Moderate Disturbance Research Articles

Hot and cold cognitive disturbances in antidepressant-free patients with major depressive disorder: a NeuroPharm study.

Cognitive disturbances are common and disabling features of major depressive disorder (MDD). Previous studies provide limited insight into the co-occurrence of hot (emotion-dependent) and cold (emotion-independent) cognitive disturbances in MDD. Therefore, we here map both hot and cold cognition in depressed patients compared to healthy individuals. We collected neuropsychological data from 92 antidepressant-free MDD patients and 103 healthy controls. All participants completed a comprehensive neuropsychological test battery assessing hot cognition including emotion processing, affective verbal memory and social cognition as well as cold cognition including verbal and working memory and reaction time. The depressed patients showed small to moderate negative affective biases on emotion processing outcomes, moderate increases in ratings of guilt and shame and moderate deficits in verbal and working memory as well as moderately slowed reaction time compared to healthy controls. We observed no correlations between individual cognitive tasks and depression severity in the depressed patients. Lastly, an exploratory cluster analysis suggested the presence of three cognitive profiles in MDD: one characterised predominantly by disturbed hot cognitive functions, one characterised predominantly by disturbed cold cognitive functions and one characterised by global impairment across all cognitive domains. Notably, the three cognitive profiles differed in depression severity. We identified a pattern of small to moderate disturbances in both hot and cold cognition in MDD. While none of the individual cognitive outcomes mapped onto depression severity, cognitive profile clusters did. Overall cognition-based stratification tools may be useful in precision medicine approaches to MDD.

Contrasting shifts in coral assemblages with increasing disturbances

Increasing incidence of major disturbances is contributing to extensive and widespread coral loss, thereby undermining the biodiversity, structure and function of reef ecosystems. The composition of coral assemblages is already changing due to selective effects of recurrent disturbances, combined with marked differences in the underlying life-history dynamics of corals, which affects their recovery. This study quantifies the effects of varying disturbance regimes on two groups of corals with divergent life histories: short-lived species with rapid growth (bushy and tabular Acropora) and long-lived species with slow growth (massive and columnar Porites). Inter-decadal shifts in the coral assemblages across four locations suggest that a high frequency of moderate disturbances favours Porites, whereas infrequent, but severe disturbances favour rapidly replenishing Acropora. Using empirical modelling, we expand these observations to show that Acropora continues to dominate so long as the interval between major disturbances is > 2 years. The only disturbance regime we considered that favoured Porites was high frequency (2-year recurrence) of moderate disturbance, whereas high frequency of severe disturbances led to local extirpation of both Acropora and Porites. Our results show that increasing incidence of major disturbances will not necessarily lead to selective loss of species that are most susceptible to disturbance, as long as these species can continue to colonise vacant space and grow quickly in the aftermath of such disturbances. This study highlights the need to consider the sensitivity of taxa to changes in both disturbance frequency and severity when forecasting changes in the composition of coral assemblages under new disturbance regimes.

Effects of a Brief Behavioral Training Program on Sleep Quality in Older Adults With Moderate Sleep Disturbances

Background: Sleep disturbances are very common among elderly population and mostly remain incurable. Practical, brief, and effective interventions are needed to promote sleep quality in older adults with moderate sleep disturbances. This study aimed to investigate the effectiveness of a brief behavioral training program in ameliorating sleep quality in older adults suffering from moderate sleep disturbances. Materials and Methods: This study was conducted on 64 older adults with moderate sleep disturbances, as defined by Pittsburgh Sleep Quality Index (PSQI) score ≥5. Participants were randomly allocated to either intervention (n=32) or control (n=32) group. Older adults in the intervention group received a brief behavioral-based sleep training program which was delivered in a single in-person session followed by four telephone sessions during 4 weeks. While their peers in the control group did not receive any intervention. The main outcome of the study was scores on the PSQI which was compared at pre- and post-intervention between both groups. Data were analyzed using the SPSS software version 19.0. Results: At 4 weeks, PSQI scores decreased in older adults receiving intervention, as compared with the scores of participants to the control group (P<0.001). Subjects in the intervention group also showed significant improvements in sleep latency, subjective sleep quality, sleep duration, and sleep efficiency (P<0.05). Conclusion: Brief behavioral interventions may be promising and useful for older adult population with moderate problems, and can be considered an efficacious and non-invasive intervention approach to improve elderly’s sleep quality.

Impact on mental health and perceptions of psychological care among medical and nursing staff in Wuhan during the 2019 novel coronavirus disease outbreak: A cross-sectional study

The severe 2019 outbreak of novel coronavirus disease (COVID-19), which was first reported in Wuhan, would be expected to impact the mental health of local medical and nursing staff and thus lead them to seek help. However, those outcomes have yet to be established using epidemiological data. To explore the mental health status of medical and nursing staff and the efficacy, or lack thereof, of critically connecting psychological needs to receiving psychological care, we conducted a quantitative study. This is the first paper on the mental health of medical and nursing staff in Wuhan. Notably, among 994 medical and nursing staff working in Wuhan, 36.9% had subthreshold mental health disturbances (mean PHQ-9: 2.4), 34.4% had mild disturbances (mean PHQ-9: 5.4), 22.4% had moderate disturbances (mean PHQ-9: 9.0), and 6.2% had severe disturbance (mean PHQ-9: 15.1) in the immediate wake of the viral epidemic. The noted burden fell particularly heavily on young women. Of all participants, 36.3% had accessed psychological materials (such as books on mental health), 50.4% had accessed psychological resources available through media (such as online push messages on mental health self-help coping methods), and 17.5% had participated in counseling or psychotherapy. Trends in levels of psychological distress and factors such as exposure to infected people and psychological assistance were identified. Although staff accessed limited mental healthcare services, distressed staff nonetheless saw these services as important resources to alleviate acute mental health disturbances and improve their physical health perceptions. These findings emphasize the importance of being prepared to support frontline workers through mental health interventions at times of widespread crisis.

Restoration Measures Supported Surface Soil Carbon and Nitrogen Density in Alpine Grassland of Sanjiangyuan Region, China

Soil carbon (C) and nitrogen (N) have different responses to different restoration measures. In this paper, surface (0-30 cm) soil C and N densities under different restoration measures in the Sanjiangyuan region were investigated and analyzed. The results showed that although there was no significant difference between rest-grazing (RG) and normal grazing ( NG) grassland, SOCD in RG increased by 10.15%, and total N density (TND) increased by 8.56% in the year of the experiment. Compared with cropland, 8 years after Grain for Green (GFG), SOCD increased by 10.49-19.31%, SICD increased by 22.47-54.20%, and TND increased by 1.3-17.45%. Compared with HTT (extreme degradation-black soil beach), 12 years after planting artificial grassland, SOCD increased by 43.97-77.21%, SICD increased by 89.19-716.22%, and TND increased by 49.16-71.40%. Conclusions: Differences in soil types and climatic zones were responsible for the differences in soil C and N in different regions. Short-term grazing rest in Sanjiangyuan region has a certain effect on soil fertility restoration. Implementing the GFG project in the agro-pastoral ecotone improved soil fertility and, concurrently, moderate disturbance should be carried out on the basis of increasing vegetation diversity. Artificial grassland planting on black soil beach can improve soil quality, and moderate grazing disturbance in winter had the best immobilization effect on SIC, while no disturbance in the whole year was beneficial to the accumulation of organic matter. Both biological and abiotic factors have affected soil C and N content and density, but the degree of the influence varied with geographic location.

Responses of Rotifer Community to Microhabitat Changes Caused by Summer-Concentrated Rainfall in a Shallow Reservoir, South Korea

Empirical studies suggest that the structural heterogeneity of aquatic ecosystem microhabitat is determined by the diversity and abundance of macrophytes. However, excessive accumulation of free-floating macrophytes on the water surface can reduce the biomass of submerged macrophytes, resulting in a relatively simplified habitat structure. We hypothesized that heavy summer rainfall disrupts the growth of free-floating macrophytes covering much of the Jangcheok Reservoir’s water surface, thereby resulting in a more complex habitat structure by allowing development of a more diverse of macrophytic community. We divided long-term (2008–2017) monitoring data (rainfall, macrophytes, and rotifers) into two groups: Rainy and Dry years, corresponding to years with annual rainfall higher and lower than the total annual average, respectively. We found that summer densities of rotifers fell sharply in Rainy years, but increased continuously in Dry years. This trend resulted in greater autumn densities in Rainy relative to Dry years, which we attributed to changes in habitat related to differential macrophyte development. Moderate disturbance of the water surface caused by high summer rainfall can promote growth of submerged macrophytes by creating large areas of open water and therefore a more complex autumnal microhabitat structure, resulting in seasonal variations in rotifer community structures and populations. Moreover, a highly complex microhabitat structure restricts foraging activity of fish (i.e., Lepomis macrochirus) that prey on rotifers. Based on these findings, we suggest that summer-concentrated rainfall plays an important role in supporting the density and species diversity of rotifers.

Distinct ecosystem types respond differentially to grazing exclosure

AbstractHere, we evaluate the ecosystem functioning and the ecosystems services supply of different vegetation types (grasslands, shrublands and woodlands) under contrasting management regimes by comparing a protected area with the surrounding landscape, which has been subjected to human disturbance in the Eastern Hills of Uruguay. We propose, based on functional attributes and vegetation physiognomy, a State and Transition Model for the dynamics of the grassland–woodland mosaic. We used remote sensing techniques to: (i) develop a land‐cover map of the study area based on supervised Landsat imagery classification, and (ii) compare attributes of the ecosystem functioning (productivity and seasonality) and service supply derived from the Normalized Difference Vegetation Index (NDVI) images provided by the moderate resolution imaging spectroradiometer (MODIS) sensor. The land‐cover map showed that grasslands and shrublands were the most extensive land covers in the study area. These vegetation types presented higher productivity, seasonality and ecosystem service supply, outside the protected area than inside it. On the other hand, woodlands showed higher productivity, ecosystem service supply and lower seasonality inside the protected area than outside of it. Two axes represented the grassland–woodland mosaic dynamic: (i) the mean annual and (ii) the intra‐annual coefficient of variation of the NDVI. Our results highlight that conservation of grasslands, shrublands and woodlands require different management strategies based on particular disturbance regimes like moderate grazing and controlled burns. Moderate disturbances may help to preserve ecosystem services provisioning in grasslands and shrublands. On the contrary, woodland conservation requires a more rigorous regime of protection against disturbances.

Model-Based Optimisation and Control Strategy for the Primary Drying Phase of a Lyophilisation Process.

The standard operation of a batch freeze-dryer is protocol driven. All freeze-drying phases (i.e., freezing, primary and secondary drying) are programmed sequentially at fixed time points and within each phase critical process parameters (CPPs) are typically kept constant or linearly interpolated between two setpoints. This way of operating batch freeze-dryers is shown to be time consuming and inefficient. A model-based optimisation and real-time control strategy that includes model output uncertainty could help in accelerating the primary drying phase while controlling the risk of failure of the critical quality attributes (CQAs). In each iteration of the real-time control strategy, a design space is computed to select an optimal set of CPPs. The aim of the control strategy is to avoid product structure loss, which occurs when the sublimation interface temperature () exceeds the the collapse temperature () common during unexpected disturbances, while preventing the choked flow conditions leading to a loss of pressure control. The proposed methodology was experimentally verified when the chamber pressure and shelf fluid system were intentionally subjected to moderate process disturbances. Moreover, the end of the primary drying phase was predicted using both uncertainty analysis and a comparative pressure measurement technique. Both the prediction of and end of primary drying were in agreement with the experimental data. Hence, it was confirmed that the proposed real-time control strategy is capable of mitigating the effect of moderate disturbances during batch freeze-drying.

Disturbance intensity overwhelms propagule pressure and litter resource in controlling the success of Pontoscolex corethrurus invasion in the tropics

The mechanisms by which exotic earthworms invade new habitats are largely unknown. Previous research concluded that factors including habitat disturbance, propagule pressure and variation in the litter resource may significantly drive the establishment of exotic earthworms, however, these studies did not conduct manipulative experiments to compare the effects of these three factors. To fill this knowledge gap, we established a moderate disturbance experiment and a severe disturbance experiment in a tropical natural forest (Xishuangbanna, China) with the exotic earthworm Pontoscolex corethrurus. The former mesocosm experiment manipulated disturbance (no disturbance vs moderate disturbance) and propagule pressure as the independent factors, while the latter mesocosm experiment manipulated propagule pressure and litter resource (difference in quality and diversity) as the independent factors that affect the establishment of P. corethrurus. In the moderate disturbance experiment: disturbance and propagule pressure did not affect the final population size of P. corethrurus, i.e., populations in all treatments declined to the same size at the end of the experiment. In the severe disturbance experiment: the population size of P. corethrurus increased in all treatments, with larger population size observed under the treatments with higher propagule pressure; litter treatments with a higher C/N ratio slightly increased the population biomass. In conclusion, our results showed that disturbance (severe vs no or moderate disturbance) overwhelmed the effects of propagule pressure and litter resource on the establishment of P. corethrurus. We suggest that the protection of tropical natural forests from severe disturbance, e.g., slash-and-burn deforestation, is the key means to prevent earthworm invasion.

Long-term observation of magnetic pulsations through the ELF Hylaty station located in the Bieszczady Mountains (south–eastern Poland)

Ground-based measurements of ultra- and extremely low-frequency waves (ULF/ELF) carried out in 2005–2016 (the 23rd and 24th solar cycle) at the ELF Hylaty station in Bieszczady Mountains (south–eastern Poland) were used to identify the days (360 days) in which magnetic pulsation events (MPEs) occurred. To reveal sources of MPEs at the Sun we considered their correlation with the basic indices describing solar activity. Our analysis, like earlier studies, did not reveal a significant positive correlation between the MPE detection rate and the sunspot numbers (SSN). On the other hand, we showed that MPEs are strongly correlated (correlation coefficient ≈0.70) with moderate (Dst < −70 nT) and intense (Dst < −100 nT) geomagnetic disturbances expressed by the Disturbance Storm Index (Dst). We recognized all sources of these geomagnetic storms associated with the considered MPEs. Only 44% of the MPEs were associated with storms caused by CMEs listed in the CDAW LASCO CME catalog. 56% of the MPEs were associated with storms caused by other phenomena including corotating interaction regions (CIRs), slow solar wind or CMEs not detected by LASCO. We also demonstrated that the CMEs associated with the MPEs were very energetic, i.e. they were extremely wide (partial and halo events) and fast (with the average speed above 1100 km s−1). CMEs and CIRs generally appear in different phases of solar cycles. Because MPEs are strongly related to both of these phenomena they cannot be associated with any phase of a solar cycle or with any indicator characterizing a 11-year solar activity. We also suggested that the low number of MPEs associated with CMEs is due to the anomalous 24 solar cycle. During this cycle, due to low density of the interplanetary medium, CMEs could easily eject and expand, but they were not geoeffective.

Testing of the applicability of European diatom indices in the tropical rift valley lake, Lake Hawassa, in Ethiopia

Quantitative ecological monitoring of African lakes is needed to understand growing human pressures on ecosystems. Diatom-based indices are routinely used for this purpose elsewhere in the world, but have not yet been produced for the flora of African freshwater lakes. Here we tested the applicability of the European diatom indices on the biomonitoring system of Lake Hawassa, Ethiopia. Physico-chemical and benthic diatom sampling was done at nine sites with different degrees of human disturbance along the lakeshore area from February to November 2015 and 2016. A percentage disturbance score (PDS) was calculated at each site and categorised from no evident disturbance (0–25%) to high disturbance (75–100%). Based on this criterion and selected physico-chemical parameters, the sampling sites categorized into minimal, moderate and high disturbance. Seventeen diatom indices were calculated using Omnidia software version 5.3. Out of a total of 17 indices that were calculated using the Omnidia software, six were selected as potential metrics. The diatom indices had a high discrimination efficiency and were significantly correlated with most the environmental parameters (r > 0.6; p < 0.05). Among these, the trophic diatom index (TDI) and generic diatom index (IDG) showed the best potential to discriminate the three clustered sites, based on their ecological classification. Accordingly, although robust locally based indices are needed, the TDI and IDG diatom indices could be used in monitoring of water quality in tropical African rift lakes.

VLF wave propagation and middle polar atmosphere as a detector of ultra-energetic relativistic electron precipitations in 1988–1992 years

In this paper we present a catalog of the new geophysical phenomena, Ultra-energetic Relativistic Electron Precipitations (UREP), and relying on our previous physics analysis of it, describe its specific quantitative characteristics. This full dataset was created based on the continuous very low frequency measurements of a polar radio path with three working frequencies during the years 1988–1992. As discussed in our previous works, the main feature of this phenomenon is that ultra-energetic relativistic electrons precipitate into the middle polar atmosphere and cause additional ionization at the altitudes 10–45 km by the bremsstrahlung X-rays and gamma rays which are generated by the ~100 MeV penetrating electrons. This new geophysical phenomenon was detected by the ground-based measurements of the Very Low Frequency (VLF) signal variations due to the signals' passing along the terrestrial waveguide with a sporadic layer of ionization created by the X-ray radiation in the middle atmosphere. Therefore, in all these abnormal cases the middle atmosphere and the processes of VLF wave propagation are the detector of this new effect.In the dataset presented, each event is identified by the abnormal values of VLF signals variations which are not typical for the measurements in the distance zone of measurements. In a case of this moderate distance from a VLF ground based source (~900 km), which is investigated here, the abnormality manifests in the qualitatively similar negative type of variations in both phase and amplitude of the detected signals for all 3 used radio wave frequencies. Such similarity appears due to the signal of strait seeing turns into the diffraction wave, the 1-st hop (ray) becomes ~ 2 times less. The indicated abnormality in the experimental variations proves that the second sky wave does not reach a receiver and there is an anti-phase interference effect between two field terms at the middle distance zone, previously unknown. Over 1988–1992 years, 135 VLF disturbances have been observed (with 17 events during the night) with mentioned abnormal behavior: 7 powerful disturbances, 72 strong disturbances and 56 moderate disturbances. It is known that the corresponding minimal values of effective height (altitude) of these VLF disturbances are: 25–35 km for powerful, 35–45 km for strong, and 45–55 km for moderate disturbances.

Relación de los pequeños mamíferos terrestres (Rodentia y Didelphimorphia) con la estructura de la vegetación en el Bosque Atlántico Interior – un análisis multivariado

The ecological importance of small mammals includes their role as dispersers of seeds, spores and propagules of plants, fungi and lichens, decomposers of organic matter and controllers of invertebrates as well as prey of a great number of vertebrates. The objective of this research was to determine the relationship between non-volant small mammals (Rodentia and Didelphimorphia) to vegetation structure and the extent of degradation of the forest in an area near the western boundary of the Upper Parana Atlantic Forest, and to evaluate seasonal and interannual variation in species’ abundances. The study was conducted in the Mbaracayu Forest Natural Reserve, Paraguay. Mark-capture methodology was employed in three sites with different degrees of degradation, in two seasons of the year (dry and rainy), in 2015 and 2016. A multivariate analysis was performed with ANOVA and MANOVA, evaluating degree of habitat disturbance and annual and seasonal variation as independent variables and species abundances as dependent variables. Sixteen small-mammal species were recorded, with 1,161 captures of 598 individuals and 563 recaptures throughout the sampling. Twelve species were of the Order Rodentia (all of the family Cricetidae, subfamily Sigmodontinae), and four of the Order Didelphimorphia (family Didelphidae). Variables that were significant for the most abundant species (Akodon montensis) were interannual variation and habitat degradation. The most common didelphid species in the study was Gracilinanus agilis, which appears well-adapted to different degrees of habitat degradation, given its occurrence in all sites. Plant communities, including their composition and degree of habitat disturbance, are important for small-mammal communities which are interacting in the different habitats of the forest. In this study we observed that Akodon montensis was most abundant in the habitat of moderate disturbance in the dry season (June). This habitat was characterized by large trees with grasses predominant in the understory. Hylaeamys megacephalus was most abundant in the dry season (June) and less so in the rainy season (November). Oligoryzomys nigripes is a habitat generalist and is less specialized in food preference. Abundance of the didelphid species Gracilinanus agilis was quite variable among sampling periods, but the species was present in all three levels of habitat degradation. The various species (especially the most abundant) exhibited different responses to habitat degradation and to interannual and seasonal variations.

Effect of disturbance on population structure, regeneration and conservation of Moghania chappar in sal forests of Gorakhpur, India

Non-seed regeneration is essentially a vagrant strategy of woody plants causing assemblage of homozygous populations in disturbed forests. We tried to understand how such hardy species like Moghania chappar produce close groups of individuals at different level of disturbance. The hypothesis of trade-off between ramet proliferation and disturbance level, and between growth pattern and resource conservation was tested. The three 1-ha sample plots of sal forest, facing low, moderate or high level of disturbance were observed within Sohagibarwa Wildlife Sanctuary. A total of 40 quadrats per 1-ha plot were sampled to record the age structure of genet and ramet populations of M. chappar. The architecture and foraging of the root-stock was mapped, the biomass of root and shoot was measured and the soil conserved by the root-complex was estimated at each disturbance level. The growth characteristics suggest that M. chappar conforms to Stone’s model of tree architecture. At moderate disturbance, the root-shoot junction sent many more sprouts, garnered much biomass and became flat and curved. The insurrection of ramets caused fragmentation of the root-complex. This clonal growth strategy, however, was neither clearly ‘phalanx’ nor ‘guerrilla’ type. It resulted in intermittent shallow cavities within fragmented root-stock that got filled with soil rich in organic matter. The growth strategy of the species showed potential to restore the soil system and to conserve the diversity of minor biota. In moderately disturbed sal forest, the understorey paved way to prolific non-seed regeneration of this fugitive mid-successional species. At moderate heat stress, the number of individuals as well as the proportion of seedlings per population was highest. The species rapidly increased the understorey foliage by producing a metapopulation of usable sprouts/ramets that facilitated retention of soil and nutrients within their root traps. The total extractible shoot biomass per plant was quite large as a ~ 6 year old individual weighed 473.5 ± 27.4 g. This study of clonal plant ecology may provide new impetus to the conservation of degraded forest ecosystems.

Nine-year physiology, nutrition and morphological development of Picea glauca reintroduced by planting in a high-graded yellow birch–conifer stand

ABSTRACTDepletion of white spruce (Picea glauca) in mixedwood forest is a frequent problem, particularly in stands that were high-graded as a result of inadequate silviculture and spruce budworm (Choristoneura fumiferana) epidemics. To provide information that will help guide restoration efforts, we assessed the effect of four seed-tree retention (STR: 0, 10, 40 and 60 trees/ha) levels and two scarification (SC: patch scarification and disk-trenching) types on white spruce reintroduced by planting in a high-graded yellow birch (Betula alleghaniensis)–conifer stand. We present the 9-year results from the seedling physiology, nutrition and morphology. Physiology and nutrition changed with years, but did not vary with STR levels and SC types. Significant increases in the number of internodal branches, height growth, and total height at the two lowest STR levels and after release suggest that the performance of white spruce in terms of morphology and growth is sensitive to small variations in available light. Because seedling morphology and growth were similar between SC types, a moderate disturbance of the forest floor by disk-trenching would be sufficient at a relatively low cost. Our findings highlight that the STR levels influenced the morphology and growth of planted white spruce seedlings more than the SC types.

Effects of anthropogenic disturbance on a Victoria crowned pigeon Goura victoria population in northern Papua, Indonesia

Most lowland tropical forests are global biodiversity hotspots, known for their high species diversity and endemism. However, conservation of these areas is challenging because of increasing human threats, including selective logging, large-scale plantation, and wildlife hunting. We conducted line transect surveys to investigate the effects of human disturbance on the population of Victoria crowned pigeon (Goura victoria) in the lowland forest of northern Papua, Indonesia. Estimated densities of G. victoria were highest in secondary forest with 7.7 [95% confidence interval (CI): 3.7-16.1] birds km-2 and in natural forest habitat with 6.9 (95% CI: 3.2-14.7) birds km-2 but much lower in logged forest with 2.3 (95% CI: 0.8-6.8) birds km-2. At transect level, there were positive correlations of encounter rates of G. victoria with canopy cover, fruiting trees, and distance to village and negative ones with ground cover, understory layer, logging debris, and wildlife traps. The results suggest that G. victoria is tolerant to moderate disturbance but suffers from severe disturbance. To protect crowned pigeons and other endemic Papuan fauna, impacts of logging and wildlife hunting must be reduced through law enforcement and integrated forest management strategies with proper involvement of all stakeholders, especially local people.

Community structure and regeneration pattern of Abies spectabilis in Sagarmatha National Park, Central Himalaya, Nepal

Community structure and regeneration pattern of Abies spectabilis was studied along the elevation gradient from 2750 to 3550 m asl in mixed forest of A. spectabilisin Sagarmatha National Park, eastern Nepal. Various community attributes (viz. importance percentage, species diversity and beta diversity) and population characteristics (e. g. density- diameter, bar diagram) were analysed. Out of the thirty four species recorded from the study forest, A. spectabilis was the co-dominant species with high species diversity. Total tree density was the highest at 3450 m and the lowest at 3550 m. Elevation appeared to be the important environmental factor that affects the community attributes of the study forest. The curve for A . spectabilis solely was lightly deviated from the typical reverse J-shaped which indicates a discontinuous regeneration pattern. The distribution of the seedling and sapling distribution was not uniform. Seedling mortality was found relatively medium and development of seedlings into saplings was also low. The lower number of sapling might be due to moderate disturbance (grazing and trampling) by livestock or due to environmental factors. The use of Abies tree for construction and firewood might be the reason of un sustainability.

Natural factors and chemical contamination control the structure of macrobenthic communities in the Santos Estuarine System (SP, Brazil)

The Santos Estuarine System (SES) is a complex of bays, islands, estuarine channels, and rivers located on the Southeast coast of Brazil, in which multiple contaminant sources are situated in close proximity to mangroves and other protected areas. In this study, the composition and structure of the macrobenthic communities of SES were described and ninety-nine species were identified, with the predominance of polychaetes and bivalve mollusks. The benthic assemblages also showed strong signs of stress, as indicated by the low abundance, richness and diversity, and the dominance of opportunistic species. Integrated analysis including sediment characteristics related to natural and anthropogenic factors (e.g., sediment chemistry, and toxicity) indicated that benthic fauna from the inner portions of the SES and vicinities of the SSOS diffusers as Santos Bay were affected. Some locations at the mouths of Santos and Sao Vicente estuaries exhibited moderate disturbance. In other sites from the mouth of São Vicente and Bertioga channels, and Santos Bay, the benthic fauna were considered not degraded. Our results suggest that a combination of both environmental factors and contaminants were responsible for the benthic community structure.

Fish species composition, distribution and community structure in the lower reaches of Ganjiang River, Jiangxi, China

The Ganjiang River (length: 823 km; drainage area: 82,809 km2) is the largest river that flows into Poyang Lake and an important tributary of the Yangtze River. In this study, fish fauna were collected from 10 stations in the lower reaches of the river (YC: Yichun, XY: Xinyu, SG: Shanggao, GA: Ganan, ZS: Zhangshu, FC: Fengcheng, NC: Nanchang, QS: Qiaoshe, NX: Nanxin, CC: Chucha) from March 2017 to February 2018. The species composition and distribution as well as spatio-temporal variation in biodiversity and abundance were then examined. Overall, 12,680 samples comprising15 families and 84 species were collected, the majority of which belonged to the Order Cypriniformes (69.05% of the total species collected) and Cyprinidae (64.29%). Moreover, of these 84 species, 36 (42.86%) were endemic to China. Dominant species were Cyprinus carpio (index of relative importance (IRI): 17.19%), Pseudobrama simoni (IRI: 10.81%) and Xenocypris argentea (IRI: 10.20%). Subsequent cluster analysis divided the samples into three significantly different groups by sample site. Meanwhile, Margalef species richness and Shannon−Wiener diversity indices were both low, and along with analyses of abundance-biomass curves suggested moderate disturbance. Current threats to the conservation of fish biodiversity in the lower reaches were also reviewed and management solutions suggested. The results will help form the basis for reasonable exploitation and protection of freshwater fish in the lower reaches of the Ganjiang River.

Disturbances amplify tree community responses to climate change in the temperate–boreal ecotone

AbstractAimClimate change causes major shifts in species distributions, reshuffling community composition and favouring warm‐adapted species (“thermophilization”). The tree community response is likely to be affected by major disturbances, such as fire and harvest. Here, we quantify the relative contributions of climate change and disturbances to temporal shifts in tree composition over the last decades and evaluate whether disturbances accelerate community thermophilization.LocationQuébec, Canada.Time period1970–2016.Taxa studiedTrees.MethodsUsing 6,281 forest inventory plots, we quantified temporal changes in species composition between a historical (1970–1980) and a contemporary period (2000–2016) by measuring temporal β‐diversity, gains and losses. The effects of climate and disturbances on temporal β‐diversity were quantified using multiple regressions and variation partitioning. We compared how community indices of species temperature preference (CTI) and shade tolerance (CSI) changed for forests that experienced different levels of disturbance. We quantified the contribution of species gains and losses to change in CTI.ResultsTemporal β‐diversity was mainly driven by disturbances, with historical harvesting as the most important predictor. Despite the prevailing influence of disturbances, we revealed a significant thermophilization (ΔCTI = +.03 °C/decade) throughout forests in Québec. However, this shift in community composition was weakly explained by climate change and considerably slower than the rate of warming (+.14 °C/decade). Importantly, thermophilization was amplified by moderate disturbances (+.044 °C/decade), almost a threefold increase compared with minor disturbances (+.015 °C/decade). The gains and losses of a few tree species contributed to this community‐level shift.ConclusionsOur study provides evidence that disturbances can strongly modify tree community responses to climate change. Moderate disturbances, such as harvesting, might reduce competition and facilitate gains of warm‐adapted species, which then accelerate thermophilization of tree communities under climate change. Although accelerated by disturbances, community thermophilization was driven by the gains and losses of a small number of species, notably gains of maples.