and Sibale, 44 gastropod species (19 families) and 11 bivalve species (9 families) were identified. Conidae and Strombidae families dominated. Average seawater parameters were conductivity 51.33, dissolved oxygen 7.45, pH 7.84, salinity 32, and temperature 28.52. Day-asan exhibited the highest species count (49), followed by Hikdop Island (42) and Sibale Island (37). Hikdop Island had the highest species density and evenness, Day-asan had the highest species diversity index, and Sibale Island had the highest species richness. Mollusk profiles showed no significant differences between sampling areas, and a strong negative correlation between pH and species evenness was observed. Surigao City displayed diverse mollusk biodiversity, but a declining trend in diversity indices was noted. This study fills a critical knowledge gap in understanding mollusk community dynamics, providing essential baseline data for future conservation and management strategies in the region, while also shedding light on the impact of environmental factors on intertidal mollusk populations in Surigao City.

Developing Multifunctional Fe-Based Catalysts for the Direct Hydrogenation of CO2 in Power Plant Flue Gas to Light Olefins

The hydrogenation of carbon dioxide (CO2) to produce light olefins is one of the most promising ways to utilize CO2 in power plant flue gas. However, the low concentration of CO2 (~10%) and the existence of water steam in the flue gas pose great challenges for the catalyst design. To address these problems, we introduced a Mg promoter and hydrophobic component into the Fe-based catalyst to improve the CO2 adsorption capacity and weaken the negative effects of water. The yield of light olefins on an optimized multifunctional Fe-based catalyst increased by 37% in low-concentration CO2 hydrogenation with water steam. A variety of characterizations proved that the Mg promoter played critical roles in regulating the adsorption capacity of CO2, increasing the surface electron density of Fe species, and promoting the formation of iron carbide active sites. The hydrophobic component mainly contributed to constraining the oxidation of iron carbides via water steam. It benefited from the rational design of the catalyst, showing how our multifunctional Fe-based catalyst has great potential for practical application in CO2 utilization.

Biomechanical adaptations enable phoretic mite species to occupy distinct spatial niches on host burying beetles.

Niche theory predicts that ecologically similar species coexist by minimizing interspecific competition through niche partitioning. Therefore, understanding the mechanisms of niche partitioning is essential for predicting interactions and coexistence between competing organisms. Here, we study two phoretic mite species, Poecilochirus carabi and Macrocheles nataliae that coexist on the same host burying beetle Nicrophorus vespilloides and use it to 'hitchhike' between reproductive sites. Field observations revealed clear spatial partitioning between species in distinct host body parts. Poecilochirus carabi preferred the ventral side of the thorax, whereas M. nataliae were exclusively found ventrally at the hairy base of the abdomen. Experimental manipulations of mite density showed that each species preferred these body parts, largely regardless of the density of the other mite species on the host beetle. Force measurements indicated that this spatial distribution is mediated by biomechanical adaptations, because each mite species required more force to be removed from their preferred location on the beetle. While P. carabi attached with large adhesive pads to the smooth thorax cuticle, M. nataliae gripped abdominal setae with their chelicerae. Our results show that specialist biomechanical adaptations for attachment can mediate spatial niche partitioning among species sharing the same host.

Controlled synthesis of NO in an atmospheric pressure plasma by suppressing NO destruction channels by plasma catalysis

NO synthesis using plasma catalysis is analyzed in a parallel-plate atmospheric pressure RF plasma from N2/O2 admixed to helium exposed to Fe and Pt catalysts on a SiO2 support. The NO x species are measured by Fourier-transform infrared spectroscopy in a multi-pass cell. The trends in species densities can be well explained by air chemistry reactions, where NO’s progressive oxidation occurs with increasing oxygen admixture and ozone generation. The sequence can be controlled by the state of the surface that preferentially quenches O3 and allows for an optimum NO production. The maximum production of NO is found at 70% N2/(N2+O2) mixture ratio at 120 ∘C using sandblasted glass, with a conversion rate of 0.085%.

Evolutionary causes of global patterns of species richness in regional fern floras across the world

AbstractAimGlobally, biodiversity is unevenly distributed, as a result of varying environmental conditions and regionally different historical processes. The influence of the latter on current diversity patterns is poorly understood. We explore geographic patterns of matches and mismatches between phylogenetic relatedness metrics measuring different depths of evolutionary history and investigate the effects of evolutionary legacy at different evolutionary depths on species density of ferns.MethodsWe divided the globe into 392 geographic regions on land, and collated species lists of ferns for each geographic region. We related species richness to phylogenetic metrics reflecting different depths of evolutionary history (standardized effect sizes of mean nearest taxon distance and mean pairwise distance, MNTDses and MPDses, respectively) for ferns in regional floras across the world.LocationGlobal.Time PeriodCurrent.TaxonFerns.ResultsWe show that different centers of fern diversity have strikingly different phylogenetic composition. We find that overall fern species diversity is negatively correlated with both MNTDses and MPDses, so that regions with high species diversity tend to have clustered species assemblages, whereas species‐poor regions tend to have overdispersed species assemblages. At the global extent, MNTDses and MPDses together explained 62.2%, 19.3%, and 65.7% of the variation in species diversity for all ferns as a whole, non‐polypod ferns, and polypods, respectively.Main ConclusionsOur study suggests that current geographic patterns of fern species richness are driven, at least in part, by evolutionary history of ferns, which varies among biogeographic regions.

Structural variation of ant nests mediates the local distribution and abundance of an associate

AbstractSymbionts form intricate associations with their hosts. They can only establish when potential hosts are present, but in addition, their distribution is often influenced by microhabitat preferences, which may not overlap those of their hosts. This leads to a patchy local distribution of the symbiont, being present with some hosts and absent with others. We studied this effect of microhabitat preferences on symbiont distribution by examining the occurrence and density of the obligately ant‐associated springtail Cyphoderus albinus Nicolet (Collembola: Paronellidae) across a mosaic of ant nests. Nest structure strongly varied both within and between ant species and included sand, dead wood, arboreal and thatch mound nests. We hypothesized that the symbiotic springtail would show the strongest preference for thermoregulated and organic‐rich nests such as thatch mounds. The springtail was found in all thatch mound nests of red wood ants and in all arboreal nests of Lasius fuliginosus (Latreille). A high occurrence (75%) was recorded in the smaller thatch nests of Formica sanguinea Latreille. Lasius, Myrmica and Formica species exhibited variation in nest structures on the ground, establishing nests in both sand and wood. For each of these three host taxa, encountering the springtail was more likely in their wood nests (medium‐to‐high occurrence), than in their sand nests where the occurrence was low. Nest structure did not only impact springtail occurrence, but their densities as well. The densities within thatch nests were much higher than those in other nest types, achieving the highest densities (1148 individuals per litre of nest material) observed for a social insect symbiont. Our findings emphasize that host nests with wood structures and thatch material provide a more favourable habitat for the springtail compared with soil nests. Overall, this study underscores the role of microhabitat variation in the spatial distribution and density of a symbiotic species.

Effects of land-use intensity on vegetation dynamics across elevation in Savanna Grassland, Southern Ethiopia

The rangeland ecosystem is currently one of the area’s most sensitive to biodiversity because of both natural and human effects. There is still much to learn about the sustainable management of dry and semi-arid rangelands in order to protect their rich biodiversity resources. This is due to the uncertain indirect effects of environmental factors, such as dryness, on vegetation species, which are mediated by shifting both living and non-living components. The purpose of this project was to ascertain the effects of land use intensity (LUI) on the various species of rangeland flora along the elevation gradient in the Borana Rangeland. We gathered a total of 37 plant species, comprising 22 grasses, 7 graminoids, and 8 forbs, from the nine sampling locations, which were exposed to LUI and included three locations within each elevation range of 500–900, 1000–1400, and 1500–1900 m.a.s.l. At every sampling site, we evaluated the dynamics of the plant species, taking into account their diversity, richness, percentage of undesirable species, and properties of the soil. We used structural equation modeling (SEM) to examine the effects of LUI on the different vegetation species along the elevation gradient. We found that the density and diversity of vegetative species decreased and the fraction of undesired species increased as elevation climbed (from lower to higher). Because of the heavy livestock grazing, these impacts were substantially linked with high LUI at lower elevations. According to our research, the complex relationships between elevation gradient and LUI have a big influence on the diversity and density of the flora. This demonstrates that we need to account for environmental gradients in order to generalize LUI's effects on rangeland biodiversity. This study sheds important light on the complex interactions between vegetation dynamics and LUI in savanna grasslands. To create practical strategies for maintaining ecosystem health and biodiversity in the Southern Ethiopian Savanna Grasslands, policymakers, environmentalists, and land managers should take these findings into account.