Changes In Species Diversity Research Articles

Nitrogen enrichment affects the competition network of aboveground species on the Inner Mongolia steppe

Nitrogen(N) enrichment changes the community structure of terrestrial ecosystems. However, the patterns and structural functions of species interaction networks under N-enrichment conditions are still unclear. We compared and analysed data from 13 years of N deposition experiments in the Inner Mongolia temperate steppe in China. We found that spatial association effectively detected intransitive networks, the structure of which was occasionally changed by species with low biomass but high-frequency occurrence, as an especially vital intermediary for forming a large network. The peak value of the network complexity was maintained at 2 gNm-2⁢year-1. In the third year after fertilization at 50 gNm-2⁢year-1, the species interaction changed to transitivity, which lasted for 8 years. Then, the environment completely replaced species interactions as the main factor affecting community composition. Surprisingly, the negative effect of N enrichment on the species network was counteracted by mowing and precipitation, which increased the probability of intransitive network formation. In the intransitive network, species diversity was not only maintained but also increased under low N-addition rates from 0 gNm-2⁢year-1 to 3 gNm-2⁢year-1. These studies indicated that N enrichment reduced the complexity of the species network and increased hierarchical differences among species competition. Intransitive competition is highly prevalent and a key driver of species coexistence and diversity maintenance in the typical steppe. Moreover, environmental factors directly affect plant intransitive competition, resulting in changes in species diversity.

Diagnostic Species Diversity Pattern Can Provide Key Information on Vegetation Change: An Insight into High Mountain Habitats in Central Apennines

High mountain ecosystems are hotspots of biodiversity that are highly vulnerable to climate warming and land use change. In Europe, high mountain habitats are included in the EC Directive 92/43/EEC (Habitats Directive) and the identification of practices facilitating effective monitoring is crucial for meeting HD goals. We analyzed the temporal changes in species composition and diversity on high mountain EU habitats and explored if the subgroup of diagnostic species was able to summarize the comprehensive information on plant community variations. We performed a re-visitation study, using a set of 30 georeferenced historical plots newly collected after 20 years on two EU habitats (Galium magellense community growing on screes (8120 EU) and Trifolium thalii community of snowbeds (6170 EU)) in the Maiella National Park (MNP), which is one of the most threatened Mediterranean mountains in Europe. The presence of several endangered species and the availability of a botanical garden, a seed bank, and a nursery, make the MNP an excellent training ground to explore in situ and ex situ conservation strategies. We compared overall and diagnostic species richness patterns over time by rarefaction curves and described the singular aspects of species diversity (e.g., richness, Shannon index, Simpson index, and Berger–Parker index), by Rènyi’s diversity profiles. Diversity values consistently varied over time and across EU habitat types, with increasing values on scree communities and decreasing values on snowbeds. These changes could be associated with both land use change, through the increase of grazing pressure of Apennine chamois (Rupicapra pyrenaica ornata), which determined a rise of nitrophilous species in the scree community, and an increase of grasses at the expense of forbs in snowbeds, and to climate change, which promoted a general expansion of thermophilous species. Despite the two opposite, ongoing processes on the two plant communities studied, our results evidenced that diagnostic species and overall species followed the same trend of variation, demonstrating the potential of diagnostics for EU habitat monitoring. Our observations suggested that the re-visitation of historical plots and the implementation of frequent monitoring campaigns on diagnostic species can provide important data on species abundance and distribution patterns in these vulnerable ecosystems, supporting optimized in situ and ex situ conservation actions.

О находках Rhipicephalus (Boophilus) annulatus (Say, 1821) (Acari, Ixodidae) на западе Атырауской области

Blood-sucking ticks are vectors of protozoal, bacterial, viral and rickettsial diseases. The study of ixodes ticks: fauna, ecology, biology is of great importance not only for epidemiology but is also of scientific interest. Changes in natural and climatic conditions, hydrological regime, rapid development of human economic activities lead to the changes in the fauna of invertebrates including ixodid ticks. As they invade new territories ticks may expand their habitats for these dangerous for animals and humans infections. That is why the study of tick fauna, changes in species diversity of ticks and monitoring of their abundance is so important for monitoring of natural foci. The emergence of a new species of ixodid tick Rhipicephalus annulatus, in western Kazakhstan, which began to be registered from 2019 in Kurmangazy district of Atyrau region, bordering the Astrakhan region of the Russian Federation and its re-finding in 2020 is a very important fact to assess the epidemiological danger for humans and animals in this territory.

Community species diversity mediates the trade-off between aboveground and belowground biomass for grasses and forbs in degraded alpine meadow, Tibetan Plateau.

Although many empirical experiments have shown that increasing degradation results in lower aboveground biomass (AGB), our knowledge of the magnitude of belowground biomass (BGB) for individual plants is a prerequisite for accurately revealing the biomass trade‐off in degraded grasslands. Here, by linking the AGB and BGB of individual plants, species in the community, and soil properties, we explored the biomass partitioning patterns in different plant functional groups (grasses of Stipa capillacea and forbs of Anaphalis xylorhiza). Our results indicated that 81% and 60% of the biomass trade‐off variations could be explained by environmental factors affecting grasses and forbs, respectively. The change in community species diversity dominated the biomass trade‐off via either direct or indirect effects on soil properties and biomass. However, the community species diversity imparted divergent effects on the biomass trade‐off for grasses (scored at −0.72) and forbs (scored at 0.59). Our findings suggest that plant communities have evolved two contrasting strategies of biomass allocation patterns in degraded grasslands. These are the “conservative” strategy in grasses, in which plants with larger BGB trade‐off depends on gigantic roots for soil resources, and the “opportunistic” strategy in forbs, in which plants can adapt to degraded lands using high variation and optimal biomass allocation.

Impact of Oreochromis niloticus (Linnaeus, 1758) (Pisces: Cichlidae) invasion on taxonomic and functional diversity of native fish species in the upper Kabompo River, northwest of Zambia.

Invasive alien species have been revealed to drastically alter the structure of native communities; however, there is scarce information on whether taxonomic and functional spaces occupied by native species are equally filled by exotic species. We investigated the diversity of native species to understand the impact of exotic Oreochromis niloticus in the upper Kabompo River, northwest of Zambia using taxonomic and functional diversity indices. To achieve this, two tests were performed (Test 1, compared natives in invaded and uninvaded sections; Test 2, compared natives in invaded section). A total of 17 species were collected for functional diversity computation, out of which fourteen (14) functional trait measurements linked to feeding, locomotion, and life history strategy were taken. Findings revealed that taxonomic and functional diversity values changed with invasion in both tests. Taxonomic diversity was 15% more in invaded than uninvaded sections in Test 1 and was not consistent across sampling points of invaded section in Test 2. Invaded areas were taxonomically less diverse, but functionally diverse in both tests. The analysis of similarity and nonmetric multidimensional scaling revealed no difference in Bray–Curtis similarity assemblages in both tests. Our findings revealed that exotic species more often occupy unfilled gaps in the communities often occupied by the native species; this is achieved by occupying functional spaces. Overall, changes in taxonomic and functional diversity of native species documented here partially confirmed impacts of O. niloticus invasion. Therefore, we recommend a multifaceted approach to assess cumulative impacts of invasion on native species.

Effect of thinning intensity on understory herbaceous diversity and biomass in mixed coniferous and broad-leaved forests of Changbai Mountain

BackgroundHerbs are an important part of the forest ecosystem, and their diversity and biomass can reflect the restoration of vegetation after forest thinning disturbances. Based on the near-mature secondary coniferous and broad-leaved mixed forest in Jilin Province Forestry Experimental Zone, this study analyzed seasonal changes of species diversity and biomass of the understory herb layer after different intensities of thinning.ResultsThe results showed that although the composition of herbaceous species and the ranking of importance values were affected by thinning intensity, they were mainly determined by seasonal changes. Across the entire growing season, the species with the highest importance values in thinning treatments included Carex pilosa, Aegopodium alpestre, Meehania urticifolia, and Filipendula palmata, which dominated the herb layer of the coniferous and broad-leaved mixed forest. The number of species, Margalef index, Shannon-Wiener index and Simpson index all had their highest values in May, and gradually decreased with months. Pielou index was roughly inverted “N” throughout the growing season. Thinning did not increase the species diversity. Thinning can promote the total biomass, above- and below-ground biomass. The number of plants per unit area and coverage were related to the total biomass, above- and below-ground biomass. The average height had a significantly positive correlation with herb biomass in May but not in July. However, it exerted a significantly negative correlation with herb biomass in September. The biomass in the same month increased with increasing thinning intensity. Total herb biomass, above- and below-ground biomass showed positive correlations with Shannon-Winner index, Simpson index and Pielou evenness index in May.ConclusionsThinning mainly changed the light environment in the forest, which would improve the plant diversity and biomass of herb layer in a short time. And different thinning intensity had different effects on the diversity of understory herb layer. The findings provide theoretical basis and reference for reasonable thinning and tending in coniferous and broad-leaved mixed forests.

Understanding arid‐region waterbird community dynamics during lake dry‐downs

AbstractThe community dynamics of organisms that exhibit multi‐scale responses to habitat change are poorly understood. We quantified changes in species diversity and the functional composition of a waterbird community over two iterations of a repeated transition, the annual drying‐down of arid‐region Lake Ngami, Botswana. We used our data to test three theoretical predictions: simplification of the bird community over time due to a reduction in habitat area and concurrent niche loss; large fluctuations in densities of mobile, opportunistic species; and high variance in predator and prey abundance. Despite temporal variance in species accumulation, we observed no obvious simplification and distinct but consistent groupings of abundance and composition across transitional stages. There were some rapid shifts in functional composition, such as loss of deepwater foragers; winners and losers also occurred within foraging guilds. We conclude that understanding community‐level trends during transitional periods will require stronger theoretical frameworks that more effectively integrate unique species traits and functional groups. For conservation managers, our study offers a cautionary tale of the importance of understanding connectivity, trajectories of change, and the potential for large fluctuations in animal communities independent of management actions during periods of ecological transition.

Phylogenomic systematics of the spotted skunks (Carnivora, Mephitidae, Spilogale): Additional species diversity and Pleistocene climate change as a major driver of diversification

Four species of spotted skunks (Carnivora, Mephitidae, Spilogale) are currently recognized: Spilogale angustifrons, S. gracilis, S. putorius, and S. pygmaea. Understanding species boundaries within this group is critical for effective conservation given that regional populations or subspecies (e.g., S. p. interrupta) have experienced significant population declines. Further, there may be currently unrecognized diversity within this genus as some taxa (e.g., S. angustifrons) and geographic regions (e.g., Central America) never have been assessed using DNA sequence data. We analyzed species limits and diversification patterns in spotted skunks using multilocus nuclear (ultraconserved elements) and mitochondrial (whole mitogenomes and single gene analysis) data sets from broad geographic sampling representing all currently recognized species and subspecies. We found a high degree of genetic divergence among Spilogale that reflects seven distinct species and eight unique mitochondrial lineages. Initial divergence between S. pygmaea and all other Spilogale occurred in the Early Pliocene (~ 5.0 million years ago). Subsequent diversification of the remaining Spilogale into an “eastern” and a “western” lineage occurred during the Early Pleistocene (~1.5 million years ago). These two lineages experienced temporally coincident patterns of diversification at ~0.66 and ~0.35 million years ago into two and ultimately three distinct evolutionary units, respectively. Diversification was confined almost entirely within the Pleistocene during a timeframe characterized by alternating glacial-interglacial cycles, with the origin of this diversity occurring in northeastern Mexico and the southwestern United States of America. Mitochondrial-nuclear discordance was recovered across three lineages in geographic regions consistent with secondary contact, including a distinct mitochondrial lineage confined to the Sonoran Desert. Our results have direct consequences for conservation of threatened populations, or species, as well as for our understanding of the evolution of delayed implantation in this enigmatic group of small carnivores.

Temporal changes in the ground vegetation in spruce forests in the Erzgebirge (Ore Mountains) — bryophytes are better indicators of the impact of liming and of sulphur and nitrogen deposition than the herb layer

AbstractQuestionsHow have species composition and diversity in the herb and bryophyte layer of spruce forest communities developed on unlimed plots and on plots with varying liming intensity under the conditions of decreasing sulphur (S) deposition and unabated high nitrogen (N) deposition?LocationSpruce stands in the Erzgebirge, East Germany.MethodsWe repeated herb and bryophyte layer surveys on 36 quasi‐permanent plots after approx. 23 years (1989/1991 vs 2012/2014). Over this period, the study area experienced a sharp decline in S deposition and repeated liming of the spruce stands. Our plots represent a gradient of liming from zero to four applications. We analyse the change in species composition and species diversity depending on the liming intensity using Ellenberg indicator values (EIV), correspondence analysis, indicator species analysis and diversity parameters (alpha diversity, Lennon similarity).ResultsOn the unlimed plots, the species composition of the herb layer remained unchanged over the study period, despite the decrease in the coverage of Calamagrostis villosa and Deschampsia flexuosa and in the total coverage of the herb layer. In contrast, the bryophyte layer showed a significant increase in coverage and species richness with the decrease in S deposition. Liming led to a sharp increase in species richness in the herb layer, due to the appearance of disturbance indicators. The mean EIVs for acidity and nitrogen (EIV‐R and EIV‐N) also increased significantly. All observed effects increased with increasing liming intensity. We also noticed an increase in species richness over time in the bryophyte layer on the limed plots. However, this was less pronounced than on the unlimed plots, and decreased with increasing liming intensity. This was because the appearance of disturbance indicators or of typical species for the Calamagrostio villosae‐Piceetum was partially compensated for by the disappearance of acid indicators as a result of liming. The species turnover was thus much higher in the bryophyte layer than in the herb layer.ConclusionsIn contrast to the herb layer, the bryophyte layer proves to be a sensitive indicator of changes in air pollution. The effects of greatly reduced S deposition on the bryophyte layer outweigh those of continuous N deposition in the study area. Liming acts as a disturbance in both the herb layer and the bryophyte layer. This influence increases with increasing liming intensity. Our results do not support a general application of liming in large, contiguous forest areas. Rather, this measure should be applied in a differentiated manner.

Transformation of an Oligotrophic Sphagnum Bog during the Process of Rewetting

The vast peatlands of the European North of Russia were drained in the 20th century. Some of the drained areas were left without management and maintenance, which led to re-waterlogging. The current trend towards peatlands restoration requires an understanding of all the changes that have taken place in such ecosystems. The study aims to assess the changes in vegetation cover relative to changes in peat deposits in the rewetted oligotrophic bogs. The objects of research were located on the south-White Sea oligotrophic bogs. The studies were carried out using generally accepted geobotanical and geoecological methods in conjunction with the authors’ method for studying the group chemical composition of peat organic matter. The species diversity, structure and spatial distribution of the vegetation cover, the structure and composition of the peat, as well as the composition of the peat organic matter have been studied. It was shown that the transformation of an oligotrophic bog during the process of rewetting manifests itself in a significant change in the vegetation species diversity, somewhat reversible concerning ecologically tolerant species. Changes occurring in the peat deposit are irreversible. That limits the possibility of restoration of species of oligotrophic habitats to the initial state.

Changes in plant nutrient utilization during ecosystem recovery after wildfire

Wildfire is the primary natural disturbance in boreal forest ecosystems. It substantially changes soil nutrient conditions and plant nutrient dynamics. After a wildfire, various plant strategies of nutrient utilization are fundamental to ecosystem recovery processes. Stability of plant nutrients reflects the ability of plants possessing relatively constant elemental concentrations in the face of nutrient changes, which can be calculated by the value of “nutrient homeostasis”. However, the mechanism of how nutrient homeostasis mediates plant community recovery in post-fire ecosystems remains unknown. The dominant tree species that survived after fire and the new emergence of regenerated tree species are the important components of a plant community during the recovery process. Our primary objective was to elucidate the nutrient homeostasis trade-off between dominant and regenerated species over years after recovery. Five treatments, namely, 2 year, 10 year, 20 year, 30 years after moderate burning severity, and unburned forests, were designed in the boreal forests of Great Xing'an Mountains, Northeast China. Compared with unburned forests, wildfire lowered the average value of homeostasis of plant nutrients (N and P). Moreover, the mean homeostasis value of the dominant species (i.e., Larix gmelinii) was higher than that of the regenerated species (i.e., Betula platyphylla). The slope of relationship between nutrient homeostasis and recovery years of the regenerated species was higher than that of the dominant species, suggesting that the nutrient homeostasis in the regenerated species recovered more quickly than dominant species after recovery. Compared with the dominant species, changes in the regenerated species' homeostasis can explained more to the changes of species diversity during the years after recovery. This study revealed plant nutrient adaptation in different species and different plant organs with years after wildfire and highlighted the importance of nutrient homeostasis in plant adaptation strategies and the recovery of plant community.

Role of seed bank in aboveground vegetation regeneration signal ecosystem transition from arid grassland to shrubland with decreasing soil moisture

This study aimed to evaluate the role of seed bank during ecosystem transitions from arid grassland to shrubland. We explored the aboveground vegetation, seed bank and soil environmental factors at 29 sites along a moisture gradient that served as a space-for-time substitution in the Qaidam Basin on the Tibetan Plateau to test whether changes seed bank composition or changes in the ability of the seed bank to restore aboveground vegetation could lead to ecosystem transition. We found that the composition of the aboveground vegetation presented nonlinear changes with decreased soil moisture and showed an inflection point in the threshold zone on the spatial scale of ecosystem transition from arid grassland to shrubland; however, an inflection point was not observed for the seed bank. Surprisingly, we also found the similarity between the aboveground vegetation and seed bank decreased obviously when soil moisture crosses the critical threshold. Our results suggest that the transition from arid grassland to shrubland ecosystem is not caused by changes of the seed bank composition but by the inhibition of the seed bank's restorability to aboveground vegetation. Future work on changes in vegetation composition and species diversity with ecosystem transitions should consider the belowground seed bank.

Intertidal microhabitats as a shelter for assemblages of chitons at southern Chile

Environmental heterogeneity is one of the main hypotheses promoting changes in species diversity. Several abiotic and biotic factors that promote environmental heterogeneity generate physical and biological microhabitats, where organisms may find refuge from environmental stress. The abundance, species richness and body size structure of chiton assemblages were estimated in different intertidal microhabitats. These microhabitats (physical: crevices, pools, and boulders; biological: mussel beds, arborescent algae, and crustose algae) were sampled in six sites of the southern Chilean coast during the austral spring of 2016. The results of our study exhibited the species Chiton granosus as the most abundant, followed by C. magnificus and Tonicia chilensis. Species richness and abundance were higher in physical microhabitats, with boulders and crevices showing the highest values, respectively. The multivariate analyses revealed three groups with high similarities within them; the first group represented by crevices, pools, and mussel beds; the second group composed of arborescent and crustose algae; and the third group comprised by boulders. Mussel beds were considered “nursery grounds” for harbouring a high abundance of juveniles of C. granosus (<10 mm), whilst physical microhabitats and algae host the biggest specimens of both C. magnificus and T. chilensis (>30 mm). We suggest that in biological microhabitats, the patterns of species richness and abundance and body size structure would be determined by a relation of functional specificity derived from feeding habits; and, in physical microhabitats, these patterns would be explained by a relation of behavioural specificity derived from negative phototactism.

Dynamics of Legionella Community Interactions in Response to Temperature and Disinfection Treatment: 7\xa0Years of Investigation

In man-made water distribution systems, Legionella community interactions remain unknown, due to their ability to change from sessile to planktonic states or live in viable but non-culturable forms, in response to anthropic and environmental stress. During 7 years of hospital Legionella surveillance, in 191 hot water positive samples, the interactions among the Legionella species, temperature, and disinfection treatment were evaluated. Legionella was isolated following ISO 11731:2017, and identification was performed by mip gene sequencing and sequence-based typing (SBT) for L. anisa or L. rubrilucens and L. pneumophila, respectively. The species with the higher frequency of isolation was L. pneumophila serogroup 1 (78.53%; 4865.36 ± 25,479.11 cfu/L), followed by L. anisa (54.45%; 558.79 ± 2637.41 cfu/L) and L. rubrilucens (21.99%; 307.73 ± 1574.95 cfu/L), which were sometimes present together. Spearman’s rho correlation test was conducted among the species with respect to temperature and disinfectant (H2O2/Ag+). The results showed a generally positive interaction among these species sharing the same environment, except for competition between L. anisa and L. rubrilucens. High temperature (48.83 ± 2.59 °C) and disinfection treatment (11.58 ± 4.99 mg/L) affected the presence of these species. An exception was observed with L. anisa, which showed disinfection treatment resistance. For the purposes of environmental surveillance, it is fundamental to better understand the interactions and dynamic of the Legionella community in man-made water systems in order to choose the proper physical or chemical treatments. The simultaneous presence of different Legionella species could result in an increased resistance to high temperature and disinfectant treatment, leading to changes in contamination level and species diversity.

Land use and elevation interact to shape bird functional and phylogenetic diversity and structure: Implications for designing optimal agriculture landscapes

Abstract The conversion of rainforests into agriculture resulted in massive changes in species diversity and community structure. Although the conservation of the remaining rainforests is of utmost importance, identifying and creating a biodiversity‐friendly agriculture landscape is vital for preserving biodiversity and their functions. Biodiversity studies in agriculture have often been conducted at low elevations. In this study, we compared the functional diversity (FD), phylogenetic diversity (PD) and community structure of birds along an interacting gradient of land use (protected rainforest, reserve buffer and agriculture) and elevation (low, middle and high) in Sri Lanka. Then, we measured the compositional change by identifying how ecological traits (dietary guild, vertical strata, body mass and dispersal ability) and conservation characteristics (forest dependence and threatened status) responded to land use types. Elevation and land use interacted with each other to shape bird FD. Depending on the elevation, FD in agriculture was either higher or similar to forest. However, PD was similar across all elevation and land use types. Bird community structure in forest was functionally and phylogenetically clustered in comparison to agriculture. Insectivorous birds declined from forest to agriculture, and so did understorey and middle‐storey birds. But frugivorous and canopy birds did not change across land use types, while nectarivores, granivores and carnivores proliferated in agriculture. Forests were dominated by birds with low dispersal abilities, but birds in agriculture had more evenly distributed dispersal abilities. About half of all the individuals in agriculture were composed of forest species, several of which were threatened. Synthesis and applications. Most farmers in Sri Lanka practice agriculture on small farms (c. 2 ha) and rely on services (e.g. pest control and pollination) provided by biodiversity for their livelihoods. Our results underline the important role of these heterogeneous agriculture landscapes in maintaining high functional diversity (FD) and harbouring several threatened species. While FD in agriculture was comparatively high, conservation decisions based on land use alone cannot be reliable, because land use effects were elevation dependent. Thus, priority setting exercises aimed at designing optimal agriculture landscapes should consider landscape features, in combination with elevation, to benefit both people and wildlife outside protected areas.

Future fire-driven landscape changes along a southwestern US elevation gradient

Over the twenty-first century, the combined effects of increased fire activity and climate change are expected to alter forest composition and structure in many ecosystems by changing postfire successional trajectories and recovery. Southwestern US mountain ecosystems contain a variety of vegetation communities organized along an elevation gradient that will respond uniquely to changes in climate and fire regime. Moreover, the twentieth-century fire exclusion has altered forest structure and fuel loads compared to their natural states (i.e., without fire suppression). Consequently, uncertainties persist about future vegetation shifts along the elevation gradient. In this study, we simulated future vegetation dynamics along an elevation gradient in the southwestern US comprising pinyon-juniper woodlands, ponderosa pine forests, and mixed-conifer forests for the period 2000–2099, to quantify the effects of future climate conditions and projected wildfires on species productivity and distribution. While we expected to find larger changes in aboveground biomass, species diversity and species-specific abundance at low elevation due to warmer and drier conditions, the largest changes occurred at high elevation in mixed-conifer forests and were caused by wildfire. The largest increase in high-severity and large fires were recorded in this vegetation type, leading to high mortality of the dominant species, Picea engelmannii and Abies lasiocarpa, which are not adapted to fire. The decline of these two species reduced biomass productivity at high elevation. In ponderosa pine forests and pinyon-juniper woodlands, fewer vegetation changes occurred due to higher abundance of well-adapted species to fire and the lower fuel loads mitigating projected fire activity, respectively. Thus, future research should prioritize understanding of the processes involved in future vegetation shifts in mixed-conifer forests in order to mitigate both loss of diversity specific to high-elevation forests and the decrease in biomass productivity, and thus carbon storage capacity, of these ecosystems due to wildfires.

Plant Community Assembly Mechanisms of a Subalpine Meadow Community Along Different Successional Time

The process of community assembly is important to explain species coexistence and the maintenance of species diversity. Succession provides a good opportunity to study the role of the deterministic and stochastic processes during the community species composition. We investigated species composition and environmental factors and calculated the change in species diversity, phylogenetic diversity, net relatedness index, and nearest taxon index along a successional chronosequence, with a series of 0.5 × 0.5 m2 plots (n = 20) from five successional subalpine meadow plant communities (ages 1, 3, 5, 15, and 30) in the Qinghai-Tibetan Plateau. In the plots, we found a significant change in species composition and abiotic environmental factors. Our redundancy analysis showed that soil nitrate nitrogen and soil organic carbon were the key environmental factors that affect the community composition in succession gradient. The community showed an overdispersion phylogenetic structure along with the early and medium succession. The ends of the succession stage showed a random or convergent phylogenetic structure. The results showed that the construction process of plant communities in the early and middle stages of succession was mainly affected by habitat filtering. In the late stage of succession, the process of community construction is more complex, which could be affected by the limiting similarity and neutral driving process. Our findings are important to be used in managing ecological restoration and protection.

Rodent Species Diversity and Occurrence of Leishmania in Northeastern Iran

The aim of the current study was to survey the species diversity and Leishmania infection of rodents in the Gonbad -e- Kavoos City and County, northeastern Iran, during 2018–2019. Totally, 20 rural and four urban areas endemic for leishmaniasis were selected and visited monthly. Rodent species diversity indices were calculated in different spatial and temporal scales. Species richness was also calculated using rarefaction curves to estimate the number of species in unequal sample sizes. A total of 167 rodents belonging to 7 species, 6 genera, and 2 families were collected. Rattus rattus (34.7%) and Rattus norvegicus (18.6%) were identified as dominant species. The largest Margalef and Menhinick species richness (DMg = 1.55; DMn = 1.01) and the highest value of the Shannon index (H′ = 1.71) were observed in rural areas. Seasonal abundance of the rodents varied among species and showed that the highest richness (DMg = 1.27; DMn = 0.65) occurred in spring and the highest value of Shannon index (H′ = 1.72) was noted in summer. Rarefaction curves confirmed that the highest species richness occurred in summer and spring in the rural area. Seasonal fluctuations of R. rattus and R. norvegicus have a significant impact on the changes in rodent species diversity. Investigations of Leishmania infection showed that amastigote forms of Leishmania were observed in 15.4% of smears taken from Rhombomys opimus and Meriones libycus and examined under the light microscope. The highest rate of Leishmania infection was observed during the summer.

Changes of tree species diversity in peatland impacted by moderate fire severity at Teluk Meranti, Pelalawan, Riau Province, Indonesia

Abstract. Syaufina L, Hamzah AA. 2021. Changes of tree species diversity in peatland impacted by moderate fire severity at Teluk Meranti, Pelalawan, Riau Province, Indonesia. Biodiversitas 22: 2899-2908. Riau is one of the fire-prone provinces in Indonesia, which contributes to environmental problems not only in the country but also in neighboring countries. Peatland fire occurs annually in the province that causes transboundary haze pollution. Despite being an important threat to biodiversity, study on peatland fire impacts seems limited. The aims of this study are to analyze changes in tree species diversity due to fire and to assess fire severity. The study was conducted at Teluk Meranti Sub-district, Pelalawan District, Riau Province, Indonesia by establishing 18 sample plots in six transect lines for both burned and unburned areas. Fire severity classification was assessed by aggregate scoring of vegetation condition (individual tree damages, burned vegetation severity, and biodiversity) and soil condition (physical properties, chemical properties, and burned peat depth) indicators. The research revealed a significant change in tree species diversity from 24 species (unburned area) to 2 species (burned area) from high diversity index (2.86) to low diversity index (0.57); only 29% of burned trees can survive; average burned peat depth was about 33 cm; a significant difference of soil condition for both areas was observed. The severity of forest fires in Teluk Meranti, Pelalawan, Riau was classified as the moderate category, with a total score of 58.80%.

Pinus massoniana population dynamics: Driving species diversity during the pioneer stage of ecological restoration

As a dominant and active component across ecological restoration processes, the population dynamics of pioneer tree species significantly affect species composition and community assemblage. To assess the effect of pioneer populations on species diversity, this study investigated species diversity and population characteristics in five secondary forests dominated by Pinus massoniana in southeastern China. For 40 years, all anthropogenic activities (e.g., logging, farming, etc.) have been banned on the hillsides of these five secondary forests to promote afforestation, for which these forests have thereafter been left to grow naturally. We found that: (1) the basal area (BA) of P. massoniana drove changes in species diversity across forest plots, explaining 31.6% of total variation. The species richness of the herb layer was negatively correlated to BA, while the diversity and evenness of the tree and shrub layers were both positively correlated to the BA. (2) As the size of individual P. massoniana specimens increased, the trend in species richness of the shrub layer and the diversity indexes of both the tree and shrub layer was first to increase and then to decrease once again, while the species richness of the tree layer stabilized after reaching a certain threshold. (3) Species diversity of the forest plots did not improve over time along with an increase in the density of the pioneer species. When the P. massoniana population density was low, the diversity indexes of both the tree and shrub layer increased with an increase in population density. Conversely, when the P. massoniana population density reached 2800 plants/ha, species diversity began to decline. However, when the P. massoniana population density increased to 3733 plants/ha, species diversity of the plant community exhibited an upward trend. Our results indicated that forest species diversity was extremely sensitive to P. massoniana population dynamics during the pioneer stage of ecological succession. Moreover, the pioneer population was the driving factor for both development and change in species diversity, and it did so through habitat adjustment of its ecological relationships.