Short Communication: Fish diversity and its relationship with environmental variables in Kamala River, Nepal

Ghimire S, Koju NP. 2021. Short Communication: Fish diversity and its relationship with environmental variables in Kamala River, Nepal. Biodiversitas 22: 4865-4871. Kamala River originates from the lower part of the Mahabharat range and flows through inner to outer Terai, providing a broad range of ecosystem services; provisioning, regulating, supporting, and cultural. However, the information regarding the environmental factors and species diversity in the river is not available enough. Hence the study aimed to explore baseline information on the diversity and abundance of fish and their relation to environmental variables. The fish diversity was assessed in five sections of Kamala River and correlated with different environmental variables. The study was carried out during September- October 2019, marking the post-monsoon season of Nepal. Fish samples were collected using cast nets, and physiochemical parameters were analysed onsite and in the laboratory. Altogether 19 freshwater fish species belonging to 5 orders, 8 families, and 15 genera were recorded. Cyprinids were the most dominant in the river, while Channids, Mastacembelids, Botiids, Sisorids, Gobiids were represented less. The Redundancy Analysis (RDA) ordination method revealed that species variation was correlated with temperature, Electrical Conductivity (EC), Total Dissolved Solids (TDS), and nitrate. Nonetheless, different river sections were disturbed due to mining, deforestation, and construction activities, which could pose a real threat to fish diversity and population, and other aquatic organisms.

Climatic-niche evolution with key morphological innovations across clades within Scutiger boulengeri (Anura: Megophryidae)

The studies of climatic-niche shifts over evolutionary time accompanied by key morphological innovations have attracted the interest of many researchers recently. We analyzed the realized niche dynamics across clades within Scutiger boulengeri using ecological niche models (ENMs), ordination method (environment principal component analysis; PCA-env), and correspondingly key morphological innovations combined phylogenetic comparative methods (PCMs) and phylogenetic generalized least squares (PGLS) regression methods throughout their distributions in Qinghai-Tibet Plateau (QTP) margins of China in Asia. Our analyses reveal that there is obvious niche divergence caused by niche expansion across S. boulengeri clades, especially in E. A, E. B and partial of E. C clades. Moreover, niche expansion is more popular than niche unfilling into novel environmental conditions. Annual mean temperature and Annual precipitation are the most important contributors in E. A and E. B clades, while Precipitation of driest month is most likely to be the leading limited factor in these two regions according to jackknife test of variable importance. In addition, we identified several key ecological and morphological traits that tend to be associated with niche expansion in S. boulengeri clades correspondingly. Specifically, we found that Elevation, Isothermality, Mean diurnal range and Max temperature of warmest month are significantly negative predictors of snout–vent length (SVL) under phylogenetic models, while the S. boulengeri toads from warmer and more arid environments tend to be larger. There seems to a trade-off strategy by trait covary of locomotor performance combined with enlarged SVL, which provide us a potential pattern of how a colonizing toad might seed a novel habit to begin the process of speciation and finally adaptive radiation. It is worth noting that we should not overlook that the Tibet continuously growing and moving northward over millions of years has laid the foundation for early divergence of clades within S. boulengeri.

The Spread and Role of the Invasive Alien Tree Quercus rubra (L.) in Novel Forest Ecosystems in Central Europe

Research Highlights: The factors that control the spread and regeneration of Quercus rubra (L.) and the functional diversity of invaded forest were studied in order to indicate the significant role of disturbances in a forest and the low functional richness and evenness of sites that are occupied by red oak. Background and Objectives: Red oak is one of the most frequent invasive trees from North America in Central Europe. It is also one of the most efficient self-regenerating invasive alien species in forests. The main goal of the study is to identify the characteristics of forest communities with a contribution of Q. rubra, and to assess its role in shaping the species diversity of these novel phytocoenoses. Materials and Methods: A total of 180 phytosociological records that have a share of Q. rubra in southern Poland were collected, including 100 randomly chosen plots from which soil samples were taken. In addition, vegetation sampling was performed in 55 plots in the vicinities that were uninvaded. Results: The probability of the self-regeneration and cover of Q. rubra seedlings depends mainly on the availability of maternal trees, and the abundance of seedlings was highest in cutting areas. The vegetation with Q. rubra differed in the plant functional types and environmental factors. According to the three-table ordination method, while the cover of red oak only affected the canopy of the remaining species, a comparison of the invaded and uninvaded plots demonstrated that the sites that were occupied by Q. rubra had lower values of functional richness and evenness, thus indicating higher habitat filtering and a lower importance of competition. Conclusions: Forest management practices play the most crucial role in the self-regeneration and occurrence of Q. rubra. However, the role of red oak in shaping the species composition and functional diversity is rather low.

Changes in alpine vegetation over 50 years in the Western Tatras (Slovakia)

This paper examines changes in alpine vegetation over 50 years in the Western Tatras part of the Western Carpathians Mountains in Slovakia. We focus on the following most widespread vegetation types: subalpine to subnival grasslands (alliance Juncion trifidi Krajina 1933), snowbed vegetation (alliance Festucion picturatae Krajina 1933) and dwarf-shrub vegetation (alliances Loiseleurio-Vaccinion Br.-Bl. in Br.-Bl. et Jenny 1926 and Vaccinion myrtilli Krajina 1933). The historical 1971–1977 sampling dataset was re-sampled in 2016–2017 and our research is based on a comparison of 40 pairs of these relevés. Herein, we studied (i) changes in species frequencies; (ii) changes in phytodiversity and site conditions using estimates of Ellenberg’s eco-indices and (iii) comparison of historical and current relevés over time using the nonmetric multidimensional scaling gradient analysis (NMDS) ordination method. The frequency curves reveal differences; especially in the most frequent species at 37.5−80%, which reach higher values in the current data. The higher 7.5−25% value of medium-frequent species in the historical relevés indicates progressive homogenisation of the examined vegetation. In addition, the Shannon-Wiener index of individual vegetation types revealed no significant differences in diversity or average number of species. The historical relevés included 75 species while 74 were confirmed in the current data. Statistically significant differences were determined in light factor for all three vegetation groups. This was due to the retreat of some light-demanding species. While NMDS indicated changes in Festucion and Vaccinion relevés over time, the Juncion group relevés did not follow this trend, thus confirming their high stability. The observed changes between current and historical data are attributed to changes in climate and altered land use with the cessation of grazing.

Co-variation in biomass and environment at the scale of a forest concession in central Africa

Drivers of forest structure in central African rain forests are largely unknown. Using forest inventory data (3024 0.4-ha plots) in a forest concession of 154 456 ha in north-eastern Gabon covering an altitudinal gradient (from 485 to 1009 m asl), relationships between above-ground plot biomass and environmental variables (soil type, altitude, slope, aspect) and floristic composition (score given by an ordination method) were tested. After controlling for confounding variables, biomass was significantly related to altitude (with a modal response peaking at 346 Mg ha–1 on western slopes at an altitude of 707 m asl) and to aspect (additional 18.3 Mg ha–1 on eastern slopes) but not to floristic composition. Biomass and basal area responded differentially to the environment. Mean wood density was significantly related to soil, altitude and floristic composition, with a predicted minimum of 0.60 g cm–3 at an altitude of 1009 m asl in stands characterized by Scorodophloeus zenkeri and a maximum of 0.69 g cm–3 at an altitude of 458 m asl in monodominant Gilbertiodendron dewevrei stands. Variation in forest structure in the concession was primarily driven by altitude while floristic composition played a role in differentiating the variation in biomass and basal area.

A morphospace of planktonic marine diatoms. II. Sampling standardization and spatial disparity partitioning

Morphospace occupation through time provides a view of diversification distinct from the more familiar taxonomic tabulations. However, this view is subject to the same geological biases long recognized in studies of taxonomic diversification, where techniques for correcting secular bias in sampling have become standard practice. In this study, we apply sampling standardization techniques to a morphospace investigation to test whether observed stratigraphic trends in morphospace occupation are artifacts of trends in sampling. When sampling bias is corrected by randomized subsampling, all disparity metrics show stationary patterns, or at most directional changes of small magnitude. Metrics describing the average dispersion of taxa in morphospace are less subject to sampling bias than those describing the total extent of morphospace occupied. We also investigate a measure of disparity that is insensitive to sampling intensity, introducing a geographic component of morphological disparity. By analogy to α and β components of taxonomic diversity, we suggest the notions of α and β disparity, and find that α disparity remains roughly constant through time. Our analysis also allows us to present the first taxonomic diversity curve of diatoms under shareholder quorum subsampling (SQS), showing similar results to previously published subsampling methods: a roughly twofold rise over the Cenozoic, with peak diversity around the Eocene/Oligocene boundary. Tests for methodological bias from choices in ordination method and data culling during morphospace construction indicate that our results are relatively insensitive to both factors: Cenozoic occupation of planktonic diatom morphospace is largely unchanging. We find a similarly stationary pattern when we directly analyze the morphological data, seeing no change in the prevalence of taxa with different sets of morphological characters. More broadly, our results make clear that a complete view of morphological disparity must consider sampling biases, which can be addressed with wellestablished, quantitative methods in morphospaces populated using occurrence-level data.