Ecosystem Properties Research Articles

Brackish water parameters monitoring dashboard using Internet of things and industry 4.0

INTRODUCTION: Brackish water aquaculture plays a crucial role in meeting the growing global demand for seafood. It offers an opportunity to diversify aquaculture production and reduce pressure on overexploited marine resources. OBJECTIVES: By harnessing the unique properties of brackish ecosystems, this practice contributes to food security, economic growth, and sustainable resource management, while also promoting the conservation of valuable marine habitats. The development of a cutting-edge Indigenous Water Quality Monitoring Prototype named "Aqua BuoySis" for precision brackish water aquaculture utilizing machine intelligence. METHODS: The prototype integrates sensors for Dissolved Oxygen (DO), pH, Temperature, Turbidity, and Total Dissolved Solids (TDS). These sensors are calibrated using a dynamic temperature-based machine-learning approach to ensure accuracy in real-time environments. Sensor calibration constants are uploaded to a server for comprehensive data calibration. RESULTS: The system collects data at 20-second intervals, associating it with specific pond IDs. Data refinement is achieved through Long Short-Term Memory (LSTM) processing. An Android and Web application, available in native languages such as Tamil and Telugu, has been developed to provide live updates to aqua farmers, facilitating informed decision-making. CONCLUSION: This technology represents a significant step towards enhancing precision in brackish water aquaculture through the fusion of machine intelligence and water quality management.

Physicochemical and ecosystem properties of the Middle to Lower Xingu River, Brazil, prior to the operation of the Belo Monte Dam Complex

Physicochemical and ecosystem properties of the Middle to Lower Xingu River, Brazil, prior to the operation of the Belo Monte Dam Complex

Invasion alters plant and mycorrhizal communities in an alpine tussock grassland.

Plant invasions are impacting alpine zones, altering key mutualisms that affect ecosystem functions. Plant-mycorrhizal associations are sensitive to invasion, but previous studies have been limited in the types of mycorrhizas examined. Consequently, little is known about how invaders that host rarer types of mycorrhizas may affect community and ecosystem properties. We studied invasion by an ericoid mycorrhizal host plant (Calluna vulgaris L., heather) in alpine tussock grasslands in New Zealand. We investigate the effects of increasing C. vulgaris density on the plant and soil microbial community and on mycorrhization in the dominant native species (Chionochloa rubra Z., red tussock), an arbuscular mycorrhizal host. We show that variation in plant community composition was primarily driven by invader density. High invader densities were associated with reductions in C. rubra diameter and in the cover, richness and diversity of the subordinate plant community. Belowground, we show that higher invader densities were associated with lower rates of mycorrhization in C. rubra and higher proportional abundance of the fungal lipid biomarker 18:2ω6 but had little effect on total microbial biomass, which may suggest increased ericoid mycorrhizal and fine root biomass in high C. vulgaris density stands. Our data suggest that disruption of native plant-arbuscular mycorrhizal networks may contribute to the competitive success of C. vulgaris, and that the dramatic decline of C. rubra with invasion reflects its relatively high mycorrhizal dependence. By exploring invasion of a plant with a less common mycorrhizal type, our study expands knowledge of the ecosystem consequences of biological invasions.

Impacts of prescribed fire and mechanical shredding of aboveground vegetation for fire prevention on ecosystem properties, structure, functions and overall multi-functionality of a semi-arid pine forest

Ecosystem multi-functionality is a key concept when measured to protect forests from natural and anthropogenic disturbances, such as fire prevention techniques, must be adopted. Despite this importance, scarce studies have analysed the impacts of prescribed burning and aboveground vegetation management on ecosystem functions and overall multi-functionality. To fill this gap, this study has evaluated the changes in some ecosystem properties and structure (associated with soil characteristics and plant diversity, respectively), in important forest functions, and the overall ecosystem multi-functionality in a Mediterranean pine forest of Castilla La Mancha (Central Eastern Spain) under three site conditions: (i) undisturbed ecosystem; (ii) forest subjected to mechanical shredding of aboveground vegetation (hereafter “AVMS”); and (iii) forest treated as above and then with prescribed fire (“AVMS + PF”). The results of the study have shown that neither the PF nor AVMS have significantly modified the structure, properties and functions as well as the overall multi-functionality of the forest ecosystem. These slight impacts of the treatments are due to the low fire severity of the prescribed burning and the long time elapsed from the vegetation management. Among the studied ecosystem functions, organic matter decomposition (driven by the enzymatic activities and soil basal respiration), water cycle (influenced by soil water content and water infiltration), carbon stock (linked to soil organic matter) and biomass production decreased, when species richness and plant diversity increased. The study is useful to indicate the feasibility of forest management actions for fire prevention in delicate forest ecosystems of the Mediterranean environments.

Kelp forests versus urchin barrens: a comparison of ecosystem functions and services provided by two alternative stable marine habitats.

Kelp forests and urchin barrens are two stable states in rocky reef ecosystems, each providing unique ecosystem functions like habitat for marine species and primary production. While studies frequently show that kelp forests support higher levels of some ecosystem functions than urchin barren habitats, no research has yet compared average differences. To address this gap, we first conducted a meta-analysis of studies that directly compared the ecosystem functions, services and general attributes provided by each habitat. We also compiled individual studies on ecosystem properties from both habitats and qualitatively assessed the benefits provided. The meta-analysis included 388 observations from 55 studies across 14 countries. We found that kelp forests consistently delivered higher levels of ecosystem properties such as biodiversity, species richness, abalone abundance and sea urchin roe quality. Urchin barrens supported higher urchin density and crustose coralline algae cover. The qualitative review further supported these findings, showing that kelp forests ranked higher in 11 out of 15 ecosystem properties. These findings can help guide decisions on managing rocky reef habitats and demonstrate the benefits of preserving or expanding kelp forests.

Functional ecology of plant communities as a guide for vegetation management

Plant functional traits determine how individual plants cope with varying environmental conditions, and extensive literature supports their role in influencing ecosystem properties. The study of plant functional traits could help the prediction of species responses to disturbances and environmental change, thus providing invaluable knowledge to refine conservation strategies of species and vegetation. However, applications of functional ecology for vegetation management are still underrepresented.The articles in this Special Issue of FLORA offer cutting-edge insights on the variation of plant traits and ecological strategies in response to environmental drivers, such as anthropogenic disturbance, climate and land use change. The results demonstrate how trait-based approaches can be used for the prediction of climate and land use change impacts on vulnerable sets of species or on biogeochemical cycles, reinforcing the concept that functional plant ecology can help identify the most effective procedures for vegetation management, such as the choice of mowing intensity in grasslands or planning vegetation recovery after wildfires.Our knowledge of plant trait coordination at the community level is still undefined, especially concerning the integration of above- and belowground traits. This represents a missed opportunity for vegetation management, especially considering that a complete understanding of the dynamics of the entire ecosystem is crucial for complete understanding of ecosystem properties. Since plant functional traits can represent a straightforward tool for monitoring changes in ecosystem structure and functions, their use could support vegetation monitoring as required by different programs of nature conservation. It would be useful to embrace a perspective that integrates plant traits with systematic conservation planning, ensuring effective and sustainable conservation efforts.

Reseeding increased plant biomass production and soil fertility, but not plant species diversity in degraded grasslands in China

Reseeding is a primary measure to restore degraded grasslands. Numerous studies have conducted experiments to investigate how the properties of grassland ecosystems respond to reseeding in China. However, there is a lack of summary of the results of these studies. Here, we conducted a hierarchical random-effects meta-analysis on the effects of reseeding on plant, soil, and microbial properties. We collected 19 variables, including plant biomass, species diversity and richness, soil organic carbon content, soil total and available nutrients, soil water content, soil microbial biomass and diversity, and enzyme activity, from a dataset of 1363 paired observations (degraded vs. reseeded) from 75 publications. The results showed that reseeding increased aboveground and belowground plant biomass by 70.2% and 68.0% on average, respectively. Reseeding increased soil organic carbon, phosphorus, and potassium contents, but did not affect soil nitrogen levels. Reseeding increased soil microbial nitrogen under conditions of tillage and fertilization. Reseeding age was found to have a positive correlation with species richness, while planting type, fertilization, and tillage did not have a significant impact on the species richness and diversity. Under the treatments of fertilization, non-tillage, and mix-planting, the response ratio of aboveground biomass to reseeding was positively correlated with the response ratio of species diversity to reseeding. Our results concluded that current reseeding practices can significantly improve plant biomass production and soil fertility but have minor effects on plant species diversity. These findings indicate that the preservation of biodiversity should receive greater attention from both researchers and practitioners in grassland remediation in China.

The Micropaleoecology Framework: Evaluating Biotic Responses to Global Change Through Paleoproxy, Microfossil, and Ecological Data Integration.

The microfossil record contains abundant, diverse, and well-preserved fossils spanning multiple trophic levels from primary producers to apex predators. In addition, microfossils often constitute and are preserved in high abundances alongside continuous high-resolution geochemical proxy records. These characteristics mean that microfossils can provide valuable context for understanding the modern climate and biodiversity crises by allowing for the interrogation of spatiotemporal scales well beyond what is available in neo-ecological research. Here, we formalize a research framework of "micropaleoecology," which builds on a holistic understanding of global change from the environment to ecosystem level. Location: Global. Time period: Neoproterozoic-Phanerozoic. Taxa studied: Fossilizing organisms/molecules. Our framework seeks to integrate geochemical proxy records with microfossil records and metrics, and draws on mechanistic models and systems-level statistical analyses to integrate disparate records. Using multiple proxies and mechanistic mathematical frameworks extends analysis beyond traditional correlation-based studies of paleoecological associations and builds a greater understanding of past ecosystem dynamics. The goal of micropaleoecology is to investigate how environmental changes impact the component and emergent properties of ecosystems through the integration of multi-trophic level body fossil records (primarily using microfossils, and incorporating additional macrofossil data where possible) with contemporaneous environmental (biogeochemical, geochemical, and sedimentological) records. Micropaleoecology, with its focus on integrating ecological metrics within the context of paleontological records, facilitates a deeper understanding of the response of ecosystems across time and space to better prepare for a future Earth under threat from anthropogenic climate change.

Research on fire accident prediction and risk assessment algorithm based on data mining and machine learning

Forest fire is a kind of natural disaster that is destructive, easy to spread, and difficult to extinguish. It greatly harms the balance of ecosystem and human life and property. The prediction and risk assessment of forest fire accidents can find forest fires as early as possible and then take corresponding remedial measures; the loss of forest fires will be minimized. This paper first collected the relevant data information in the Lesser Hinggan Mountain region, established the fire driving factor database, and then analyzed the impact and distribution characteristics of forest fire driving factors such as temperature and rainfall. Finally, a fire accident prediction model was built based on a deep neural network, and the model’s performance was compared with the SVM and RF models. The analysis results show that this paper’s fire accident prediction model is more accurate.

Changing dominance of invasive Phragmites australis and native plant colonization with variation in management, wildfires, and soils in a desert wetland

Abstract Among the most widely distributed species globally, common reed (Phragmites australis (Cav.) Trin. ex Steud.) has generated extensive interest in invasive plant science and management because its introduced strains are highly invasive and often form monocultures that alter ecosystem properties. In desert wetlands in Las Vegas, Nevada, USA, where management goals included reducing hazardous P. australis fuels and increasing native plant diversity, we assessed variation in P. australis cover, the degree of native plant colonization, and soil seed banks after P. australis management treatments (cutting, glyphosate-imazapyr herbicide) and wildfires across gradients in soil properties. Based on change in P. australis cover during six measurement events over 24 months, 24 study sites formed three groups: 1) decreasing cover, where initially high P. australis cover (60-85%) decreased to < 5% following multiple cutting or herbicide treatments; 2) sustaining low cover, where wildfire or clearing was associated with initially low P. australis cover which remained low (< 30%) after multiple herbicide applications; and 3) sustaining high cover (45-100% initially and remaining 30-100%), including sites unmanaged or treated/burned only once. High soil salinity correlated with low post-management P. australis cover. No native plants were detected in the sustaining high P. australis cover group, despite natives occurring in the seed bank. Where management reduced P. australis cover, minimal native plant colonization did occur. Secondary invasion by other non-native plants was nearly absent. Our results suggest that if P. australis can be initially cleared, multiple herbicide applications can persistently keep cover low, especially on drier, saline soils. Slow native plant colonization suggests that a phased approach may be useful to initially reduce P. australis cover, keep it low via repeated treatments, and actively revegetate sites with native species tailored to the moisture-salinity gradient across P. australis-invaded habitats.

Influence of Terrain on MODIS and GLASS Leaf Area Index (LAI) Products in Qinling Mountains Forests

Leaf Area Index (LAI), as a pivotal parameter in characterizing the structural properties of vegetation ecosystems, holds significant importance in assessing the carbon sink function. Given the availability of multiple long-term LAI products, validating these LAI products with consideration of topographic factors is a prerequisite for enhancing the quality of LAI products in mountainous areas. Therefore, this study aims to evaluate the performance of MODIS LAI and GLASS LAI products from 2001 to 2021 by comparing and validating them with ground-measured LAI data, focusing on the spatio-temporal and topographic aspects in the Qinling Mountains. The results show that the GLASS LAI product is a better choice for estimating LAI in the Qinling Mountains. The GLASS LAI product has better completeness and generally higher values compared to the MODIS LAI product. The time-series curve of the GLASS LAI product is more continuous and smoother than the MODIS LAI product. Both products, however, face challenges in quantifying LAI values of evergreen vegetation during winter. The MODIS and GLASS LAI products exhibit differences between sunny and shady slopes, with mean LAI values peaking on sunny slopes and reaching their lowest on shady slopes. When the slope ranges from 0 to 10°, the mean values of GLASS LAI product show a higher increasing trend compared to the MODIS LAI product. At elevations between 1450 and 2450 m, the mean LAI values of the GLASS LAI product are higher than the MODIS LAI product, primarily in the southern Qinling Mountains. Compared to ground-measured LAI data, the GLASS LAI product (R² = 0.33, RMSE = 1.62, MAE = 0.61) shows a stronger correlation and higher accuracy than the MODIS LAI product (R² = 0.24, RMSE = 1.61, MAE = 0.68).

Ground beetle trophic interactions alter available nitrogen in forest soil

It is generally held that microbes exert primary control over nitrogen availability in temperate forests. Yet the role of soil and litter‐dwelling invertebrates to provide additional control via the breakdown of organic matter is an area of current exploration. Through trophic interactions within soil food webs, predators may indirectly affect prey with cascading effects on litter breakdown and nitrogen availability. The importance of these interactions, however, may be context‐dependent, varying with the stage of forest development and associated decomposer species composition given that young and old forests have vast differences in nitrogen availability, vegetation litter, soil properties and invertebrate functional groups. We examined ground beetle control over soil nitrogen and soil properties using a 68‐day mesocosm experiment that manipulated trophic structure (omnivore + predator beetles, predator beetles, and no beetles) in a young and old forest stand in the northeastern United States. In the young forest, net nitrogen mineralization decreased under predator + omnivore and the bulk soil C:N ratio in the old forest. However, we found no response in either forest context to the predator only treatment. Our study demonstrates the potential for ground beetles to strongly impact nitrogen availability and soil properties in forest ecosystems. Therefore, animal trophic interactions and their contexts must be included in our paradigm of nutrient cycles in temperate forests.

The biogeochemical model Biome-BGCMuSo v6.2 provides plausible and accurate simulations of the carbon cycle in central European beech forests

Abstract. Process-based ecosystem models are increasingly important for predicting forest dynamics under future environmental conditions, which may encompass non-analogous climate coupled with unprecedented disturbance regimes. However, challenges persist due to the extensive number of model parameters, scarce calibration data, and trade-offs between the local precision and the applicability of the model over a wide range of environmental conditions. In this paper, we describe a protocol that allows a modeller to collect transferable ecosystem properties based on ecosystem characteristic criteria and to compile the parameters that need to be described in the field. We applied the procedure to develop a new parameterisation for European beech (Fagus sylvatica L.) for the Biome-BGCMuSo model, the most advanced member of the Biome-BGC family. For model calibration and testing, we utilised multiyear forest carbon data from 87 plots distributed across five European countries. The initial values of 48 new ecophysiological parameters were defined based on a literature review. The final values of six calibrated parameters were optimised for single sites as well as for multiple sites using generalised likelihood uncertainty estimation (GLUE) and model output conditioning that ensured plausible simulations based on user-defined ranges of carbon stock output variables (carbon stock in aboveground wood biomass, soil, and litter) and finding the intersections of site-specific plausible parameter hyperspaces. To support the model use, we tested the model performance by simulating aboveground tree wood, soil, and litter carbon across a large geographical gradient of central Europe and evaluated the trade-offs between parameters tailored to single plots and parameters estimated using multiple sites. Our findings indicated that parameter sets derived from single sites provided an improved local accuracy of simulations of aboveground wood, soil, and litter carbon stocks by 35 %, 55 %, and 11 % in comparison to the a priori parameter set. However, their broader applicability was very limited. A multi-site optimised parameter set, on the other hand, performed satisfactorily across the entire geographical domain studied here, including on sites not involved in the parameter estimation, but the errors were, on average, 26 %, 35 % and 9 % greater for the aboveground wood, soil, and litter carbon stocks than those obtained with the site-specific parameter sets. Importantly, model simulations demonstrated plausible responses across large-scale environmental gradients, featuring a clear production optimum of beech that aligns with empirical studies. These findings suggest that the model is capable of accurately simulating the dynamics of European beech across its range and can be used for more comprehensive experimentations.

Land use drives prokaryotic community composition of directly adjacent grasslands

AbstractUnderstanding the impact of agricultural land use on the soil prokaryotic communities in connected downslope sites is crucial for developing sustainable strategies to preserve ecosystem properties and mitigate agriculture’s environmental impacts. In this study, we investigated topsoil samples collected at three time points in 2022 (March, June, and November) from two adjacent catenas, reaching from hillslope to floodplain. The catenas differed in land use (extensive grassland vs. extensive cropland) at the top and middle parts, while the floodplain remained an extensive grassland due to legal restrictions. Using quantitative real-time PCRs and metabarcoding, we assessed prokaryotic abundance and prokaryotic community composition. Results show higher bacterial abundance in the cropland-influenced floodplain part across all time points compared to the grassland-influenced floodplain part. Temporal dynamics revealed a progressive decrease in the shared prokaryotic communities of the floodplain parts, peaking at the summer sampling time point, indicating a significant influence of the respective management type of the agricultural sites over the bacterial and archaeal communities of the floodplain parts. Differential abundance analyses identified several nitrifying taxa as more abundant in the cropland-influenced floodplain. Upstream land use also influenced the prokaryotic network of the cropland-floodplain, with some cropland taxa becoming keystone taxa and altering network morphology, an effect not observed in the grassland-influenced floodplain. These findings suggest that upstream agricultural land use practices have exerted a long-term influence on the floodplain prokaryotic communities over the past three decades. Moreover, there is evidence suggesting that these prokaryotic communities may undergo a potential reset during winter, which requires further investigation.

An integrated fast-slow plant and nematode economics spectrum predicts soil organic carbon dynamics during natural restoration.

Aboveground and belowground attributes of terrestrial ecosystems interact to shape carbon (C) cycling. However, plants and soil organisms are usually studied separately, leading to a knowledge gap regarding their coordinated contributions to ecosystem C cycling. We explored whether integrated consideration of plant and nematode traits better explained soil organic C (SOC) dynamics than plant or nematode traits considered separately. Our study system was a space-for-time natural restoration chronosequence following agricultural abandonment in a subtropical region, with pioneer, early, mid and climax stages. We identified an integrated fast-slow trait spectrum encompassing plants and nematodes, demonstrating coordinated shifts from fast strategies in the pioneer stage to slow strategies in the climax stage, corresponding to enhanced SOC dynamics. Joint consideration of plant and nematode traits explained more variation in SOC than by either group alone. Structural equation modeling revealed that the integrated fast-slow trait spectrum influenced SOC through its regulation of microbial traits, including microbial C use efficiency and microbial biomass. Our findings confirm the pivotal role of plant-nematode trait coordination in modulating ecosystem C cycling and highlight the value of incorporating belowground traits into biogeochemical cycling under global change scenarios.

A low-cost alternative to LiDAR for site index models: applying repeated digital aerial photogrammetry data in the modelling of forest top height growth

Abstract Environmental and forest structural information derived from remote sensing data has been found suitable for modelling forest height growth and site index and therefore forest productivity assessment, with the advances in airborne laser scanning (ALS) playing a major role in this development. While there is growing interest in the use of ALS-derived point clouds, point clouds from high-resolution digital aerial photography (DAP) are also often used for mapping and estimating forest ecosystem properties due to their lower acquisition costs. In this study, we document the applicability of bi-temporal DAP data for developing top height (TH) growth models for Scots pine stands. Our results indicate that DAP data can function as an alternative to traditional TH measurements used in growth modelling when corrected based on a limited sample of field-measured reference TH values. As the correction cannot be constant for each DAP dataset due to the different parameters during data acquisition, we propose a straightforward method for the bias correction of DAP-derived TH estimates. By undertaking iterative random sampling, we were able to find the minimum number of reference measurements needed to calculate the TH correction in order to achieve the desired accuracy of the TH estimations based on DAP. Here, we used ALS data as the reference data; however, the ALS measurements can be replaced by any other reliable source of TH values. The presented method for determining TH can be used not only for site index and forest growth modelling but also in forest inventories.

Climate and topography control variation in the tropical dry forest-rainforest ecotone.

Ecotones are the transition zones between ecosystems and can exhibit steep gradients in ecosystem properties controlling flows of energy and organisms between them. Ecotones are understood to be sensitive to climate and environmental changes, but the potential for spatiotemporal dynamics of ecotones to act as indicators of such changes is limited by methodological and logistical constraints. Here, we use a novel combination of satellite remote sensing and analyses of spatial synchrony to identify the tropical dry forest-rainforest ecotone in Area de Conservación Guanacaste, Costa Rica. We further examine how climate and topography influence the spatiotemporal dynamics of the ecotone, showing that ecotone is most prevalent at mid-elevations where the topography leads to moisture accumulation and that climatic moisture availability influences up and downslope interannual variation in ecotone location. We found some evidence for long-term (22 year) trends toward upslope or downslope ecotone shifts, but stronger evidence that regional climate mediates topographic controls on ecotone properties. Our findings suggest the ecotone boundary on the dry forest side may be less resilient to future precipitation reductions and that if drought frequency increases, ecotone reductions are more likely to occur along the dry forest boundary.

Functional traits and ecosystem implications in the Multiple Use Marine Protected Area Almirantazgo Sound: A baseline study of scallop banks and benthic communities

Amid escalating environmental challenges confronting marine ecosystems, the proliferation of coastal and marine protected areas (MPAs) has emerged as a pivotal strategy for mitigating biodiversity loss and fostering sustainable resource management. This research advocates for a paradigm shift towards a trait-based approach to assess functional diversity (FD) within MPAs, with a specific focus on the ecologically crucial Austrochlamys natans banks in Parry Bay, MPA Almirantazgo Sound. By surveying 28 invertebrate species across eight phyla, a PCA using fuzzy-coded functional traits revealed five distinct groupings primarily based on feeding, movement, and reproductive modes. Mobile predators and scavengers clustered distinctly from sessile suspension feeders and limited-mobility grazers, indicating a scarcity of mobile predator species in Parry Bay, which impacts the ecosystem's dynamics. FD indices highlighted low functional α-diversity, emphasizing trait redundancy that enhances resilience but relies heavily on a few unique and specialized species. The potential extinction or migration of these species could directly affect unique ecosystem properties. While revealing the resilience of the benthic community, this research underscores its dependence on a handful of species that are crucial for both ecological functions and regional commercial significance. Urgent conservation and management measures are imperative to protect these species and maintain the delicate balance of this ecosystem.

Grazing intensity by sheep affects spatial diversity in botanical composition of Inner Mongolian grassland

Overgrazing by sheep causes degradation of grasslands in the Inner Mongolian steppe, yet our understanding of its impact on grassland plant communities is limited by lack of observations at high spatial resolution. Employing a nested experimental design in a long-term grazing experiment provides insights into effects of increasing sheep grazing intensity on community composition, diversity, and spatial patterns in the grassland vegetation. Effects of observed changes in the plant community are discussed based on monthly weight gain of sheep during grazing. The design of the long-term experiment included four triplicated grazing intensities applied during an 8-year period. At the end of that period, we evaluated vegetation coverage, categorized plant species by functional groups, and analyzed the data using a mixed linear model. Moreover, spatial autocorrelation methods were employed to investigate spatial patterns, visualized via a kriging model. We found that the plant community composition differed among grazing treatments, with high grazing intensity showing higher plant species richness and stronger clustering of plants at our fine scale of observation. These fine-grained spatial scale observations are usually not recorded in larger spatial scale analyses of grassland responses to overgrazing. While the grazing intensities used in our study did not influence individual sheep weight gain, total sheep weight gain per hectare increased with an increase in grazing intensity. Our study shows that in a sheep grazing intensity experiment in Inner Mongolia grasslands total sheep weight gain may increase at the expense of fine-scale species composition and spatial dynamics of the grassland vegetation. These insights may be used for determining trade-offs of sheep meat production with original composition and structure of grassland plant communities. Effects on other ecosystem properties and functions, such as on belowground biodiversity, remain to be assessed.

Ecosystem Size Drives Patterns and Control Mechanisms of Mixotrophs Success Across Tropical Lakes: A Large-Scale Assessment of the Grand Écart Hypothesis

Mixotrophy, a physiological trait combining autotrophy and heterotrophy in one organism, significantly contributes to energy and matter transfer in aquatic ecosystems. However, understanding how environmental factors influence mixoplankton success across freshwater ecosystems has been uncertain. The grand écart hypothesis (GEH) posits that light and nutrient availability are key components of mixotrophs' niche, suggesting that ecosystem properties determine opposing gradients of light and nutrients, creating environmental filtering for mixotrophs. We hypothesized that ecosystem size, a property of lake ecosystems, mediates the prevalence of patterns and control mechanisms predicted by the GEH on mixoplankton relative biomass (MRB). Using data from 98 tropical lakes, we demonstrated that lake size mediates the inverse relationship between light and nutrient availability across ecosystems. Larger lakes have more light but low nutrients, while smaller lakes have more nutrients but greater shading. Light availability better explains MRB in small lakes, and nutrients better explain MRB in large lakes, with MRB values being higher in small lakes, with secondary influence from zooplankton herbivory. Our results validate the GEH as a significant framework for explaining patterns and control mechanisms of mixoplankton across tropical lakes. This study highlights the significance of lake size as an ecosystem property that generates opposing light and nutrient gradients, further emphasizing its importance for understanding mechanisms regulating freshwater phytoplankton community structure and functioning. Integrating lake size within the conceptual framework of the GEH could aid in explaining mixoplankton success over macroecological scales.