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Abstract This clinical trial aimed to assess the impact of Nutrition Bio-shield superfood (NBS) on clinical status among critically ill ICU patients suffering from acute respiratory distress syndrome (ARDS) due to the Omicron variant of COVID-19. A total of 400 patients with confirmed Omicron-related ARDS were randomly assigned to either the intervention group (n = 200) or the control group (n = 200). Patients in the intervention group received 1.5 g of NBS powder daily for 2 weeks in addition to standard antiviral treatment, while the control group received a placebo alongside standard antiviral therapy. Serum samples were collected from all patients in both groups, and various clinical and laboratory parameters, including ESR, CRP, D-Dimer, CPK, WBC count, lymphocyte count, and lymphocyte percentage, were measured using established methodologies. Following a 14-day intervention period, the intervention group exhibited a significant reduction in mean serum levels of CRP (15.39 vs. 48.49; P

Abstract Background and Aims Gastric cancer is a significant global issue with a high death rate. This malignancy could be associated with several viral agents such as EBV, CMV, HHV‐6, JCV, and BKV. Objective Evaluation of EBV, CMV, HHV‐6 ,and JCV, BKV frequency among gastric cancer patients. Methods In this cross‐sectional study, a total number of 60 gastric cancer specimens (32 male, 28 female) were retrieved from the pathology lab. Formalin‐fixed paraffin‐embedded tissue was used for molecular testing. DNA was extracted from samples, according to protocol, and used for PCR reaction. Polymerase chain reactions were used to assess CMV, EBV, HHV‐6, JCV, and BKV frequency. Results and Conclusion The mean age of the participants was 61 years and 53.3% (32) of the participants were Male. A total number of 5 samples (8.34%) were infected with viral agents. Four male gastric samples were infected with EBV (6.67%) and only one female sample contained the BKV genome (1.67%). Totally 8.34% of the samples were infected with EBV and BKV. The CMV, HHV‐6, and JCV genome was not detected in the samples. In conclusion, the presence of two viral agents including EBV and BKV among male and female samples respectively, and the genome of other viruses were not detected.

OBJECTIVE: To answer the question of whether viral infections such as Human papillomavirus (HPV) and Epstein-Barr virus (EBV) are involved in the occurrence of breast cancer or not. METHODOLOGY: In this case-control study, 50 paraffin-embedded breast samples (FFPE) and 50 non-cancerous FFPE samples were prepared from patients referred to Abadan hospitals from 2018 to 2021 to identify the genome of HPV and EBV by polymerase chain reaction (PCR). Data were analyzed using SPSS 15 with P-values of 0.05. Confirmed breast cancer biopsy samples with no medical history of chemotherapy and/or radiotherapy, the patient not being pregnant at the time of sampling, not using anti-cancer treatments, and not suffering from systemic inflammatory diseases such as rheumatoid arthritis. Patients of any age, with any breast cancer, and any size or stage of tumor were included without restrictions. RESULTS: Using PCR, HPV DNA was detected in 7/50 (14%) and 2/50(4%) of breast cancers and normal control, respectively. Moreover, 71.42% and 28.57% of HPV-infected persons in the patient's group were genotypes 16 and 18, respectively. All HPV-infected people in the control group were low-risk genotypes 26 and 53. Also, EBV DNA was found in 2/50 (4%) and 6/50 (12%) of breast cancers and control samples, respectively. Co-infection was not detected in samples. CONCLUSION: Although our study does not provide substantial Evidence about the role of viral infection in the progressiveness of breast tumors, significant studies have shown the critical role of these infections in the progression of breast tumors.

Background and purpose: Despite advances in oral health and dental industry, tooth decay remains one of the most common oral diseases. One of the new methods to combat dental plaque, which is the main cause of caries, is using specific lytic bacteriophage. This study aimed to investigate the effect of isolated specific lytic phage against growth and biofilm inhibition of Streptococcus mutans and Streptococcus sanguinis isolated from decayed dental plaque samples. Materials and methods: In this descriptive cross-sectional study, dental plaque samples were cultured in MSA-specific medium to isolate S. mutans and S. sanguinis. Suspicious isolates were examined by biochemical tests and finally confirmed molecularly by PCR. The ability to form biofilm was measured by crystal violet colorimetry on a microtiter plate. Lytic bacteriophage was isolated from urban raw sewage using double layer agar method and phage morphology was examined by TEM electron microscopy. The effect of lytic phage on the growth of S. mutans and S. sanguinis was measured by agar spot and well diffusion and its inhibition effect on biofilm was assayed by microtiter plate method. Results: Out of 150 plaque samples, S. mutans and S. sanguinis strains were isolated from 65 (43.33%) and 40 (26.67%) samples, respectively. S. mutans isolates showed stronger biofilm formation (OD= 0.43). The results of TEM showed lytic bacteriophage belonging to Siphoviridae family with a good inhibitory effect on the growth of S. mutans and S. sanguinis that was able to inhibit biofilm formation up to 96%. Conclusion: Due to the small size of the phage particles that can have good penetration power to enter the biofilm layers, it can be concluded that the phage has the ability to fight dental plaque.

Background : The importance of neural stem cell (NSC) survival in the appropriate brain function, synapsis formation, and neural cell communication is to the degree that any perturbation in this process leads to many neurodegenerative diseases. Numerous therapeutic approaches have recently been developed to prolong the survival of NSCs, so that these multipotent stem cells could differentiate into other neural cells and improve the function of the brain. Methods : In this study, we aimed to investigate whether the treatment of isolated NSCs from the Wistar rats with the nutrition bio-shield (NBS) supplement could boost the survival of NSCs. Results : Of note, we found that the extract had negative effects neither on the biochemical and hematological parameters nor on the morphology of hepatocytes of the rats, suggestive of the lack of toxicity of the extract. Our results also suggested that the extract robustly increased the survival and the proliferative capacity of NSCs by elevating the metabolic activity of the cells. The NBS supplement also prevented the induction of apoptotic cell death in NSCs, as revealed by the decrease in the number of terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL)-positive cells as compared to the control group. Conclusion : Overall, this study highlighted the potent efficacy of the NBS supplement in prolonging the survival of NSCs and proposed the possibility of the clinical use of the extract in the treatment of different neural diseases. However, further investigations in this field are required to provide the extract?s mechanism of action.

Background and purpose: Dental plaque is a biofilm that is formed on the surface of the tooth. Carious lesions are caused by inappropriate ecological changes in microbial flora of the plaque biofilm. In this study, the effect of Lactobacillus casei bacteriocin, isolated from dairy products, was investigated on Streptococcus salivarius biofilm formation. Materials and methods: In this experimental study, MRS Broth and MRS Agar medium were used to isolate three strains of Lactobacillus casei probiotic from milk samples under microaerophilic conditions. The initial identification of Lactobacillus casei was performed by sugar fermentation and other biochemical tests. Then, 16SrRNA encoding gene was confirmed by PCR and sequenced. At last, Bacteriocin was isolated by ammonium sulfate sedimentation and its molecular weight was measured by SDS-PAGE and the antimicrobial activities were investigated. The Streptococcus salivarius were isolated from dental plaque and phenotypically and biotypically identified. Molecular confirmation of the isolates was performed using gtfK specific gene by PCR. The ability to form Streptococcus salivarius biofilm and the effect of bacteriocin on biofilm formation were measured by microtiter plate. Results: After partial purification of Lactobacillus casei probiotic from dairy products, two LC3 and LC1 protein samples formed bands (35-40 kDa and about 75 kDa, respectively). The supernatant fluid from the cultivation of Lactobacillus casei and bacteriocins showed antibacterial effects against Streptococcus salivarius isolates from dental plaque and the formation of biofilm by this bacterium. Conclusion: According to this study, bacteriocin and supernatant fluid from Lactobacillus casei cultures could inhibit the growth of Streptococcus salivarius and also reduced biofilm formation, so, it could be used in oral care products.

Novel coronavirus outbreak in December 2019 leads to current pandemic condition worldwide. Severe acute respiratory syndrome coronavirus-2 known as the aetiologic agent of coronavirus disease 2019 (COVID-19). The major characterisation of COVID-19 is to involve lung and induce pneumonia, multiorgan failure, hypoxia and deat h. This systematic literature review aimed to assess the clinical manifestation and laboratory and radiologic features in patients with COVID-19. A literature review of the indexed articles in the Web of Science, PubMed, Scopus and Embase was performed to evaluate pathophysiology of COVID-19. Between 77,406 assessed COVID-19 patients, the most reported background diseases were cardiovascular and cerebrovascular disease. After fever, cough was the second most common repeated clinical feature. Furthermore, the laboratory investigations reveal that the C-reactive protein (CRP) increasing is the most common frequent laboratory finding. Chest imaging assessment indicates that bilateral involvement of the lungs is more common than unilateral involvement. Despite the fact that some of the COVID-19-infected patients are asymptomatic, the majority of patients showed a broad range of manifestation. The clinical findings help in better understanding of COVID-19 pathogenesis and patient's management. The primary concept of understanding of COVID-19 pathophysiology is necessary for reach to target therapeutics approach. According to the results, further in vivo investigations on animal models could be recommended for the treatment of COVID-19 patients in future.

Today, various biological approaches are used to combat dental plaque biofilms. In the current study, we aimed to compare the effect of extracted bacteriocin and lytic bacteriophage on the expression of biofilm associated genes in Streptococcus mutans. Streptococcus mutans was isolated from plaques of decayed dental and the existence of their gtfs genes was confirmed by PCR. For bacteriocin extraction, at first two probiotic lactobacilli were isolated from traditional foods, then bacteriocin was extracted by partial purification method, and SDS-PAGE was used for estimation of its molecular weight. The previously extracted lytic bacteriophage from raw urban sewage was used against Streptococcus mutans. Finally, the effect of isolated bacteriocin and bacteriophage on gtfs genes expression level was measured by real-time PCR. Out of 81 dental plaque samples, 32 (39.5%) Streptococcus mutans strains were isolated. The frequency of genes was as follows: gtfD32 (100%), gtfB 17 (53.12%), and gtfC 19 (53.37%). 120 traditional food samples (milk, yogurt, pickle, and salty pickle) were evaluated for isolation of lactobacillus. Three strains of Lactobacillus fermentum and four Lactobacillus plantarum with probiotic potential activity were isolated. Two types of bacteriocins from Lactobacillus fermentum and a single type of bacteriocin from Lactobacillus plantarum were extracted, and their molecular weights were 60, 58, and 70 kDa, respectively. In our previous study, two bacteriophages belonging to the Siphoviridae and Tectiviridae families were isolated. Real-time PCR results had shown that both bacteriocin and bacteriophage had a decreasing effect on the expression of gtfs genes. The different modes in our study for the effects of bacteriocin and bacteriophage showed that both of them had good potential as suitable options to fight dental plaque biofilms, and bacteriophages alone showed a stronger reducing effect.

Introduction/aims: Since the start of a pandemic from Wuhan, China in 2019, there is tremendous attention in the COVID-19 manifestation. One of the most important COVID-19 clinical presentations is gastrointestinal symptoms. The current systematic review study aims to focus on the implication of the gastrointestinal tract in patients infected with SARS-CoV-2. Methods: For that we searched literature in MEDLINE, Scopus, Web of Science, and Embase. Also, the medRxiv was searched for preprints. The search was performed by using the following keywords "Covid-19", "Coronavirus", "SARS-CoV-2 infection", "SARS-CoV-2", "Gastrointestinal", "Gastrointestinal Tract", "digestive system". All the studies were conducted based on the PRISMA criteria. Results: Of 3028 retrieved documents, 111 studies with 21126 COVID-19 cases were included. The prevalence of any Gastrointestinal symptoms was 17.22% (14.48 to 20.13). The prevalence of diarrhea was 13.75% (12.07 to 15.44), anorexia 27.41% (21.53 to 33.29) and Nausea/vomiting 8.11% (6.87 to 9.35). Furthermore, the prevalence of other symptoms in our current study was fever 76.70% (73.42 to 79.83), cough 58.07% (54.59 to 61.52) and dyspnea/shortness of breath 24.63% (20.06 to 29.48). According to meta-regression results, age (p: 0.027) and fever (p

Background. Currently, a novel coronavirus found in 2019 known as SARS-CoV-2 is the etiological agent of the COVID-19 pandemic. Various parameters including clinical manifestations and molecular evaluation can affect the accuracy of diagnosis. This review aims to discuss the various clinical symptoms and molecular evaluation results in COVID-19 patients, to point out the importance of onset symptoms, type, and timing of the sampling, besides the methods that are used for detection of SARS-CoV-2. Methods. A systematic literature review of current articles in the Web of Science, PubMed, Scopus, and EMBASE was conducted according to the PRISMA guideline. Results. Of the 12946 patients evaluated in this investigation, 7643 were confirmed to be COVID-19 positive by molecular techniques, particularly the RT-PCR/qPCR combined technique (qRT-PCR). In most of the studies, all of the enrolled cases had 100% positive results for molecular evaluation. Among the COVID-19 patients who were identified as such by positive PCR results, most of them showed fever or cough as the primary clinical signs. Less common symptoms observed in clinically confirmed cases were hemoptysis, bloody sputum, mental disorders, and nasal congestion. The most common clinical samples for PCR-confirmed COVID-19 patients were obtained from throat, oropharyngeal, and nasopharyngeal swabs, while tears and conjunctival secretions seem to be the least common clinical samples for COVID-19 diagnosis among studies. Also, different conserved SARS-CoV-2 gene sequences could be targeted for qRT-PCR detection. The suggested molecular assay being used by most laboratories for the detection of SARS-CoV-2 is qRT-PCR. Conclusion. There is a worldwide concern on the COVID-19 pandemic and a lack of well-managed global control. Hence, it is crucial to update the molecular diagnostics protocols for handling the situation. This is possible by understanding the available advances in assays for the detection of the SARS-CoV-2 infection. Good sampling procedure and using samples with enough viral loads, also considering the onset symptoms, may reduce the qRT-PCR false-negative results in symptomatic COVID-19 patients. Selection of the most efficient primer-probe for target genes and samples containing enough viral loads to search for the existence of SARS-CoV-2 helps detecting the virus on time using qRT-PCR.

Background: Owing to restricted treatment options, Vancomycin-resistant Enterococci (VRE) was considered a prominent cause of nosocomial infections. This study was undertaken to evaluate the presence of Van-type and virulence determinants in the clinical isolates of E. faecium (Ent. faecium) in Shariati Hospital. Materials and Methods: A total of 150 Enterococcal isolates were surveyed. Antimicrobial susceptibility testing was performed by disc diffusion and E-test as well as the genotypic method. The presence of virulence factors, including hyaluronidase (hyl), gelatinase (gelE), aggregation substance (asa1), and Enterococci surface protein (ESP) were identified by Polymerase chain reaction (PCR). Results: Overall, 66.67 percent (80/120) of VRE Ent. faecium strains were confirmed by the PCR method. The maximum number of isolates was from urine specimens (p < 0.05) and blood samples. Among the 80 VRE Ent. faecium isolates, 76 isolates showed high-level resistance (MICs to Vancomycin 32 > µg/ml) and carried a VanA phenotype (p < 0.05). In all the isolates, asa1, gelE, and ESP genes were identified in 14% (17/5), 26/3% (21/80), and 45% (36/80), respectively. E. Ent. faecium carried ESP at a significantly higher frequency presented in VRE strains (p < 0.001). The prevalence of hly determinants in the E. faecium was 20% (16) (P < 0.001). Conclusion: We, in our hospital, are faced with a high rate of VRE Ent. faecium isolates with a VanA-positive phenotype. With increasing resistance of the VRE strains to linezolid, we will encounter a serious challenge in treating VRE patients in future years. An interesting finding from the present study is that the spreading rates of ESP and hly among Ent. faecium isolates are higher.

Background: Hepatitis B virus is one of the transfusion transmissible infections. Despite the availability of hepatitis B virus (HBV) vaccine and screening tests but still danger of virus transmission via blood transfusion is high in some regions. The objective of this study was to determine the trend of seroprevalence of hepatitis B in over an 11-year period (2005–2015). Methods: In this study, 355,083 blood donors were estimated for hepatitis B surface antigen (HBs Ag) seropositivity during 2005–2015 who referred to blood infusion centers of Lorestan province. Third-generation ELISA method was used to detect HBs Ag. Results: The prevalence of HBs Ag in blood donors was 0.29% (1017). It was decreased steadily from 2005 to 2015 (0.68% to 0.12%) but increased in 2008 year. The trend prevalence of HBs Ag seropositivity significantly decreased over the study period (P < 0.001). The decline in HBV infection rates was more prominent in regular and repeated donor's groups compared to people who donated blood for the first time (P < 0.001). Conclusions: The result of present study was indicated, Lorestan city in west of Iran can be classified as a low-income region because the low prevalence of HBs Ag in blood donors. Also the prevalence of HBs Ag in first-time donors was higher than other groups.

Background and Aim: Early diagnosis of pregnancy is very important to prevent fetal damage due to specific drug consumption and high-risk behaviors. The objective of this study was to compare the sensitivity and specificity of quantitative agglutination pregnancy tests in urine and rapid β hCG immunoenzymatic assay test in serum as a gold standard. Materials and Methods: This cross-sectional study was performed among 390 women who referred to healthcare centers where their urine samples were tested with latex agglutination (direct agglutination and agglutination inhibition) and the results were compared with rapid β hCG immunoenzymatic assay test in serum as a gold standard. Results: The sensitivity of direct agglutination (82.05 % ) was more than that of agglutination inhibition (81.2 % ), but the specificity of the tests were equal (99.27 % ). The agreement coefficients between direct agglutination and agglutination inhibition on the one hand and rapid β HCG immunoenzymatic assay on the other were 0.859 and 0.853, respectively. Conclusion : The possibility of negative results in direct agglutination is more than that of agglutination inhibition, but the specificity of both qualitative tests is equal. Besides, both tests may have an equal possibility of false positive results. Since the occurrence of false negative results in qualitative tests is higher than that in serum gold standard, the negative results of such tests should be confirmed with more sensitive methods such as rapid β hCG immunoenzymatic assay.

In the original article [...]

Anthropogenic industrial dust decreases productivity and slows down the growth of plants. Quantifying the effects of industrial dust on vegetation and determining the distance over which factories scatter dust are of paramount importance for biodiversity conservation and sustaining ecosystem services. This study aims at quantifying the effect of dust emitted by the Neka cement plant (NCP), Mazandaran province, northern Iran, on the surrounding Hyrcanian forests based on an analysis of the Leaf Area Index (LAI) retrieved from Sentinel-2 imagery. An Inductively Coupled Plasma Mass Spectrometer (ICP-MS) was used to quantify the concentrations of cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), calcium (Ca), magnesium (Mg), sodium (Na), silicon (Si) and zinc (Zn) in leaves of the dominant Chestnut-leaved Oak (Quercus castaneifolia). A feed-forward neural network algorithm and field measurements were used to retrieve the leaf area index (LAI) from Sentinel-2 data with a RMSE of 0.42 (m2/m2). MODIS-NDVI and EVI time series spanning 17 years (2000 to 2017) were analysed to ensure the independence of the variation in the condition of the vegetation from drought or other environmental factors. The results indicate that Sentinel-2 data can be used to map degradation due to pollution from the cement plant and quantify the effect of the dust spatially. Dust from the cement plant (dust source) was carried approximately 4700 meters in the direction of the prevailing wind. A significant correlation of 0.849 was recorded between LAI and distance from the NCP. It is concluded that dust from the NCP had adverse ecological effects on the neighbouring forest ecosystems recently designated a UNESCO World Heritage Site.

Mangrove forests distributed along the coast of southern Iran are an important resource and a vital habitat for species communities and the local people. In this study, accurate mapping and spatiotemporal change detection were conducted on Iran’s mangroves for three decades, using the Landsat imagery available for the years 1990, 2000, 2010, and 2020. Four general vegetation indices and eight mangrove-specific indices were employed for mangrove mapping in three study sites. Additionally, six important landscape metrics were implemented to quantify the spatiotemporal alteration of the mangrove forests during the study period. Our results showed the robustness of the submerged mangrove recognition index (SMRI), validated as the most effective index (F1-score ≥ 0.89), which was used for mangrove identification within all nine sites. The mangrove area of southern Iran was estimated at approximately 13,000 ha in 2020, with an overall increase of 2313 ha over the whole period. A similar trend could be observed for both the landscape connectivity and complexity. Our results revealed that a stronger connectivity and higher complexity could be detected in most sites, while there was increased fragmentation and a weaker connection in some locations. This study provides an accurate map of Iran’s mangrove forests over time and space.

Background and Aim: Early diagnosis of pregnancy is very important to prevent fetal damage due to specific drug consumption and high-risk behaviors. The objective of this study was to compare the sensitivity and specificity of quantitative agglutination pregnancy tests in urine and rapid β hCG immunoenzymatic assay test in serum as a gold standard. Materials and Methods: This cross-sectional study was performed among 390 women who referred to healthcare centers where their urine samples were tested with latex agglutination (direct agglutination and agglutination inhibition) and the results were compared with rapid β hCG immunoenzymatic assay test in serum as a gold standard. Results: The sensitivity of direct agglutination (82.05%) was more than that of agglutination inhibition (81.2%), but the specificity of the tests were equal (99.27%). The agreement coefficients between direct agglutination and agglutination inhibition on the one hand and rapid β HCG immunoenzymatic assay on the other were 0.859 and 0.853, respectively. Conclusion: The possibility of negative results in direct agglutination is more than that of agglutination inhibition, but the specificity of both qualitative tests is equal. Besides, both tests may have an equal possibility of false positive results. Since the occurrence of false negative results in qualitative tests is higher than that in serum gold standard, the negative results of such tests should be confirmed with more sensitive methods such as rapid β hCG immunoenzymatic assay. [ABSTRACT FROM AUTHOR]

Abstract Backgrounds There are many satellite systems acquiring environmental data on the world. Acquired global remote sensing datasets require ground reference data in order to calibrate them and assess their quality. Regarding calibration and validation of these datasets with broad geographical extents, it is essential to register zones which might be considered as Homogeneous Patches (HPs). Such patches enable an optimal calibration of satellite data/sensors, and what is more important is an analysis of components which significantly influence electro-magnetic signals registered by satellite sensors. Methods We proposed two structurally different methods to identify HPs: predefined thresholding-based one (static one), and statistical thresholding-based technique (dynamic one). In the first method, 3 different thresholds were used: 5%, 10%, and 20%. Next, it was aimed to assess how delineated HPs were spatially matched to satellite data with coarse spatial resolution. Selected cell sizes were 25, 50, 100, 250, and 500 m. The number of particular grid cells which almost entirely fell into registered HPs was counted (leaving 2% cell area tolerance level). This procedure was executed separately for each variant and selected structural variables, as well as for their intersection parts. Results The results of this investigation revealed that ALS data might have the potential in the identification of HPs of forest stands. We showed that different ALS based variables and thresholds of HPs definition influenced areas which can be treated as similar and homogeneous. We proved that integration of more than one structural variable limits size of the HPs, in contrast, visual interpretation revealed that inside such patches vegetation structure is more constant. Conclusions We concluded that ALS data can be used as a potential source of data to “enlarge” small ground sample plots and to be used for evaluation and calibration of remotely sensed datasets provided by global systems with coarse spatial resolutions.

The spatial pattern of trees is one of the structural characteristics of forest stands that affects the efficiency of sampling methods. This study aimed at investigating the effect of spatial distribution of trees on the efficiency of distance and plot sampling methods. For this purpose, a dispersed Persian oak stand in Kohgilouye-Boyerahmad province (47 ha) and a clumped wild pistachio stand in Fars province (45 ha) were selected. Six distance and six plot sampling methods were applied on a 100 m × 100 m grid in the stands to estimate the density and canopy cover. The efficiency of methods was evaluated by statistical comparison of the results with true values, accuracy criterion, and root mean square error percent. The true density and canopy cover percent of wild pistachio and Persian oak stands were 19.4 trees ha-1 and 5.1% and 22.3 trees ha-1 and 17.1%, respectively. The results showed that between distance sampling methods, nearest individual (density: 19.5 trees ha-1, canopy cover: 5.2%) and nearest neighbour (density: 20.1 trees ha-1, canopy cover: 4.9%) methods in wild pistachio stand and line intersect method (density: 21.0 trees ha-1, canopy cover: 17.3%) in Persian oak stand were efficient. Moreover, all plot sampling methods were efficient in both stands (except square method). In general, the results showed that in contrast to plot sampling methods, the spatial distribution of trees influences significantly the accuracy and precision of distance sampling methods.

Although woody plant encroachment of tropical forest ecosystems has been related to altered disturbance regimes, its impacts on the nearest neighborhood structures and community phylogenetics are still poorly understood. Streblus macrophyllus is a light-demanding species during its early life stages and is shade-tolerant as a mature tree. S. macrophyllus can be found in tropical karst evergreen forests in northern Vietnam. It often regenerates at high densities in anthropogenic disturbed forest stands. To understand the structural patterns of disturbed forests encroached by S. macrophyllus at different abundance levels, three fully mapped 1-ha plots were established in Cuc Phuong National Park. Methods considering the phylogenetic community and nearest neighbor statistics were applied to identify how community structure changes during S. macrophyllus encroachment. Results showed that phylogenetic distance, phylogenetic diversity, and mean phylogenetic distance increased when species diversity increased and the abundance of S. macrophyllus decreased in forest communities. Net related index values were positive, which indicates a clustered phylogenetic structure among all sampled forest communities. S. macrophyllus trees were mixed well with heterospecifics and had regular to aggregated distributions, whereas the species showed evidence of being a strong competitor with its neighbors. Competition could be a major ecological process regulating forest communities encroached by S. macrophyllus. According to the forest disturbance effects, phylogenetic community properties showed the loss of phylogenetic relatedness when S. macrophyllus increased in abundance. To our knowledge, S. macrophyllus encroaches tropical rain forest communities as a disturbance-adapted species.

The spatial distribution analysis of woody plants in arid and semi-arid environments explains their interactions and how they influence one another. This study was aimed to evaluate the intraspecific interactions of Eshnan (Seidlitzia rosmarinus) shrubs across a portion of central Iranian arid lands using different summary statistics including pair correlation g(r), O-ring O(r), nearest neighbor distribution D(r), spherical contact distribution Hs(r) and mark correlation kmm(r) functions. A 160 × 160 m2 plot purely covered by Eshnan was selected in Qehi protected area, Isfahan province. The point map of all 989 Eshnan shrubs was obtained by Trimble R8 differential global positioning system with a positional accuracy of 3 mm ± 0.1 ppm. The observed pattern of shrubs showed significant spatial heterogeneity as compared to inhomogeneous Poisson process (α=0.05). The results of g(r) and O(r) revealed the significant aggregation of Eshnan shrubs up to scale of 3 m (α=0.05). The results of D(r) and Hs(r) also showed maximum distance to nearest shrub to be 6 m. It was additionally shown that the distribution of gap sizes was significantly different from random up to this spatial scale. Finally, kmm(r) for height, mean crown diameter, and crown area indicated the aggregation of Eshnan individuals at all scales. In general, positive interactions were concluded to exist amongst Eshnan shrubs at small scales, and they were aggregated due to their intraspecific facilitation effects in the study area.

Explaining the high diversity of tree species in tropical forests remains a persistent challenge in ecology. The analysis of spatial patterns of different species and their spatial diversity captures the spatial variation of species behaviors from a ‘plant’s eye view’ of a forest community. To measure scale-dependent species-species interactions and species diversity at neighborhood scales, we applied uni- and bivariate pair correlation functions and individual species area relationships (ISARs) to two fully mapped 2-ha plots of tropical evergreen forests in north-central Vietnam. The results showed that (1) positive conspecific interactions dominated at scales smaller than 30 m in both plots, while weak negative interactions were only observed in P2 at scales larger than 30 m; (2) low numbers of non-neutral interactions between tree species were observed in both study plots. The effect of scale separation by habitat variability on heterospecific association was observed at scales up to 30 m; (3) the dominance of diversity accumulators, the species with more diversity in local neighborhoods than expected by the null model, occurred at small scales, while diversity repellers, the species with less diversity in local neighborhoods, were more frequent on larger scales. Overall, the significant heterospecific interactions revealed by our study were common in highly diverse tropical forests. Conspecific distribution patterns were mainly regulated by topographic variation at local neighborhood scales within 30 m. Moreover, ISARs were also affected by habitat segregation and species diversity patterns occurring at small neighborhood scales. Mixed effects of limited dispersal, functional equivalence, and habitat variability could drive spatial patterns of tree species in this study. For further studies, the effects of topographical variables on tree species associations and their spatial autocorrelations with forest stand properties should be considered for a comprehensive assessment.

Structural complexity and local biodiversity of species-rich tropical forests can be characterized by their spatial patterns, which contribute to species intra- and interspecific interactions. Aiming to describe spatial patterns of species at fine spatial scales, we applied the quantitative analyses based on the relationships of nearest neighbors of conspecific and heterospecific trees. In a two-hectare plot of a tropical broadleaved forest stand in central Vietnam with minimal human influence, all tree individuals with diameter at breast height ≥ 2.5 cm were mapped and their characteristics were recorded. We applied two different types of analyses: (1) Intraspecific structural characteristics using nearest neighbor statistics; (2) overall interspecific associations through a classification scheme based on bivariate nearest neighbor distribution function D12(r) and Ripley’s K function K12(r). The findings showed that: (1) Most of studied species in the forest were highly mixed with other species, while conspecifics were regular to aggregated distribution at small spatial scales. Tree individuals with different diameter values were surrounded by heterospecific trees; (2) The majority of 306 species-species pairs showed spatial independence (66.7%), whereas 29.8% of all species showed an overall positive association and negative association consisted only a small percentage (3.5%) up to spatial scales of 50 m. We found significant evidences of the main ecological theories such as dispersal limitation, Neutral theory, Janzen-Connell hypothesis, and other effects like the stochastic dilution. We suggest using both the bivariate distribution of the structural parameters and the spatial point pattern analysis based on nearest neighbor distance as advantageous approaches for further understanding of population structure, as well as discovering and protecting biodiversity in the future.