Changes In Species Composition Research Articles

Floristic Patterns and Conservation Values of Mojave and Sonoran Desert Springs in California

In the face of a rapidly changing climate, spring-fed habitats are increasingly vulnerable to numerous threats. Botanical inventories provide valuable information to assess the conservation value of desert springs, and can serve as indicators to document changing conditions, including the proportion of native vs. nonnative taxa, diversity of life forms present that influence structure and function of ecosystems, species persistence and longevity, and the proportion of taxa that are rare and sensitive to land use change. Here we evaluate plant species composition and richness within and between springs, and evaluate botanical diversity with respect to physical parameters including hydrology and geography. We find that desert springs collectively support a large proportion of plant diversity, or nearly 22% of the total vascular plant diversity known within the California desert in only 0.000005% of the total land area. The springs we sampled are highly dissimilar in plant species composition, thus, restoration and management activities likely need to be highly individualized and site specific. Monitoring and inventory programs can increase opportunities for restoration and protection by providing information to assess warning signs of habitat degradation, such as changing species composition and local extirpation of wetland-dependent species.

Wetland attributes significantly affect patterns of bird species distribution in the Sardinian wetlands (Italy): An uncertain future for waterbird conservation

Abstract The Sardinian wetlands belong to the Sardinia‐Corsica corridor of the central eastern Mediterranean bird flyway. They supply the food and shelter for many waterbird species and act as stopover sites during migratory journeys. Despite policies and laws of the European Union, the Sardinian wetlands are severely threatened by anthropic activities and ongoing climate change, making the condition of the associated avifauna critical. We (a) inventoried the avian metacommunity of the largest coastal wetlands in Sardinia during the summer period, (b) investigated the metacommunity structure, (c) quantified the effects of wetland attributes on avian diversity at species and guild level and (d) predicted future changes in species composition of this metacommunity. We recorded 60 bird species (of which 21 belonged to Annex I of the Birds Directive). The metacommunity structure resulted was significantly nested and non‐modular. Salinity negatively affected the presence of 48 species out of 60, followed by tourism pressure (44 species), wetland isolation (42 species) and water discharges (36 species). The mean water level resulting from artificial regulation for anthropic activities was too high for 63% of the species, which disadvantaged primarily small waders, species feeding on invertebrates and trans‐Saharan migrants. In addition, water‐level fluctuations (that would favour avian diversity) were prevented by artificial regulation during the summer period in many wetlands, producing further negative effects on the avifauna. We found 45% of the recorded bird species at risk of disappearance from this avian metacommunity. Synthesis and applications. Our study indicates that, as things stand, the avian metacommunity of the Sardinian wetlands is destined to experience reductions in the short term and mid‐term. This decline will be accelerated by increased saltwater intrusions due to sea‐level rise. Nevertheless, the nested and non‐modular structure of this avian metacommunity would allow for pro‐active conservation measures (e.g. restriction for tourism activities, construction of artificial dune cordons to minimize saltwater intrusions, water‐level regulation that keeps into account also the ecological requirements of waterbird species) to counteract the effects of current and future threats.

Induced drought strongly affects richness and composition of ground-dwelling ants in the eastern Amazon.

Species loss in tropical regions is forecast to occur under environmental change scenarios of low precipitation. One of the main questions is how drought will affect invertebrates, a key group for ecosystem functioning. We use 1year of data from a long-term rainwater exclusion experiment in primary Amazonian rainforest to test whether induced water stress and covarying changes in soil moisture, soil respiration, and tree species richness, diversity, size, and total biomass affected species richness and composition (relative abundance) of ground-dwelling ants. Data on ant abundance and environmental variables were collected at two sites (control and experimental) in the Eastern Amazon. Since 2002, drought has been induced in the experimental plot by excluding 50% of normal rainfall. Ant species richness in the experiment plot was reduced and some generalist species responded positively. Ant species richness also increased in the experimental plot with increasing diversity of the plant species of the leaf litter. The relative abundance of ants differed between plots. The experimental plot was characterized by a higher frequency of generalist and other species that appeared to be favored by the reduction in rainfall. Between-plot comparisons suggested loss and changes in ant species composition in tropical forests were affected by increasing dryness. These changes could ultimately lead to cascading effects on ecosystem processes and the services they mediate.

The key to temperate savanna restoration is to increase plant species richness reasonably

Changes in species composition and diversity-productivity relationships during vegetation succession are of great significance for the restoration of degraded grasslands. However, the human intervention of grassland restoration mostly considers the single ecological (diversity) or production (biomass) function of grasslands, and does not fully consider the relationships between the two to improve the restoration effects. In this study, three vegetation types (desert grassland, sandy grassland and temperate savanna) were considered to simulate the three stages of restoration of degraded temperate savanna (early, middle and late restoration). Changes in species composition, diversity, and diversity-productivity relationships during the temperate savanna restoration were explored through spatiotemporal substitution. The results showed that with the progress of succession, xerophytes decreased significantly, mesophytes and hygrophytes increased, C4 plants decreased gradually, and C3 plants increased. The change of species richness was the main reason for community differences in the process of community succession, and species replacement mainly occurred between communities in the early and middle stages of succession. Species richness increased significantly from early to late stage of restoration. Latitude was significantly negatively correlated with species diversity. In the process of vegetation restoration, the impact of species richness, Pielou’s evenness, and β-diversity on biomass gradually developed positively and continued to increase, while the Simpson index showed the opposite effect. This study provides references for the restoration of temperate savanna and emphasizes the ecological and productive functions of the grassland should be taken into account in the restoration strategy.

Long-term effects of environmental alterations in protected grasslands – Land-use history determines changes in plant species composition

Nutrient-poor, semi-natural grasslands are among the most species-rich ecosystems across Europe. However, due to the transition from pre-industrial farming to modern agriculture, the extent of such grasslands has greatly decreased and the remaining patches have often suffered from habitat deterioration. Here, we analysed the effects of land-use and climate change as well as of nitrogen deposition on plant communities of dry (sand) (n = 118) and wet grasslands (n = 30) in a protected area, representative for the NE German young moraine landscape. Our study revealed that over a time period of 25 years, plant species composition in protected grasslands has changed considerably. Overall, plant species richness increased in both dry and wet grasslands from 1994 to 2019. The number of threatened species, however, decreased in dry but increased in wet grasslands. Land-use history was identified as the major driver of changes in species composition within the studied semi-natural grasslands. In wet grasslands, after >30 years of abandonment prior to the first survey, species-rich communities such as the Molinietalia have successfully been restored through the re-introduction of continuous, low-intensity management (mostly mowing once in late summer) shortly before the first survey. This has led to an increase of often threatened, light-demanding species of nutrient-poor wet grasslands. In dry grasslands, however, changes in vegetation were often contrary to those in wet grasslands; for example dry grasslands exhibited an increase in the nitrogen indicator value while it decreased in wet grasslands. Overall, open, nutrient-poor dry grasslands rich in stress-tolerant and often threatened species have been replaced by dense, more mesophytic grasslands with competitive generalists and some ruderal annuals. These successional changes were caused in particular by (i) an increase in abandonment on the least productive soils, (ii) undergrazing in permanent pastures and (iii) an insufficient time period since the re-introduction of grazing combined with a too low grazing pressure in new pastures on more productive soils. Nitrogen deposition was a further driver, especially on more acidic, dry soils. Additionally, grassland ruderalization was favoured by cropping of some plots and climate change since warm winters and severe summer droughts have led to an increase of annual ruderal species.

Climate-driven shifts in pelagic fish distributions in a rapidly changing Pacific Arctic

Baseline surveys of offshore pelagic fishes in the eastern Chukchi Sea in 2012 and 2013 found that age-0 Arctic cod (Boreogadus saida) dominated the pelagic fish community in summer, with relatively few adults present in the region. Since this time, drastic changes in the ocean-atmosphere-ice feedback loop have led to continued warming, further reducing ice cover, and increased northward transport has led to an increase in Pacific-origin waters on the Chukchi shelf in summer. To examine potential bottom-up effects of these environmental changes on pelagic fishes in this rapidly changing environment, we extended a time series of large-scale acoustic-trawl surveys with additional surveys in 2017 and 2019. Age-0 Arctic cod were the most abundant pelagic fish in all four survey years, comprising 68–93% of fish abundance. However, age-0 walleye pollock (Gadus chalcogrammus), which were scarce (<0.1% of fishes) and confined to the southern Chukchi in 2012 and 2013, were present in high abundance (>21% of fish abundance) throughout the Chukchi shelf in 2017 and 2019. Age-0 Arctic cod were substantially more abundant in 2017 than in other years, possibly due to increased survivorship of larvae under warm conditions. Unlike in 2017, Arctic cod and pollock were spatially separated in 2019 due to enhanced transport, with Arctic cod primarily present in the northeastern portion of the survey area, which was characterized by cool surface and bottom temperatures. The substantial increase in abundance of age-0 pollock in recent years suggests that environmental conditions now allow this species to extend its northern range into the southern and central Chukchi Sea, at least on a seasonal basis. The changes in abundance and species composition of pelagic fishes in the 2012–2019 time series are tightly coupled to recent changes in sea ice, temperature, and the increasing transport of Bering Sea waters through Bering Strait into the Chukchi Sea. Given that the environment is expected to experience further warming and increased transport, these northward shifts in species distribution are likely to persist in the future.

Understanding local ecosystem dynamics in three provinces of the lowlands of Nepal

Incidences of failure of sustainable ecosystem management policies, especially in the developing world are partly attributable due to a lack of political will and inadequate understanding of ecosystem dynamics (ED) at the local levels. In this study, we endeavor to comprehend the dynamics of two ecosystems – forest and agriculture – by employing a resource-friendly participatory approach based on stake-taking the experiences of indigenous and forest-dependent local stakeholders in three lowland provinces of Nepal and is guided by the theory of socio-ecological concept. An in-depth survey (n = 136) was conducted using semi-structured questionnaires, key informant interviews (n = 9), and focus group discussions (n = 4) for data generation, and generalized linear models were used to test whether understanding of ED is uniform across the socio-ecological landscape. We identified that various attributes of forests and agricultural ecosystems have altered substantially earlier than 30 years (hereafter, earlier decade) relative to the present (hereafter, later decade). Apart from the natural processes including anthropogenic and climatic factors, technological innovations played a significant role in altering ecosystems in the later decade. Understanding of ED among forest-dependent stakeholders significantly varied with respect to gender, occupation, age group, gender-based water fetching responsibility, and water-fetching duration, however, no significant correlation was observed with their level of education across the landscape. The studied ecosystem attributes significantly correlate with water regime changes, signifying that water-centric ecosystem management is crucial. The attributes that observed significant dynamics in the forest ecosystem include changes in forest cover, structure and species composition, the severity of invasive species, wildfires, water regimes, and abundance and behavioral changes in mammals and avifauna. The alteration of crop cultivation and harvesting season which results in a decrease in yield, increased use of chemicals (fertilizers and pesticides), an increase in fallow land, and the proliferation of hybrid variety cultivation in the later decade are significant disparities in the dynamics of the agriculture ecosystem. To withstand the accelerated ED, stakeholders adopt various strategies, however, these strategies are either obtained from unsustainable sources entail high costs and technology, or are detrimental to the ecosystems. In relation, we present specific examples of ecosystem attributes that have significantly experienced changes in the later decade compared to the earlier decades along with plausible future pathways for policy decisions sustaining and stewardship of dynamic ecosystems across the socio-ecological landscape.

Changes in taxonomic and functional diversity of an urban stream fish assemblage: A 30-year perspective

Globally, freshwater fish diversity is rapidly changing in response to land use change, including urbanization. Time series of freshwater fish communities can help elucidate the underlying mechanisms of species loss and gains, as well as promote conservation strategies. Traditional approaches to understand the dynamics of fish assemblages is traditionally focused on taxonomic diversity, one aspect among many dimensions of biodiversity. Thus, using complementary analytical methods, such as functional diversity, can help researchers to develop a stronger predictive framework on the effects of the species loss or gains in response to urbanization. We assessed temporal changes of fish assemblages in an urban stream in East Texas between four seasonal surveys of 1989–1990 and 2018–2019. We explored the similarities and differences in species richness, composition, and functional diversity of fishes. Although the species richness and functional richness between the two time periods were similar, we observed changes in species composition. We also observed higher functional dispersion and evenness in the 2018–2019 assemblage compared to 1989–1990 assemblage. Some fish species were locally extirpated, while others colonized the system, increasing the functional diversity of the current assemblage. Urbanization has commonly been associated with declines in diversity and richness, however, our findings suggest that the addition of a few invasive generalist species (e.g., blue tilapia) and native tolerant (e.g., redbreast sunfish, blacktail shiner) in this stream system could be associated with increased human activities in this small, urbanized area in East Texas. Streams in East Texas support very diverse fish assemblages, with some sentinel species (e.g., imperiled shiners: Sabine shiner, a habitat-affinity, broadcast spawner) rapidly responding to stream alterations. Multiple stressors can underlie the dynamics and composition of fish assemblages; thus, it is essential for more comparative studies of current and historical data of fish assemblages. Likewise, studies targeting sentinel fish species may have more utility for the evaluation of freshwater ecosystems.

Successional Change and Fire History in Montane Longleaf Pine-Dominated Ecosystems of Northwestern Georgia, USA

In the absence of fire, Pinus palustris (Longleaf Pine) ecosystems in the southeastern United States are vulnerable to successional change including mesophication, a process where increases in the importance of mesic and fire-intolerant species reduce biodiversity and thwart efforts to restore these systems. To determine the degree and nature of this successional trajectory at a local scale, we examined changes in species composition of a montane Longleaf Pine ecosystem in northwest Georgia using modern vegetation surveys and historical “witness tree” data. We also determined historical fire frequency using fire scars within Longleaf Pine stumps cross-dated to extant Longleaf Pine trees. Modern forest composition contained significantly more fire-intolerant taxa than the historical forest due to increased abundance of mesophytic species, especially Acer rubrum (Red Maple) and decline of Pinus spp. (pines) and some pyrophytic Quercus spp. (oaks). Counter to expectation, there were few differences in species composition between northeastern- and southwestern-facing slopes in modern or historical data. Fire scars indicated a historical mean fire-return interval of 5.5 years and suggest that without the reintroduction of more frequent prescribed fire, regeneration of montane Longleaf Pine is unlikely. Additional restorative techniques may also help these stands support greater biodiversity over time. For instance, co-dominance of pines and oaks in the historical forest suggests that fire-tolerant oaks should be retained in montane restoration efforts.

Taxonomic and functional macrofaunal diversity along a gradient of sewage contamination: A three-year study

We investigated the structural and functional changes of the soft-bottom macrofaunal community following the improvement of a wastewater treatment-WWT plant. The macrofauna was collected at increasing distance from the main outfall in 2018, 2019, and 2021. Organic matter and nutrients were analysed in the water column near the outfalls to detect possible changes due to the improved treatment. We examined Functional Entities-FEs (i.e. a unique combination of species functional traits), species richness, Shannon-Wiener diversity-H′, and taxonomic and functional β-diversity. From 2018 (before the year of the treatment change), to 2021, we noted a gradual decrease of organic carbon in the water column. In contrast, sediment characteristics (i.e. grain-size) did not change before and after treatment enhancement, with the exception of redox potential. Species richness and FEs gradually increased moving far from the source of organic contamination and after wastewater treatment enhancement, especially near the outfall. We observed different phases of macrofaunal succession stage after the WWT amelioration. A ‘normal stage’, i.e. slightly lower species richness, was reflected in decreasing functional richness. Higher taxonomic β-diversity values with significant turnover components indicated that the community was subjected to broad changes in species composition. However, functional β-diversity did not follow the same pattern. After treatment improvement, modified environmental conditions led to the establishment of new species, but with the same functions. Towards 2021, the community improved its resilience by increasing functional redundancy and reduction of vulnerability, which enhanced community stability. The latter was also reflected in the well-balanced proportion of macrofaunal feeding habits after the WWT upgrade. Integrating the classical taxonomic approach with the analysis of FEs, and environmental characteristics can provide an accurate insight into macrofauna sensitivity to stressors that are likely to lead to changes in the ecological state of an area.

Formation of phytocoenotypes in soils of different degree of erosion

The paper focuses on issues related to problems of eroded soils and subsequent processes of development of serial communities aimed at formation of a stable climax phytocoenosis. A series is considered as a set of species that briefly inhabit a given territory replacing each other. Soil erosion development is caused by anthropogenic and natural factors; hence, this process is of a mixed natural-anthropogenic type. Soil erosion on slopes with elemental landscapes of any exposure affects the environmental conditions for the formation of phytocoenotypes and species composition of plant communities due to secondary successions and variation in dominants and subdominants. In this case, plant communities of herbaceous phytocoenoses of eroded soils exhibit both sequential and rapid changes in species composition with the appearance of species adapted to decreased soil fertility. The orientation, rate and number of successional changes depend on the intensity of erosion development. Severely eroded soils significantly increase the heterogeneity of the soil environment, creating optimal conditions for introduction of species that are often nontypical of the considered phytocoenoses; the number of assectators therefore increases in soils of this type. In case weakly eroded soils are used as the control, the number of assectators in severely eroded soils increases two to three fold, with possible fluctuation changes aimed at reducing assectators due to ecotopic and phytocoenobiotic selections.

Black summer bushfires caused extensive damage to estuarine wetlands in New South Wales, Australia

SummaryThere is now considerable evidence that, as the climate continues to warm, bushfires are becoming more common and severe, particularly in regions such as south‐eastern Australia. The extraordinary Australian bushfires over the summer of 2019/2020 resulted in the burning of habitats such as highland peat swamps and intertidal estuarine wetlands over unprecedented spatial scales. Across New South Wales, these bushfires affected 183 ha of saltmarshes and 23 ha of mangroves in 19 estuaries. The percentage of fire‐affected saltmarsh ranged from 51% to 81% in the worst impacted estuaries, although typically ≤15% of mapped saltmarsh was damaged. Just over 50% of mangroves were burnt in Wonboyn Lake (although this constituted &lt;0.2 ha), whereas in all other estuaries, ≤5% of mangroves were burnt. At the state‐wide scale, the likelihood of saltmarshes being affected by fire was unrelated to adjacent terrestrial vegetation; however, mangroves adjacent to burnt wet sclerophyll forest were more likely to burn than not. Burnt mangroves were almost exclusively associated with extreme or high severity fires in adjacent terrestrial vegetation, yet saltmarshes were also impacted in some cases by moderate or low‐intensity fires. Many species of saltmarsh plants had re‐sprouted or germinated after 6–24 months, but the extent of any recovery or changes in species composition were not quantified. The majority of fire‐affected mangrove trees appeared to be dead 24 months after the fires, despite observations of epicormic growth on some trees after six months. Bushfire impacts to estuarine wetlands are likely to become more frequent and results from our work can help target hazard reduction burning that might be considered for minimising damage to mangroves. More work is required to better understand potential longer term impacts and the capacity for natural recovery of estuarine wetlands from bushfires.

Drivers of wildfire burn severity in the montane rainforests of northern Vietnam

Background Fire impacts and drivers of wildfire burn severity remain poorly understood for tropical forests. Aims To assess variation and environmental drivers of burn severity for nine forest fires in northern Vietnam. Methods Burn severity was estimated from satellite image analyses, and associations with a remotely sensed index of annual fuel production, topographic factors (elevation, slope, aspect) and weather variables (temperature, rainfall, relative humidity, wind speed) were evaluated. Key results High severity burn areas were found to be fairly uncommon and were associated with steeper, south-west facing slopes, higher elevations and lower fuel abundance. There was a weak tendency for higher burn severity on days with lower relative humidity. Conclusions Conditions that increase fire intensity and the dryness and flammability of fuels are important contributors to high severity fires in wet tropical systems. However, the pattern of higher burn severity at high elevation, where forests tend to be denser and more humid, is counter to this interpretation and may be due to species compositional changes and greater vulnerability of high-elevation forests to fire impacts. Implications Better understanding of fire risk and where in the montane forests of northern Vietnam fires are most likely to burn at high severity will assist forest fire management and recovery strategies.

Analyzing The Effect of “Lantana Amara” Invasion on Density, Frequency, Dominance, And Important Value Index of Woody Species in The Lake Tana Sub Basin

Invasive plant species can disrupt recovery pathways by altering species interactions and ecosystem structure and functioning. The species compositional changes induced by Lantana invasion are primarily driven by gradual changes in species density. This research tries to analyze the effect of Lantana camara invasion of density, dominance, important value index, species richness, and evenness in the Lake Tana subbasin. The finding revealed that species dominance (48.36) in the not invaded area is higher than invaded area (121.07). The total number of species recode in invaded (2031) area was lower than in the uninvaded area (5085). The uninvaded area (3.73) is richer in terms of species composition than invaded area (2.84). The invasive species Lantana camara affects the density, frequency, and important value index of other species by suppressing their composition. It also affects the species distribution by affecting species evenness and richness of the study area. The invasive species affect biodiversity composition and ecosystem services in the Lake Tana sub-basin. Comprehensive management strategies should be designed by the government, policymakers, and environmentalists to minimize the effect of Lantana camara invasion on biodiversity composition.

Fatores associados à diversidade beta de macrófitas na Baía de Caxiuanã, localizada na Amazônia Oriental

Abstract Aim In this study, we investigated the beta diversity of macrophytes (total, turnover, and nestedness) in Caxiuanã Bay, localized in the Eastern Amazon. We also investigated the environmental factors determining the beta diversity and its components. Methods Macrophytes and physical-chemical variables (pH, water temperature, electrical conductivity, dissolved oxygen, and water turbidity) were sampled in 45 sites in 2017. Beta diversity was calculated based on Jaccard dissimilarity (using a presence/absence matrix) and partitioned in turnover and nestedness. We performed a Generalized Dissimilarity Modeling to analyze the influence of local (physical-chemical) and spatial factors (geographic distance) on total beta diversity and its components. Results A total of 16 macrophyte species were identified belonging to five morphological groups (free-floating, emergent, submerged, epiphytes, and rooted with floating leaves). The total beta diversity of macrophytes was 0.29, the turnover component had the highest contribution to total beta compared to nestedness. The beta total was influenced by geographic distance and conductivity, turnover by geographic distance and turbidity, and nestedness was explained by conductivity and pH. Conclusions In our study, physical-chemical factors influenced the structure of the macrophyte community, indicating that niche processes (deterministic) were acting and changing species composition. However, the spatial component and the low explanatory power of the models, especially for turnover, can also indicate the influence of stochastic processes such as ecological drift and/or limitations in dispersal. Our study provides new insights into the diversity patterns of macrophytes in Amazonian ecosystems, particularly in blackwater rivers. Our data also contribute to a better understanding of the processes that structure the species composition of macrophytes in these environments.

The adventive species community changes in the Cheboksary reservoir during 2001-2021

Generally publications devoted to invasive fish species in the Volga-Kama cascade of reservoirs represents relative indicators and do not provide data on the abundance, numbers and invasive communities’ single species dynamics. It does not allow providing a correct assessment of population’s state and changes in the nonindigenous species composition. In this work, changes in the abundance and species structure of the Cheboksary reservoir’s invasive fish community during 2001-2021 were estimated. The total fish count was determined on data of active fishing gears catches and precise reservoir area. Differentiation into mass, widespread and relatively numerous and locally found with a small average abundance species was noted. A decrease in the species evenness of the invasive community was recorded in consequence of the Black Sea-Caspian sprat Clupeonella cultriventris (Nordmann, 1840) and the round goby Neogobius melanostomus (Pallas, 1814) domination rise. The Black Sea-Caspian sprat and the round goby put together for 98.7% of the total number of invasive fish in the current period. Due to this two dominant species there is a tendency to increase the relative abundance of invasive fish species in the reservoir up to 561 unit/ha despite a significant decrease in the abundance of some other invaders.

High‐severity burned area and proportion exceed historic conditions in Sierra Nevada, California, and adjacent ranges

AbstractAlthough fire is a fundamental ecological process in western North American forests, climate warming and accumulating forest fuels due to fire suppression have led to wildfires that burn at high severity across larger fractions of their footprint than were historically typical. These trends have spiked upwards in recent years and are particularly pronounced in the Sierra Nevada–Southern Cascades ecoregion of California, USA, and neighboring states. We assessed annual area burned (AAB) and percentage of area burned at high and low‐to‐moderate severity for seven major forest types in this region from 1984 to 2020. We compared values for this period against estimates for the pre‐Euro‐American settlement (EAS) period prior to 1850 and against a previous study of trends from 1984 to 2009. Our results show that the total average AAB remained below pre‐EAS levels, but that gap is decreasing (i.e., ~14% of pre‐EAS for 1984–2009, but 39% for 2010–2020 [including ~150% in 2020]). Although the average AAB has remained low compared with pre‐EAS, both the average annual area burned at high severity (AAHS) and the percentage of wildfire area burned at high severity have increased rapidly. The percentage of area burned at high severity, which was already above pre‐EAS average for the 1984–2009 period, has continued to rise for five of seven forest types. Notably, between 2010 and 2020, the average AAHS exceeded the pre‐EAS average for the first time on record. By contrast, the percentage of area that burned at low‐to‐moderate severity decreased, particularly in the lower elevation oak and mixed conifer forest types. These findings underline how forests historically adapted to frequent low‐to‐moderate severity fire are being reshaped by novel proportions and extents of high‐severity burning. The shift toward a high‐severity‐dominated fire regime is associated with ecological disruptions, including changes in forest structure, species composition, carbon storage, wildlife habitat, ecosystem services, and resilience. Our results underscore the importance of finding a better balance between the current management focus on fire suppression and one that puts greater emphasis on proactive fuel reduction and increased forest resilience to climate change and ecological disturbance.

K’gari (Fraser Island) World Heritage Area: evaluating change in plant species richness and composition over two decades

Context K’gari (Fraser Island) World Heritage Area in eastern Queensland is the largest sand island in the world and is characterised by a diversity of landscapes, ecosystem types and cultural values. The biodiversity values are threatened by degradation associated with increasing visitor numbers, inappropriate fire regimes, invasive plants and animals, and climate change. Aim This study investigated changes in vegetation community attributes (species richness and composition) monitored for over two decades. Methods Twenty-two long-term vegetation monitoring sites established in 1995 were resurveyed in 2021 and analysed. Key results The sites experienced between one to five fire events in the period from 1994 to 2020. Species richness and the overall differences within regional ecosystems through time were not statistically significant at P ≤ 0.05. A comparison between observed species in the 2021 survey against a list of expected species within each regional ecosystem showed no statistically significant difference (t7 = 0.649, P = 0.268). Recently burnt sites showed the greatest degree of dissimilarity. Six invasive plant species that are known environmental weeds were recorded. Conclusion Our research suggests that most vegetation communities in K’gari are adversely affected by widespread, severe bushfire but are resilient; except for Casuarina equisetifolia subsp. incana communities on exposed frontal areas and dry peat swamps. Implications Targeted planned burning is a key management tool that aims to achieve fire regimes appropriate to the ecosystems and to mitigate risk of severe bushfires. Hence, timely implementation of the existing planned burn guidelines for the south-east Queensland Bioregion is imperative.

Developing understanding of biotic turnover

Over the last 50 years A.A. Titlyanova with her colleagues from the Laboratory of Biogeocenology in the Institute of Soil Science and Agrochemistry of the Siberian Branch of the Russian Academy of Sciences has been actively studying biotic turnover components and processes: the flow of carbon and its stocks in various ecosystem blocks were estimated, and turnover regimes revealed. The performed field experiments showed that the nearer an ecosystem is to the stationary state, the more closed its biotic turnover becomes, and the lesser role is played by abiotic processes. The studies in diverse ecosystems confirmed that climatic and weather conditions, soil properties as well as ecosystem’s relief position and exposition are the main factors driving the net primary production of grassland ecosystems. The article presents and discuss earlier results about phytomass dynamics and provides estimates of the net primary production, both above- and belowground. The belowground plant organs, i.e. roots and rhizomes, preserve life of a grassland ecosystem under any climatic conditions. Sustainability of grasslands in time depends on the changes in plant species composition, diverse survival strategies, high productivity of the dominant plant species, soil seed bank and their aeolian and water transportation from other ecosystems, rapid release of nutrients from residues by mineralization. Analysis of different successions in ecosystems allowed concluding that the number of succession types is higher than only two main types of primary and secondary succession. The primary succession refers only to those successions that occur by spontaneous revegetation at sites without any history of previous vegetation, whereas the secondary successions are more diverse and include pyrogenic (renovating succession), pasture (continuous and reversible), abandoned field successions and others. Not only the biotic turnover, but strong in- and outcoming flows of matter and energy operate in each and every ecosystem. Presently turnover can be better described as a network of diversified processes, rather than a circle per se.

Spring distribution of beetles (Coleoptera: Carabidae) in abandoned agroecosystems and surrounding forests

In most habitats in temperate zones, Carabidae show clear intra-annual changes in abundance and species composition. In the spring, we studied the beetle fauna in 5 different biotopes differing in the degree of overgrowth of the birch forest over a period of three years. According to three years of research, 10,528 specimens (64 species from 6 subfamilies) were collected. Twelve species of beetles were found in all biotopes. The highest numbers were obtained in the 12-15-year birch forest; the lowest numbers were obtained in abandoned lands. The highest biodiversity was obtained in the ecotone at the border of young birch forest and fallow lands. A high Shannon Biodiversity Index and a low Simpson Index indicate that the communities of beetles in the abandoned lands are equalized. There is a significant dominance of 1–3 species in fallow lands overgrown with birch forests.