Community Composition In Response Research Articles

Role of soil biotic and abiotic properties in plant community composition in response to nitrogen addition

AbstractNutrient addition can alter plant–soil‐microbe interactions. However, knowledge remains limited about how the soil biotic and abiotic properties drive changes in plant community composition and diversity after nitrogen (N) addition. In this study, four N addition rates (N0, N3, N6, and N9: 0, 3, 6, and 9 g N m −2 yr−1) were applied to a grassland community on the Loess Plateau (China) to evaluate the response of plant community biomass, evenness, and composition to N addition. Overall, N addition significantly increased plant shoot and root biomass by 27.75%–31.37% and 39.60%–65.42% compared with N0, but no significant difference was observed among N3, N6, and N9. N addition significantly decreased shoot/root biomass ratio by 7.17%–21.84%, and plant community evenness by 3.80%–8.80% compared with N0, particularly under N3 and N6 treatments. Furthermore, N addition enhanced the abundance of bacteria and fungi, but their composition was not altered. Responses of plant biomass and evenness to N addition were correlated to changes in NO3−‐N, soil total phosphorus, and the abundance of bacteria and fungi; additionally, the composition was primarily affected by the microbial abundance. Our research indicates that N addition can significantly alter plant community composition, particularly at low addition rates, and such alteration may be more affected by the soil microbial abundance. The findings of this study have important implications for the sustainable management of grassland ecosystems.

History predicts contemporary community diversity within a biogeographic province of freshwater fish

AbstractAimHistorical biogeography and community ecology both seek to uncover the patterns and processes governing the structure and composition of communities, though typically at different temporal and spatial scales. Recent work has called to integrate these two fields; however, it is typically assumed that history plays little role in assembling contemporary, local communities. We incorporated phylogeographic data into traditional metacommunity analyses of freshwater fish communities to analyse if history can shape local community structure.LocationStreams in the Nicaraguan Depression in north‐eastern Costa Rica.TaxonFreshwater fish communities.MethodsWe sampled community composition in 14 streams of the San Juan River Basin during the dry season of 2019 and evaluated variability in community composition in response to local and landscape‐scale environmental variability, spatial distance and historic processes using redundancy analyses. We measured environmental and spatial variables using typical methods utilized in metacommunity studies and approximated the effects of history with samova genetic groupings of three livebearing fishes native to the area. We also used PERMANOVAs to test if community composition exhibits similar spatial structure as seen in the genetic data of the three livebearing fishes used as historical proxies.ResultsLarge‐scale patterns of genetic diversity predicted the patterns of local community diversity with community composition showing similar spatial structuring. Additionally, history variables were the only variables that significantly explained community composition and accounted for 20.6% of the total variability.Main ConclusionsSpecies‐specific incidence patterns within Costa Rican freshwater fish communities vary according to biogeographic history, indicating that history can impact local community assembly. These observed patterns are likely due to colonization history following eustatic sea level change. Phylogeography can bridge the gap between classical biogeography and community ecology by enhancing inferences regarding community assembly through time and space, therefore studies should incorporate both genetic and local community data when assessing community assembly.

Comparison of bacterial and fungal diversity and network connectivity in karst and non-karst forests in southwest China

Microbial communities contribute to sustaining the function of terrestrial ecosystems and are influenced by soil type and climate gradients. The effects of karst and non-karst soils on bacterial and fungal profiles for seven climate gradients were assessed to better understand bacterial and fungal diversity and community composition in response to soil type with changes in soil physicochemical properties under different temperatures and precipitations. Bacterial and fungal abundance, diversity, and community composition differed between karst and non-karst forests. Bacterial and fungal richness, Shannon index, and bacterial abundance in karst forests were higher than non-karst forests, but the fungal abundance was lower. Mean annual temperature was negatively correlated with bacterial diversity in the karst forest and fungal abundance in karst and non-karst forests. The community composition of bacteria and fungi differed among these two soil types. The karst forest had greater connectivity among bacterial and fungal communities than non-karst forests. The bacterial members of Acidobacteria, Proteobacteria, Actinobacteria, and fungal groups of Ascomycota and Basidiomycota were mainly connected with other taxa in the network, implying that taxa were associated with highly functional potential. The relative abundance of Actinobacteria and Ascomycota was higher in karst than in non-karst forests. Proteobacteria and Basidiomycota showed the opposite results. A random forest and multiple regression tree analyses revealed that soil properties, specifically pH, calcium, and total nitrogen, were the main factors influencing the variation in bacterial and fungal profiles between karst and non-karst forests. This study provides novel evidence that the abundant microbial taxa were kinless hubs in co-occurrence patterns. Controlling complex networks of species interactions may contribute to improving soil nutrient processes rather than microbial diversity, enhancing our understanding of developing sustainable recovery strategies in fragile ecosystems.

Establishing the relationship between benthic macroinvertebrates and water level fluctuation in subtropical shallow wetlands.

Wetland water level fluctuations often influence benthic macroinvertebrate communities through changes in water quality, substrate, and macrophytes and, hence, affect the structure and function of aquatic ecosystems. However, there is lack of understanding on how water level fluctuations affect the structure and composition of benthic macroinvertebrates in subtropical shallow wetlands in Nepal. Here, we assessed the changes in benthic macroinvertebrate community composition in response to water level fluctuations and identified indicator taxa sensitive to such fluctuations. A study was conducted over 4 seasons covering one annual cycle of water level fluctuation in 4 wetlands of Koshi Tappu Wildlife Reserve, Nepal. The study revealed that benthic macroinvertebrate composition significantly differed across water levels. Dissimilarities in macroinvertebrate community composition were mainly attributed by families Atyidae, Dytiscidae, Baetidae, Planorbidae, Chironomidae, Bithyniidae, Sphaeriidae, and Thiaridae. Taxon specific richness, densities, and biomass varied across the water levels while no difference was documented for overall family richness, density, and biomass. Ephemeroptera and Trichoptera richness decreasedwhen water levels were low while Coleoptera and Diptera richness increased. Medium water level supported high benthic macroinvertebrate diversity. Indicator taxa analysis identified Coleoptera: Hydrophilidae and Dytiscidae, Hemiptera: Pleidae, Diptera: Muscidae and Mollusca: Sphaeriidae, Viviparidae, and Thiaridae, as indicators of low water level. Similarly, Coleoptera: Scirtidae, Hemiptera: Micronectidae and Oligochaeta: Tubificidae as indicators of medium water level, and Trichoptera: Polycentropodidae and Ephemeroptera: Caenidae as indicators of high water level. Redundancy analysis identified water level as one of the most influencing factors in benthic macroinvertebrate community variation. Considering the significant response of benthic macroinvertebrates to water level fluctuations, theyare important as ecological indicators in research aimed at developing environmental flow frameworks. Indicator speciesare likely to be a vital tool in environmental impact assessment and monitoring in relation to hydrological development. The outcomesof this research have important implications to conservation and management of wetlands to preserve the valuable ecosystem functions provided by wetlands.

Arbuscular mycorrhizal fungal community structure following different grazing intensities in an alpine grassland

AbstractGrazing alters the plant communities, soil properties, and habitat conditions of the alpine grassland. Arbuscular mycorrhizal fungi (AMF) are involved in the nutrient cycling of grassland ecosystems and form a mutual symbiosis with their host plants. Thus, AMF are sensitive to the impact of livestock grazing. However, the effects of grazing intensity on the AMF community composition and the association between AMF and environmental factors, such as soil physicochemical properties, enzyme activity, and glomalin‐related soil proteins, remain unclear. Here, the response of the soil AMF community to grazing intensity gradients (i.e., light, moderate, and heavy grazing) was studied in an alpine grassland on the Qinghai‐Tibet Plateau. The dominant AMF families included Glomeraceae, Gigasporaceae, Claroideoglomeraceae, Diversisporaceae, and Ambisporaceae. Significant shifts in the AMF community composition in response to grazing intensity were found in both surface and subsurface soils. Soil C/N ratio, plant diversity, soil compactness, chitinase activity, aboveground biomass, total N, soil moisture, and NO3−–N significantly correlated with changes in the AMF community composition. Heavy grazing intensity was associated with the highest AMF alpha diversity, whereas moderate grazing intensity had the lowest AMF alpha diversity in both surface and subsurface soils. Grazing intensity, dominant plants, soil C and N concentrations, and soil compactness were significantly correlated with AMF diversity. These results demonstrated a significant response of the AMF community to grazing intensity, suggesting that plants increase their reliance on AMF symbioses with higher alpha diversity in the heavily degraded alpine grasslands of the Qinghai‐Tibet Plateau.

Response of Soil Fungal Diversity and Community Composition to Varying Levels of Bamboo Biochar in Red Soils.

Soil fungi play a vital role in soil nutrient dynamics, but knowledge of their diversity and community composition in response to biochar addition into red soil is either limited or inconsistent. Therefore, we determined the impact of bamboo biochar (BB) with increasing concentrations (0, 5, 20, and 80 g kg−1 of soil, referred to as B0, BB5, BB20, and BB80, respectively) on soil physicochemical properties and fungal communities (Illumina high-throughput sequencing) in red soil under Fokenia hodginsii (Fujian cypress). We found that increasing BB levels effectively raised the soil pH and soil nutrients, particularly under BB80. BB addition significantly increased the relative abundance of important genera, i.e., Basidiomycota, Mucoromycota, and Chytridiomycota that could play a key role in ecological functioning, e.g., wood degradation and litter decomposition, improvement in plant nutrients uptake, and resistance to several abiotic stress factors. Soil amended with BB exhibited a substantial ability to increase the fungal richness and diversity; BB80 > BB20 > BB5 > B0. Basidiomycota, Mucoromycota, Glomeromycota, Rozellomycota, Aphelidiomycota, Kickxellomycota, and Planctomycetes were positively associated with soil pH, total nitrogen, phosphorous, and carbon, and available potassium and phosphorous. Besides, the correlation analysis between the soil fungal communities and soil properties also showed that soil pH was the most influential factor in shaping the soil fungal communities in the red soil. These findings have significant implications for a comprehensive understanding of how to ameliorate acidic soils with BB addition, as well as for future research on sustainable forest management, which might increase soil fungi richness, diversity, and functionality in acidic soils.

Distinct microbial community along the chronic oil pollution continuum of the Persian Gulf converge with oil spill accidents

The Persian Gulf, hosting ca. 48% of the world’s oil reserves, has been chronically exposed to natural oil seepage. Oil spill studies show a shift in microbial community composition in response to oil pollution; however, the influence of chronic oil exposure on the microbial community remains unknown. We performed genome-resolved comparative analyses of the water and sediment samples along Persian Gulf’s pollution continuum (Strait of Hormuz, Asalouyeh, and Khark Island). Continuous exposure to trace amounts of pollution primed the intrinsic and rare marine oil-degrading microbes such as Oceanospirillales, Flavobacteriales, Alteromonadales, and Rhodobacterales to bloom in response to oil pollution in Asalouyeh and Khark samples. Comparative analysis of the Persian Gulf samples with 106 oil-polluted marine samples reveals that the hydrocarbon type, exposure time, and sediment depth are the main determinants of microbial response to pollution. High aliphatic content of the pollution enriched for Oceanospirillales, Alteromonadales, and Pseudomonadales whereas, Alteromonadales, Cellvibrionales, Flavobacteriales, and Rhodobacterales dominate polyaromatic polluted samples. In chronic exposure and oil spill events, the community composition converges towards higher dominance of oil-degrading constituents while promoting the division of labor for successful bioremediation.

Changes in Community Composition Induced by Experimental Warming in an Alpine Meadow: Beyond Plant Functional Type

Climate warming exerts profound effects on plant community composition. However, responses to climate warming are often reported at the community and functional type levels, but not at the species level. To test whether warming-induced changes are consistent among community, functional type, and species levels, we examined the warming-induced changes at different levels in an alpine meadow from 2015 to 2018. The warming was achieved by deploying six (open top) chambers [including three non-warmed chambers and three warmed chambers; 15 × 15 × 2.5 m (height) for each] that resulted in a small increase in mean annual temperature (0.3–0.5°C, varying with years) with a higher increase during the non-growing season (0.4–0.6°C) than in the growing season (0.03–0.47°C). The results show that warming increased plant aboveground biomass but did not change species richness, or Shannon diversity and evenness at the community level. At the functional type level, warming increased the relative abundance of grasses from 3 to 16%, but decreased the relative abundance of forbs from 89 to 79%; relative abundances of sedges and legumes were unchanged. However, for a given functional type, warming could result in contrasting effects on the relative abundance among species, e.g., the abundances of the forb species Geranium pylzowianum, Potentilla anserine, Euphrasia pectinate, and the sedge species Carex atrofusca increased in the warmed (compared to the non-warmed) chambers. More importantly, the difference in species identity between warmed and non-warmed chambers revealed warming-induced species loss. Specifically, four forb species were lost in both types of chambers, one additional forb species (Angelica apaensis) was lost in the non-warmed chambers, and two additional species (one forb species Saussurea stella and one sedge species Blysmus sinocompressus) were lost in the warmed chambers. Consequently, changes at the species level could not be deduced from the results at the community or functional type levels. These data indicate that species-level responses to climate changes must be more intensively studied. This work also highlights the importance of examining species identity (and not only species number) to study changes of community composition in response to climate warming.

Soil Fungal Diversity and Community Composition in Response to Continuous Sweet Potato Cropping Practices

Soil fungi are extremely important for maintaining soil health and plant production in agricultural systems. Currently, the effect of continuous cropping of sweet potato on soil fungal communities and physiochemical parameter... | Find, read and cite all the research you need on Tech Science Press

Effects of temperature on composition and stability of bacterial community in colonial <i>Microcystis aeruginosa</i> culture systems

微囊藻藻际细菌影响微囊藻的生长及其水华的生消.然而特定微囊藻群体中藻际细菌群落组成对温度变化的响应规律仍不清楚.本文把一株从太湖分离得到的群体铜绿微囊藻，置于不同温度（15、20、25和30℃）下进行培养，分析各培养体系中不同粒径附生或游离细菌群落组成的异同.结果表明：温度显著影响微囊藻群体（>20 μm）附生、单细胞小群体（3~20 μm）附生和游离（0.2~3 μm）细菌群落的组成（PERMANOVA，P<0.01），Sphingomonadales、Pseudomonadales和Cytophagales分别是3组细菌群落中的最优势菌目，相对丰度分别为21.35%、19.74%和33.44%.在3组细菌群落中都存在一些核心优势细菌类群，其丰度相对稳定，对温度变化不敏感.其中在微囊藻群体附生细菌群落中，优势菌属Brevundimonas和OPB56在20~30℃之间培养时其相对丰度较为稳定；单细胞小群体附生细菌群落中的核心优势菌属Mariniradius相对丰度也是在20~30℃之间较为稳定，而Gemmobacter相对丰度在4种温度下均较为一致；游离细菌群落中的核心优势菌属Porphyrobacter相对丰度在20~30℃之间时也相对稳定.另外，在15℃时，单细胞小群体附生和游离细菌群落的多样性都达到最高，总体细菌群落物种相关性网络复杂度最高，但合作性关联最弱.该研究结果对于深入了解微囊藻群体的藻菌关系有重要意义.;Bacteria in phycosphere of Microcystis affect growth, development and decline of Microcystis blooms. In specific Microcystis colony, however, the pattern of bacterial community composition in response to different temperatures are still unclear. In this study, a colonial Microcystis aeruginosa strain isolated from Lake Taihu was cultivated at different temperatures (15, 20, 25 and 30℃) to analyse the similarities and differences in the composition of different particle attached or free living bacterial communities in each culture system. Temperature significantly affected community compositions of bacteria including Microcystis colony (>20 μm) attached bacteria, single cell-small colony (3-20 μm) attached bacteria and free-living (0.2-3 μm) bacteria (PERMANOVA,P<0.01), Sphingomonadales, Pseudomonadales and Cytophagales were the most dominant order in the three groups, accounting for 21.35%, 19.74% and 33.44% of the total relative abundance, respectively. There were some core dominant bacterial species in the three groups of bacterial communities, which were relatively stable in abundance and insensitive to temperature changes. The relative abundance of Brevundimonas and OPB56, the dominant genus among the core bacterial community attached with Microcystis colony, were relatively stable when temperature changed from 20 to 30℃. The relative abundance of Mariniradius, the dominant genus among the core bacteria attached with single cell-small colony, was also relatively stable when temperature changed from 20 to 30℃, and the relative abundance of Gemmobacter, the another dominant genus among the core bacteria attached with single cell-small colony, was relatively stable in response to temperature changes. The relative abundance of Porphyrobacter, the dominant genus among the core bacterial community in free-living bacteria, were also relatively stable when temperature changed from 20 to 30℃. Compared with the situations at other three higher temperatures, the complexity of species correlation network at 15℃ was the highest but the cooperative correlation was the weakest. The results of this study were of great significance for understanding the algal-bacterial relationships in phycosphere of colonial Microcystis.

Buffering effects of soil seed banks on plant community composition in response to land use and climate

AbstractAimClimate and land use are key determinants of biodiversity, with past and ongoing changes posing serious threats to global ecosystems. Unlike most other organism groups, plant species can possess dormant life‐history stages such as soil seed banks, which may help plant communities to resist or at least postpone the detrimental impact of global changes. This study investigates the potential for soil seed banks to achieve this.LocationEurope.Time period1978–2014.Major taxa studiedFlowering plants.MethodsUsing a space‐for‐time/warming approach, we study plant species richness and composition in the herb layer and the soil seed bank in 2,796 community plots from 54 datasets in managed grasslands, forests and intermediate, successional habitats across a climate gradient.ResultsSoil seed banks held more species than the herb layer, being compositionally similar across habitats. Species richness was lower in forests and successional habitats compared to grasslands, with annual temperature range more important than mean annual temperature for determining richness. Climate and land‐use effects were generally less pronounced when plant community richness included seed bank species richness, while there was no clear effect of land use and climate on compositional similarity between the seed bank and the herb layer.Main conclusionsHigh seed bank diversity and compositional similarity between the herb layer and seed bank plant communities may provide a potentially important functional buffer against the impact of ongoing environmental changes on plant communities. This capacity could, however, be threatened by climate warming. Dormant life‐history stages can therefore be important sources of diversity in changing environments, potentially underpinning already observed time‐lags in plant community responses to global change. However, as soil seed banks themselves appear, albeit less, vulnerable to the same changes, their potential to buffer change can only be temporary, and major community shifts may still be expected.

Do changes in temperature affect EU Water Framework Directive compliant assessment results of central European streams?

BackgroundBenthic invertebrate communities are an integral and longstanding component of stream biomonitoring. However, multiple stressors driven by global change threaten benthic invertebrate communities. In particular, climate warming is expected to disrupt freshwater ecosystems. While an increasing number of studies have shown changes in benthic invertebrate community composition in response to climate warming, the effect on stream assessments has rarely been investigated. As several community composition metrics are also used in stream assessments, we predicted that climate warming would worsen stream assessment results. Therefore, we used a comprehensive data set of 2865 benthic invertebrate samples taken between 2000 and 2014 from small central European low mountain streams. We examined the effects of changes in temperature on common community and stream assessment metrics. We used 31 metrics covering composition, richness, tolerance and function of communities, of which many are used in various stream assessment schemes.ResultsAgainst our expectations, we identified a decreasing air temperature trend of − 0.18 °C over 15 years. This trend was accompanied by significant changes in community composition, for example, increases in species richness and decreases in the community temperature index (CTI). Further, we identified slight concomitant improvements of various globally used stream quality assessment metrics, such as a decreasing saprobic index and an increasing BMWP.ConclusionsWhile temperature increased by + 0.9 °C during the past 30 years (1985–2014), our 15-year study period (2000–2014) showed a decrease by − 0.18 °C. Therefore, we regard the concomitant improvement in several assessment metrics as a recovery from prior increasing temperatures. In turn, we assume that increases in water temperature will lead to opposite effects and therefore cause declining assessment results. Water managers should be aware of this linkage that in turn could provide a chance to mitigate the effects of global warming by, for example, planting trees along the rivers and the removal of artificial barriers to increase current velocity to minimize a warming effect.

Effects of cold plasma on wheat grain microbiome and antimicrobial efficacy against challenge pathogens and their resistance

The safety and quality of cereal grain supplies are adversely impacted by microbiological contamination, with novel interventions required to maximise whole grains safety and stability. The microbiological contaminants of wheat grains and the efficacy of Atmospheric Cold Plasma (ACP) for potential to control these risks were investigated. The evaluations were performed using a contained reactor dielectric barrier discharge (DBD) system; samples were treated for 0–20 min using direct and indirect plasma exposure. Amplicon-based metagenomic analysis using bacterial 16S rRNA gene and fungal 18S rRNA gene with internal transcribed spacer (ITS) region was performed to characterize the change in microbial community composition in response to ACP treatment. The antimicrobial efficacy of ACP against a range of bacterial and fungal contaminants of wheat, was assessed to include individual isolates from grains as challenge pathogens. ACP influenced wheat microbiome composition, with a higher microbial diversity as well as abundance found on the untreated control grain samples. Culture and genomic approaches revealed different trends for mycoflora detection and control. A challenge study demonstrated that using direct mode of plasma exposure with 20 min of treatment significantly reduced the concentration of all pathogens. Overall, reduction levels for B. atrophaeus vegetative cells were higher than for all fungal species tested, whereas B. atrophaeus spores were the most resistant to ACP among all microorganisms tested. Of note, repeating sub-lethal plasma treatment did not induce resistance to ACP in either B. atrophaeus or A. flavus spores. ACP process control could be tailored to address diverse microbiological risks for grain stability and safety.

Dynamics of phosphorus speciation and the phoD phosphatase gene community in the rhizosphere and bulk soil along an estuarine freshwater-oligohaline gradient

Estuarine tidal marshes play a key role in phosphorus (P) retention and cycling; however, they are suffering from small but significant increases in tidal saltwater intrusion. The likely impacts of these low-level saltwater intrusions on P availability and microbial activity are unclear. Here, we investigated soil P speciation, alkaline phosphatase (ALP) activity, and the phoD phosphatase gene community along a freshwater-oligohaline gradient in the Min River estuary, southeast China. The results indicated that with the transition from freshwater to oligohaline water, the levels of soil-water salinity, pH and sulfate content were greater, and ALP activity was lower, which were associated with higher concentrations of organic P, available P, aluminum-bound P, calcium-bound P, and occluded P and lower levels of iron-bound P. There was a strong shift in the phoD phosphatase community composition in response to the freshwater-oligohaline gradient. Our findings showed that with the transition from freshwater to an oligohaline environment, in addition to the associated increases in salinity and soil pH and decreases in general microbial and biological activity and soil organic carbon, there is a shift in soil P toward more recalcitrant and immediately available fractions with less labile forms.

Hiseq Base Molecular Characterization of Soil Microbial Community, Diversity Structure, and Predictive Functional Profiling in Continuous Cucumber Planted Soil Affected by Diverse Cropping Systems in an Intensive Greenhouse Region of Northern China.

Cover crops are key determinants of the ecological stability and sustainability of continuous cropping soils. However, their agro-ecological role in differentially reshaping the microbiome structure and functioning under a degraded agroecosystem remains poorly investigated. Therefore, structural and metabolic changes in soil bacterial community composition in response to diverse plant species were assessed. Winter catch leafy vegetables crops were introduced as cover plants in a cucumber-fallow period. The results indicate that cover crop diversification promoted beneficial changes in soil chemical and biological attributes, which increased crop yields in a cucumber double-cropping system. Illumina high-throughput sequencing of 16S rRNA genes indicated that the bacterial community composition and diversity changed through changes in the soil properties. Principal component analysis (PCA) coupled with non-metric multidimensional scaling (NMDS) analysis reveals that the cover planting shaped the soil microbiome more than the fallow planting (FC). Among different cropping systems, spinach–cucumber (SC) and non-heading Chinese cabbage–cucumber (NCCC) planting systems greatly induced higher soil nutrient function, biological activity, and bacterial diversity, thus resulting in higher cucumber yield. Quantitative analysis of linear discriminant analysis effect size (LEfSe) indicated that Proteobacteria, Actinobacteria, Bacteroidetes, and Acidobacteria were the potentially functional and active soil microbial taxa. Rhizospheres of NCCC, leaf lettuce–cucumber (LLC), coriander–cucumber (CC), and SC planting systems created hotspots for metabolic capabilities of abundant functional genes, compared to FC. In addition, the predictive metabolic characteristics (metabolism and detoxification) associated with host–plant symbiosis could be an important ecological signal that provides direct evidence of mediation of soil structure stability. Interestingly, the plant density of non–heading Chinese cabbage and spinach species was capable of reducing the adverse effect of arsenic (As) accumulation by increasing the function of the arsenate reductase pathway. Redundancy analysis (RDA) indicated that the relative abundance of the core microbiome can be directly and indirectly influenced by certain environmental determinants. These short-term findings stress the importance of studying cover cropping systems as an efficient biological tool to protect the ecological environment. Therefore, we can speculate that leafy crop diversification is socially acceptable, economically justifiable, and ecologically adaptable to meet the urgent demand for intensive cropping systems to promote positive feedback between crop–soil sustainable intensification.

A novel approach involving the use of Odonata as indicators of tropical forest degradation: When family matters

• Odonata can be effective and cost-efficient indicators of habitat status. • Coenagrionidae and Libellulidae as indicator groups. • Odonata adult-based bioassessment method is reliable. • The method may be easily applied in any tropical forest habitat worldwide. Odonata have proven to be good indicators of freshwater as well as terrestrial habitat conditions. Several studies have shown changes in odonate species richness and/or community composition in response to deforestation, suggesting their potential as bioassessment tools in the tropics. However, former approaches using Odonata as an indicator group required comparative samples from differently disturbed sites and/or knowledge of the focal species environmental specificity. Here, we tested a robust, adult-based bioassessment method assuming that the level of tropical forest degradation reflects the proportional representation of the taxa above species. Based on Web of Science, ScienceDirect, and Scopus databases, we used data from previously published studies linking odonate assemblages to human-mediated disturbances in tropical forests. We hypothesized that along a disturbance gradient (from primary forest to non-forest), (i) the proportion of the suborder Zygoptera (mostly habitat specialists sensitive to deforestation) will decrease in favor of the suborder Anisoptera (high proportion of generalists); and (ii) the proportions of largely generalist families Coenagrionidae and Libellulidae will increase at the expense of other Zygoptera and Anisoptera, respectively. Our results revealed that a ratio of Zygoptera/Anisoptera is a poor indicator of tropical forest conditions, probably because of ecological diversity within these groups. However, the proportions of Coenagrionidae/other Zygoptera and Libellulidae/other Anisoptera significantly increased along a disturbance gradient, suggesting their potential to be a good indicator of well-preserved, altered, and heavily degraded forest habitats. Therefore, our results are in line with studies presenting the usefulness of adult Odonata as versatile indicators for assessing human-mediated changes in tropical forest environments, supporting the practical use of this group in biological monitoring.

Conservation of the Mediterranean coastal pine woodlands: How can management support biodiversity?

Forest management decisions may have unintentional effects on what they were originally not designed for, including effects on woodland species and communities. In protected areas of coastal dune woodlands, some sites are fenced as a part of forestry management. In this study, we hypothesised that different states of disturbance (disturbed vs non-disturbed) created by fencing generate unintentional heterogeneity in species composition (and possibly richness) in plant communities and soil biota. We surveyed vascular plants, oribatid mites and soil properties in fenced and nearby non-fenced places in protected coastal pine woodlands in Italy. The fenced areas were undisturbed for at least 30 years, whereas the non-fenced areas were subjected to thinning and trampling. Effects of fencing on community composition and soil properties were assessed by (distance based) redundancy analysis. Congruence between plant and mite community composition in response to fencing was tested using a series of (partial) Mantel tests. Finally, linear mixed-effects models were used to study species richness. Both plant and mite community composition showed a significant congruent response to fencing. Species richness of plants decreased due to fencing, while that of mites was unaffected. We conclude that the fencing of small areas creates biotic heterogeneity and increases beta diversity in the Mediterranean coastal woodlands. Therefore, we support the use of fencing as a relatively cheap and effective method of conservation management for maintaining the biodiversity of both above- and belowground communities in the coastal pine woodlands of the Mediterranean area.

Major disturbances test resilience at a long-term boreal forest monitoring site.

The impact of disturbances on boreal forest plant communities is not fully understood, particularly when different disturbances are combined, and regime shifts to alternate stable states are possible after disturbance. A long‐term monitored semi‐natural forest site subject to intense combined storm and bark beetle damage beginning in 2005 provided an opportunity to investigate the postdisturbance development of the vegetation community. Previous studies suggest that a shift from Picea abies to Fagus sylvatica domination was possible.We analyzed pre‐ and postdisturbance vegetation data to investigate to what extent vascular plant species abundances, diversity, traits, and community composition have changed. We were particularly interested in differences between remaining apparently unaffected areas (potential refugia) and disturbed areas, and in signs of consistent change over time in community composition in response to disturbance that could indicate an impending regime shift.We found that the vegetation community present in the refuge areas has remained substantially intact through the period of disturbance. Nonrefuge areas diverged from the refuges in community composition and showed increased taxonomic and functional diversity. Despite this, and an increase in deciduous tree species (particularly F. sylvatica), P. abies has shown strong postdisturbance regeneration. The refuges may be important in the apparent ongoing recovery of the disturbed areas to a P. abies‐dominated state similar to that found predisturbance. This fast recovery is interpreted as evidence of a system resilient to a potential shift to a deciduous‐dominated state. Synthesis: Our results show that even powerful combined disturbances in a system with multiple stable states can be insufficient to initiate a regime shift. Resilience of the P. abies‐dominated forest community is increased by the survival of refuge areas functioning as a form of ecological memory of the previous ecosystem state. The results also demonstrate the value of data generated by long‐term monitoring programs.

Using a combination of PLFA and DNA-based sequencing analyses to detect shifts in the soil microbial community composition after a simulated spring precipitation in a semi-arid grassland in China

Increased spring precipitation in semi-arid grasslands could improve annual primary productivity. However, little is known about the responses of soil microbes to individual spring precipitation. In this study, we combined phospholipid fatty acid (PLFA) and DNA-based high-throughput sequencing analyses to investigate short-term (days) shifts in the soil microbial community composition after a simulated spring precipitation. Under field conditions, the soils (approx. −0.3 MPa) were exposed to either a watering of 20 cm or natural drought, and soil samples were collected at days 1, 3, 5, 8, and 12 after watering. Soil labile organic carbon (C) and nitrogen (N) as well as microbial biomass C (MBC) were positively correlated with soil water content (SWC). Spring watering significantly increased plant phosphorus (P) uptake, but had no impact on soil available P (AP). Watering increased the PLFA biomarkers indicative for Gram-negative (G−) bacteria and fungi. Two phyla of G− bacteria, Proteobacteria and Bacteroidetes, as well as the fungal phylum Ascomycota were more abundant when SWC increased. In addition to SWC and its related environmental factors such as C and N availabilities, AP appeared to be an important factor in shaping the soil microbial community composition. The study highlights the combination use of the methods based on different microbial biomarkers (PLFA vs. DNA), and the results were in line with each other. While the PLFA-based method was more sensitive to short-term shifts in soil microbial community composition in response to a precipitation event, DNA-based method could provide more information on the microbial taxa at a finer taxonomic resolution. Our results provide methodological insights for future research on short-term response of soil microbial community to changing environmental conditions.

Transition of Ethiopian highland forests to agriculture-dominated landscapes shifts the soil microbial community composition

BackgroundLand use changes and related land management practices significantly alter soil physicochemical properties; however, their effects on the soil microbial community structure are still unclear. In this study, we used automated ribosomal intergenic spacer analysis to determine the fungal and bacterial community composition in soils from different land use areas in the Ethiopian highlands. Soil samples were collected from five areas with different land uses, natural forest, eucalyptus plantation, exclosure, grassland and cropland, which had all historically been natural forest.ResultsOur results showed a significant shift in the soil bacterial and fungal community composition in response to land use change. We also identified soil physicochemical factors corresponding to the changes in bacterial and fungal communities. Although most soil attributes, including soil organic carbon, total soil nitrogen, labile P, soil pH and soil aggregate stability, were related to the change in bacterial community composition, the total soil nitrogen and soil organic carbon had the strongest relationships. The change in fungal community composition was correlated with soil nutrients, organic carbon, soil nitrogen and particularly the labile P concentration.ConclusionsThe fungal community composition was likely affected by the alteration of vegetation cover in response to land use change, whereas the bacterial communities were mainly sensitive to changes in soil attributes. The study highlights the higher sensitivity of fungal communities than bacterial communities to land use changes.