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Background Knowledge of the distribution and habitat preference of freshwater snail intermediate hosts can provide information to initiate and set-up effective snail control programmes. However, there is limited research conducted on the factors driving the occurrence and abundance of freshwater snail intermediate hosts in the Ethiopian Rift Valley. Hence, in this study, we investigated how environmental and biotic factors influence the occurrence and abundance of the snail intermediate hosts in Ethiopian Rift Valley region. Methods Data on freshwater snails, physico-chemical water quality parameters, physical characteristics of habitat, predators and competitors, and anthropogenic activity variables were collected from 174 sampling sites during the wet season of 2017 and 2018. Generalized linear models were used to identify the main environmental and biotic factors affecting the occurrence and abundance of the snail species. Results It was found that Bulinus globosus (31.7%) was the most abundant snail species followed by Lymnaea natalensis (21.6%), Lymnaea truncatula (15.1%) and Biomphalaria pfeifferi (14.6%). Generalized linear models indicated that physico-chemical parameters (water temperature, turbidity, chlorophyll- a , dissolved oxygen, chemical oxygen demand, alkalinity, calcium, magnesium, nitrate and ammonia), physical habitat characteristics (water depth, canopy cover, macrophyte cover and substrate type) and biotic factors (abundance of predators and competitors) were found to be the main variables determining the occurrence and abundance of snail species in the Ethiopian Rift Valley region. In terms of anthropogenic activities, human settlement, farming, bathing and swimming, clothes washing, grazing, drainage of land, car washing, boating, fishing and silviculture were also important variables determining the occurrence and abundance of snail species in the region. Conclusions The findings reported herein suggest that integrated snail control strategies should be considered to control snails via protection of water bodies from disturbance by anthropogenic activities. In this way, it is possible to reduce the concentration of organic matter and dissolved ions in aquatic ecosystems which are conducive for the presence of snails.

Soil microbiomes are extremely complex, with dense networks of interconnected microbial species underpinning vital functions for the ecosystem. In advanced agricultural research, rhizosphere microbiome engineering is gaining much attention, as the microbial community has been acknowledged to be a crucial partner of associated plants for their health fitness and yield. However, single or combined effects of a wide range of soil biotic and abiotic factors impact the success of engineered microbiomes, as these microbial communities exhibit uneven structural and functional networks in diverse soil conditions. Therefore, once a deep understanding of major influential factors and corresponding microbial responses is developed, the microbiome can be more effectively manipulated and optimized for cropping benefits. In this mini-review, we propose the concept of a microbiome-mediated smart agriculture system (MiMSAS). We summarize some of the advanced strategies for engineering the rhizosphere microbiome to withstand the stresses imposed by dominant abiotic and biotic factors. This work will help the scientific community gain more clarity about engineered microbiome technologies for increasing crop productivity and environmental sustainability.Key points• Individual or combined effects of soil biotic and abiotic variables hamper the implementation of engineered microbiome technologies in the field.• As a traditional approach, reduced-tillage practices coinciding with biofertilization can promote a relatively stable functional microbiome.• Increasing the complexity and efficiency of the synthetic microbiome is one way to improve its field-application success rate.• Plant genome editing/engineering is a promising approach for recruiting desired microbiomes for agricultural benefit.

Abstract Vindoline is an important alkaloid produced in Catharanthus roseus leaves. It is the more important monomer of the scarce and costly anticancer bisindole alkaloids, vincristine, and vinblastine, as unlike catharanthine (the other monomer), its biosynthesis is restricted to the leaves. Here, biotic (bacterial endophyte, phytoplasma, virus) and abiotic (temperature, salinity, SA, MeJa) factors were studied for their effect on vindoline accumulation in C. roseus. Variations in vindoline pathway-related gene expression were reflected in changes in vindoline content. Since allene oxide cyclase (CrAOC) is involved in jasmonate biosynthesis and MeJa modulates many vindoline pathway genes, the correlation between CrAOC expression and vindoline content was studied. It was taken up for full-length cloning, tissue-specific expression profiling, in silico analyses, and upstream genomic region analysis for cis-regulatory elements. Co-expression analysis of CrAOC with vindoline metabolism-related genes under the influence of aforementioned abiotic/biotic factors indicated its stronger direct correlation with the tabersonine-to-vindoline genes (t16h, omt, t3o, t3r, nmt, d4h, dat) as compared to the pre-tabersonine genes (tdc, str, sgd). Its expression was inversely related to that of downstream-acting peroxidase (prx) (except under temperature stress). Direct/positive relationship of CrAOC expression with vindoline content established it as a key gene modulating vindoline accumulation in C. roseus.

Broad-leaved deciduous forests in the transitional region from temperate to subtropical climate in China exhibit a diverse assemblage of species. The effects of potential biotic and abiotic factors on forest species diversity are currently of great interest. Here, we quantified the diversity of woody plant species across vertical strata in a fully recorded 25-ha permanent forest dynamics plot (500 × 500 m) in the Mts. Qinling of China using 4 indices: Pielou evenness index (JSW), Shannon entropy (H), species richness (S), and species abundance. Analysis of multivariate linear regression was employed to compare the influences of potential biological, topography, and soil variables on the alpha diversity for each of the 625 sub-plot (20 × 20 m) in the canopy layer, substory layer, and understory layer. The results displayed that the indices of the alpha diversity significantly varied among different forest vertical strata and they were mostly and significantly related to the DBH structure variable, soil available phosphorus (P), and altitude. Despite vertical strata of the studied forest, biological, topographic, and soil factors jointly showed reasonably strong explanatory power for species diversity. More than 12% of the variations of the alpha diversity in canopy layer and 16% in substory layer as well as 8% in understory layer could be collectively explained by biological, topographic, and soil factors. Our findings can contribute to the understanding of how environmental and biological factors interact to affect species diversity and thus are of great implication for the preservation of forest species diversity.

Key messageKorean pine trees expressed significant crown displacement. Nearest neighbor competition had the largest effect on the crown displacement compared to the slope direction and mean direction of wind.The crown displacement of individual trees exhibits an adaptive response driven by neighbors, but it can also be the result of wind force and slope effects. In our research, we focused on the crown displacement of planted Korean pine trees in northeast China. A total of 51 trees aged 8–56 years were destructively harvested to measure branch attributes. The gravity centers of the upper, lower and entire crown were calculated. The Markov chain Monte Carlo (MCMC) algorithm, generalized mixed effects model, and circular statistics were used to determine the response of crown displacement to biotic and abiotic factors. The results showed that the dominant tree had the largest absolute crown displacement, and the suppressed tree expressed the largest relative crown displacement. The lower crown showed more apparent crown displacement than the upper crown. The Korean pine was displaced in a northeastern direction. Nearest neighbor competition had the largest effect on the crown displacement compared to the slope direction. Slope direction had a slightly larger effect than the mean direction of wind. The crown displacement for the lower crown was more affected by the interaction of the wind, slope and neighbor competition than the upper crown. No relationship between crown displacement and stem eccentricity for the planted Korean pine was detected.

This paper reviews more than 40 journal articles that describe the traits of phytoplankton functional groups (FGs) and their responses to biotic and abiotic factors in freshwater environments. Scholars have used different approaches with varying assumptions, making it necessary to subject the available information to a modest review. The paper sheds light on the potential responses of phytoplankton assemblages to biotic factors such as allelopathy, vertical migration, prey-predator interactions, macrophytes dominance, zooplankton grazing, and abiotic factors such as nutrient deficiency, turbulence and mixing processes, light, and temperature. It also highlights the status of studies on phytoplankton FGs in Ethiopian water bodies. While FGs have relevant applications in ecosystem assessment and monitoring, the difficulties faced are briefly discussed.

Lianas are a crucial component of karst seasonal rainforests, yet research on them has predominantly focused on non-karst regions. Consequently, their abundance and species richness remain relatively understudied within karst ecosystems. We aimed to document the abundance and species richness of lianas and investigate their relationships with abiotic and biotic factors, based on data from a fully mapped 15 ha plot in a karst seasonal rainforest of Nonggang (SW China). Structural equation models (SEMs) were employed to estimate the path coefficients and variation of dependent variables, enabling a comprehensive analysis of the factors affecting the abundance and species richness of liana. Within the 15 ha plot, a total of 23,819 lianas were identified, encompassing 113 species from 34 families. These lianas constituted 24.16% of the total woody plant density and 33.44% of the species present, but only 4.32% of the total woody plant basal area. Lianas are primarily influenced by abiotic factors, especially elevation and phosphorus (P), with less impact from biotic factors. Our findings reveal that lianas, despite constituting a relatively small percentage of the total woody plant basal area, significantly contribute to the density and diversity of the forest. Notably, abiotic factors such as elevation and phosphorus availability predominantly shape the distribution and richness of lianas, highlighting the importance of these environmental variables. The findings offer valuable insights for future liana studies and the preservation of karst forests’ biodiversity.

Marine parasite communities can exhibit temporal and spatial changes in response to seasonal and local variations in several biotic and abiotic environmental factors. Limited attention has been given to the influence of abiotic factors, so their effects on parasite community structure remain unclear. A total of 496 specimens of Euthynnus lineatus were collected over a 7-year period (2012–2018) from Acapulco Bay, Mexico. Their parasite communities were analyzed to determine if they experience interannual variations due to local biotic and abiotic factors. Thirty-three metazoan parasite species were recovered and identified: four species of Monogenea (adults); 16 of Digenea (one larvae and 15 adults); two of Acanthocephala (adults); two of Cestoda (larvae); three of Nematoda (two larvae and one adult); and six of Crustacea (three Copepoda, and three Isopoda). Species richness was greatest among the digeneans, which represented 48% of the total species recovered, followed by the crustaceans (19% of total species). Species richness at the component community level (14–24 species) was similar to reported richness in other small tuna species. The component communities and infracommunities of E. lineatus exhibited a similar pattern: high species richness and diversity, and numerical dominance by a single species, mainly by one of the didymozoids Allopseudocolocyntotrema claviforme or Pseudocolocyntotrema yaito. Parasite community structure and species composition varied among sampling years. Variations were possibly caused by a combination of abiotic and biotic factors which generated notable changes in the infection levels of several component species during the study period. These communities may therefore be unpredictable in terms of structure and species composition, as has been suggested for other communities of marine parasites.

Understanding how geomorphic landscape features affect physical habitat conditions is essential for predicting if such geomorphic landscape features may act as conduits facilitating invasive species expansion in coastal ecosystems. Although the effects of various abiotic and biotic factors on plant invasion in salt marshes have been well studied, little is known about the impact of tidal channels on plant invasion. Here, we examined the effects of bottom-up determinants on the lateral expansion of Spartina alterniflora in tidal channel margins of different elevational marsh zones: the low, middle and high marsh, in the Yellow River Delta, China. Field observations and experiments showed that the microhabitats of tidal channel margins are characterized by relatively low soil salinity and high inundation, which significantly facilitated the establishment, growth, colonization and sexual reproduction of S. alterniflora. Moreover, the facilitating effect of tidal channel margins on plant landward invasion appeared more sensitive in middle and high marshes compared with the low marshes. High propagule pressure combined with suitable physical conditions of the structural microhabitats formed within tidal channels potentially promoted the rapid expansion of S. alterniflora along the tidal channel margins. Based on these results, a conceptual model was built illustrating the lateral expansion mechanisms of the invasive plant mediated by tidal channels. These results highlight the importance of tidal channel-mediated gradients in bottom-up abiotic and biotic-dispersal factors in facilitating the expansion of coastal invasive plants. For wetlands management, our results imply that geomorphic landscape features should be incorporated into ecological management and risk assessment of invasive plants.

Background Understanding variations in tree mortality and survival is essential to interpreting community dynamics and demographic processes. Tree size and both biotic and abiotic factors are among the local-scale drivers proposed to be essential to explain patterns of tree survival. However, detailed studies of their actual importance are lacking, particularly in tropical dry forests. Methods We investigated the influence of local topographic (i.e., abiotic) and biotic factors on tree survival at the community, guild, and species levels using data from a 4 ha (200 m × 200 m) permanent plot established in a mixed deciduous tropical dry forest at the Mae Klong Watershed Research Station, western Thailand. Censuses were conducted within the plot in December every 2 years from 1994 to 2022, in which tree mortality was assessed and measurements were performed on all trees with diameter at breast height ≥ 2 cm. Factors influencing tree survival were analyzed using a generalized linear mixed model. Results We found that tree size was the most important factor influencing tree survival, with a significant positive relationship for all but the largest trees. Among abiotic factors, only elevation had a significant positive effect on the longevity of shade-tolerant species. Of the biotic factors examined, tree density and total basal area significantly impacted tree survival in certain guilds and/or species. Conclusions Overall, the relative significance of factors influencing tree survival patterns in these tropical dry forests differed significantly across species guilds, tree size classes, and shade tolerance groups. These findings inform forest management in the study region and offer essential data for further research on forest dynamics.