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The scaling exponent relating the mean and variance of the density of individual organisms in space (i.e., Taylor's slope: zspace) is well studied in ecology, but the analogous scaling exponent for temporal datasets (ztime) is underdeveloped. Previous theory suggests the narrow distribution of ztime (e.g., typically 1–2) could be due to interspecific competition. Here, using 1694 communities time series, we show that ztime can exceed 2, and reaffirm how this can affect our inference about the stabilizing effect of biodiversity. We also develop a new theory, based on temporal change in the ranks of species abundances, to help account for the observed ztime distribution. Specifically, we find that communities with minimal turnover in species' rank abundances are more likely to have higher ztime. Our analysis shows how species‐level variability affects our inference about the stability of ecological communities. [ABSTRACT FROM AUTHOR]

The collection of photos during the systematic monitoring activities is useful to witness the ecological role of marine phanerogams as hosts for a rich variety of organisms in coastal and transitional waters. Cymodocea nodosa is present in the Taranto seas. In Mar Piccolo, it reached high coverage in a short amount of time, up to 100%, due to the improvement in environmental conditions. The most recent observations showed that it offers a welcoming habitat for several vertebrates and invertebrates, native and non-indigenous, as well as to micro- and macroalgae. The NPPR-funded activities will make these observations more robust and structural. [ABSTRACT FROM AUTHOR]

We measured light‐related patterns of primary productivity within a topographically complex Oregon watershed over a 30‐year period. Second‐growth conifer densities were experimentally altered in 1981. Plots receiving at least 3434 MJ m−2 over a 6‐month growing season averaged 40% greater aboveground net primary productivity (ANPP) than those receiving less light (p = 0.000). Unthinned stands potentially built enough LAI to compensate for low light, but risked mortality that exceeded resilience. The two light levels acted as basins of attraction for other physiological and ecological processes, including size–density relationships and limiting foliar nutrients. Initial (1981) LAI and the irradiation step (above or below 3434 MJ m−2) explained 60% of variation in a 30‐year ANPP. Irradiation within each light group did not affect ANPP. At high irradiation, foliar N/Ca and slope steepness (both negative) explained 58% of the variation in residuals from the initial models, while at low irradiation on north, east, and west aspects, 83% of residual variation was explained by foliar Mg (+), understory cover (+), and 30‐year mortality (−). Light use efficiency (LUE) of fully stocked stands correlated with LAI and foliar N/K. Results suggest that understory influence on tree foliar N (+ or −) enhances ANPP by regulating critical nutrient ratios. Mortality reduced or eliminated differences among thinning levels, which did not vary at low light and only between unthinned and heavily thinned at high light. Values associated with relatively open forests (biodiversity, resilience) may be attained without large sacrifice of long‐term carbon sinks. In our study, light interacts with topography to produce nonlinear dynamics in which small changes in irradiation can have large consequences. Reduced sunlight has been suggested as a geoengineering option to combat global warming. Ecological changes out of proportion to lowered irradiation are a distinct possibility, including sharp reductions in terrestrial carbon sinks. [ABSTRACT FROM AUTHOR]

Cities support abundant human and wildlife populations that are shaped indirectly and directly by human decisions, often resulting in unequal access to environmental services and accessible open spaces. Urban land cover drives biodiversity patterns across metropolitan areas, but at smaller scales that matter to local residents, neighborhood socio‐cultural factors can influence the presence and abundance of wildlife. Neighborhood income is associated with plant and animal diversity in some cities, but the influence of other social variables is less well understood, especially across desert ecosystems. We explored wildlife distribution across gradients of neighborhood ethnicity in addition to income and landscape characteristics within residential areas of metropolitan Phoenix, Arizona, USA. Utilizing data from 38 wildlife cameras deployed in public parks and undeveloped open spaces within or near suburban neighborhoods, we estimated occupancy and activity patterns of common mammal species, including species native to the Sonoran Desert (coyote [Canis latrans] and desert cottontail rabbit [Sylvilagus audubonii]), and non‐native domestic cat (Felis catus). Neighborhood ethnicity (percentage of Latino residents) appeared to exhibit a negative relationship with occupancy for coyotes and cottontail rabbits. Additionally, daily activity patterns of coyotes occurred later in the evenings and mornings in neighborhoods with higher proportions of Latino residents, but activity was unaffected by differences in neighborhood income. This study is one of the first to show that social‐ecological mechanisms associated with patterns of neighborhood ethnicity as well as income may help to shape wildlife distribution in cities. These findings have implications for equitable management and provisioning of ecosystem services for urban residents and highlight the importance of considering a range of social covariates to better understand biodiversity outcomes in urban and urbanizing areas. [ABSTRACT FROM AUTHOR]

Tracking insect biodiversity trends and predicting future trajectories is limited by a lack of monitoring data across large spatiotemporal scales. DNA metabarcoding is a time‐ and cost‐efficient method to obtain these data, but has several potential limitations in comparison to traditional morphological approaches. For example, metabarcoding may miss low‐abundance or smaller bodied individuals and is limited to presence/absence information, which may bias estimates of biodiversity and community composition. However, few comparisons of metabarcoding and morphology‐based identification have been made using insects, the by far most diverse animal taxonomic group.Here, we compared terrestrial insect communities identified via morphology versus metabarcoding across four different habitats and three seasons (late spring, mid‐summer and early autumn) during 2019. We compared identified species and community richness, composition and body size, with a focus on key taxonomic groups of bees, true bugs, butterflies and hoverflies.We identified 252 total species, with 54.8% identified by both methods, whereas 21.4% and 19.8% were solely detected with metabarcoding or morphology, respectively. Overall, total community richness, taxonomic composition and community body size were similar between methods. Metabarcoding detection successes declined in low‐abundance and smaller taxa, particularly bees, hoverflies and true bugs; however, species richness of hoverflies and butterflies tended to be higher compared with morphological identification.Our results show that metabarcoding can provide an accurate overview of insect community differences that are comparable to those determined via morphological identification. We recommend that insect monitoring programmes consider incorporating metabarcoding, although future research is needed to overcome some remaining limitations. [ABSTRACT FROM AUTHOR]

Picophytoplankton are a ubiquitous component of marine plankton communities and are expected to be favored by global increases in seawater temperature and stratification associated with climate change. Eukaryotic and prokaryotic picophytoplankton have distinct ecology, and global models predict that the two groups will respond differently to future climate scenarios. At a nearshore observatory on the Northeast US Shelf, however, decades of year‐round monitoring have shown these two groups to be highly synchronized in their responses to environmental variability. To reconcile the differences between regional and global predictions for picophytoplankton dynamics, we here investigate the picophytoplankton community across the continental shelf gradient from the nearshore observatory to the continental slope. We analyze flow cytometry data from 22 research cruises, comparing the response of picoeukaryote and Synechococcus communities to environmental variability across time and space. We find that the mechanisms controlling picophytoplankton abundance differ across taxa, season, and distance from shore. Like the prokaryote, Synechococcus, picoeukaryote division rates are limited nearshore by low temperatures in winter and spring, and higher temperatures offshore lead to an earlier spring bloom. Unlike Synechococcus, picoeukaryote concentration in summer decreases dramatically in offshore surface waters and exhibits deeper subsurface maxima. The offshore picoeukaryote community appears to be nutrient limited in the summer and subject to much greater loss rates than Synechococcus. This work both produces and demonstrates the necessity of taxon‐ and site‐specific knowledge for accurately predicting the responses of picophytoplankton to ongoing environmental change. [ABSTRACT FROM AUTHOR]

Long-term ecological research of deep Lake Mondsee covers over more than six decades of phytoplankton observation. According to our study, phytoplankton groups of various phenological traits are suitable to address the impact of two major environmental stressors: nutrient surplus by eutrophication from 1968 to 1998 and warming by climate change. Here, we focus on phytoplankton biovolume, phytoplankton assemblage structure, net changes rates, and phytoplankton biodiversity. Biweekly net change-dependent persistence of phytoplankton assemblages followed a dome-shaped relationship of observations. A short-term persistence of taxonomic traits along weeks is predominant and contributes to the structural stabilization of phytoplankton assemblages. This short-term persistence is interpreted by the benefit of lifetime adjustment of phytoplankton organisms. The long-term development phytoplankton structure is discussed as an alignment of organisms over generations. Single key taxa, as Planktothrix rubescens (De Candolle ex Gomont) Anagnostidis &Komárek 1988, which are omnipotent players in phytoplankton assemblages and occur during different environmental scenarios in the long-term, are most suitable for long-term ecological research. Our findings interpret that phytoplankton taxa are excellent organisms to track the impact of environmental constraints due to their short generation time (1), their lifetime adjustment (2), and the re-occurrence in the long-term over generations (3). [ABSTRACT FROM AUTHOR]

Abstract We measured light‐related patterns of primary productivity within a topographically complex Oregon watershed over a 30‐year period. Second‐growth conifer densities were experimentally altered in 1981. Plots receiving at least 3434 MJ m−2 over a 6‐month growing season averaged 40% greater aboveground net primary productivity (ANPP) than those receiving less light (p = 0.000). Unthinned stands potentially built enough LAI to compensate for low light, but risked mortality that exceeded resilience. The two light levels acted as basins of attraction for other physiological and ecological processes, including size–density relationships and limiting foliar nutrients. Initial (1981) LAI and the irradiation step (above or below 3434 MJ m−2) explained 60% of variation in a 30‐year ANPP. Irradiation within each light group did not affect ANPP. At high irradiation, foliar N/Ca and slope steepness (both negative) explained 58% of the variation in residuals from the initial models, while at low irradiation on north, east, and west aspects, 83% of residual variation was explained by foliar Mg (+), understory cover (+), and 30‐year mortality (−). Light use efficiency (LUE) of fully stocked stands correlated with LAI and foliar N/K. Results suggest that understory influence on tree foliar N (+ or −) enhances ANPP by regulating critical nutrient ratios. Mortality reduced or eliminated differences among thinning levels, which did not vary at low light and only between unthinned and heavily thinned at high light. Values associated with relatively open forests (biodiversity, resilience) may be attained without large sacrifice of long‐term carbon sinks. In our study, light interacts with topography to produce nonlinear dynamics in which small changes in irradiation can have large consequences. Reduced sunlight has been suggested as a geoengineering option to combat global warming. Ecological changes out of proportion to lowered irradiation are a distinct possibility, including sharp reductions in terrestrial carbon sinks.

Abstract Cities support abundant human and wildlife populations that are shaped indirectly and directly by human decisions, often resulting in unequal access to environmental services and accessible open spaces. Urban land cover drives biodiversity patterns across metropolitan areas, but at smaller scales that matter to local residents, neighborhood socio‐cultural factors can influence the presence and abundance of wildlife. Neighborhood income is associated with plant and animal diversity in some cities, but the influence of other social variables is less well understood, especially across desert ecosystems. We explored wildlife distribution across gradients of neighborhood ethnicity in addition to income and landscape characteristics within residential areas of metropolitan Phoenix, Arizona, USA. Utilizing data from 38 wildlife cameras deployed in public parks and undeveloped open spaces within or near suburban neighborhoods, we estimated occupancy and activity patterns of common mammal species, including species native to the Sonoran Desert (coyote [Canis latrans] and desert cottontail rabbit [Sylvilagus audubonii]), and non‐native domestic cat (Felis catus). Neighborhood ethnicity (percentage of Latino residents) appeared to exhibit a negative relationship with occupancy for coyotes and cottontail rabbits. Additionally, daily activity patterns of coyotes occurred later in the evenings and mornings in neighborhoods with higher proportions of Latino residents, but activity was unaffected by differences in neighborhood income. This study is one of the first to show that social‐ecological mechanisms associated with patterns of neighborhood ethnicity as well as income may help to shape wildlife distribution in cities. These findings have implications for equitable management and provisioning of ecosystem services for urban residents and highlight the importance of considering a range of social covariates to better understand biodiversity outcomes in urban and urbanizing areas.

Non‐perennial streams, which lack year‐round flow, are widespread globally. Identifying the sources of water that sustain flow in non‐perennial streams is necessary to understand their potential impacts on downstream water resources, and guide water policy and management. Here, we used water isotopes (δ18O and δ2H) and two different modeling approaches to investigate the spatiotemporal dynamics of young water fractions (Fyw) in a non‐perennial stream network at Konza Prairie (KS, USA) during the 2021 summer dry‐down season, as well as over several years with varying hydrometeorological conditions. Using a Bayesian model, we found a substantial amount of young water (Fyw: 39.1–62.6%) sustained flows in the headwaters and at the catchment outlet during the 2021 water year, while 2015–2022 young water contributions estimated using sinusoidal models indicated smaller Fyw amounts (15.3% ± 5.7). Both modeling approaches indicate young water releases are highly sensitive to hydrological conditions, with stream water shifting to older sources as the network dries. The shift in water age suggests a shift away from rapid fracture flow toward slower matrix flow that creates a sustained but localized surface water presence during late summer and is reflected in the annual dynamics of water age at the catchment outlet. The substantial proportion of young water highlights the vulnerability of non‐perennial streams to short‐term hydroclimatic change, while the late summer shift to older water reveals a sensitivity to longer‐term changes in groundwater dynamics. Combined, this suggests that local changes may propagate through non‐perennial stream networks to influence downstream water availability and quality. Plain Language Summary: Non‐perennial streams, which periodically dry, are common worldwide. Identifying the origin and age of water in non‐perennial streams will help guide water policy and management strategies. We used water isotopes (δ18O and δ2H), a common hydrologic tracer, to identify stream water sources and age during the 2021 summer dry‐down period of a non‐perennial watershed at the Konza Prairie (KS, USA) with two different statistical methods. We found that water sources and flow paths changed as the stream network dried. Approximately half of summer streamflow is young water, meaning it took less than 3 months to travel from precipitation to the stream. However, as the summer progressed, stream water shifted to older sources. We interpret this shift in the water age to indicate a shift in the source of water from rapid flow paths early in the summer to slower flow paths later in the summer, which sustain localized surface water during the driest parts of the year. Taken together, the substantial amount of young water highlights the vulnerability of non‐perennial streams to short‐term weather changes and longer‐term changes in groundwater dynamics that can alter the quantity and quality of water flowing through non‐perennial stream networks to ultimately influence downstream water availability and quality. Key Points: Stream isotopic composition was progressively enriched in δ18O and δ2H as the stream network driedStream isotopic enrichment is caused by evaporative effects and a decrease in surface water connectivityMost streamflow was young water (stored in the subsurface <3 months), with older and more variable water age as the stream network dried [ABSTRACT FROM AUTHOR]

The dynamic of the processes in an ecosystem requires long-term observations. This paper presents a specific methodology for estimating forest ecosystem characteristics as a part of the Long-Term Ecological Research (LTER) network. Permanent sample plots in Western Stara Planina in Bulgaria are determined to monitor the processes in forest ecosystems. Methods based on remotely sensed vegetation index are commented on. The main phenology's life cycle events, such as the start, peak, end, and length of the growing season, are described. Methods for phytocoenotic structure are presented: complete floristic composition, total projective coverage of horizons, and species abundance. Methods for stand growth and yield estimation, diameter calculation, basal area, volume increment, and description of tree diameter distribution are summarized. Chemical methods for deposition determination are commented on. [ABSTRACT FROM AUTHOR]

The collection of photos during the systematic monitoring activities is useful to witness the ecological role of marine phanerogams as hosts for a rich variety of organisms in coastal and transitional waters. Cymodocea nodosa is present in the Taranto seas. In Mar Piccolo, it reached high coverage in a short amount of time, up to 100%, due to the improvement in environmental conditions. The most recent observations showed that it offers a welcoming habitat for several vertebrates and invertebrates, native and non-indigenous, as well as to micro- and macroalgae. The NPPR-funded activities will make these observations more robust and structural.

Based on 40 years of meteorological data, we characterized and analysed long‐term climatic trends in the Chamela‐Cuixmala Biosphere Reserve on the Pacific coast of central Mexico. The region is still covered by a large proportion of well‐preserved tropical dry forest, characterized by a short period of rain and a dry season of around 8 months. We found a sustained temperature increase which is likely driven by global climate change. An increasing trend in rainfall was also found, but the trend was detected only during the wet season. Correspondingly, an increase in runoff during the rainfall season was also detected; this seems to be linked with an increasing number of intense rainfall events, rather than an increase in the total number of rainy days. El Niño years are likely to present below average precipitation during the wet season and above average precipitation during the dry season. The opposite is expected during La Niña years, when tropical cyclones are likely to come closer to the coast and cause intense rainfall events during the hurricane season. As many of the studied variables are likely to change under climate change scenarios, our results highlight the need to understand the expected impacts of global climate change on tropical dry forests. In particular, it is necessary to monitor changes in water availability to anticipate its consequences for the forest and the human communities that depend on it. [ABSTRACT FROM AUTHOR]

Tropical dry forests (TDF's) are seasonal ecosystems that develop under complex hydrological systems. We analyzed the hydrological processes in three micro-basins on the southern coast of the state of Jalisco, Mexico, which sustain a TDF in a state of conservation on fractured granite. Although there is available information spanning more than 40 years regarding their physical and biotic dynamics, little is known about the functioning of their groundwater. The analysis was conducted using the following methods: 1) LiDAR images and fieldwork, 2) vegetation distribution and characterization of the fractured environment; 3) automated measurements of the precipitation-runoff response; 4) numerical simulations of the soil used to study the process of infiltration towards the fractured medium, and 5) integration and synthesis of existing multidisciplinary knowledge which includes key ecosystem components constituting the physiology of the soil-plant-atmosphere continuum. The results indicate that the distribution of vegetation and its phenology follow patterns suggesting the existence of local underground flows. Furthermore, the process of infiltration through the soil is remarkably fast towards the fractured rock, resulting in base flow in the streams. Consequently, the levels of infiltration and groundwater recharge are greater than previously considered. We propose a conceptual model of groundwater movement to guide research on ecosystem hydrology in seasonal contexts and in fractured rock environments. [ABSTRACT FROM AUTHOR]

The reed belt of Lake Neusiedl, covering half the size of the lake, is subject to massive changes due to the strong decline of the water level over the last several years, especially in 2021. In this study, we investigated the spatial and temporal variations within a long-term ecosystem research (LTER) site in a reed ecosystem at Lake Neusiedl in Austria under intense drought conditions. Spatio-temporal data sets from May to November 2021 were produced to analyze and detect changes in the wetland ecosystem over a single vegetation period. High-resolution orthomosaics processed from RGB imagery taken with an unmanned aerial vehicle (UAV) served as the basis for land cover classification and phenological analysis. An image annotation workflow was developed, and deep learning techniques using semantic image segmentation were applied to map land cover changes. The trained models delivered highly favorable results in terms of the assessed performance metrics. When considering the region between their minima and maxima, the water surface area decreased by 26.9%, the sediment area increased by 23.1%, and the vegetation area increased successively by 10.1% over the investigation period. Phenocam data for lateral phenological monitoring of the vegetation development of Phragmites australis was directly compared with phenological analysis from aerial imagery. This study reveals the enormous dynamics of the reed ecosystem of Lake Neusiedl, and additionally confirms the importance of remote sensing via drone and the strengths of deep learning for wetland classification. [ABSTRACT FROM AUTHOR]

In order to investigate how familial biodiversity structures forests in the critically important Amazon, I combined past plot samplings to investigate the contributions of tree families in those samplings to the structure of common Amazon forest types. I found that the families Arecaceae, Fabaceae, Clusiaceae, and Malvaceae had the most stems; Staphyleaceae, Caricaceae, and Anacardiaceae had the largest stems; Arecaceae, Fabaceae, Lecythidaceae, and Malvaceae had the largest basal area; Fabaceae, Malvaceae, and Sapotaceae had the most genera; Annonaceae, Euphorbiaceae, Fabaceae, Lauraceae, Malvaceae, Moraceae, and Sapotaceae had the most species, and the maximum Fisher’s α diversity index was found for many families. Together, results suggest that Fabaceae and Malvaceae are the most important families structuring these forests, but also that Arecaceae and Sapotaceae may be important. Thus, conservationists and managers may help sustain structure in these forests by propagating and maintaining species in these families. Finally, correlations between total number of stems and basal area, and between total number of genera and total number of species, suggest a causal relationship between them as they structure these forests, but the lack of correlations with Fisher’s α suggest it has little structural utility for these forests.

Abstract Long-term-ecological-research (LTER) faces many challenges, including the difficulty of obtaining long-term funding, changes in research questions and sampling designs, keeping researchers collecting standardized data for many years, impediments to interactions with local people, and the difficulty of integrating the needs of local decision makers with “big science”. These issues result in a lack of universally accepted guidelines as to how research should be done and integrated among LTER sites. Here we discuss how the RAPELD (standardized field infrastructure system), can help deal with these issues as a complementary technique in LTER studies, allowing comparisons across landscapes and ecosystems and reducing sampling costs. RAPELD uses local surveys to understand broad spatial and temporal patterns while enhancing decision-making and training of researchers, local indigenous groups and traditional communities. Sampling of ecological data can be carried out by different researchers through standardized protocols, resulting in spatial data that can be used to answer temporal questions, and allow new questions to be investigated. Results can also be integrated into existing biodiversity networks. Integrated systems are the most efficient way to save resources, maximize results, and accumulate information that can be used in the face of the unknown unknowns upon which our future depends.

Land-use change is highly dynamic globally and there is great uncertainty about the effects of land-use legacies on contemporary environmental performance. We used a chronosequence of urban grasslands (lawns) that were converted from agricultural and forested lands from 10 to over 130 years prior to determine if land-use legacy influences components of soil biodiversity and composition over time. We used historical aerial imagery to identify sites in Baltimore County, MD (USA) with agricultural versus forest land-use history. Soil samples were taken from these sites as well as from existing well-studied agricultural and forest sites used as historical references by the National Science Foundation Long-Term Ecological Research Baltimore Ecosystem Study program. We found that the microbiomes in lawns of agricultural origin were similar to those in agricultural reference sites, which suggests that the ecological parameters on lawns and reference agricultural systems are similar in how they influence soil microbial community dynamics. In contrast, lawns that were previously forest showed distinct shifts in soil bacterial composition upon recent conversion but reverted back in composition similar to forest soils as the lawns aged over decades. Soil fungal communities shifted after forested land was converted to lawns, but unlike bacterial communities, did not revert in composition over time. Our results show that components of bacterial biodiversity and composition are resistant to change in previously forested lawns despite urbanization processes. Therefore land-use legacy, depending on the prior use, is an important factor to consider when examining urban ecological homogenization. [ABSTRACT FROM AUTHOR]

Long‐term ecological research has revealed the impact of climate on marine ecosystems at multiple time scales. Changes in the pelagic system have been detected at the LTER‐MC site in the Gulf of Naples (Tyrrhenian Sea, western Mediterranean) since 1984. Here we analyzed the time series to determine whether zooplankton had significantly changed over the three decades 1984–2015. In addition to the seasonal cycle as the main mode of temporal variability, we observed long‐term trends in the functional groups and species. Copepods, the most abundant group, declined over the years owing to a decrease in the abundance of Acartia clausi, Centropages typicus, the Paracalanus parvus complex, and Oithona spp. Increasing trends were observed for strict carnivores (chaetognaths) and typical filter feeders (cladocerans, appendicularians, and thaliaceans); the latter may be linked to a higher density of <5 μm phytoplankton. Two main temporal shifts were detected: (i) in 1985–87, similarly to the regime shifts registered in other basins of the Northern Hemisphere, and (ii) after 2011, likely related to local atmospheric forcing. The disappearance or decrease in some neritic copepods and the increased abundance of typical offshore species seem to reflect the enhanced influence of the open Tyrrhenian waters at the sampling site. Despite these changes, no significant trends were detected in the total zooplankton abundance and overall composition, which indicates restructuring within the whole community. These results underline the need to examine the entire zooplankton diversity spectrum and improve our knowledge of their ecological traits to detect and interpret long‐term variability. [ABSTRACT FROM AUTHOR]

Coastal phytoplankton present remarkable variability because of complex patterns and relationships of hydrological parameters at the land–sea interface. We analysed a time series of 917 phytoplankton samples collected in the period 1984–2010 at the coastal station LTER‐MC (Gulf of Naples, Mediterranean Sea) with the aims of determining: (i) whether recurrent species associations are recognizable in this variable coastal environment; (ii) what are their composition and seasonal patterns; (iii) what are the environmental variables driving their distributions, and (iv) to what extent those associations are functionally homogeneous. Using a cluster analysis of a dataset of the 87 more frequent and abundant species in the samples, we identified seven main groups of species. Five of them were recurrent over the years in the same seasons, while two other groups showed a bimodal occurrence or no clear seasonality, respectively. Differences in the occurrence of those assemblages were primarily associated with the season (i.e., temperature), and the coastal nature of the site (mainly salinity). Except for the winter cluster, which included mostly coccolithophores and silicoflagellates, diatoms were present in all associations, along with species belonging to diverse phylogenetic groups. The diversity of morphological features defining ecological traits varied across the different associations, with a maximum divergence in the spring association and a minimum in winter. We conclude that the stability of the associations is related to the marked phenological recurrence of their individual species and their overlap in specific periods of the year, while convergent or divergent trait compositions in the different associations indicate a variable strength of the environmental filtering across the seasonal succession. [ABSTRACT FROM AUTHOR]

The presence of phytoplankton parasites along the water column was explored at the Long‐Term Ecological Station MareChiara (LTER‐MC) in the Gulf of Naples (Mediterranean Sea) in October 2019. Microscopy analyses showed diatoms dominating the phytoplankton community in the upper layers (0–20 m). Metabarcoding data from the water column showed the presence of Chytridiomycota predominantly in the upper layers coinciding with the vertical distribution of diatoms. Laboratory incubations of natural samples enriched with different diatom cultures confirmed parasitic interactions of some of those chytrids—including members of Kappamyces—with diatom taxa. The temporal dynamics of diatoms and chytrids was also explored in a 3‐year metabarcoding time‐series (2011–2013) from surface waters of the study area and in sediment samples. Chytrids were recurrently present at low relative abundances, and some taxa found to infect diatoms in the incubation experiments were also identified in the ASV time‐series. However, co‐occurrence analyses did not show any clear or recurrent pairing patterns for chytrid and diatom taxa along the 3 years. The chytrid community in the sediments showed a clearly different species composition compared with that recorded in the water column samples, with higher diversity and relative abundance. The combination of observations, incubations, and metabarcoding confirmed that parasites are a common component of marine protist communities at LTER‐MC. Host–parasite interactions must be determined and quantified to understand their role and the impact they have on phytoplankton dynamics. [ABSTRACT FROM AUTHOR]

In order to investigate how familial biodiversity structures forests in the critically important Amazon, I combined past plot samplings to investigate the contributions of tree families in those samplings to the structure of common Amazon forest types. I found that the families Arecaceae, Fabaceae, Clusiaceae, and Malvaceae had the most stems; Staphyleaceae, Caricaceae, and Anacardiaceae had the largest stems; Arecaceae, Fabaceae, Lecythidaceae, and Malvaceae had the largest basal area; Fabaceae, Malvaceae, and Sapotaceae had the most genera; Annonaceae, Euphorbiaceae, Fabaceae, Lauraceae, Malvaceae, Moraceae, and Sapotaceae had the most species, and the maximum Fisher’s α diversity index was found for many families. Together, results suggest that Fabaceae and Malvaceae are the most important families structuring these forests, but also that Arecaceae and Sapotaceae may be important. Thus, conservationists and managers may help sustain structure in these forests by propagating and maintaining species in these families. Finally, correlations between total number of stems and basal area, and between total number of genera and total number of species, suggest a causal relationship between them as they structure these forests, but the lack of correlations with Fisher’s α suggest it has little structural utility for these forests. [ABSTRACT FROM AUTHOR]

Enhancing understanding of community assembly rules hinges on shared conceptualizations that operate across scales and levels of ecological organization. Knowledge of the biogeography of life‐history strategies is especially limited but crucial for building fundamental information on the relationships between trait diversity and species richness.The goals of this study were to (i) demonstrate how life histories can be classified using a previously identified triangular continuum of evolutionary trade‐offs; (ii) test whether spatial and temporal heterogeneity in species abundances is linked to life‐history strategy; (iii) compare species‐area relationships across the primary life‐history strategist groups and (iv) explore how species life‐history niche spaces are shaped by ecosystem size and landscape architecture.Fish communities were sampled in 40 lakes that varied widely in volume; 11 lakes were sampled annually for 28 or 42 years. Seventy‐one species were classified as equilibrium, periodic or opportunistic strategists, and species‐area curves were quantified and compared among strategy types.As predicted by life‐history theory, relative abundances of opportunistic strategists were extremely variable over space and time, whereas abundances of equilibrium and periodic strategists were more stable. Small lakes were often dominated by only one species, usually an opportunistic strategist. Species richness increased with ecosystem size, but larger ecosystems were increasingly inhabited by equilibrium, and then, periodic strategists. Richness of periodic species increased with ecosystem size at a faster rate compared with opportunistic species showing that colonization‐extinction points fundamentally vary by strategy. Similarly, life‐history niche space increased with ecosystem size in accord with species‐area relationships but showed saturation behaviour. Niche space became increasingly crowded in large lakes, particularly in lakes with higher hydrologic connectance.Ecosystem size mediates the assembly of communities through effects on environmental stability, hydrology and life‐history filtering. This finding provides novel insights into community assembly at multiple scales and has broad conservation applications. Because ecosystem size filters towards orthogonal and inverse life histories, conservation actions (e.g. fish stockings) that do not consider life‐history and community filtering rules will probably fail. [ABSTRACT FROM AUTHOR]

The snowbed habitats represent a relevant component of the alpine tundra biome, developing in areas characterized by a long-lasting snow cover. Such areas are particularly sensitive to climate changes, because small variations in air temperature, rain, and snowfall may considerably affect the pedoclimate and plant phenology, which control the soil C and N cycling. Therefore, it is fundamental to identify the most sensitive abiotic and biotic variables affecting soil nutrient cycling. This work was performed at seven permanent snowbed sites belonging to Salicetum herbaceae vegetation community in the northwestern Italian Alps, at elevations between 2,686 and 2,840 m.a.s.l. During a four-year study, we investigated climate, pedoclimate, floristic composition, phenology, and soil C and N dynamics. We found that lower soil water content and earlier melt-out day decreased soil N-NH4+, N-NO3−, dissolved organic carbon (DOC), dissolved organic nitrogen (DON), total dissolved nitrogen (TDN), microbial nitrogen (Nmicr), microbial carbon (Cmicr), and C:Nmicr ratio. The progression of the phenological stages of Salix herbacea reduced soil N-NH4+ and increased DOC. Our results showed that the snow melt-out day, soil temperature, soil water content, and plant phenological stages were the most important factors affecting soil biogeochemical cycles, and they should be taken into account when assessing the effects of climate change in alpine tundra ecosystems, in the framework of long-term ecological research.

Premise: Anthropogenic nitrogen (N) addition alters the abiotic and biotic environment, potentially leading to changes in patterns of natural selection (i.e., trait–fitness relationships) and the opportunity for selection (i.e., variance in relative fitness). Because N addition favors species with light acquisition strategies (e.g., tall species), we predicted that N would strengthen selection favoring those same traits. We also predicted that N could alter the opportunity for selection via its effects on mean fitness and/or competitive asymmetries. Methods: We quantified the strength of selection and the opportunity for selection in replicated populations of the annual grass Setaria faberi (giant foxtail) growing in a long‐term N addition experiment. We also correlated these population‐level parameters with community‐level metrics to identify the proximate causes of N‐mediated evolutionary effects. Results: N addition increased aboveground productivity, light asymmetry, and reduced species diversity. Contrary to expectations, N addition did not strengthen selection for trait values associated with higher light acquisition such as greater height and specific leaf area (SLA); rather, it strengthened selection favoring lower SLA. Light asymmetry and species diversity were associated with selection for height and SLA, suggesting a role for these factors in driving N‐mediated selection. The opportunity for selection was not influenced by N addition but was negatively associated with species diversity. Conclusions: Our results indicate that anthropogenic N enrichment can affect evolutionary processes, but that evolutionary changes in plant traits within populations are unlikely to parallel the shifts in plant traits observed at the community level. [ABSTRACT FROM AUTHOR]

Protected areas (PAs) are a widely recognized tool for biodiversity and ecosystem conservation. However, megadiverse countries struggle to manage, maintain, and expand PAs as they face mounting human pressures. The Brazilian Cerrado biome (a biodiversity hotspot) is experiencing increasing land-use changes paired with a loss of natural vegetation, and only 3.2% of its land area is under strict protections. The Brazilian Long-Term Ecological Research Program (LTER) was created in 1997 to monitor long-term changes in protected and non-protected areas in Brazilian biomes. The Environmental Protected Area of the Gama and Cabeça de Veado (AGCV) watersheds in Central Brazil's core distribution of the Cerrado (Brasília, Federal District), was one of the first sites to participate in the Brazilian LTER. The main goal of the AGCV-LTER site is to monitor long-term changes and ecological processes in aquatic and terrestrial ecosystems in PAs that are surrounded by landscapes facing extreme ecosystem shifts. Over 22 years, we investigated the effects of drivers such as fire, noise and light pollution, eutrophication, and biological invasions on aquatic (invertebrates and water quality) and terrestrial ecosystems (vegetation, vertebrates, and invertebrates). The results indicate that even within a PA, changes in the surrounding landscape affects biodiversity and ecosystem functions, revealing the essential nature of continuous monitoring for biodiversity conservation.

The reed belt of Lake Neusiedl, covering half the size of the lake, is subject to massive changes due to the strong decline of the water level over the last several years, especially in 2021. In this study, we investigated the spatial and temporal variations within a long-term ecosystem research (LTER) site in a reed ecosystem at Lake Neusiedl in Austria under intense drought conditions. Spatio-temporal data sets from May to November 2021 were produced to analyze and detect changes in the wetland ecosystem over a single vegetation period. High-resolution orthomosaics processed from RGB imagery taken with an unmanned aerial vehicle (UAV) served as the basis for land cover classification and phenological analysis. An image annotation workflow was developed, and deep learning techniques using semantic image segmentation were applied to map land cover changes. The trained models delivered highly favorable results in terms of the assessed performance metrics. When considering the region between their minima and maxima, the water surface area decreased by 26.9%, the sediment area increased by 23.1%, and the vegetation area increased successively by 10.1% over the investigation period. Phenocam data for lateral phenological monitoring of the vegetation development of Phragmites australis was directly compared with phenological analysis from aerial imagery. This study reveals the enormous dynamics of the reed ecosystem of Lake Neusiedl, and additionally confirms the importance of remote sensing via drone and the strengths of deep learning for wetland classification.

Lake Maggiore is a site of the Long-Term Ecosystem Research (LTER) network, belonging to the deep subalpine Lake District in Northern Italy. Studies on the physical, chemical, and biological features of the lake have been performed continuously since the 1980s. The lake recovered from eutrophication reaching the present oligotrophic condition. In the last decade, climate change represents the main driving factor for the long-term evolution of the lake, affecting its hydrodynamics, nutrient status, and biological communities. In 2020 a high-frequency monitoring (HFM) system was deployed, with the aim to integrate long-term monitoring based on discrete sampling and analysis. The system consists of a buoy equipped with sensors for limnological variables and algal pigments. The high-frequency monitoring program is part of a cross-border project between Italy and Switzerland focusing on lake quality monitoring as a critical input for successful lake management. In this paper we focus on Chlorophyll-a data, with the aim to test whether in-situ fluorescence measurements may provide a reliable estimate of lake phytoplankton biovolume and its seasonal dynamic. Sensor’s performance was regularly tested comparing chlorophyll-a data taken by the in-situ fluorescent sensors (Cyclops7, Turner Design), data from laboratory fluorescence analysis (FluoroProbe, BBE Moldaenke), values obtained from chlorophyll-a analysis by UV-VIS spectrophotometry and data from phytoplankton microscopy analysis. We found a general good agreement between the Chlorophyll-a data obtained with the different methods, confirming the use of in-situ sensors as a reliable approach to measure algal pigments, especially to assess their variability in the short-term, but also to describe the seasonal pattern of phytoplankton biovolume. However, phytoplankton community composition played a substantial role in the performance of the different methods and in the reliability of in-situ data as a tool to assess algal biovolume. This study demonstrates that high-frequency monitoring (HFM), used in conjunction with discrete chemical and biological monitoring, represents an important advance and support in the long-term monitoring of freshwaters and is a useful tool to detect ecological changes. Regular checking and validation of the sensor readings through laboratory analyses are important to get trustworthy data.

Previous studies have evaluated how changes in atmospheric nitrogen (N) inputs and climate affect stream N concentrations and fluxes, but none have synthesized data from sites around the globe. We identified variables controlling stream inorganic N concentrations and fluxes, and how they have changed, by synthesizing 20 time series ranging from 5 to 51 years of data collected from forest and grassland dominated watersheds across Europe, North America, and East Asia and across four climate types (tropical, temperate, Mediterranean, and boreal) using the International Long-Term Ecological Research Network. We hypothesized that sites with greater atmospheric N deposition have greater stream N export rates, but that climate has taken a stronger role as atmospheric deposition declines in many regions of the globe. We found declining trends in bulk ammonium and nitrate deposition, especially in the longest time-series, with ammonium contributing relatively more to atmospheric N deposition over time. Among sites, there were statistically significant positive relationships between (1) annual rates of precipitation and stream ammonium and nitrate fluxes and (2) annual rates of atmospheric N inputs and stream nitrate concentrations and fluxes. There were no significant relationships between air temperature and stream N export. Our long-term data shows that although N deposition is declining over time, atmospheric N inputs and precipitation remain important predictors for inorganic N exported from forested and grassland watersheds. Overall, we also demonstrate that long-term monitoring provides understanding of ecosystems and biogeochemical cycling that would not be possible with short-term studies alone. [ABSTRACT FROM AUTHOR]

Methane and carbon dioxide effluxes from aquatic systems in the Arctic will affect and likely amplify global change. As permafrost thaws in a warming world, more dissolved organic carbon (DOC) and greenhouse gases are produced and move from soils to surface waters where the DOC can be oxidized to CO2 and also released to the atmosphere. Our main study objective is to measure the release of carbon to the atmosphere via effluxes of methane (CH4) and carbon dioxide (CO2) from Toolik Lake, a deep, dimictic, low-arctic lake in northern Alaska. By combining direct eddy covariance flux measurements with continuous gas pressure measurements in the lake surface waters, we quantified the k600 piston velocity that controls gas flux across the air–water interface. Our measured k values for CH4 and CO2 were substantially above predictions from several models at low to moderate wind speeds, and only converged on model predictions at the highest wind speeds. We attribute this higher flux at low wind speeds to effects on water-side turbulence resulting from how the surrounding tundra vegetation and topography increase atmospheric turbulence considerably in this lake, above the level observed over large ocean surfaces. We combine this process-level understanding of gas exchange with the trends of a climate-relevant long-term (30 + years) meteorological data set at Toolik Lake to examine short-term variations (2015 ice-free season) and interannual variability (2010–2015 ice-free seasons) of CH4 and CO2 fluxes. We argue that the biological processing of DOC substrate that becomes available for decomposition as the tundra soil warms is important for understanding future trends in aquatic gas fluxes, whereas the variability and long-term trends of the physical and meteorological variables primarily affect the timing of when higher or lower than average fluxes are observed. We see no evidence suggesting that a tipping point will be reached soon to change the status of the aquatic system from gas source to sink. We estimate that changes in CH4 and CO2 fluxes will be constrained with a range of +30% and −10% of their current values over the next 30 years.

Whether and how alpine organismic communities respond to ongoing environmental changes is difficult to assess quantitatively, given their intrinsically slow responses, remote locations and limited data. Here we provide a synthesis of the first five years of a multidisciplinary, highly standardized, long-term monitoring programme of terrestrial and aquatic ecosystems in the Austrian Hohe Tauern National Park and companion sites in northern Italy and the central Swiss Alps. The programme aims at evidencing the ecological state and trends in largely late-successional, high-elevation ecosystems. We present the conceptual framework, the study design and first results. Replicated over five regions, different sites and a multitude of permanent plots, the abiotic (microclimate, physics and chemistry of soils and water bodies), biodiversity (plants, animals, microbes), and productivity data (alpine grassland, lakes, streams) provide a representative reference for future re-assessments. The wide spectrum of biological baseline data presented and their spatial and temporal variation also illustrate the degree of uncertainty associated with smaller-scale and short-term studies and the role of stochasticity in long-term biological monitoring. [ABSTRACT FROM AUTHOR]

Dissolved organic carbon (DOC) is a key variable impacting stream biogeochemical processes. The relationship between DOC concentration (C) and stream discharge (q) can elucidate spatial and temporal DOC source dynamics in watersheds. In the ephemeral glacial meltwater streams of the McMurdo Dry Valleys (MDV), Antarctica, the C‐q relationship has been applied to dissolved inorganic nitrogen and weathering solutes including silica, which all exhibit chemostatic C‐q behavior; but DOC‐q dynamics have not been studied. DOC concentrations here are low compared to temperate streams, in the range of 0.1–2 mg C l−1, and their chemical signal clearly indicates derivation from microbial biomass (benthic mats and hyporheic biofilm). To investigate whether the DOC generation rate from these autochthonous organic matter pools was sufficient to maintain chemostasis for DOC, despite these streams' large diel and interannual fluctuations in discharge, we fit the long‐term DOC‐q data to a power law and an advection‐reaction model. Model outputs and coefficients of variation characterize the DOC‐q relationship as chemostatic for several MDV streams. We propose a conceptual model in which hyporheic carbon storage, hyporheic exchange rates, and net DOC generation rates are key interacting components that enable chemostatic DOC‐q behavior in MDV streams. This model clarifies the role of autochthonous carbon stores in maintaining DOC chemostasis and may be useful for examining these relationships in temperate systems, which typically have larger sources of bioavailable autochthonous organic carbon than MDV streams but where this autochthonous signal could be masked by a stronger allochthonous contribution. Plain Language Summary: This study assesses the relationship between instream dissolved organic carbon (DOC) concentrations and streamflow in the McMurdo Dry Valleys, Antarctica (MDV). DOC comes from the breakdown of organic matter (e.g., plants, microbes). In temperate streams, DOC mostly comes from plants and soil outside of the stream; this is not the case in the MDV, where most DOC comes from inside the stream. There are no vascular plants, but some MDV streams host abundant microbial mats ‐ like a shag carpet on the streambed. Organic material from these mats is stored in the underlying streambed sediments, which are saturated with stream water. MDV streamflow is derived entirely from glacial melt in summer and varies on a daily and interannual basis. We used two different models to evaluate whether and how DOC changed with changing streamflow. Both models indicated that stream DOC concentrations are relatively stable (0.1–2 mg l−1) over large changes in streamflow (1–1,000 l s−1). We conclude that the streambed storage zone is key to maintaining DOC concentrations across all streamflow conditions. We present a conceptual model that may also provide insight into the role that streambeds play in contributing DOC to streams in non‐polar environments. Key Points: Although dissolved organic carbon (DOC) concentrations in McMurdo Dry Valleys streams are very low, DOC‐flow relationships are chemostaticTerrestrial vegetation does not influence DOC levels in Dry Valleys streams, unlike other systems where terrestrial inputs often dominateBiogeochemical processes in microbial mats and the hyporheic zone support DOC chemostasis in Dry Valleys streams [ABSTRACT FROM AUTHOR]

Given the large and increasing amount of urban, suburban, and exurban land use on Earth, there is a need to accurately assess net primary productivity (NPP) of urban ecosystems. However, the heterogeneous and dynamic urban mosaic presents challenges to the measurement of NPP, creating landscapes that may appear more similar to a savanna than to the native landscape replaced. Studies of urban biomass have tended to focus on one type of vegetation (e.g., lawns or trees). Yet a focus on the ecology of the city should include the entire urban ecosystem rather than the separate investigation of its parts. Furthermore, few studies have attempted to measure urban aboveground NPP (ANPP) using field‐based methods. Most studies project growth rates from measurements of tree diameter to estimate annual ANPP or use remote sensing approaches. In addition, field‐based methods for measuring NPP do not address any special considerations for adapting such field methods to urban landscapes. Frequent planting and partial or complete removal of herbaceous and woody plants can make it difficult to accurately quantify increments and losses of plant biomass throughout an urban landscape. In this study, we review how ANPP of urban landscapes can be estimated based on field measurements, highlighting the challenges specific to urban areas. We then estimated ANPP of woody and herbaceous vegetation over a 15‐year period for Baltimore, MD, USA using a combination of plot‐based field data and published values from the literature. Baltimore's citywide ANPP was estimated to be 355.8 g m−2, a result that we then put into context through comparison with other North American Long‐Term Ecological Research (LTER) sites and mean annual precipitation. We found our estimate of Baltimore citywide ANPP to be only approximately half as much (or less) than ANPP at forested LTER sites of the eastern United States, and more comparable to grassland, oldfield, desert, or boreal forest ANPP. We also found that Baltimore had low productivity for its level of precipitation. We conclude with a discussion of the significance of accurate assessment of primary productivity of urban ecosystems and critical future research needs. [ABSTRACT FROM AUTHOR]

The McMurdo Dry Valleys (MDVs; 77.50°S, 162.25°E) make up the largest ice‐free region of Antarctica at ~3500 km2. Their position near the coast of the Ross Sea provides for a milder climate than much of the rest of the continent. Alpine and piedmont glaciers in the MDVs melt during the austral summer providing water to down gradient streams and terminal lakes on valley floors. There are currently 14 meteorological stations and 17 stream gauges operating across the MDVs, some with continuous records that go back to 1969. This relatively high density of monitoring stations reflects the fact that glaciers of different sizes and elevation ranges are the main source of water to streams. Thus, each glacier represents a different watershed. The bulk of these records start in the late 1980s/early 1990s. These data collection activities directly support research endeavours of the McMurdo Dry Valleys Long Term Ecological Research project, as well as a host of other science groups working in the MDVs. As such, both real time data and archived data from these sites is available through the online database interface of the project (http://mcmlter.org). [ABSTRACT FROM AUTHOR]

Long-range transport of atmospheric pollutants threatens the pristine high-elevation environments, highly sensitive to environmental changes such as the global increase of nitrogen (N) emissions. Atmospheric depositions is an important component of N cycle transferring reactive nitrogen species from the atmosphere to terrestrial and aquatic compartments. Despite this, monitoring of atmospheric deposition in Alpine tundra regions is lacking. To reduce this gap, we present the chemical and isotopic composition (δ 15N, δ 18O in nitrate) of rain and snow deposition collected over a 3-year period (2018–2020) in a LTER site (A. Mosso Scientific Institute) in NW Italian Alps at 2901 m a.s.l. The highest annual volume-weighted mean (VWM) concentrations of oxidized and reduced N species (18 and 22 μeq L−1, respectively) occurred in summer, while the lowest (5.8 and 3.6 μeq L−1, respectively) occurred during the snow season. The N wet deposition load (3.9 kg ha−1 y−1.) greatly exceeded the N critical threshold, revealing that the area is exposed to excessive N input through atmospheric deposition with potentially detrimental consequences for aquatic ecosystems. The contribution of rain to inorganic N varied between 39 and 68 %, highlighting the importance of monitoring the composition of the rain component, in addition to the snowpack, even at high-altitude sites. The nitrate isotopic composition of wet deposition showed seasonal variation with lower δ15N–NO 3 values (−10.6 ‰ to −2.2 ‰) in the summer months, reflecting the influence of vehicle emissions likely combined with an increase in emissions from agricultural sources, when the air masses originate from the Po Valley. Surface meteorological data coupled to the analysis of stable isotopes and air mass back trajectories showed that local mountain-valley breeze and the elevation of the continuous aerosol layer altitude in the warm season expose the study site to N-air pollutants originating from lowland and more distant anthropized areas (e.g., Po Valley). The reported data suite represents, to date, the first documentation for ecosystems above the tree line in the European scenario. [Display omitted] • The concentration of N species was higher in rain than in snow deposition. • The proportional contribution of rain to the total N deposition load was ∼50%. • N load exceeded the critical threshold for sensitive high-elevation ecosystems. • Thermally driven winds expose the Alps to polluted air masses from the Po Valley. • An increased influence of vehicle and agriculture emission sources in summer was found. [ABSTRACT FROM AUTHOR]

The period of disrupted human activity caused by the COVID‐19 pandemic, coined the "anthropause," altered the nature of interactions between humans and ecosystems. It is uncertain how the anthropause has changed ecosystem states, functions, and feedback to human systems through shifts in ecosystem services. Here, we used an existing disturbance framework to propose new investigation pathways for coordinated studies of distributed, long‐term social‐ecological research to capture effects of the anthropause. Although it is still too early to comprehensively evaluate effects due to pandemic‐related delays in data availability and ecological response lags, we detail three case studies that show how long‐term data can be used to document and interpret changes in air and water quality and wildlife populations and behavior coinciding with the anthropause. These early findings may guide interpretations of effects of the anthropause as it interacts with other ongoing environmental changes in the future, particularly highlighting the importance of long‐term data in separating disturbance impacts from natural variation and long‐term trends. Effects of this global disturbance have local to global effects on ecosystems with feedback to social systems that may be detectable at spatial scales captured by nationally to globally distributed research networks. [ABSTRACT FROM AUTHOR]

Among the many concerns for biodiversity in the Anthropocene, recent reports of flying insect loss are particularly alarming, given their importance as pollinators, pest control agents, and as a food source. Few insect monitoring programmes cover the large spatial scales required to provide more generalizable estimates of insect responses to global change drivers.We ask how climate and surrounding habitat affect flying insect biomass using data from the first year of a new monitoring network at 84 locations across Germany comprising a spatial gradient of land cover types from protected to urban and crop areas.Flying insect biomass increased linearly with temperature across Germany. However, the effect of temperature on flying insect biomass flipped to negative in the hot months of June and July when local temperatures most exceeded long‐term averages.Land cover explained little variation in insect biomass, but biomass was lowest in forests. Grasslands, pastures, and orchards harboured the highest insect biomass. The date of peak biomass was primarily driven by surrounding land cover, with grasslands especially having earlier insect biomass phenologies.Standardised, large‐scale monitoring provides key insights into the underlying processes of insect decline and is pivotal for the development of climate‐adapted strategies to promote insect diversity. In a temperate climate region, we find that the positive effects of temperature on flying insect biomass diminish in a German summer at locations where temperatures most exceeded long‐term averages. Our results highlight the importance of local adaptation in climate change‐driven impacts on insect communities. [ABSTRACT FROM AUTHOR]

Ecologists search for rules by which traits dictate the abundance and distribution of species. Here we search for rules that apply across three common taxa of litter invertebrates in six North American forests from Panama to Oregon. We use image analysis to quantify the abundance and body size distributions of mites, springtails, and spiders in 21 1‐m2 plots per forest. We contrast three hypotheses: two of which focus on trait–abundance relationships and a third linking abundance to species richness. Despite three orders of magnitude variation in size, the predicted negative relationship between mean body size and abundance per area occurred in only 18% of cases, never for large bodied taxa like spiders. We likewise found only 18% of tests supported our prediction that increasing litter depth allows for high abundance; two‐thirds of which occurred at a single deciduous forest in Massachusetts. In contrast, invertebrate abundance constrained species richness 76% of the time. Our results suggest that body size and habitat volume in brown food webs are rarely good predictors of variation in abundance, but that variation in diversity is generally well predicted by abundance. [ABSTRACT FROM AUTHOR]

Abstract The period of disrupted human activity caused by the COVID‐19 pandemic, coined the “anthropause,” altered the nature of interactions between humans and ecosystems. It is uncertain how the anthropause has changed ecosystem states, functions, and feedback to human systems through shifts in ecosystem services. Here, we used an existing disturbance framework to propose new investigation pathways for coordinated studies of distributed, long‐term social‐ecological research to capture effects of the anthropause. Although it is still too early to comprehensively evaluate effects due to pandemic‐related delays in data availability and ecological response lags, we detail three case studies that show how long‐term data can be used to document and interpret changes in air and water quality and wildlife populations and behavior coinciding with the anthropause. These early findings may guide interpretations of effects of the anthropause as it interacts with other ongoing environmental changes in the future, particularly highlighting the importance of long‐term data in separating disturbance impacts from natural variation and long‐term trends. Effects of this global disturbance have local to global effects on ecosystems with feedback to social systems that may be detectable at spatial scales captured by nationally to globally distributed research networks.

The snowbed habitats represent a relevant component of the alpine tundra biome, developing in areas characterized by a long-lasting snow cover. Such areas are particularly sensitive to climate changes, because small variations in air temperature, rain, and snowfall may considerably affect the pedoclimate and plant phenology, which control the soil C and N cycling. Therefore, it is fundamental to identify the most sensitive abiotic and biotic variables affecting soil nutrient cycling. This work was performed at seven permanent snowbed sites belonging to Salicetum herbaceae vegetation community in the northwestern Italian Alps, at elevations between 2,686 and 2,840 m.a.s.l. During a four-year study, we investigated climate, pedoclimate, floristic composition, phenology, and soil C and N dynamics. We found that lower soil water content and earlier melt-out day decreased soil N-NH4 +, N-NO3 -, dissolved organic carbon (DOC), dissolved organic nitrogen (DON), total dissolved nitrogen (TDN), microbial nitrogen (Nmicr), microbial carbon (Cmicr), and C:Nmicr ratio. The progression of the phenological stages of Salix herbacea reduced soil N-NH4 + and increased DOC. Our results showed that the snow melt-out day, soil temperature, soil water content, and plant phenological stages were the most important factors affecting soil biogeochemical cycles, and they should be taken into account when assessing the effects of climate change in alpine tundra ecosystems, in the framework of long-term ecological research. [ABSTRACT FROM AUTHOR]

In order to synthesize changes in pollinating insect communities across space and time, it is necessary to understand whether, and how, sampling methods influence assessments of community patterns. We compared how two common sampling methods—yellow combined flight traps and net sampling—influence our understanding of the species richness, abundance and composition of wild bees and hoverflies, and addressed whether these patterns resulted from potentially biased sampling of individuals or species with different types of functional traits. We sampled bee and hoverfly communities in six sites over three seasons in Saxony-Anhalt, Germany. We captured more species and individuals of bees with traps and more species and individuals of hoverflies with net sampling. However, rarefied richness results were less dramatic between the sampling methods for bees and were not different between the sampling methods for hoverflies. Thus, differences in species richness across sampling methods were mostly due to differences in the number of individuals captured in the different methods. We captured more small-sized bees and hoverflies with traps. We tested if the different methods collected individuals and species with different functional traits, such as nesting preferences, sociality and flower specialization for bees and floral preference, migratory status and habitat preference for hoverflies. For most traits, we collected more individuals but not more species with a certain trait in the different methods. This was mainly due to a high abundance of one species being collected in the different methods. These results suggest that the best methodology depends on the aim of the survey, and that the methods cannot be easily combined into synthesis research. Our results have implications for the development of monitoring schemes for pollinators and for synthesis of trends that can identify threats to pollinators and inform research of pollinator conservation strategies.

Abandoned agricultural lands often accumulate soil carbon (C) following depletion of soil C by cultivation. The potential for this recovery to provide significant C storage benefits depends on the rate of soil C accumulation, which, in turn, may depend on nutrient supply rates. We tracked soil C for almost four decades following intensive agricultural soil disturbance along an experimentally imposed gradient in nitrogen (N) added annually in combination with other macro‐ and micro‐nutrients. Soil %C accumulated over the course of the study in unfertilized control plots leading to a gain of 6.1 Mg C ha−1 in the top 20 cm of soil. Nutrient addition increased soil %C accumulation leading to a gain of 17.8 Mg C ha−1 in fertilized plots, nearly a threefold increase over the control plots. These results demonstrate that substantial increases in soil C in successional grasslands following agricultural abandonment occur over decadal timescales, and that C gain is increased by high supply rates of soil nutrients. In addition, soil %C continued to increase for decades under elevated nutrient supply, suggesting that short‐term nutrient addition experiments underestimate the effects of soil nutrients on soil C accumulation. [ABSTRACT FROM AUTHOR]

The challenges posed by climate and land use change are increasingly complex, with rising and accelerating impacts on the global environmental system. Novel environmental and ecosystem research needs to properly interpret system changes and derive management recommendations across scales. This largely depends on advances in the establishment of an internationally harmonised, long-term operating and representative infrastructure for environmental observation. This paper presents an analysis evaluating 743 formally accredited sites of the International Long-Term Ecological Research (ILTER) network in 47 countries with regard to their spatial distribution and related biogeographical and socio-ecological representativeness. “Representedness” values were computed from six global datasets. The analysis revealed a dense coverage of Northern temperate regions and anthropogenic zones most notably in the US, Europe and East Asia. Significant gaps are present in economically less developed and anthropogenically less impacted hot and barren regions like Northern and Central Africa and inner-continental parts of South America. These findings provide the arguments for our recommendations regarding the geographic expansion for the further development of the ILTER network.

As the focus of land-sea interactions, estuarine and coastal ecosystems perform numerous vital ecological service functions, although they are highly vulnerable to various kinds of disturbance, both directly and indirectly related to human activity, that have attracted much recent attention. Critical zone science (CZS) has emerged as a valuable conceptual framework that focuses on quantitative interactions between diverse components of the environment and is able to integrate anthropogenic disturbance with a view to predicting future trajectories of change. However, coastal and estuarine environments appear to have been overlooked in CZS and are notably under-represented, indeed not explicitly represented at all, in the global network of critical zone observatories (CZOs). Even in the wider network of environmental observatories globally, estuarine and coastal wetland ecosystems are only very rarely an explicit focus. Further strengthening of integrated research in coastal and estuarine environments is required, more especially given the threats these ecosystems face due to growing population at the coast and against the background of climate change and sea level rise. The establishment of one or more CZOs, or their functional equivalents, with a strong focus on estuarine and coastal wetlands, should be urgently attended to. [ABSTRACT FROM AUTHOR]

• Investigation of high-resolution temporal variations of nitrate in mountain pond. • Integration of in-situ UV–Vis spectrophotometric measurements with weekly samples. • Nitrate seasonal variations driven by snow-melt duration and temperature. • Summer storms and rain-on-snow events greatly influence nitrate dynamics. • Better understanding of biogeochemical processes occurring in tundra pond. High-resolution temporal measurements in remote, high-elevation surface waters are required to better understand the dynamics of nitrate (NO 3 −) in response to changes in meteoclimatic conditions. This study reports on the first use of a UV–Vis submersible spectrophotometric probe (UV–Vis probe) to measure the hourly concentration of nitrate nitrogen (NO 3 −-N) in a pond located at 2722 m a.s.l. in an alpine tundra area (NW Italian Alps), during two snow-free seasons (July–October) in 2014 and 2015. Weekly analyses of NO 3 −-N and stable isotopes of water (δ18O and δ2H), together with continuous meteorological, water temperature, and turbidity measurements, were performed over the same period. The integration of in-situ UV–Vis spectrophotometric measurements with weekly samples allowed depicting the role of summer precipitation, snow melt, and temperature (air and water) in influencing NO 3 − dynamics. Short-duration meteorological events (e.g., summer storms and rain-on-snow events) produced rapid variations of in-pond NO 3 − concentration, i.e., fivefold increase in 18 h, that would not be detectable using the traditional manual collection of discrete samples. The observed seasonal variability of NO 3 − concentration, negatively correlated with water temperature, highlighted the important role of in-pond biological processes leading to an enhanced N uptake and to the lowest NO 3 − concentration in the warmer periods. The occurrence of heavy rainfall events critically altered the expected seasonal NO 3 − trends, increasing the N supply to the pond. The comparison of N dynamics in two years characterised by extremely different meteoclimatic conditions allowed us to obtain insights on the potential effects of climate changes (e.g., high air temperature, heavy rainfalls, and rain-on-snow events) on sensitive aquatic ecosystems as high-elevation ponds. [ABSTRACT FROM AUTHOR]

Understanding how biotic mechanisms confer stability in variable environments is a fundamental quest in ecology, and one that is becoming increasingly urgent with global change. Several mechanisms, notably a portfolio effect associated with species richness, compensatory dynamics generated by negative species covariance and selection for stable dominant species populations can increase the stability of the overall community. While the importance of these mechanisms is debated, few studies have contrasted their importance in an environmental context. We analyzed nine long-term data sets of grassland species composition to investigate how two key environmental factors, precipitation amount and variability, may directly influence community stability and how they may indirectly influence stability via biotic mechanisms. We found that the importance of stability mechanisms varied along the environmental gradient: strong negative species covariance occurred in sites characterized by high precipitation variability, whereas portfolio effects increased in sites with high mean annual precipitation. Instead of questioning whether compensatory dynamics are important in nature, our findings suggest that debate should widen to include several stability mechanisms and how these mechanisms vary in importance across environmental gradients.