Loss Of Species Richness Research Articles

Recurrent wildfires alter forest structure and community composition of terra firme Amazonian forests

Abstract Wildfires associated with land-use and climate change have considered a key driver to the Amazon forest collapse. However, achieving a detailed understanding of how human-related disturbances impact forest successional trajectories needs comprehensive information spanning forest strata. Here, we investigate the impact of recurrent wildfires on forest structure, species diversity, and composition, making a comprehensive assessment of the regenerating, understory, and canopy tree communities in a sustainable use reserve in the eastern Amazon. Plant communities were described across 16 forest stands (old-growth, burned once and twice) sampling a total of 3620 individuals and 326 tree and palm species. Wildfires affected all attributes of forest structure. Aboveground biomass decreased by 44% in forest burned once, and 71% in twice-burned forest stands. Forest canopy was the most affected strata after the second fire, with a 44%-decrease compared to unburned forest. The same pattern emerged for basal area, which decreased by an average of 27.5% after the first fire and 53.8% following the second fire event. Overall, plant communities experienced a 50%-loss of species richness after two fires, including both dominant and rare species. Plant communities also became more dissimilar as fire events accumulated, with 58%–61% increase in species dissimilarity following two fires events. As wildfires reoccured, the old-growth forests of our focal landscape were converted into a mosaic of regenerating forest stands dominated by local short-lived pioneers (i.e. low-biomass early-regenerating forest stands) and a few tree species less sensitive to fire. Our findings highlight the urgent need to secure a resilient future for Amazonian forests with actions needed to support local livelihoods whilst reducing the prevalence of ignitions sources and allowing forest recovery.

Assessing the potential of species loss caused by deforestation in a mature subtropical broadleaf forest in central China

Deforestation is a major type of land use change to accommodate growing population, especially in developing countries. The risk of diversity loss due to habitat loss can be estimated using the species-area relationship based on abundance of each species. However, deforestation often occurs before there is any understanding of the impact of deforestation on tree diversity. Here, we assessed the potential effect of forest habitat destruction on the loss of species richness in a mature subtropical broadleaf forest in central China. We surveyed and constructed the species-area relationship for 54 400 m2 plots, and simulated habitat loss scenarios by randomly and aggregately sampling plots. Rank-abundance of the 21 tree species was best fitted by the Zipf-Mandelbrot model, and our sample size was sufficient by the criterion of Hill numbers at orders q = 0, 1, and 2. We found that the number of species lost due to habitat loss was well predicted by the random placement species loss-area loss curve, and was lower than that due to aggregated habitat destruction by less than one species. The probability of losing one species reached 40% when losing 16 plots by aggregated sampling, 10 plots fewer than that by random sampling. Moreover, the probability of losing two species was 10–22 % higher by aggregately sampling than that by randomly sampling when losing 17 – 34 plots (0.68 – 1.36 ha). Considering that aggregated deforestation is common in reality, the results imply that the number of tree species lost due to deforestation could be higher than the theoretical estimation. Our study suggests the importance of assessing the impact of deforestation on tree diversity before selective logging in subtropical forests.

Current and future patterns of vascular plant species richness across a forest–grassland–desert transect in East Asia

AbstractQuestionsRapid climate change has profoundly altered the spatial distribution of terrestrial plants especially in arid and semi‐arid biomes. However, it remains poorly documented how climate shapes the current and future patterns of plant diversity within and across these vulnerable vegetation types.LocationParts of Mongolia, southeastern Russia, and northern China (94.78°–126.78°E, 34.60°–54.27°N).MethodsUsing a random forest model trained by a comprehensively compiled database on vascular plant species richness (i.e., the number of species within a defined plot area) and corresponding climate variables, soil conditions and vegetation types (forest, grassland, desert), we assessed the current pattern of vascular plant species richness across a typical forest–grassland–desert transect in East Asia. We further predicted future changes in vascular plant species richness under three climate scenarios (SSP1‐2.6, SSP3‐7.0, and SSP5‐8.5).ResultsVascular plant species richness generally showed a decrease from northeast to southwest across the transect, mainly explained by spatial variations in growing‐season precipitation and the minimum temperature of the coldest month. More than half of the transect area will likely experience a loss in vascular plant species richness in 2041–2070 under all three scenarios. The decrease in vascular plant species richness will likely occur in a smaller area under the low‐emission scenario (SSP1‐2.6). We also predict distinct changes in vascular plant species richness for different vegetation types, including a slight increase in forests but an overall decrease in both grasslands and deserts.ConclusionsOur findings suggest a dominant role of growing‐season precipitation in shaping the spatiotemporal patterns of vascular plant species richness across the forest–grassland–desert transect and highlight a risk of plant diversity loss in the regional dryland ecosystems in response to future climate change.

Impacts of climate change in taxonomic, phylogenetic and functional diversity in snakes in largest dry forest ecoregion, the Gran Chaco

The impacts of anthropogenic activities have significantly contributed to recent and future climate changes worldwide. The future effects of climate change on biodiversity have been intensively studied globally over the past two decades. Currently, dry ecoregions are among the most threatened ecosystems in the world. In South America, three such seasonal dry ecoregions stand out: the Cerrado, Caatinga, and the Gran Chaco. Among these, the Chaco has experienced high deforestation rates and landscape degradation over the last decade, making it a top priority for conservation efforts. In this study, we employed ecological niche modeling to estimate the present and future distribution of snakes in the Chaco region. Our goal was to assess how snake diversity will change with projected climate changes across this geographic area. Our findings suggest that snake assemblages in the Chaco will undergo significant changes under future climatic conditions, with a clear trend toward biotic homogenization of the ecoregion and a decrease in species richness. These negative changes will likely extend to the protected areas within the Chaco, resulting in biotic homogenization and a loss of species richness.

Come rain or come shine, the species richness will decline in the Moroccan mountains

Plant species richness in mountainous regions generally follows a unimodal distribution with lower values at both low and high altitudes in relation to precipitation. In the Atlas mountains, Morocco, plant species richness is currently highest at 800–1200 m elevation, but the extent and altitudinal limits of this species-rich belt have shifted in the past with climate change.Here, we trace the evolution of pollen taxonomic richness (PTR) as a proxy for plant species richness, with the aim of understanding the relationship with climatic changes over the past 19,000 years, and make some assumptions about future changes in species richness. Past PTR was inferred through an analogy with an extensive modern pollen dataset, and past climatic variables were reconstructed from a fossil record collected in the Middle Atlas, Morocco.We found that the current PTR distribution in Morocco is more closely associated with precipitation than with temperature. During the last glacial period, both PTR and annual precipitation were low, and the analogs were located at lower altitudes than the altitude of the fossil record. During the early Holocene, the PTR increased by approximately 15%, and the modern analogs were found approximately 600–800 m higher than the analogs of the last glacial period. After 6000 years BP, we observe a steady decline in annual precipitation of approximately 30%, resulting in a species richness loss of approximately 18% and a retreat of the upper boundary of the species-rich belt.Climate projections suggest that annual precipitation in Northwest Africa will decrease by 20–30% over the next 50 years, an annual amount comparable to that of the last glacial period, but under much warmer conditions and in a significantly shorter time. Such a decline in precipitation could result in an unprecedented loss of plant species richness of approximately 15% in just a few decades and put 35% of the protected areas at risk. The forested mountains above 1600 m could then resemble the treeless and less diverse steppes found at higher altitudes above today's tree line.

Changes in submerged macrophyte diversity, coverage and biomass in a biosphere reserve site after 20 years: A plea for conservation efforts

The conservation of submerged vegetation is crucial in the functioning of aquatic ecosystems. We have assessed, by means of subaquatic quantitative sampling transects, the current status of the hydrophytic flora in 14 lakes in the Lagunas de Ruidera Natural Park, a Biosphere Reserve site in central Spain, surrounded by a semi-arid landscape. The conforming lakes have endured several anthropic pressures for decades (e.g., eutrophication, land-use changes, etc.). By comparing the current with the former status (20 years ago) of hydrophytes in the natural park, substantial negative (species richness loss, decrease in submerged meadow coverage, particularly in the upstream lakes) and positive (natural recovery of meadows after the cut-off of sudden disturbances caused by point pollution sources, improving of trophic state in some lakes, no presence of exotic hydrophytes) changes in the lakes were noticed. We have analyzed that the disappearance of all the hydrophyte (mainly charophytes) stands would represent the loss of ecosystem services. For example, up to 70 t CH4 might be released from the charophyte detritus, an internal pool of phosphorus (as high as 1400 mgP/m2) stored in the charophytes stands could be liberated. Some lakes require special measures, but overall, to preserve this lake complex, and other similar ones, we propose to study, in detail, the causes of submerged vegetation deterioration (focusing on the presence of pesticides –in water and sediments-, and other reasons) to assess the ecological risks, to protect the groundwater resources, preventing the lakes from receiving surficial point and non-point sources of pollution.

Contrasting responses of forest phenological guilds to complex floodplain change

Abstract Understanding the seasonal dynamics of the forest herb layer and the factors that influence it is essential for predicting how the forest ecosystem, including mutualistic interactions, will respond to global change. However, to date, no research has investigated how understorey phenological guilds respond to major environmental threats and forest interventions. We showed the marked changes in the phenological structure of floodplain forest plant communities over half a century at a multi‐regional scale in Central Europe. Unlike previous studies focusing on individual species' responses to climate change, we examined shifts in species richness, frequency and abundance between phenological guilds within the plant community. We examined the effects of temporal variation in climate, hydrology, soil conditions and canopy structure, and assessed the effects of non‐intervention and intervention management on phenological guild responses. Our results show a significant loss of local species richness and a decline in species frequency in the forest understorey vegetation, associated with species exhibiting summer phenology. In contrast, an increase in abundance and richness of spring flowering species was observed, attributed to high nutrient loads and reduced flooding, respectively. The abundance of spring species increased only in stands where canopy cover increased over time, probably due to the suppression of summer flowering species, allowing spring flowering species to spread on open, bare ground. The community experienced a shift in maximum flowering plant richness from June to May. Despite management interventions such as clearcutting and tree planting, our data show similar temporal trajectories in intervention and non‐intervention forests, indicating that changes in phenological structure are largely independent of recent management activities. Synthesis. We propose that a complex interplay of environmental factors, rather than climate change alone, is shaping shifts towards earlier phenological guilds in floodplain forests. This study highlights the importance of considering a comprehensive view of phenological guild dynamics and the impact of environmental factors on forest plant community structure in the face of global change.

Taxonomic and functional homogenization of butterfly communities along an urban gradient

Abstract Urbanization is a major cause of global insect declines, yet some species can persist, and even thrive, in cities. Research on butterflies frequently report reduced diversity in urban habitats compared to rural ones, but less is known about whether urbanization favours butterflies with specific functional traits. Further, few studies have evaluated whether urbanization leads to the biotic homogenization of butterfly communities, despite being frequently reported for other taxa. Here, we investigate how butterfly community composition changes along an urban gradient by surveying 44 sites around Montréal, Quebec, Canada. We test the hypothesis that urban butterfly communities are homogenized at the taxonomic and functional levels. We found clear differences in the structure of urban versus rural butterfly communities with urban areas favouring a few, highly abundant, non‐native species. These shifts were defined by losses of native species richness and abundance combined with increases in non‐native species abundance. For most of the butterfly community, species with longer flight periods were more common in urban areas. Finally, urban communities were homogenized at the taxonomic and functional levels as demonstrated by reductions in beta diversity and variation in several key functional traits (wingspan, larval diet breadth, oviposition style) in urban habitats compared to rural ones. Overall, urban habitats in this region support less diverse butterfly communities that are homogenized. Since urban areas are growing worldwide, a better understanding of how biotic homogenization arises and what its consequences are will be key to guiding future conservation efforts.

Catastrophic flooding effects on a Wisconsin wet prairie remnant: A shift in the disturbance regime?

Climate change is likely to imperil native biodiversity through the increased frequency of extreme events. Here we address the short-term effects of an extreme flooding event on an unplowed prairie reserve, the Faville Prairie Wisconsin State Natural Area. This 25-ha property is a remnant of the formerly extensive Crawfish Prairie that lay on the east bank of the Crawfish River, Jefferson County, Wisconsin USA. The Faville remnant has historically been subject to late winter to spring flooding in its lower portions. In June of 2008, however, an extreme rainfall event caused flooding unprecedented in the 87-year history of streamflow, inundating the entire site. Data were available from 180 permanently marked plots sampled in 1978-79. We assessed the change by resampling these plots in 2010-2015. At the m2 scale, we found significant losses of species richness, a result of most species having fewer occurrences than in the earlier data. There was near extinction of several important prairie species and a relative increase in wetland tolerant species. Lower elevation plots, subject to the encroachment of woody plants and the invasion of Phalaris arundinacea for decades prior to the flood, had the lowest levels of species richness. However, some prairie species survived the flooding with little change, and recent anecdotal observations show that others are rebuilding their populations. Thus, if extreme floods are infrequent, the prairie should be able to recover to its former state. If, however, the hydrological regime shifts toward more frequent, growing-season floods, we predict further decline in those plant species that were the object of the preservation of this remnant. It is critical that fire management continue along with monitoring to track species' recovery or replacement, so that corrective measures can be identified and tested to sustain the native prairie species diversity.

Nitrogen addition drives changes in arbuscular mycorrhizal fungal richness through changes in plant species richness in revegetated alpine grassland

Nitrogen (N) addition not only promotes the restoration of degraded grasslands, but also threatens ecosystem functioning through the loss of species richness. Thus, a deep understanding of the effect of N addition on the richness of key organisms in restored grasslands is critical to sustainably restoring degraded grasslands. We conducted a 4-year N addition experiment to investigate the response of both plant and arbuscular mycorrhizal (AM) fungal richness to the combined addition of ammonium (Am) and nitrate (Ni) in a revegetated grassland rehabilitated (with a focus on restoration) on the Qinghai–Tibet Plateau. Both nitrogen forms were added at three levels: 0, 10, and 20 g N m−2 year−1. By itself, Ni addition of 20 g N m−2 year−1 (Ni20) reduced both plant and AM fungal richness, while Am addition of 20 g N m−2 year−1 (Am20) had no significant effect on them. However, when Ni and Am were combined, only Ni20 plus Am20 among all combinations reduced both plant and AM fungal richness. Both soil nitrate-N and plant species richness jointly drove changes in AM fungal richness, but plant species richness was the main factor affecting AM fungal richness under N addition. Our results suggest that minimizing the loss of AM fungi caused by plant species loss resulting from N addition is a key means to sustainably restore degraded grasslands.

The Architectonicidae and Mathildidae (Gastropoda, Heterobranchia) of the Miocene Paratethys Seavictims of the Miocene Climatic Transition.

The Architectonicidae of the Miocene of the Central Paratethys Sea comprise 18 species placed in eight genera. The coeval Mathildidae are documented by nine species, placed into three genera. We present descriptions of these species and illustrate type material wherever possible. Several species suggest relationships with Late Miocene to Holocene species of the Mediterranean Sea, although none of the species is known from modern faunas. Both families attained their maximum diversity during the early Middle Miocene (Langhian), and both families experienced a dramatic loss in species richness at the Langhian/Serravallian boundary. This Architectonicidae/Mathildidae turnover evidently coincided with the Miocene Climatic Transition, suggesting climate as the driving force. As members of both families feed on coelenterates, we assume that the climatic cooling of that phase caused a retreat of cnidarians, which is reflected in a decline in their predators. Ammotectonica nov. gen., Simplexollata nov. gen. and Pseudotuba nov. gen. are introduced as new genera. Ammotectonica gregorovae nov. sp., Simplexollata anticollata nov. sp., Nipteraxis deformatus nov. sp., Solatisonax? transversa nov. sp., Heliacus globosus nov. sp., Solatisonax tavianii nov. sp., and Pseudotorinia grasemanni nov. sp. are described as new species. Solarium (Torinia) criticum Boettger, 1907 and Discohelix quinquangularis Boettger, 1902 are treated as subjective junior synonyms of Heliacus berthae (Boettger, 1902) and Spirolaxis cornicula (Boettger, 1902).

Resistance of freshwater sediment bacterial communities to salinity disturbance and the implication for industrial salt discharge and climate change-based salinization

The impact of salinization on freshwater ecosystems became apparent during the 2022 ecological disaster in the Oder River, located in Poland and Germany, which was caused by salt discharge from mining activities. How bacterial communities respond to salinization caused by industrial salt discharge, or climate change-driven events, depends on the sensitivity of these complex bacterial communities. To investigate the sensitivity of bacterial communities to pulse salinization, we performed an experiment in the salinity range from 0.2 to 6.0. In addition, we sampled similar salinities in the littoral zone of the Baltic Sea where the bacterial communities are permanently exposed to the aforementioned salinities. To simulate a major disturbance, we included an ampicillin/streptomycin treatment in the experiment. Although the addition of antibiotics and increase in salinity had a significant impact on the water bacterial richness and community composition, only antibiotics affected the sediment bacterial community in the experiment. In contrast, sediment bacterial communities from the Baltic Sea littoral zone clustered according to salinity. Hence, sediment bacterial communities are more resistant to pulse changes in salinity than water bacteria but are able to adapt to a permanent change without loss in species richness. Our results indicate that moderate pulse salinization events such as industrial salt discharge or heavy storms will cause changes in the water bacterial communities with unknown consequences for ecosystem functioning. Sediment bacterial communities, however, will probably be unaffected in their ecosystem functions depending on the disturbance strength. Long-term disturbances, such as sea level rise or constant salt discharge, will cause permanent changes in the sediment bacterial community composition.

The impact of the German timber footprint on potential species loss in supply regions

Previous own assessments have shown that a) Germany has a wood consumption above global average, b) is strongly dependent on imports and c) has a domestic roundwood production that is at the limit of the sustainable harvest potential. Thereby Germany further increases the pressures on global forests which are already stressed by climate-change related impacts and a continuously growing global demand for wood. This leads to negative impacts on the biodiversity in the areas where wood is harvested. This paper aims to show the connection between Germany's timber consumption footprint and the impact on the biodiversity in the regions where the roundwood is sourced. A two-step process is used. In the first step, high-resolution land cover and land use maps are used as a basis for the countryside species-area relationship model, assessing the projected loss of the four taxa amphibians, birds, mammals and reptiles in relation to undisturbed natural ecosystems due to forests occupied for roundwood production. In the second step, roundwood equivalents consumed in Germany in 2015 are traced back to the region of origin using an environmentally-extended input-output analysis and the thereby induced potential species loss is calculated. We show that the highest impact on projected species richness loss caused by roundwood logging is taking place in Oceania (3.34E−03 species/m3), Carribean (1.56E−04 species/m3), and East Asia (1.43E−04 species/m3). German roundwood consumption has the highest projected species loss in the United States (7.4 species), followed by China (7.3 species) and Brazil (4.8 species). From a biodiversity impact perspective, Germany could theoretically reduce its impact by relocating imports to European countries. In view of the planetary boundary of sustainable roundwood consumption, which has already been exceeded, reducing consumption appears to be the only viable long-term option for high-consumption countries such as Germany to reduce negative impacts on global biodiversity.

Geographical trends of soil‐associated biodiversity changes due to tree plantations in South America: Biome and climate constraints revealed through meta‐analysis

AbstractAimTo evaluate the interaction between climate and biome structure when explaining changes in species richness of soil‐associated communities due to tree plantations developed in different biomes. Compare the response of plants, soil invertebrates and soil microorganisms, and to test whether they should be considered sensitive‐coupled biotas.LocationContinental South America.Time Period1996–2023.Major Taxa StudiedPlants, soil invertebrates and soil microorganisms.MethodsThrough a meta‐analysis, the change in species richness (i.e. response ratio) associated with tree plantations was evaluated in 127 points of study across South America, considering soil‐associated communities of plants, invertebrates and microorganisms. The influence of biome structure (open vs. closed habitats) on the response ratio, and its interaction with the actual evapotranspiration (AET) and temperature seasonality was evaluated. Differentiated responses of different taxa were tested by comparing models with and without an interaction term referring to the taxon studied. The regional agricultural cover and plantation age were considered as anthropogenic variables.ResultsModels containing the AET were better at explaining the trend of change in species richness than those with temperature seasonality. The response of the change in species richness was oppositely related to the AET in open and closed biomes. Plants presented a higher loss in species richness than soil invertebrates and microorganisms. The three taxa were positively associated with AET, while seasonality was not relevant in any case. Both anthropogenic variables significantly lessened the change in species richness in all models.Main ConclusionsThe structural contrast between the anthropogenic habitat and the biome where it is developed is a key factor influencing the response of soil‐associated communities to tree plantations. Nevertheless, its influence must be assessed together with climatic and anthropogenic variables given that their interaction can explain different geographical trends in the change in species richness across regions.

What is a suitable management for Typha latifolia control in wet meadows?

AbstractAimTypha latifolia causes serious problems in wet meadows by overgrowing and suppressing other native plants. To determine suitable management for T. latifolia control, we addressed the following question: What are the effects of long‐term cutting at different frequencies (once or twice per year and no management) and biomass removal on cover and other characteristics of T. latifolia, and on sward productivity and plant species composition?LocationMalá Strana nature reserve, Jizerské hory Mountains, Czechia.MethodsA long‐term experiment arranged in a randomised block design with three blocks was established in 2005. Data were collected from five treatments: unmanaged control; cutting once a year in June without biomass removal and with biomass removal; cutting twice per year in June and August without biomass removal and with biomass removal. Percentage cover of T. latifolia and other vascular plant species was visually estimated and T. latifolia characteristics (tiller density, height, dry‐matter biomass [DMB] yield and litter), sward height and DMB yield were measured during 2005–2018 at the end of June.Results and DiscussionRegular cutting once or twice per year regardless of cut biomass removal led to reductions in tiller density, height, litter and DMB yield of T. latifolia. Biomass removal had only a slight tendency to affect T. latifolia characteristics. The higher frequency of cutting significantly decreased the mean T. latifolia cover, litter and DMB yield. Cutting once or twice per year regardless of biomass removal led to successive changes in plant species composition but had no effect on the species richness and evenness.ConclusionsCutting at least once per year without biomass removal seems to be sufficient to achieve a decrease in DMB yield and litter of T. latifolia plants, and thereby maintain the wet‐meadow vegetation without loss of species richness and also preventing the overgrowth of shrubs and trees.

Hydropower Plants as Dispersal Barriers in Freshwater Species Distribution Models: Using Restrictions through Asymmetrical Dispersal Predictors.

Hydropower plants represent one of the greatest threats for freshwater fish by fragmenting the habitat and avoiding the species dispersal. This type of dispersal barrier is often disregarded when predicting freshwater species distribution due to the complexity in inserting the species dispersal routes, and thus the barriers, into the models. Here, we evaluate the impact of including hydroelectric dams into species distribution models through asymmetrical dispersal predictors on the predicted geographic distribution of freshwater fish species. For this, we used asymmetrical dispersal (i.e., AEM) as predictors for modeling the distribution of 29 native fish species of Tocantins-Araguaia River basin. After that, we included the hydropower power plant (HPP) location into the asymmetrical binary matrix for the AEM construction by removing the connections where the HPP is located, representing the downstream disconnection a dam causes in the fish species dispersal route. Besides having higher predicted accuracy, the models using the HPP information generated more realistic predictions, avoiding overpredictions to areas suitable but limited to the species dispersal due to an anthropic barrier. Furthermore, the predictions including HPPs showed higher loss of species richness and nestedness (i.e., loss of species instead of replacement), especially for the southeastern area which concentrates most planned and built HPPs. Therefore, using dispersal constraints in species distribution models increases the reliability of the predictions by avoiding overpredictions based on premise of complete access by the species to any area that is climatically suitable regardless of dispersal barriers or capacity. In conclusion, in this study, we use a novel method of including dispersal constraints into distribution models through a priori insertion of their location within the asymmetrical dispersal predictors, avoiding a posteriori adjustment of the predicted distribution.

Linking levels of trace-metal concentrations and ambient toxicity to cladocerans to levels of effects on macroinvertebrate communities

Ecological impacts of chemicals such as metal mixtures in the field are predicted by one of two approaches: component-based and whole-mixture approaches. Knowledge about how to relate results of these approaches to field effect levels is limited. We aimed to examine the ability of two methods to discriminate field effect levels: (1) a component-based approach that calculates a cumulative criterion unit (CCU) equal to the sum of the ratios of four trace-metal concentrations (Cd, Cu, Zn, and Pb) to the corresponding US EPA hardness-adjusted water quality criterion, and (2) a whole-mixture approach that employs three ambient toxicity levels based on acute and chronic toxicity tests with cladocerans. To assess field effect levels, we used data from benthic macroinvertebrate surveys conducted at 26 sites, including 13 metal-contaminated sites, in four river basins across Japan. Based on decreases in mayfly richness and abundances of two metal-sensitive mayfly families, we defined four field effect levels 0–3: (0) no significant effect; (1) a significant decrease in ephemerellid and/or heptageniid mayfly abundance; (2) a significant decrease in mayfly richness; and (3) no mayflies or a few baetid mayfly species present. Sites with CCU values of ∼5–10 were assigned to either field effect level 1 or 2, while a site with a CCU value of 27 was assigned to field effect level 3. Sites with significant chronic toxicity to cladocerans (ambient toxicity level 1) were assigned to field effect level 1 or 2, whereas those with significant acute and chronic toxicity (ambient toxicity level 2) were assigned to field effect level 2 or 3. CCU values and ambient toxicity levels were both significantly correlated with field effect levels. These results provide encouraging evidence that field effect levels such as losses of species richness can be approximately discriminated by CCU values and ambient toxicity levels.

Discrete patterns of microbiome variability across timescales in a wild rodent population

Mammalian gastrointestinal microbiomes are highly variable, both within individuals and across populations, with changes linked to time and ageing being widely reported. Discerning patterns of change in wild mammal populations can therefore prove challenging. We used high-throughput community sequencing methods to characterise the microbiome of wild field voles (Microtus agrestis) from faecal samples collected across 12 live-trapping field sessions, and then at cull. Changes in α- and β-diversity were modelled over three timescales. Short-term differences (following 1–2 days captivity) were analysed between capture and cull, to ascertain the degree to which the microbiome can change following a rapid change in environment. Medium-term changes were measured between successive trapping sessions (12–16 days apart), and long-term changes between the first and final capture of an individual (from 24 to 129 days). The short period between capture and cull was characterised by a marked loss of species richness, while over medium and long-term in the field, richness slightly increased. Changes across both short and long timescales indicated shifts from a Firmicutes-dominant to a Bacteroidetes-dominant microbiome. Dramatic changes following captivity indicate that changes in microbiome diversity can be rapid, following a change of environment (food sources, temperature, lighting etc.). Medium- and long-term patterns of change indicate an accrual of gut bacteria associated with ageing, with these new bacteria being predominately represented by Bacteroidetes. While the patterns of change observed are unlikely to be universal to wild mammal populations, the potential for analogous shifts across timescales should be considered whenever studying wild animal microbiomes. This is especially true if studies involve animal captivity, as there are potential ramifications both for animal health, and the validity of the data itself as a reflection of a ‘natural’ state of an animal.

Biocultural, Productive, and Ecocentric Restoration in La Mintzita Spring-fed Wetland, Michoacán, México

<h3>ABSTRACT</h3> The increasing loss of wetlands at the global scale demands immediate response by improving management practices and ecological restoration. When people degrade wetlands, environmental restoration must overcome biotic and economic barriers that can be considerable. We assessed the floristic composition of a wetland subjected to anthropic disturbances and expansion of invasive species, then compared our results with historical data from 2005 to 2015. The result revealed that changes in floristic composition and dominant native and invasive dominant species occurred during this 16-year period. In the dry season, we found significant differences in species richness between the years 2005 and 2021, with a significant reduction in species richness in the latter year. This loss of species richness represents an unfavorable change in the floristic composition trajectory, which we explain as an effect of sustained anthropic disturbance. Floristic data from the rainy season was not conclusive. <i>Typha domingensis</i>, and the invasives <i>Phragmites australis</i> and <i>Festuca arundinacea</i> have been favored by disturbances and increased their cover at the expense of other wetland species, reducing the wetland’s floristic diversity. Our objective was to redirect the floristic composition trajectory in the La Mintzita wetland by proposing management strategies for controlling the above-mentioned species based on three ecological restoration strategies: biocultural (targeting simultaneously the loss of biodiversity and of traditional use of <i>Typha</i>), productive (to control expansion of <i>P. australis</i> which has no traditional use in the region, we propose a new use), and ecocentric (to control <i>F. arundinacea</i> and recover native species cover).

Diversified land conversion deepens understanding of impacts of rapid rubber plantation expansion on plant diversity in the tropics

Understanding the status and changes of plant diversity in rubber (Hevea brasiliensis) plantations is essential for sustainable plantation management in the context of rapid rubber expansion in the tropics, but remains very limited at the continental scale. In this study, we investigated plant diversity from 10-meter quadrats in 240 different rubber plantations in the six countries of the Great Mekong Subregion (GMS)—where nearly half of the world's rubber plantations are located—and analyzed the influence of original land cover types and stand age on plant diversity using Landsat and Sentinel-2 satellite imagery since the late 1980s. The results indicate that the average plant species richness of rubber plantations is 28.69 ± 7.35 (1061 species in total, of which 11.22 % are invasive), approximating half the species richness of tropical forests but roughly double that of the intensively managed croplands. Time-series satellite imagery analysis revealed that rubber plantations were primarily established in place of cropland (RPC, 37.72 %), old rubber plantations (RPORP, 27.63 %), and tropical forests (RPTF, 24.12 %). Plant species richness in RPTF (34.02 ± 7.62) was significantly (p < 0.001) higher than that in RPORP (26.41 ± 7.02) and RPC (26.34 ± 5.37). More importantly, species richness can be maintained for the duration of the 30-year economic cycle, and the number of invasive species decreases as the stand ages. Given diverse land conversions and changes in stand age, the total loss of species richness due to rapid rubber expansion in the GMS was 7.29 %, which is far below the traditional estimates that only consider tropical forest conversion. In general, maintaining higher species richness at the earliest stages of cultivation has significant implications for biodiversity conservation in rubber plantations.