Relative Richness Research Articles

Emerging Evidence of the Value of Culturally Specific Organizations: Results of a Delphi and Consumer Voice Study

A set of culturally specific organizations in Portland, Oregon has been generating excellent results for clients and communities of color. Four of them have developed a collective impact initiative to reduce child poverty among communities of color, with backbone support from United Way, and the inclusion of one “culturally responsive” organization. This research seeks to answer, “How do these organizations achieve excellent results with clients of color?” Our answer, through a two-part Delphi and Consumer Voice study, identifies a far-ranging set of assets, only part of which are staffing characteristics. These assets have been affirmed by a statistically significant survey of consumers, encompassing the following nine domains: being community embedded, creating a culture of success, being responsive to community needs, advocating to improve community and client success, being culturally relevant, and providing a comprehensive continuum of services. Delivery attributes include relying heavily on a rich relationship model, being inclusive, and having staff be personally invested in client success. Clients confirmed that all nine domains are important to their lives, and rated their overall satisfaction with the organizations at 92.7%, far above the published national average of 77%. The paper concludes with a synthesis of the study’s relevance for policy makers, funders and practitioners.

BurstBiRank: Co-Ranking Developers and Projects in GitHub with Complex Network Structures and Bursty Interactions

With the wide adoption of social collaborative coding, more and more developers participate and collaborate on platforms such as GitHub through rich social and technical relationships, forming a large-scale complex technical system. Like the functionalities of critical nodes in other complex systems, influential developers and projects usually play an important role in driving this technical system to more optimized states with higher efficiency for software development, which makes it a meaningful research direction on identifying influential developers and projects in social collaborative coding platforms. However, traditional ranking methods seldom take into account the continuous interactions and the driving forces of human dynamics. In this paper, we combine the bursty interactions and the bipartite network structure between developers and projects and propose the BurstBiRank model. Firstly, the burstiness between each pair of developers and projects is calculated. Secondly, a weighted developer-project bipartite network is constructed using the burstiness as weight. Finally, an iterative score diffusion process is applied to this bipartite network and a final ranking score is obtained at the stationary state. The real-world case study on GitHub demonstrates the effectiveness of our proposed BurstBiRank and the outperformance of traditional ranking methods.

Do Dominant Ants Affect Secondary Productivity, Behavior and Diversity in a Guild of Woodland Ants?

The degree to which competition by dominant species shapes ecological communities remains a largely unresolved debate. In ants, unimodal dominance–richness relationships are common and suggest that dominant species, when very abundant, competitively exclude non-dominant species. However, few studies have investigated the underlying mechanisms by which dominant ants might affect coexistence and the maintenance of species richness. In this study, we first examined the relationship between the richness of non-dominant ant species and the abundance of a dominant ant species, Formica subsericea, among forest ant assemblages in the eastern US. This relationship was hump-shaped or not significant depending on the inclusion or exclusion of an influential observation. Moreover, we found only limited evidence that F. subsericea negatively affects the productivity or behavior of non-dominant ant species. For example, at the colony-level, the size and productivity of colonies of non-dominant ant species were not different when they were in close proximity to dominant ant nests than when they were away and, in fact, was associated with increased productivity in one species. Additionally, the number of foraging workers of only one non-dominant ant species was lower at food sources near than far from dominant F. subsericea nests, while the number of foragers of other species was not negatively affected. However, foraging activity of the non-dominant ant species was greater at night when F. subsericea was inactive, suggesting a potential mechanism by which some non-dominant species avoid interactions with competitively superior species. Gaining a mechanistic understanding of how patterns of community structure arise requires linking processes from colonies to communities. Our study suggests the negative effects of dominant ant species on non-dominant species may be offset by mechanisms promoting coexistence.

Temporal variations in abundance and species richness of phytoplankton with emphasis on diatoms in the subtidal waters of Umm Al-Namil Island, north-western Arabian Gulf of the ROPME Sea Area

Aim: The present study aimed to understand the physico-chemical factors affecting the abundance and species richness of phytoplankton communities, with emphasis on diatoms at the end of the intertidal zone and start of subtidal zone. Methodology: Water quality and phytoplankton community species richness and abundance were measured in the subtidal waters of Umm Al-Namil Island, Kuwait Bay. Kruskal-Wallis statistical approach was used to measure the effect of various environmental parameters on abundance and species richness as well as abundance-species richness relationships using R statistical software. Results: The physico-chemical parameters showed variations at each sampling event as well as within the same season. Total phytoplankton mean abundance values in summer (22.26 ± 0.66 ind. 5l-1) and winter (21.63 ± 0.52 ind. 5l-1) did not significantly vary and the lowest mean abundance was observed during spring (26.36 ± 0.33 ind. 5l-1). Species abundance showed clear pattern with the events, resulting in somehow a negative relationship. Mean species richness was highest during autumn (24.59 ± 1.51), while no significant difference was observed between spring (11.09 ± 0.33), winter (10.47 ± 0.51) and summer (10.11 ± 0.66). The results indicate that phytoplankton species richness and species abundance in Umm Al-Namil Island varied temporally in response to fluctuations in environmental conditions. Interpretation: The end of intertidal zone and beginning of subtidal zone is affluent in diverse forms of phytoplankton species, specifically diatoms since Kuwait Bay is a eutrophic area mainly due to sewage and urbanization. Therefore, a temporal monitoring is required in order to observe any changes in either physico-chemical or biological factors with time and that will help in future conservation and restoration programs. Conservation approaches should be considered seriously since some diatoms like Melosira moniliformis, Gyrosigma diminutum, Fragilaria martyi, Hemidiscus cuneiformis, Planktoniella sol and Amphiprora plicata have been observed only at one event despite abundance and season.

Biomass and species richness relationships in macroalgal communities that span intertidal and subtidal zones

Investigations of the strong environmental gradients within intertidal and subtidal rocky reefs have contributed significantly to our understanding of ecological processes, but studies exploring how algal community structure responds to the extreme environmental transition of the intertidal-subtidal interface are rare. Our objective was to examine patterns in macroalgal distribution and species richness with depth on temperate rocky reefs. Standing algal biomass and richness were measured on 6 representative reefs in southern New Zealand, across 5 depth strata from the high intertidal zone, 1.5 m above mean low water (MLW), to the subtidal zone, 10 m below MLW. We found a unimodal relationship between algal richness and biomass across the depths, where maximum species richness occurred at intermediate levels of biomass. These results are consistent with many terrestrial plant studies across strong environmental gradients. Biomass decreased down the shoreline, with the exception of the high intertidal where the lowest biomass was recorded, whilst species richness increased down the shoreline. Additionally, strong patterns of dominance were observed, with a single species (not always the same species) contributing >56% of the total biomass across all depth strata examined. This dominance could have important implications for ecosystem provisioning across this system, particularly if dominant species are found to be vulnerable to the impacts of local and/or global change. The strong environmental gradients that characterise the intertidal-subtidal transition on rocky reefs over relatively small and experimentally tractable spatial scales enable opportunities to further advance our understanding of the mechanisms controlling the distribution of biodiversity.

Pollen and plant diversity relationships in a Mediterranean montane area

Understanding the significance of pollen diversity is key to reconstructing plant diversity over long timescales. Here we present quantitative pollen-plant diversity comparisons for a mountainous area of the Western Mediterranean region. Samples were collected between 430–1,865 m elevation and pollen-plant diversity assessed through richness and turnover (beta-diversity) metrics. We found statistically significant relationships between pollen diversity metrics and the diversity of pollen-equivalent plant taxa in the surrounding vegetation. The strongest richness relationships emerged from the exclusion of trees and with standardisation of the sample size (rarefaction) applied to both plant and pollen datasets. Three different metrics for turnover produced similar results, but emphasise different components of beta diversity (replacement vs richness differences). These results pave the way for reconstructing biodiversity trends from pollen sequences, with a number of caveats. Fossil pollen is a potentially rich source of information on past biodiversity in the Mediterranean region.

Drivers of plant species richness and structure in dry woodland of Prosopis flexuosa

Prosopis flexuosa (Fabaceae), a key species in desert environments, provides ecosystem services whereby it mitigates desertification and supports biodiversity conservation. To understand the relative importance of drivers of species diversity and structure of P. flexuosa-dominated woodland at different scales, we propose (1) to assess whether species richness is affected by predictors such as productivity, woodland structure, soil heterogeneity, mammal occurrence, and human activities; (2) to assess whether woodland structure is explained by productivity, soil heterogeneity, mammal occurrence and human activities; (3) to determine whether productivity and human activities affect mammal occurrence. We quantified drivers and indicators of composition and structure of P. flexuosa-dominated woodland in Ischigualasto Provincial Park and its area of impact, using both field- and remotely-based measurements. Plant species richness was positively explained by texture measures of the Soil-Adjusted Total Vegetation Index at 3x3 (0.81 ha) and 5x5 (2.25 ha) moving-window scales, as a surrogate for productivity, and by abundance of trees in the woodland stand (0.15 ha). The structure of P. flexuosa-dominated woodland was positively accounted for by productivity at the 5x5 moving-window scale and by occurrence of exotic species (positively -Bos taurus- and negatively -Lepus europaeus-). Soil heterogeneity and human activities did not affect woodland richness or structure. Occurrence of native species was explained by productivity at the 5x5 moving-window scale (positively for Microcavia maenas and negatively for Dolichotis patagonum), whereas occurrence of native (Lama guanicoe) and exotic (Equus asinus) species was affected by human activities (positively for distance to nearest village and negatively for distance to road, respectively). Understanding the relationships of dry woodland species richness and structure with different drivers is important to its conservation and management. We found that drivers such as productivity, abundance of trees and occurrence of exotic mammal species would affect richness and structure of P. flexuosa-dominated woodland.

How transcription factors drive choice of the T cell fate.

Recent evidence has elucidated how multipotent blood progenitors transform their identities in the thymus and undergo commitment to become T cells. Together with environmental signals, a core group of transcription factors have essential roles in this process by directly activating and repressing specific genes. Many of these transcription factors also function in later T cell development, but control different genes. Here, we review how these transcription factors work to change the activities of specific genomic loci during early intrathymic development to establish T cell lineage identity. We introduce the key regulators and highlight newly emergent insights into the rules that govern their actions. Whole-genome deep sequencing-based analysis has revealed unexpectedly rich relationships between inherited epigenetic states, transcription factor-DNA binding affinity thresholds and influences of given transcription factors on the activities of other factors in the same cells. Together, these mechanisms determine T cell identity and make the lineage choice irreversible.

Research on the Classification of Aviation Safety Reports Based on Text and Knowledge Graph

The existing automatic classification methods of aviation safety reports are mainly traditional machine learning classification algorithms, which have the disadvantages of relying on manual feature extraction and selection, unable to consider domain information and dealing with complex dependencies, which limits the improvement of classification accuracy. Therefore, this paper proposes an automatic classification algorithm for aviation safety reports that combines text and knowledge graph. The algorithm uses the knowledge triples with rich relationships as the background knowledge in the aviation safety field into the word2vec word vector training process so that the words can not only learn context information in training but also learn the complex semantics between words in the aviation field information, so that the trained word vectors can express richer semantic features, thereby improving the classification effect. Through a series of comparative experiments, the results show that the algorithm has the highest F1-score value and has a classification accuracy rate of up to 91.4%.

Event-Centric Hierarchical Representation for Dense Video Captioning

Dense video captioning aims to localize and describe multiple events in untrimmed videos, which is a challenging task that draws attention recently in computer vision. Although existing methods have achieved impressive performance, most of them only focus on local information of event segments or very simple event-level context, overlooking the complexity of event-event relationship and the holistic scene. As a result, the coherence of captions within the same video could be damaged. In this article, we propose a novel event-centric hierarchical representation to alleviate this problem. We enhance the event-level representation by capturing rich relationship between events in terms of both temporal structure and semantic meaning. Then, a caption generator with late fusion is developed to generate surrounding-event-aware and topic-aware sentences, conditioned on the hierarchical representation of visual cues from the scene level, the event level, and the frame level. Furthermore, we propose a duplicate removal method, namely temporal-linguistic non-maximum suppression (TL-NMS) to distinguish redundancy in both localization and captioning stages. Quantitative and qualitative evaluations on the ActivityNet Captions and YouCook2 datasets demonstrate that our method improves the quality of generated captions and achieves state-of-the-art performance on most metrics.

Island biogeography of native and alien plant species: Contrasting drivers of diversity across the Lesser Antilles

AbstractAimUnderstanding the factors driving the diversity of alien and native species on islands is crucial for predicting the spread of alien species and for proposing management practices to protect the unique native biodiversity that often occurs in insular ecosystems. The main objective of this study was to evaluate whether native and alien plant species respond similarly to natural biogeographic and human‐related drivers.LocationLesser Antilles, Caribbean.MethodsWe compiled a dataset with the verified status of native and alien plant species occurring on 15 islands across the Lesser Antilles. We assessed the relationship of native and alien plant species richness and identified the biogeographic and socio‐economic variables that best explain the diversity patterns of both alien and native species on these islands by combining correlation analysis and generalized linear models.ResultsThe final dataset comprises a total of 2,438 plant species with 1,825 native species and 613 alien species. For the 15 islands analysed, native and alien species richness is strongly and positively correlated, but different variables explained their diversity patterns. We found that biogeographic drivers such as island area, elevation and distance to the mainland best explain patterns of native species richness. On the other hand, alien species richness was well predicted by a combination of geographic and socio‐economic variables, with per capita gross domestic product (GDP) and island area having the strongest effect. Species composition of alien floras is also significantly influenced by the historical colonial identity of these islands.Main conclusionsWhile native species are clearly associated with biogeographic variables, alien species are strongly influenced by variables related to human activities and therefore anthropogenic disturbance processes. Modification of natural areas by human activities can result in high alien species richness even on islands with high native species richness.

Evaluating the potential of full‐waveform lidar for mapping pan‐tropical tree species richness

AbstractAimMapping tree species richness across the tropics is of great interest for effective conservation and biodiversity management. In this study, we evaluated the potential of full‐waveform lidar data for mapping tree species richness across the tropics by relating measurements of vertical canopy structure, as a proxy for the occupation of vertical niche space, to tree species richness.LocationTropics.Time periodPresent.Major taxa studiedTrees.MethodsFirst, we evaluated the characteristics of vertical canopy structure across 15 study sites using (simulated) large‐footprint full‐waveform lidar data (22 m diameter) and related these findings to in‐situ tree species information. Then, we developed structure–richness models at the local (within 25–50 ha plots), regional (biogeographical regions) and pan‐tropical scale at three spatial resolutions (1.0, 0.25 and 0.0625 ha) using Poisson regression.ResultsThe results showed a weak structure–richness relationship at the local scale. At the regional scale (within a biogeographical region) a stronger relationship between canopy structure and tree species richness across different tropical forest types was found, for example across Central Africa and in South America [R2 ranging from .44–.56, root mean squared difference as a percentage of the mean (RMSD%) ranging between 23–61%]. Modelling the relationship pan‐tropically, across four continents, 39% of the variation in tree species richness could be explained with canopy structure alone (R2 = .39 and RMSD% = 43%, 0.25‐ha resolution).Main conclusionsOur results may serve as a basis for the future development of a set of structure–richness models to map high resolution tree species richness using vertical canopy structure information from the Global Ecosystem Dynamics Investigation (GEDI). The value of this effort would be enhanced by access to a larger set of field reference data for all tropical regions. Future research could also support the use of GEDI data in frameworks using environmental and spectral information for modelling tree species richness across the tropics.

The origin of tetrapod herbivory: effects on local plant diversity.

The origin of herbivory in the Carboniferous was a landmark event in the evolution of terrestrial ecosystems, increasing ecological diversity in animals but also giving them greater influence on the evolution of land plants. We evaluate the effect of early vertebrate herbivory on plant evolution by comparing local species richness of plant palaeofloras with that of vertebrate herbivores and herbivore body size. Vertebrate herbivores became diverse and achieved a much greater range of body sizes across the Carboniferous-Permian transition interval. This coincides with an abrupt reduction in local plant richness that persists throughout the Permian. Time-series regression analysis supports a negative relationship of plant richness with herbivore richness but a positive relationship of plant richness with minimum herbivore body size. This is consistent with studies of present-day ecosystems in which increased diversity of smaller, more selective herbivores places greater predation pressures on plants, while a prevalence of larger bodied, less selective herbivores reduces the dominance of a few highly tolerant plant species, thereby promoting greater local richness. The diversification of herbivores across the Carboniferous-Permian boundary, along with the appearance of smaller, more selective herbivores like bolosaurid parareptiles, constrained plant diversity throughout the Permian. These findings demonstrate that the establishment of widespread vertebrate herbivory has structured plant communities since the late Palaeozoic, as expected from examination of modern ecosystems, and illustrates the potential for fossil datasets in testing palaeoecological hypotheses.

A Thematic Similarity Network Approach for Analysis of Places Using Volunteered Geographic Information

The research presented in this paper proposes a thematic network approach to explore rich relationships between places. We connect places in networks through their thematic similarities by applying topic modeling to the textual volunteered geographic information (VGI) pertaining to the places. The network approach enhances previous research involving place clustering using geo-textual information, which often simplifies relationships between places to be either in-cluster or out-of-cluster. To demonstrate our approach, we use as a case study in Manhattan (New York) that compares networks constructed from three different geo-textural data sources—TripAdvisor attraction reviews, TripAdvisor restaurant reviews, and Twitter data. The results showcase how the thematic similarity network approach enables us to conduct clustering analysis as well as node-to-node and node-to-cluster analysis, which is fruitful for understanding how places are connected through individuals’ experiences. Furthermore, by enriching the networks with geodemographic information as node attributes, we discovered that some low-income communities in Manhattan have distinctive restaurant cultures. Even though geolocated tweets are not always related to place they are posted from, our case study demonstrates that topic modeling is an efficient method to filter out the place-irrelevant tweets and therefore refining how of places can be studied.

Long-term altitudinal change in bird richness in a Mediterranean mountain range: habitat shifts explain the trends

The altitudinal distribution of species richness is affected by climate and habitat changes, and the balance between these drivers will produce an idiosyncratic pattern in each mountain range. However, the potential effect of habitat change has rarely been included in studies designed to detect the effect of climate change on mountain biodiversity. This paper explores the changes in the altitudinal distribution of forest bird richness in the Guadarrama Mountains (600–2400 m a.s.l., Central Spain) over the last several decades. These mountains are affected by global warming and increased tree density resulting from rural abandonment. Nothing is known, however, about the way these changes have affected the altitudinal distribution of bird richness. Bird counts carried out in 1976–1980 were repeated in 2014–2015 along an altitudinal succession of forest belts. The results show that the relationship of bird richness to elevation shifted from a hump-shaped model typical of dry mountains to a monotonic negative model characteristic of humid mountains. These trends diverged from predictions on the effects of climate warming and were related to a loss of bird richness in endemic Scots pinewoods in the upper parts of the mountains. Variations in the composition of bird assemblages suggested that these pinewoods have experienced a process of tree densification and understory loss. As a result, the reshuffling of the altitudinal distribution of bird richness produced by habitat changes has eclipsed any effects of climate warming. These results emphasize the importance of considering habitat and climate interactions when exploring the altitudinal shift of species richness in the context of global change.

The influence of matrix type in the relationship between patch size and amphibia richness: A global Meta-Analysis

The species-area relationship (SAR) is one of the main topics debated in ecology. Amphibians are highly sensitive to habitat loss and fragmentation, due to their traits and reproductive requirements. In the present study, we developed a meta-analysis to address a mean effect size to SAR regarding forest amphibians in man-made fragmented landscapes, and tested the influence of seven in-study and landscape variables that may affect this relationship globally. We conducted a search using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) protocol and calculated an effect size for each one of the 28 studies elected by our criteria. There is a positive relationship between amphibia richness and patch area, with a mean effect size of 0.68 and high heterogeneity among studies. The meta-regressions showed that only the matrix type surrounding the patches affected the variance between studies, explaining 46%. Clear cut was the matrix with the highest effect size, followed by silviculture, but both had a low representation of studies. Agriculture, grazing and urban matrices had a significant influence on patch area and the species richness relationship, but with distinct mean effects sizes and variances between-studies. The matrix type around the remnants may substantially affect results and interpretation of the SAR, possibly due to the varying capacity of amphibia species to cross and inhabit each matrix type. If possible, SAR should be compared within a context of multiple landscapes, and not only with a patch-focused and local approach.

Channel Interaction Networks for Fine-Grained Image Categorization

Fine-grained image categorization is challenging due to the subtle inter-class differences. We posit that exploiting the rich relationships between channels can help capture such differences since different channels correspond to different semantics. In this paper, we propose a channel interaction network (CIN), which models the channel-wise interplay both within an image and across images. For a single image, a self-channel interaction (SCI) module is proposed to explore channel-wise correlation within the image. This allows the model to learn the complementary features from the correlated channels, yielding stronger fine-grained features. Furthermore, given an image pair, we introduce a contrastive channel interaction (CCI) module to model the cross-sample channel interaction with a metric learning framework, allowing the CIN to distinguish the subtle visual differences between images. Our model can be trained efficiently in an end-to-end fashion without the need of multi-stage training and testing. Finally, comprehensive experiments are conducted on three publicly available benchmarks, where the proposed method consistently outperforms the state-of-the-art approaches, such as DFL-CNN(Wang, Morariu, and Davis 2018) and NTS(Yang et al. 2018).

A Qualitative Evaluation of an Interprofessional Collaboration between an Academic Organization and Hospital Foundation Trust

Background: Research recognizes that collaborative working between academic organizations and clinical institutions may help realize the effective delivery of patient care. Yet, few studies report on the processes required to effect the necessary changes. Ths article reports on a research process that was delivered by a team of academics and clinicians that aimed to illuminate processes of interprofessional collaboration.Methods and findings: Semi-structured interviews were conducted with eight participants selected from both a university and a foundation trust. Data were analyzed using thematic analysis.Conclusions: The fruits of interprofessional practice and collaboration have beneficialeffects, especially for the patient. These are realized through the collegialefforts of stakeholders from each organization, where consistent effort, cooperativeand inclusive actions facilitate participative agency, resulting in rich relationships.

High correlation of species diversity patterns between specialist herbivorous insects and their specific hosts

AbstractAimThe relative importance of biotic and abiotic factors in shaping the species diversity of temperate organisms has been debated for a long time. Here, we used drepanosiphine aphids as a model group to validate the ‘resource‐dependent hypothesis’ based on the biotic interactions for specialist herbivorous insects, a hypothesis stating that their intricate relationship with host plants for resources might constrain their species diversity from being positively correlated with the species diversity of their hosts, and to assess the role of biotic and abiotic factors in shaping the global species diversity pattern of temperate organisms.LocationGlobal and regional.Time periodCurrent.TaxonDrepanosiphine aphids (Insecta: Hemiptera: Aphidoidea).MethodsWe first investigated the global species diversity pattern of drepanosiphine aphids. Then we used ordinary least squares (OLS) and spatial simultaneous autoregressive (SAR) models to conduct regression analyses to test for the relationships of global and regional species richness between drepanosiphine aphids and their host plants, and other predictor variables describing entire woody plants, environmental energy, water availability, climate seasonality, topographical heterogeneity and land cover. Finally, structural equation models (SEMs) were further used to test for direct and indirect effects of key ecological variables.ResultsThe distribution hotspots of species richness and endemism were both located in temperate zones, supporting the notion that drepanosiphine aphids were representative of temperate organisms. The specific host plant was the most important ecological variable in explaining global and regional drepanosiphine species richness, showing a strong positive relationship. The climatic variables mainly showed an indirect effect on global and regional drepanosiphine species richness via specific hosts.Main ConclusionsThe global and regional drepanosiphine species richness was primarily shaped by specific host plants as opposed to all woody trees, with indirect effects of climatic factors via host plants, which supported the ‘resource‐dependent hypothesis’ based on the biotic interactions for specialist herbivorous insects. This finding sheds new light on the ‘biotic interactions hypothesis’ that states biotic interactions can primarily affect the distributions and diversity patterns of both tropical and temperate organisms not only at the local scale but also at the regional to global scales.

Estructura de la taxocenosis de diatomeas y su relación con variables ambientales en tres cuencas de la provincia de San Luis (Argentina)

La composición y distribución de las asociaciones de algas en ecosistemas lóticos son el resultado de condiciones en el medio ambiente y en particular pueden reflejar su estructura y funcionamiento.El objetivo de este trabajo fue estudiar la relación de la riqueza, abundancia y diversidad de las especies de diatomeas con las características ambientales en tres cuencas de la provincia de San Luis. Para ello se seleccionaron 14 sitios de muestreo en tres cuencas: en la cuenca del río Conlara siete sitios, otros tres en la cuenca del río Quinto y finalmente cuatro en la cuenca del Bebedero. En cada sitio de muestreo se registraron parámetros hidráulicos y fisicoquímicos. Se colectaron muestras epilíticas que fueron obtenidas por raspado de pequeñas rocas del fondo. La estructura de la comunidad estuvo caracterizada por el predominio de las diatomeas pennales que se destacaron tanto cualitativa como cuantitativamente. Las variaciones de parámetros fisicoquímicos influyeron en la composición específica de las taxocenosis y permitieron establecer dos grupos de especies: el primero constituido por Nitzschia palea, Melosira varians, Navicula tripunctata y Halamphora veneta que se vincularon a arroyos de mayor número de orden y mayor conductividad. Mientras que Geissleria decussis, Epithemia sorex y Cymbella affinis constituyeron el segundo grupo relacionado con mayor caudal y pH, en tanto que Navicula radiosa y Rophalodia gibba estuvieron asociadas a la altitud y concentración del oxígeno disuelto, respectivamente. Una referencia florística confiable de diatomeas permite hacer diagnósticos fundamentados sobre el estado ecológico de los arroyos, así como para establecer programas de monitoreo en la provincia.