Accumulation Curves Research Articles

Vegetation databases augment but do not replace species distribution atlases in species richness assessment

Mapping of species richness (SR) patterns is pivotal for biogeography and nature conservation. Vegetation plot databases serve as a new source of information, but they are inherently affected by the methodological background of data collection. This background could bias the SR assessment. Here, we compared two different data sources: (1) a vegetation-plot database, the Polish Vegetation Database (PVD), and (2) a species distribution atlas, the Atlas of Distribution of Vascular Plants in Poland (ATPOL). We calculated species richness recorded by the PVD (PVD SR), the ATPOL (ATPOL SR), and the two harmonized databases (total SR). The sampling bias in the PVD (PVD bias) was assessed by calculating the number of species found in the ATPOL, but not recorded by the PVD. Analogically, the ATPOL bias was calculated. We calculated correlation between the PVD bias and both the number of vegetation plots and the number of vegetation classes. Additionally, the completeness of the PVD dataset was assessed using the species accumulation curve approach. The mean slope of the last 1% of plots number was used as a proxy of inventory completeness and correlated with PVD bias. The results show that the SR documented by the PVD is significantly lower than that recorded by the ATPOL, yet it indicates a significantly increased total SR. The PVD SR increased as more plots and vegetation classes were sampled. However, even with the best sampling, the PVD SR was still significantly lower than that in the ATPOL. Further, although the values for the species accumulation curves suggested high sampling completeness in the PVD, the real bias was still substantial, and no correlation was found between PVD bias and species accumulation curve values. In general, the PVD underestimated SR at a landscape level, yet it augmented information stored in the ATPOL. The underestimations could result from limited sampling effort or from focusing on particular vegetation types, as well as the exclusion of transitional vegetation types and/or disturbed patches of vegetation from sampling.

Numerical Assessment of Standard Firebrand Accumulation Curve When Transferring Temperature to Contact Surfaces

This work presents research concerning the numerical assessment of two previously measured temperatures due to firebrand accumulation on surfaces, which was determined in former thermal experimental campaigns. A 3D numerical model using thermal transient non-linear analysis is used to validate the thermal outputs of these two previous experimental campaigns, and therefore, corroborating the previous temperature vs. time curves created with a prescribed flux in the firebrand accumulation area. The firebrand thermal heat transfer to the plane surface is simulated using convection and radiation film conditions, in which a 3D non-linear, time-dependent finite element simulation is used. Then, the previous proposed standard firebrand accumulation curve, ISO 834, and external fire curve are numerically compared with the results from previous firebrand accumulation curves in a wood corner wall. Finally, the merit assessment of the proposed standard firebrand accumulation curve shows a visible improvement, which has low values and is in accordance with the experimental results in the temperature field distribution of firebrand accumulation onto a contact surface. It is fair to argue that it constitutes a point to search for an efficient design for structures at elevated temperatures due to firebrand accumulation.

Diet analyses of the pelagic thresher shark, Alopias pelagicus (Lamniformes: Alopiidae), from the Lombok Strait waters, Indonesia

Abstract. Alghozali FA, Salsabila R, Gustianto MWD, Putri HMIH, Himawan MR, Yuneni RR, Hatmoro CK, Rezkiani M. 2023. Diet analyses of the pelagic thresher shark, Alopias pelagicus (Lamniformes: Alopiidae), from the Lombok Strait waters, Indonesia. Biodiversitas 24: 3708-3714. The pelagic thresher shark, Alopias pelagicus, is an endangered shark species estimated to be declining in the Pacific and Indian Oceans because of overexploitation, including from target fisheries and bycatch. Despite its importance in providing better information for species management, the ecological aspects of this species are still rarely studied. This study aims to provide information on the feeding ecology of the pelagic thresher sharks from the Lombok Strait. Stomach samples from 178 specimens were sampled from 2020-2021, and 149 stomachs that contained food contents were analyzed for species diet characterization. Prey Species Accumulation Curve slope values are <0.1 and the percentage of prey coverage for all sharks combined is 92.1%, suggesting reliable inventory in the number of prey represented. The resulting diet indexes suggest that A. pelagicus in Lombok Strait waters is a specialist predator (Ba=0.3) with few prey variations (H=2.21) and no competition between sexes and maturity stages of the species (C=0.64 and 0.81, respectively). The top three prey species found for A. pelagicus in the study area are the Auxis thazard (85.8 %IRI), Sthenoteuthis oualaniensis (8.5 %IRI), and Dasyscopelus spinosus (1.11 %IRI). A better understanding of the overlap of A. pelagicus and its diet, which includes economic fish commodities, will inform authorities to develop better fisheries and conservation management for the species in Indonesia.

Sex ratio of the coprophagous beetle community (Coleoptera: Scarabaeidae: Scarabaeinae) in the Andean Amazon, Caquetá, Colombia.

Objective: Our study aimed to test whether the populations of dung beetle maintain the Fisherian sexes ratio a primary forest of an Andean-Amazonian ecosystems. Scope. Promote knowledge of the diversity of Scarabaeidae: Scarabaeinae from Caquetá, Colombia. Methodology: Coprophagous beetles were collected using 50 Pitfall traps baited with human feces separated from each other by 10 meters. Each trap was active for 72 continuous hours. Species were classified according to the trophic guilds and three size categories. Sampling effort was explored using an accumulation curve, meanwhile, Hill numbers were calculated to measure diversity. the Fisher test was performed to analyze the sexual ratio. A Chi-Square (X2) goodness test was performed to analyze if there were significant differences between trophic guild, species, sex and sizes. Results: In total, 693 individuals were collected, distributed in 12 genera and 26 species. The most abundant species were Eurysternus cayennensis Castelnau, 1840 and Dichotomius ( ichotomius) quinquelobatus (Felsche, 1910). The dominant trophic guilds were Diggers. The accumulation curve showed that the sampling effort were satisfactory, meanwhile, the Hill index showed that the abundances between species are heterogeneous. Fisher’s test showed a sexual ratio of 1.4:1 male-female. The X2 test showed that there were significant differences between the trophic guild, species, sex and sizes. This study is the first approximation of the sexual ratio of dung beetles in the Colombian Andean-Amazonian region. Conclusions: This study provides relevant information on the sex ratio and habits occurrence for 12 genera and 26 species of Scarabaeidae that occur in the Parque Nacional Natural Alto Fragua Indi Wasi, San José del Fragua, Caquetá, Colombia.

Composition and Community Structure of Plant Species in A Secondary Growth Forest in the Central Philippines

Mt. Bandila-an Forest Reserve (MBFR) is among the remaining areas with patches of closed forests in Siquijor. This forest reserve is one of the potential key biodiversity areas in Central Visayas, yet the vegetation is not fully documented. This study was conducted to determine the species composition and diversity of plant species. Eight randomly distributed nested plots, each with a dimension of 20m×100m and subdivided to 5 equal segments of 20m×20m, were established. A total of 188 plant species was recorded from the plots, representing 131 tree species, 23 shrub, 14 vine, 11 herb, and 9 fern species. Common plant families with more than 6 representative species were Moraceae, Rubiaceae, Fabaceae, Araceae, Euphorbiaceae, Meliaceae and Myrtaceae. There were 19 threatened (vulnerable to critically endangered) and 33 endemic species recorded in the forest reserve highlighting the importance to further conserve the area. The cluster analysis and species accumulation curve suggest that plant species are not homogeneously distributed which implies that different management and conservation strategies should be implemented across MBFR. These results not only indicate the importance of MBFR, but also highlight areas with higher diversity and concentration of threatened and endemic species as a special area of concern. J. Biodivers. Conserv. Bioresour. Manag. 2023, 9(1): 13-28

Wild fauna as roadkill on a highway in the semiarid region of northeastern Brazil

The death of wild vertebrates run over by motor vehicles on highways is one of the main causes of the loss of wildlife diversity. The aim of the present study was to investigate the diversity of wild fauna in roadkill incidents on a stretch of highway in the semiarid region of Brazil. The survey was conducted between March 2020 and May 2021 through active searches using a motorcycle. Killed vertebrates were analyzed and photographed in situ. Wild fauna was studied based on ecological descriptors, speed of movement and average rate of roadkill incidents. We compared total observed richness to that expected using nonparametric estimators. A total of 464 road-killed vertebrates were represented by two species of amphibians, 17 reptiles, 17 birds and 10 mammals. Amphibians were the most affected, totaling 245 individuals. Colubridae was the family with the largest number of species affected. Boiruna sertaneja and Boa constrictor were the only medium-size to large snakes killed. Herpailurus yagouaroundi and Leopardus tigrinus are respectively categorized as “least concern” and “vulnerable” according to the IUCN. The species accumulation curves continued to rise, showing no sign of approaching to an asymptote. Chao 2 and Jack 2 were the main estimators for road-killed wild vertebrates considering total richness. The diversity reported here is considered to be underestimated and greater monthly sampling efforts are required. Conservation strategies are urgently needed for the protection of wild vertebrate fauna to mitigate the staggering loss of biodiversity caused by the construction and operation of roads and highways in Brazil.

Obstruction of biodiversity conservation by minimum patch size criteria.

Minimum patch size criteria for habitat protection reflect the conservation principle that a single large (SL) patch of habitat has higher biodiversity than several small (SS) patches of the same total area (SL>SS). Nonetheless, this principle is often incorrect, and biodiversity conservation requires placing more emphasis on protection of large numbers of small patches (SS>SL). We used a global database reporting the abundances of species across hundreds of patches to assess the SL>SS principle in systems where small patches are much smaller than the typical minimum patch size criteria applied for biodiversity conservation (i.e., ∼85% of patches <100ha). The 76 metacommunities we examined included 4401 species in 1190 patches. From each metacommunity, we resampled species-area accumulation curves to evaluate how biodiversity responded to habitat existing as a few large patches or as many small patches. Counter to the SL>SS principle and consistent with previous syntheses, species richness accumulated more rapidly when adding several small patches (45.2% SS>SL vs. 19.9% SL>SS) to reach the same cumulative area, even for the very small patches in our data set. Responses of taxa to habitat fragmentation differed, which suggests that when a given total area of habitat is to be protected, overall biodiversity conservation will be most effective if that habitat is composed of as many small patches as possible, plus a few large ones. Because minimum patch size criteria often require larger patches than the small patches we examined, our results suggest that such criteria hinder efforts to protect biodiversity.

Bird Species Diversity, Distribution, and Community Composition in Different Forest Types in Papua New Guinea

This study investigates the species diversity, distribution, and community composition of birds in different forest types in Papua New Guinea in response to environmental factors. The study further focused on individual feeding guilds. The analyzed data originate from 13 sites across the country. Each site was surveyed by standardized point count methods (seven point count 50-m radius points, 15 min per point). In total, we recorded 6,835 bird individuals belonging to 231 bird species. Specifically, this article addresses the results of surveys of bird communities of Forest Inventory from 13 sites that include the Eastern Highlands, Western Highlands, Morobe, and Madang provinces. We analyze these data in respect to various forest types that include disturbed and undisturbed selections. Across the complete study, the number of species rose rapidly for the first 40 point counts and then decelerated but continued to increase for the entire sampling, which means that not whole regional diversity of birds was surveyed. Yet, the species accumulation curves within each study site demonstrate a slow but steady increase in species diversity, with observed numbers close to those predicted by Chao 1. Species diversity was not consistent with elevation. Insectivores dominated bird communities, followed by frugivorous, nectarivores, and especially carnivores more rarely observed. Individual species have shown preferences in their distribution for specific elevations, but less so for a particular disturbance intensity.

Composition and structure of Heteroptera (Insecta: Hemiptera) assemblages along a vegetational gradient at Itacolomi State Park, southern Brazil

Heteroptera are insects highly abundant and rich in the Atlantic Forest in Brazil. Despite their use as bioindicators and biocontrol agents, this group is not charismatic and thus is often not included in environmental assessments. Minas Gerais is a state in Southern Brazil with high level of species endemism where parks such as the Itacolomi State Park are suggested biodiversity hotspots. In this study we evaluated the composition, abundance and species richness of Heteroptera along a vegetational gradient (climax, early succession and rupestrian field). Samples were collected between December 2010 and October 2011, totalling 336 hours over 28 sampling events across all four seasons. One thousand individuals of 38 morphospecies were collected. Abundance was significantly higher in the Summer and lower in the Winter, and it was the highest in the rupestrian field. Richness and diversity also varied across seasons, but not between sites. The most abundant morphospecies was Euchilocoris sp. (22.1%), followed by Neostenotus sp. (21.4%), both in the Miridae family. Combining the high number of singletons identified in our study (8 spp.) with the accumulation curves that show new species records still being added in our last sampling season, we suggest that there are likely more species that were not collected. Despite the fact that our specimens were only identified to the genus level in most cases, this is the first study to characterize the Heteroptera fauna at Itacolomi State Park, as the park management plan did not include hemipterans.

A spatiotemporal deconstruction-based approach for identifying flash drought expansion: Normalized Area-Time Accumulation curve

Though flash drought is an intrinsically three-dimensional phenomenon that evolves in both temporal and spatial dimensions, most studies have overlooked its spatiotemporal features by analyzing its characteristics at individual grid points. The rapid expansion of drought over time and space also brings great challenges for drought monitoring and management strategies. Focusing on the mapping of rapid development trajectories of drought in the three-dimensional space, this study proposes the Normalized Area-Time Accumulation (NATA) curve to describe the evolution characteristics of flash drought. Using the NATA curve, information about the expansion rate of drought area over time and the dominant severity of drought area can be extracted. On this basis, such drought events were classified and investigated, considering drought monitoring difficulty and potential drought damages. Results showed that the shape of proposed NATA curve and the slope of curves of varying severity levels had explicit indicative function for distinguishing drought events characterized by “flash” and “drought” events from traditional slowly-evolving drought events. Drought events which have a rapid rate of area expansion and high drought severity mostly meets the characteristics of flash droughts in the spatiotemporal dimensions. The findings highlight the significance of incorporating information on drought area expansion with time for an efficient recognition and improved accuracy of rapid drought development from a three-dimensional perspective. This is a step forward for flash drought identification in a higher dimension. The proposed NATA curve provides intuitive and comprehensive information on how drought evolves over time and space and is a promising alternative method to analyze drought characteristics from a three-dimensional perspective.

Pelagic copepod diversity (Crustacea: Copepoda) in the southern Caribbean: evidence of a pending assignment

The Southern Caribbean (SCA) represents the most productive ecoregion of the Tropical Northwestern Atlantic (TNWA) province. In order to assess the diversity of pelagic copepods in the ecoregion, we present an inventory based on unpublished data obtained from several oceanographic cruises made in oceanic and neritic waters of Venezuela (1967-1968). We complement this information with previous regional surveys to obtain a revised systematic checklist of the pelagic copepod species in the SCA. We included in our list a total of 346 species and 2 subspecies; up to 11 species represent new records. This study allowed us to: 1) expand the distributional range of some species within the TNWA, 2) record the occurrence, in the SCA, of all species known to 12 of 42 families to occur in the TNWA, 3) determine that the number of species of Corycaeidae and Paracalanidae in the SCA is greater than previously documented for the TNWA. Overall, the species accumulation curve resulting from our data analysis allowed us to determine that the diversity of pelagic copepods is underestimated; our estimations suggest that the potential species number that can be recorded in the SCA is 12 to 48% above the figure herein established.

Estimating mountainous plant species richness and diversity for monitoring global change in a protected grassland park

AbstractAssessments of species diversity and richness are essential to understand present ecological and biodiversity conditions for effective conservation management strategies. Biodiversity indicators determine rangeland health and response to grazing, fire regimes and climate change. This research examined species richness, diversity and composition in a protected mountainous grassland. Two data sets, both collected from a 30 × 30 m plot, with similar species composition and cover were combined. One data set was collected using a 100‐step point survey and the other from a series of 16 plots. A single‐factor analysis of variance was used to test if the mean species richness and diversity of the sites differed across the study area. Species accumulation curves were used to determine the relationship between species richness and the number of sampling units per site. The results from fitting a species–area equation showed that the estimated maximum species richness was slightly greater than the observed species pool in all sites, meaning that the sampling units were not adequate (albeit by small margins) to capture all vascular plant species in the sites. Diversity metrics could, thus, be used to monitor species change within grassland plant communities.

A Camera-Trap Survey of Mammals in Thung Yai Naresuan (East) Wildlife Sanctuary in Western Thailand.

The Thung Yai Naresuan (East) Wildlife Sanctuary (TYNE), in the core area of the Western Forest Complex of Thailand, harbors a diverse assemblage of wildlife, and the region has become globally significant for mammal conservation. From April 2010 to January 2012, 106 camera traps were set, and, in 1817 trap-nights, registered 1821 independent records of 32 mammal species. Of the 17 IUCN-listed (from Near Threatened to Critically Endangered) mammal species recorded, 5 species listed as endangered or critically endangered included the Asiatic elephant (Elephas maximus), tiger (Panthera tigris), Malayan tapir (Tapirus indicus), dhole (Cuon alpinus), and Sunda pangolin (Manis javanica). The northern red muntjac (Muntiacus vaginalis), large Indian civet (Viverra zibetha), Malayan porcupine (Hystrix brachyuran), and sambar deer (Cervus unicolor) were the most frequently recorded species (10-22 photos/100 trap-nights), representing 62% of all independent records, while the golden jackal (Canis aureus), clouded leopard (Neofelis nebulosa), marbled cat (Pardofelis marmorata), and Sunda pangolin were the least photographed (<0.1/100 trap-nights). Species accumulation curves indicated that the number of camera trap locations needed to record 90% of taxa recorded varied from 26 sites for herbivores to 67 sites for all mammals. TYNE holds a rich community of mammals, but some differences in photo-rates from an adjacent sanctuary and comparisons with other research on local mammals suggest that some species are rare and some are missed because of the limitations of our technique. We also conclude that the management and conservation plan, which involves the exclusion of human activities from some protected areas and strict protection efforts in the sanctuaries, is still suitable for providing key habitats for endangered wildlife populations, and that augmented and regular survey efforts will help in this endeavor.

Production of Biogas from Distillation Residue as a Waste Material from the Distillery Industry in Poland

In this paper, the possibility to obtain an alternative source of energy from methane fermentation, catalysed by biomass, has been discussed in detail. As a main substrate, the distillation residue from the distillery industry was taken in the case of mono-fermentation and its co-fermentation with sewage sludge. The results showed that higher biogas and methane production can be obtained in a mono-fermentation process. Fermentation lasted for 23 days, and during this time, 333.14 and 249.64 L/kg VS of the total biogas for mono- and co-fermentation was subsequently obtained, which gives around 63% and 50% of methane in both types of the process, respectively. Additionally, to interpret the experimental data obtained and to predict the trend of the accumulation curves, a simple Gompertz model has been applied. The application of the Gompertz model has enabled us to estimate some important parameters with a strict physical meaning, namely, the maximum production value of the biogas and its components, the production rate of a given gas, as well as the incubation phase time. Finally, an approximate analysis of the potential volume of biogas production was also carried out, based on the mass of distillation residue produced annually in Poland.

Multi-Source Partial Discharge Fault Location with Comprehensive Arrival Time Difference Extraction Method and Multi-Data Dynamic Weighting Algorithm

The location of the partial discharge source is an important part of fault diagnosis inside power equipment. As a key step of the ultra-high frequency location method, the extraction of the time difference of arrival can generate large errors due to interference. To achieve accurate time difference extraction and further multi-source partial discharge location, a location method with comprehensive time difference extraction and a multi-data dynamic weighting algorithm is proposed. For time difference extraction, the optimized energy accumulation curve method applies wavelet transform and mode maximization calculations such that it overcomes the effect of interference signals before the wave peak. The secondary correlation method improves the interference capability by performing two rounds of correlation calculations. Both extraction methods are combined to reduce the error in time difference extraction. Then, the dynamic weighting algorithm effectively utilizes multiple data and improves the location accuracy. Experimental results on multi-source partial discharge locations performed in a transformer tank validate the accuracy of the proposed method.

Variation characteristics of rainfall erosivity in tropical China and its impact on river sediment load

Rainfall erosivity is one of the important factors leading to soil and water erosion, affecting the intensity of soil erosion and the variation of river sediment load. This work aimed to explore the distribution and variation characteristics of rainfall erosivity in the Nandu River Basin in tropical China and to clarify the effect of rainfall erosivity on sediment load variation. The daily rainfall data of 13 meteorological stations in the Nandu River Basin during 1971–2020 were used to calculate the rainfall erosivity of the river basin by using the rainfall erosivity model based on the daily rainfall. The analyses were conducted using the Mann-Kendall non-parametric trend/abrupt test, wavelet analysis, inverse distance weighted interpolation and other research methods to determine the temporal and spatial fluctuation patterns of rainfall erosivity and sediment load. The annual mean rainfall erosivity in the Nandu River Basin during 1971–2020 was 16,497.67 MJ mm·ha−1·h−1, which showed an upward trend. The distribution of rainfall erosivity was concentrated from July to September. Except spring, the variation of rainfall erosivity in summer, autumn and winter showed an upward trend. Spatially, rainfall erosivity showed a decreasing trend from south to north. The variation coefficient of each meteorological station ranged from 0.24 to 0.43, showing high regional variability. The correlation between rainfall erosivity and erosive rainfall in the basin was the highest, followed by altitude and latitude. From 1980 to 2020, the sediment load in the Nandu River Basin showed an overall upward trend, with obvious periodic changes. The main change period was 25 years, and the sediment load had a large inter-annual variation. Taking the period before the inflection point of the double accumulation curve of sediment load and rainfall erosivity as the base period, since 2009, the river sediment load increased by 46.36% compared with the base period. The influence of the variation of rainfall erosivity on sediment load is −22.23%, and that of human activities on sediment load is 122.23%. These findings can provide a scientific reference for soil erosion model prediction, soil and water conservation and environmental management in tropical basins of China.

Beta diversity of urban spontaneous plants and its drivers in 9 major cities of Yunnan province, China

Urbanization has significantly reshaped regional biodiversity structure globally. Previous studies suggested that urban communities of spontaneous plants are well adapted to the urban environment. However, a perspective of urbanization that accounts for the joint impacts of the current state (as expressed by urbanization intensity) and the historical progress of urbanization (as expressed by urbanization rate) to reveal the mechanisms underlying the biodiversity patterns of spontaneous plants in cities is still lacking. Here we present data and analysis of spontaneous plants sampled in 709 patches within 82 sites of built-up areas from nine cities distributed across climatic and floristic zones in Yunnan province, a biodiversity hotspot in China. We used the exponent (z) of a species accumulation curve (SAC) model to characterize beta diversity among patches in a site, and found a higher beta diversity of native species compared with non-natives, indicating that the species composition of native plants is more heterogeneous. The beta diversity of all species groups was best explained by the constant c of the SAC (a proxy of alpha diversity), followed by the urbanization intensity (as expressed by the proportion of sealed surface and patches’ Shannon diversity index), and urbanization rate (as expressed by the sealed surface expansion rate). Moreover, beta diversity of non-native species was additionally negatively correlated with altitude. Our results suggest that the interplay of natural environmental factors and human-induced urbanization shape diversity of urban spontaneous plants in Yunnan province. Our findings emphasize that urban spontaneous plants diversity is not only a reflection of the current state of urbanization, but also a consequence of historical processes of urbanization.

Biomass accumulation and growth curve in sugarcane fertigated with nitrogen doses

This study aimed to evaluate the growth curve, biomass and N accumulation in aboveground sugarcane as a function of nitrogen doses applied by subsurface drip irrigation during the crop growth cycle. The experiment was developed under field conditions Jau city, São Paulo state, Brazil. The treatments were four nitrogen doses – namely 50, 100, 150 and 200 kg ha-1 N – in urea form, in addition to a control treatment (without N), with completely randomized block and four repetitions. The N doses were applied gradually by subsurface drip irrigation spread throughout the sugarcane crop cycle. Biometrics and physiologic parameters and biomass accumulation were evaluated at five sampling times. Linear and quadratic responses of these parameters were verified as a function of N application. Elevating the N dose from 100 to 200 kg ha-1 increased the biomass and the N accumulation of sugarcane above ground by 20 Mg ha-1 and 95 kg ha-1, respectively. The nitrogen fertilization applied by subsurface drip irrigation increased the biomass and N accumulation of aboveground sugarcane, as well as the production rate of all parameters. The gap between maximum biomass accumulation rate (BAR) and nitrogen accumulation rate (NAR) was smooth due drip irrigation management. The irrigation management combined with better plant nutrition show highest results to biomass production

Environmental factors shaping copepod distributions in cave waters of the Lessinian unsaturated karst (NE-Italy)

The unsaturated karst represents a transitional zone connecting the land surface to the water table of the underlying saturated zone through percolating water and small perched aquifers. It constitutes a significant groundwater reservoir and hosts a high biodiversity of specialized and endemic species. Whereas investigating this ecotone can shed light on the invertebrate diversity of the whole karst system, ecological studies in the unsaturated karst have been hampered by access, mapping, and sampling challenges. We studied the unsaturated zone of 52 caves in the Lessinian Massif (NE-Italy), which is dominated by carbonate rocks interspersed with spot areas composed mainly of igneous rocks. Our aim was to understand which ecological and historical factors may have shaped the distribution of the groundwater crustacean copepods at a regional spatial scale in the Lessinian unsaturated karst. We collected 33 species belonging to the orders Harpacticoida and Cyclopoida. Species richness estimators and related species accumulation curves suggest an exhaustive sampling effort. A hydrologic analysis performed in a Geographic Information System environment divided the study area in three distinct drainage basins: Eastern Lessini, Lessinian Core, and Western Lessini. Regression analyses indicated that richness of non-stygobitic copepods (i.e., surface-water species which exploit groundwater for different purposes) was mainly driven by inter-basin differences. Richness of stygobitic copepods (i.e., obligate groundwater dwellers) was instead strongly related to lithological features and responded negatively to surface thermal variability. Next, we used a kernel density estimation to spatially explore diversity patterns in the area. The highest density of stygobitic harpacticoids was identified in the Eastern Lessinian basin, which is lithologically more heterogeneous and surrounded by practically non-aquiferous igneous rocks that may limit dispersal. Conversely, the Western Lessinian basin hosted a high density of stygobitic cyclopoid species. This spatial pattern suggests different colonization pathways for the two taxa, with a strong effect of igneous rocks in hampering dispersal of most harpacticoids. Lithological barriers seemingly did not affect non-stygobitic copepods, which were found across the whole area. Altogether, these results emphasize the key role played by the interaction of hydrological features, climate, and lithology in determining different copepod biodiversity patterns in the unsaturated karst.

Diversity and Seasonality of Aquatic Beetles (Coleoptera) in Three Localities of the State of Tlaxcala, Central Mexico

Aquatic beetle diversity was compared between three study sites in the state of Tlaxcala, central Mexico: Stream 1 (San Ambrosio), stream 2 (San Tadeo), and a lake (Acuitlapilco). Sampling took place bimonthly during an annual cycle. A total of 2968 specimens were obtained, which were grouped into twenty three species, fifteen genera, and six families (Elmidae, Dryopidae, Dytiscidae, Gyrinidae, Haliplidae, and Hydrophilidae). Stream 2 showed the highest values of abundance (1570 individuals), while stream 1 had the highest richness (18 species). Abundance values showed two peaks each in rainy and dry seasons. The proportion of rare and dominant species was similar in all study sites. Based on species accumulation curves, the maximum estimated number of species has not been achieved in either of the three sites. Regarding alpha diversity (effective number of species), stream 1 presented the highest zero-order diversity estimated with 18.5 species. Regarding beta diversity, lotic systems (streams 1 and 2) presented a similarity of 75%. Finally, regarding the trophic structure of the adult aquatic beetle community, herbivores, predators, and decomposers were most representative in this study. Based on our results, Tlaxcala probably holds a significant diversity of aquatic beetles. This appears to indicate that species composition in geographic areas, regardless of their relatively small size, is worth documenting and, of course, preserving.