Taofeek Olatunbosun Muraina

Land cover data are commonly used to model the terrestrial carbon (C) sink, yet these data have wide margins of error that significantly alter estimates of global C storage. Here we demonstrate this data vulnerability in grasslands, which are critical to C cycling but whose estimated distribution has varied by >50 million km ² (3.5–42% of the Earth’s terrestrial surface). Comparing multiple high-resolution land cover products with expertly annotated grassland data from six continents, we show sources of mapping error and discuss C implications based on 2023 United Nations (UN) FAO estimates. Past misidentification arose from inconsistent definitions on grassland identity and classification flaws especially relating to woody plant cover. Correcting these errors adjusted grassland coverage to 22.8% of the terrestrial land base (30.1 million km ² ), elevating UN projections of soil C stocks to 155.02 Pg (0–30 cm depth). These findings underscore the challenges of biome mapping for ecosystem accounting and policy, when lacking field-validated remotely sensed data.

Increasing drought events may impair carbon (C) storage in terrestrial ecosystems, but the impacts of isolated vs. recurrent droughts on soil C and its drivers remain unclear. We studied how isolated drought (66% reduction in growing season precipitation over two years) and recurrent drought (the same reduction applied to plots that had previously experienced a 4-year drought followed by two recovery years) influence shallow soil C and its plant-related drivers in two semi-arid grasslands. Despite a one-third decline in soil moisture under both droughts, the responses of above- and belowground C pools and species richness were limited and inconsistent, and soil C remained stable across years, sites, and treatments. Soil C resistance to these droughts was unrelated to the resistance of above- and belowground C pools in the first year of this study. In the second year, the resistance of aboveground forb C pool and belowground C pool promoted soil C resistance under isolated and recurrent drought, respectively. Relationships were observed only at one site, where soil C resistance increased with greater resistance of aboveground biomass, forb, and belowground C pools under isolated drought but decreased with higher species richness under recurrent drought. Overall, short-term isolated or recurrent drought events may not alter shallow soil C when plant-related C drivers show limited negative responses. However, caution is warranted when extrapolating these results, as soil C changes slowly and its response to drought may differ over time and across grassland types.

Community diversity exhibits partial recovery following the cessation of nitrogen (N) addition, yet the underlying mechanisms remain insufficiently understood. In this study, we examined the short-term responses of plant communities and environmental factors to N cessation in an alpine meadow on the eastern Qinghai-Tibetan Plateau after a decade-long period of N addition. Our study reveals a transient window of opportunity for the resurgence of rare species following N cessation. This recovery of rare species was the primary driver of the observed increase in plant species diversity. During this temporary phase, increased light availability and reduced soil nutrient (nitrogen and phosphorus) levels disrupted historical competitive hierarchies by enhancing the performance of rare species while weakening dominant species. These findings offer novel insights into community reassembly under nutrient enrichment stress and highlight the potential for short-term, targeted interventions to facilitate near-natural restoration, providing valuable guidance for ecosystem management and biodiversity conservation in grassland ecosystems.

Increases in droughts may disrupt the life‐supporting services of grasslands, including the forage provision for herbivores. However, less is known about drought impacts on forage quality (i.e., dynamics of the cell characteristics of leaves and stems of herbs). Leaf economic traits reflect drought effects on plant communities, but whether they can predict forage quality patterns under drought remains unclear. We assessed the effects of early‐ and late‐season extreme droughts on (i) forage quality parameters [readily digestible, internal cellular constituents: protein, minerals, water‐soluble carbohydrate (WSC); and non‐readily digestible, cell wall components: neutral detergent fibre (NDF) and acid detergent fibre (ADF)]; (ii) community‐weighted leaf traits [specific leaf area (cwmSLA) and leaf dry matter content (cwmLDMC)]; and (iii) leaf traits–quality parameters relationships across three grasslands over two growing seasons. Both early and late droughts decreased ash and ADF and increased WSC across sites, while early drought slightly reduced protein and NDF. Both droughts decreased cwmSLA and increased cwmLDMC across sites. Community‐weighted leaf traits and forage quality parameters were unrelated under early ambient conditions, but their relationships under early‐season drought imply that lower cwmSLA and higher cwmLDMC communities had higher forage quality (higher protein and less lignified fibre contents) than higher cwmSLA and lower cwmLDMC communities. Under late‐season ambient or drought conditions, most relationships indicate that lower cwmSLA and cwmLDMC communities had higher forage quality (higher protein and ash, and more digestible fibre contents) than higher cwmSLA and cwmLDMC communities. Overall, forage quality was higher under late‐season ambient conditions compared to the early season, and both drought types had limited negative effects on forage quality in the studied grasslands. Moreover, leaf traits can predict forage quality patterns and plants' adaptation under certain circumstances, including regular intra‐seasonal dry periods and extreme drought conditions.

Extreme droughts are intensifying, yet their impact on temporal variability of grassland functioning and its drivers remains poorly understood. We imposed a 6‐year extreme drought in two semiarid grasslands to explore how drought influences the temporal variability of ANPP and identify potential stabilising mechanisms. Drought decreased ANPP while increasing its temporal variability across grasslands. In the absence of drought, ANPP variability was strongly driven by the dominant plant species (i.e., mass‐ratio effects), as captured by community‐weighted traits and species stability. However, drought decreased the dominance of perennial grasses, providing opportunities for subordinate species to alter the stability of productivity through compensatory dynamics. Specifically, under drought, species asynchrony emerged as a more important correlate of ANPP variability than community‐weighted traits or species stability. Our findings suggest that in grasslands, prolonged, extreme droughts may decrease the relative contribution of mass‐ratio effects versus compensatory dynamics to productivity stability by reducing the influence of dominant species.

Although variation in effect sizes and predicted values among studies of similar phenomena is inevitable, such variation far exceeds what might be produced by sampling error alone. One possible explanation for variation among results is differences among researchers in the decisions they make regarding statistical analyses. A growing array of studies has explored this analytical variability in different fields and has found substantial variability among results despite analysts having the same data and research question. Many of these studies have been in the social sciences, but one small “many analyst” study found similar variability in ecology. We expanded the scope of this prior work by implementing a large-scale empirical exploration of the variation in effect sizes and model predictions generated by the analytical decisions of different researchers in ecology and evolutionary biology. We used two unpublished datasets, one from evolutionary ecology (blue tit, Cyanistes caeruleus, to compare sibling number and nestling growth) and one from conservation ecology (Eucalyptus, to compare grass cover and tree seedling recruitment). The project leaders recruited 174 analyst teams, comprising 246 analysts, to investigate the answers to prespecified research questions. Analyses conducted by these teams yielded 141 usable effects (compatible with our meta-analyses and with all necessary information provided) for the blue tit dataset, and 85 usable effects for the Eucalyptus dataset. We found substantial heterogeneity among results for both datasets, although the patterns of variation differed between them. For the blue tit analyses, the average effect was convincingly negative, with less growth for nestlings living with more siblings, but there was near continuous variation in effect size from large negative effects to effects near zero, and even effects crossing the traditional threshold of statistical significance in the opposite direction. In contrast, the average relationship between grass cover and Eucalyptus seedling number was only slightly negative and not convincingly different from zero, and most effects ranged from weakly negative to weakly positive, with about a third of effects crossing the traditional threshold of significance in one direction or the other. However, there were also several striking outliers in the Eucalyptus dataset, with effects far from zero. For both datasets, we found substantial variation in the variable selection and random effects structures among analyses, as well as in the ratings of the analytical methods by peer reviewers, but we found no strong relationship between any of these and deviation from the meta-analytic mean. In other words, analyses with results that were far from the mean were no more or less likely to have dissimilar variable sets, use random effects in their models, or receive poor peer reviews than those analyses that found results that were close to the mean. The existence of substantial variability among analysis outcomes raises important questions about how ecologists and evolutionary biologists should interpret published results, and how they should conduct analyses in the future.

Global change is associated with variable shifts in the annual production of aboveground plant biomass, suggesting localized sensitivities with unclear causal origins. Combining remotely sensed normalized difference vegetation index data since the 1980s with contemporary field data from 84 grasslands on 6 continents, we show a widening divergence in site-level biomass ranging from +51% to −34% globally. Biomass generally increased in warmer, wetter and species-rich sites with longer growing seasons and declined in species-poor arid areas. Phenological changes were widespread, revealing substantive transitions in grassland seasonal cycling. Grazing, nitrogen deposition and plant invasion were prevalent in some regions but did not predict overall trends. Grasslands are undergoing sizable changes in production, with implications for food security, biodiversity and carbon storage especially in arid regions where declines are accelerating.

Recent Socio-economic changes resulted to mass abandonment of agricultural lands in Central-Eastern Europe. This leads to landscapes homogenisation, especially the disappearance of semi-open habitats of the farmland-woodland interface. The information on potentials of transforming feral, abandoned landscapes to wood-pastures is limited. We studied the ecological features and silvopastoral benefits of a landscape subjected to intensive cattle grazing after ~20 years of abandonment, i.e. the mosaic of habitats, cattle’s preference for habitats and for arboreal forages. The nutritional characteristics of arboreal forage and herbaceous forage were compared. After the initial increase in the landscape’s woodland share, cattle grazing halted further woody succession and stabilised the landscape structure, with treeless grassland occupying 49% of the landscape (most preferred by cattle with regard to the time spent), followed by treed grassland (19%), pioneering birch/alder groves (13%), riparian vegetation (12%, least preferred by cattle), and close-canopy woods (6%). The consumption intensity of arboreal forages was on about 4.5 folds higher than that of herbaceous forage. Our study proved that the grazing herd of arobust cattle breed can turn a feral, post-agricultural land into a working wood pasture, consisting of interconnected open grasslands and various facets of woodland, which seldom occur in contemporary high forests. We advocate for the transition management of abandoned farmlands towards integrated silvopastoral landscapes for sustainable provision of multiple ecosystem services that cannot be provided by segregated agriculture and forestry.

Asexual reproduction plays a fundamental role in the structure, dynamics and persistence of perennial grasslands. Thus, assessing how asexual reproductive traits of plant communities respond to drought may be key for understanding grassland resistance to drought and recovery following drought. Here, we quantified three asexual reproductive traits (i.e. above‐ground tiller abundance, below‐ground bud abundance and the ratio of tillers to buds) during a 4‐year severe drought and a 2‐year drought recovery period in four grasslands that spanned an aridity gradient in northern China. We also assessed the relationship between these traits and the resistance and recovery of above‐ground net primary productivity (ANPP). We found that drought had limited and largely inconsistent effects on asexual reproduction among drought and recovery years and grasslands overall. Drought increased tiller abundance in the first treatment year and reduced bud banks by the fourth treatment year across grasslands. However, neither of the three asexual reproductive traits were correlated with drought resistance of ANPP. Drought legacies differed among the four grasslands with positive, negative and no legacies evident for the three asexual reproductive traits, and no clear relationship with aridity. Bud banks and tiller to bud ratio decreased and increased, respectively, in the first recovery year, but not in the second recovery year. In contrast to drought resistance, community bud abundance was strongly related to recovery, such that communities with higher bud abundance had greater ANPP recovery following drought. Synthesis. These results suggest that asexual reproductive traits may be important drivers of ecosystem recovery after drought, but that variable responses of these asexual reproduction traits during drought complicates predictions of overall grassland responses.