Impacts of large herbivores on terrestrial ecosystems

Lateral jaw motion in fish expands the functional repertoire of vertebrates and underpins the success of a dominant herbivore lineage

The primary function of the vertebrate jaw is the dorsoventral movement that occurs during opening and closing. Yet, several lineages have evolved the ability to move their jaws laterally, enabling major innovations, like chewing. While lateral jaw motions are primarily known in tetrapods, here, we show that an ecologically dominant lineage of reef fishes (Zanclidae and Acanthuridae) has evolved the ability to laterally rotate their jaws during feeding. This unique function substantially expands both the kinematic versatility and known diversity of vertebrate jaw mechanisms, adding to the growing list of innovations that followed the origin of jaws. Within Acanthuridae, this increased kinematic versatility may allow for algal detachment with minimal movement of the rest of the body, facilitating rapid biting within the same microtopographic location, and thus, this lineage having the highest bite rates among biting reef fishes. This innovation may have thus helped create one of the most ecologically diverse and speciose herbivorous reef fish lineages. Our results highlight the ecological and evolutionary impact of lateral jaw rotation within vertebrates, and potentially how this novelty led to a significant change in coral reef trophodynamics.

Temperate forest plants are associated with heterogeneous semi-open canopy conditions shaped by large herbivores

Temperate forest plant diversity is declining despite increasing conservation efforts. The closed forest paradigm, emphasizing dense, continuous canopy cover, dominates current forest management strategies. However, this approach may overlook the historical role of large herbivores in maintaining semi-open forest conditions. Here we analyse the light and herbivory preferences of 917 native temperate forest plant species across central and western Europe, comparing these preferences with light availability in untouched closed-canopy forests and pasture woodlands. Plant species are 0.1-10 Myr old, with phylogenetic conservatism in habitat affinities (niche optima); thus, their distribution reflects long-term environmental states. We found that most temperate forest plants favour heterogeneous, semi-open-canopy conditions associated with high large-herbivore impacts, rather than uniform closed-canopy environments. On the basis of Red List criteria, high-affinity forest plants associated with higher herbivory and lower herbaceous biomass face higher extinction risk, indicating that low large-herbivore densities drive extinctions in present-day forests. These results align with palaeoecological evidence and high biodiversity in modern open woodlands, suggesting that closed-canopy dominance is a recent consequence of human-driven herbivore loss. Recognizing the role of large herbivores in maintaining semi-open vegetation offers new insights for biodiversity conservation and challenges the suitability of closed-canopy models in forest management.

Mammalian Browsers Disrupt Eco-Evolutionary Dynamics in a Forest Tree Restoration Planting

Native and restored forests are increasingly impacted by pests and diseases, including large herbivores. While community- and species-level impacts of these tree enemies are often well-documented, there is little understanding of their influence on finer-scale eco-evolutionary processes. We here study the influence of large-mammal herbivory on the survival and height growth of trees in a mixed species restoration planting of the Australian forest trees, Eucalyptus ovata and E. pauciflora, in Tasmania, Australia. Common-garden field trials mixing the two species were compared in adjacent unbrowsed (fenced) and browsed (unfenced) plantings. The browsed planting was exposed to mammal browsing by native marsupials, as well as feral introduced European fallow deer (Dama dama). Each tree species was represented by open-pollinated families from 22 paired geographic areas, allowing the assessment of the effects of browsing on the species and population differences, as well as on family variation within each species. In the browsed planting, a marked reduction in species and population differences, as well as in family variance, was observed for both height growth and survival. The pattern of height growth and survival of the populations of both species also differed between browsing regimes, with significant changes of climate relationships involving both focal tree attributes detected. Our results argue for a major disruption of the eco-evolutionary dynamics of restored forests in the presence of browsing by large mammalian herbivores, at the observed period of the tree life cycle. Importantly for forest restoration and conservation in the face of global change, our results challenge the choice of tree populations for translocation based solely on predicted or observed relationships of their home-site climate with current and predicted future climates of the restoration sites, while emphasising the need for genetic diversity to provide future resilience of restored forests to both biotic and abiotic stresses.

Litter biomass was the main factor driving plant diversity following grazing exclusion in shrub - Grassland ecotone of eastern Qilian Mountains

Plant diversity loss induced by grassland degradation poses a serious problem to the ecological environment and economic industry. Grazing exclusion is widely adopted as an effective management practice to enhance the sustainability of grassland ecosystems. However, limited information exists regarding the effects of grazing exclusion on plant diversity and its interaction with plant and soil characteristics, particularly in shrub‒grassland ecotones, which are highly sensitive to environmental changes. This study investigated a shrub‒grassland ecotone with light and heavy degradation during a 4-7 year restoration process to evaluate plant species diversity, plant and soil characteristics, and the coupling or decoupling between these factors following grazing exclusion. Containment monitoring experiments over 4 years at the same site revealed the following: 1) Grazing exclusion significantly increased the aboveground biomass, root biomass of herbage and shrub, as well as litter biomass. The aboveground biomass and root biomass of herbage and shrub, as well as litter biomass at the LI site increased by 15.7-22.4 % and 7.2-19.7 %, 21.1-27.0 % and 4.4-24.7 %, 3.33-6.0 times, compared to those at the LO site; Similarly, at the HI site, these metrics increased by 0.78-1.10 and 0.21-0.94 times, 0.25-0.57 and 0.15-0.36 times, and 8.28-15.10 times, compared to those at the HO site. However, grazing exclusion significantly reduced the Shannon‒Wiener index and evenness index of herbage, shrub and plant community, as well as the richness index of herbage and plant community. While increasing shrub richness. For herbage at the LI and HI sites, the Shannon‒Wiener index, evenness index, and richness decreased by 19.3-27.4 % and 4.0-13.8 %, 1.0-4.6 % and 1.8-6.1 %, and 32.2-53.3 % and 1.0-22.4 %, respectively. For shrubs, the Shannon‒Wiener index and evenness index (excluding richness) decreased by 2.4-7.0 % 0.9-3.2 %, and 1.7-29.0 % and 19.5-21.3 %; and that of plant community decreased by 13.5-18.7 % and 4.9-6.7 %,1.7-19.8 % and 2.6-15.7 %, 20.1-47.5 % and 8.1-10.3 %. The shrub richness, however, increased by 2.7-36.6 % and 26.8-29.2 % at the LI and HI sites compared to the LO and HO sites. 2) Grazing exclusion significantly increased soil organic matter, available nitrogen, phosphorus, potassium, and enzymatic activities (sucrase, catalase, alkaline phosphatase, urease, and cellulase). Soil organic matter, available nitrogen, available phosphorus and available potassium at the LI and HI sites increased by 7.5-23.0 % and 10.8-35.4 %, 6.9-11.0 % and 19.9-27.8 %, 10.5-16.8 % and 13.8-22.6 %, 5.3-37.8 % and 15.7-46.1 %, and 12.8-23.85 and 26.3-41.6 %, and soil sucrase, soil catalase, soil alkaline phosphatase, soil urease and soil cellulase activities increased by 4.1-34.5 % and 29.4-46.4 %, 19.5-43.6 % and 21.0-54.2 %, 23.6-52.1 % and 26.8-45.9 %, 21.6-60.0 % and 61.8-87.4 %, and 16.1-23.4 % and 18.8-43.5 %, compared to those at the LO and HO sites, respectively. 3) Sucrase activity exhibited the direct positive effects on the diversity of herbaceous and shrub, soil temperature and soil sucrase had a direct positive effect on plant community diversity. 4) Soil organic matter, soil mass water content and litter biomass had direct negative effects on herbaceous diversity; shrubs aboveground biomass, soil catalase and litter biomass had direct negative effects on shrub diversity; shrub coverage and litter biomass had direct negative effects on plant community diversity. 5) A piecewise structural equation model revealed that litter biomass was the main factor driving herbage, shrub and plant community diversity. Our research provides evidence that grazing exclusion for 4-7 years was not beneficial to maintaining plant diversity. We suggest that grazing exclusion over 4-7 years is not conducive to maintaining plant diversity. Integrating grazing exclusion with other management practices is recommended to preserve plant diversity, reverse grassland degradation, and support ecosystem restoration and reconstruction.

A call for increased integration of experimental approaches in movement ecology

Rapid developments in animal-tracking technology have enabled major advances in the field of movement ecology, which seeks to understand the drivers and consequences of movement across scales, taxa, and ecosystems. The field has made ground-breaking discoveries, yet the majority of studies in movement ecology remain reliant on observational approaches. While important, observational studies are limited compared to experimental methods that can reveal causal relationships and underlying mechanisms. As such, we advocate for a renewed focus on experimental approaches in animal movement ecology. We illustrate a way forward in experimental movement ecology across two fundamental levels of biological organisation: individuals and social groups. We then explore the application of experiments in movement ecology to study anthropogenic influences on wildlife movement, and enhance our mechanistic understanding of conservation interventions. In each of these examples, we draw upon previous research that has effectively employed experimental approaches, while highlighting outstanding questions that could be answered by further experimentation. We conclude by highlighting the ways experimental manipulations in both laboratory and natural settings provide a promising way forward to generate mechanistic understandings of the drivers, consequences, and conservation of animal movement.

Interactive Effects of Climate and Large Herbivore Assemblage Drive Plant Functional Traits and Diversity

Large herbivore communities are changing globally, with populations of wild herbivores generally declining while domestic herbivore populations are increasing, influencing ecosystem function along with the impacts of climate change. Manipulative experiments have rarely captured the interaction between patterns of large herbivore assemblage change and climatic conditions. This interaction may affect the functional traits and functional diversity of herbaceous communities; this requires investigation, as these metrics have been useful proxies for ecosystem function. We used a large herbivore exclosure experiment replicated along a topo-climatic gradient to explore the interaction between climate and herbivore assemblage on community-level functional traits and the functional diversity of herbaceous plant understories. Our findings demonstrate interacting effects between large herbivore assemblages and climate. We found a shift from drought-tolerant traits to drought-avoidant traits with increasing aridity, specifically with regard to plant leaf area and specific leaf area. We also determined that plant community responses to grazing changed from an herbivore avoidance strategy at drier sites to a more herbivore-tolerant strategy at wetter sites. We observed that the effects of herbivores on community-level traits can sometimes counteract those of climate. Finally, we found that cattle and large wild herbivores can differ in the magnitude and direction of effects on functional traits and diversity.

Sodium Retention in Large Herbivores: Physiological Insights and Zoogeochemical Consequences

The assimilation, retention, and release of nutrients by animals fundamentally shapes their physiology and contributions to ecological processes (e.g., zoogeochemistry). Yet, information on the transit of nutrients through the bodies of large mammals remains scarce. Here, we examined how sodium (Na), a key element for animal health and ecosystem functioning, travels differently through fecal and urinary systems of cows (Bos taurus) and horses (Equus ferus caballus). We provided a large dose of Na and compared its timing of release in feces and urine to that of nonabsorbable markers. Na excretion by urine occurred approximately twice as fast as excretion by feces, yet both were shorter than indigestible particle markers. These differences correspond to rapid absorption of Na in the upper gastrointestinal tract and transport by blood to the kidneys (urine Na excretion) or resecretion of Na into the lower intestinal tract (fecal Na excretion). Interestingly, for cows, we found a second peak of Na excretion in urine and feces > 96 h after dosage. This result may indicate that surplus Na can be rapidly absorbed and stored in specific body cells (e.g., skin), from which it is later released. Using a propagule dispersal model, we found that the distance of cattle- and horse-driven nutrient dispersal by urine was 31% and 36% less than the fecal pathway and 60% and 41% less than the particle marker pathway, which is commonly used to estimate nutrient dispersal. Future physiological and zoogeochemical studies should resolve different pathways of nutrient retention and release from large mammals.

Enamel carbon, oxygen, and strontium isotopes reveal limited mobility in an extinct rhinoceros at Ashfall Fossil Beds, Nebraska, USA

Ashfall Fossil Beds in Nebraska, USA, was a mid-Miocene (11.86 ± 0.13 Ma) watering-hole that preserved hundreds of herbivores in volcanic ash. The short-legged, barrel-bodied rhinoceros, Teleoceras major (Mammalia; Rhinocerotidae), is abundant at Ashfall (> 100 individuals), leading some researchers to suggest individuals formed large groups, while others have argued they congregated at Ashfall seeking refuge from the ash that ultimately caused their death. Here, we evaluated three types of mobility-natal dispersal of subadults, seasonal migration, and response to natural disaster-using carbon, oxygen, and strontium isotope ratios in tooth enamel from thirteen T. major adult individuals. We bulk and serially sampled enamel from mandibular second and third molars, which should respectively record behaviour after weaning but before and after possible natal dispersal. Results indicate that all sampled individuals had limited mobility and were local to Ashfall. Semi-aquatic adaptations likely restricted T. major to wet habitats and prohibited long-distance movement. Social (rather than spatial) dispersal, seasonal dietary flexibility, and elevated Miocene primary productivity could have allowed individuals to maintain genetic diversity and avoid depleting local resources. Reconstructing how extinct ungulates utilized ancient landscapes provides important context for understanding their paleoecology and sociality as well as the environments they inhabited.

Factors Affecting the Occupancy of Gaur (Bos gaurus) During Winter Season in Parsa National Park, Nepal

Gaur (Bos gaurus) is a globally vulnerable species with a decline of more than 80% of their global distribution in the past 100 years. Understanding the species distribution pattern and associated factors is essential for developing effective conservation strategies. We examined the effects of forest area, human detections, presence of tiger (Panthera tigris), presence of competing species like Asian elephant (Elephas maximus), and sambar deer (Rusa unicolor), and distance to water, on gaur occupancy in Parsa National Park (PNP), Nepal, using camera traps which were deployed at 67 locations from December 2022 to March 2023. We used single season single species occupancy modeling to estimate the relationship of selected covariates with gaur occupancy. We recorded a total of 54 gaur detections in our study. We found that gaur occupancy had a significant positive association with the distance to water bodies and was negatively associated with forest area and the presence of elephants; however, there was no significant association with number of humans detected, or the presence of tigers, or sambar deers. Gaur had greater detection probabilities in southcentral portions of PNP, i.e., flat plains and areas near the Chure region and the lowest detection probabilities in the eastern and western parts of PNP. These findings highlight the importance of considering eco-environmental factors in the management and conservation of gaur, particularly in human-dominated landscapes. We recommend further multi-seasonal studies to better understand the dynamic interactions between gaur, their environment, and other species, to inform effective conservation strategies.

Does death drive the scaling of life?

The magnitude of many kinds of biological structures and processes scale with organismal size, often in regular ways that can be described by power functions. Traditionally, many of these "biological scaling" relationships have been explained based on internal geometric, physical, and energetic constraints according to universal natural laws, such as the "surface law" and "3/4-power law". However, during the last three decades it has become increasingly apparent that biological scaling relationships vary greatly in response to various external (environmental) factors. In this review, I propose and provide several lines of evidence supporting a new ecological perspective that I call the "mortality theory of ecology" (MorTE). According to this viewpoint, mortality imposes time limits on the growth, development, and reproduction of organisms. Accordingly, small, vulnerable organisms subject to high mortality due to predation and other environmental hazards have evolved faster, shorter lives than larger, more protected organisms. A MorTE also includes various corollary, size-related internal and external causative factors (e.g. intraspecific resource competition, geometric surface area to volume effects on resource supply/transport and the protection of internal tissues from environmental hazards, internal homeostatic regulatory systems, incidence of pathogens and parasites, etc.) that impact the scaling of life. A mortality-centred approach successfully predicts the ranges of body-mass scaling slopes observed for many kinds of biological and ecological traits. Furthermore, I argue that mortality rate should be considered the ultimate (evolutionary) driver of the scaling of life, that is expressed in the context of other proximate (functional) drivers such as information-based biological regulation and spatial (geometric) and energetic (metabolic) constraints.

Water economics of African savanna herbivores: How much does plant moisture matter?

Water is an essential and often limiting resource that pervades all aspects of animal ecology. Yet, water economics are grossly understudied relative to foraging and predation, leaving ecologists ill-equipped to predict how the intensifying disruption of hydrological regimes worldwide will impact communities. For savanna herbivores, reliance on surface water can increase exposure to predators and competitors, and thus strategies that reduce the need to drink are advantageous. Yet, the extent to which increasing dietary water intake while decreasing water loss enables animals to forego drinking remains unknown. We studied water budgets of sympatric African savanna antelopes that differ in size, bushbuck (Tragelaphus sylvaticus, ~35 kg) and kudu (T. strepsiceros, ~140 kg). We hypothesized that both species compensate for seasonally declining water availability by increasing consumption of moisture-rich plants and reducing faecal water loss, and that these adjustments are sufficient for small-bodied-but not large-bodied-herbivores to avoid spending more time near permanent water sources as the dry season advances. We tested our predictions using temporally explicit data on antelope movements, diets, plant traits and drinking behaviour in Gorongosa National Park, Mozambique. Water content declined between the early and late dry seasons in roughly half of plant taxa consumed by antelope. Although both species reduced faecal water loss and shifted their diets towards relatively moisture-rich plants as the dry season progressed, dietary water intake still declined. Contrary to expectation, kudu reduced selection for surface water in the late dry season without adjusting total time spent drinking, whereas bushbuck increased selection for surface water. We developed a generalizable approach for parsing the importance of dietary and surface water for large herbivores. Our results underscore that variation in surface-water dependence is a key organizing force in herbivore communities, that simple allometric predictions about the behavioural and ecological consequences of this variation are unreliable. Understanding wildlife water economics is a research frontier that will be essential for predicting changes in species distribution and community composition as temperatures rise and droughts intensify.

The Late-Quaternary Extinctions Gave Rise to Functionally Novel Herbivore Assemblages

Various authors have suggested that extinctions and extirpations of large mammalian herbivores during the last ca. 50,000 years have altered ecological processes. Yet, the degree to which herbivore extinctions have influenced ecosystems has been difficult to assess because past changes in herbivore impact are difficult to measure directly. Here, we indirectly estimated changes in (theorised) herbivore impact by comparing the functional composition of current large (≥ 10 kg) mammalian herbivore assemblages to those of a no-extinction scenario. As an assemblage's functional composition determines how it interacts with its environment, changes in functional compositions should correspond to changes in ecological impacts. We quantified functional composition using the body mass, diet and life habit of all wild herbivorous mammal species (n = 502) present during the last 130,000 years. Next, we assessed whether these changes in functional composition were large enough that the resulting assemblages could be considered functionally novel. Finally, we assessed where novel herbivore assemblages would most likely lead to changes in biome state. We found that 47% of assemblages are functionally novel, indicating fundamental changes in herbivore impacts occurred across much of the planet. On 20% of land, functionally novel herbivore assemblages have arisen in areas where alternative biome states are possible depending on the disturbance regime. Thus, in many regions, the late-Quaternary extinctions and extirpations altered herbivore assemblages so profoundly that there were likely major consequences for ecosystem functioning.

Rapid Assessment of Non-Volant Mammals in Selected Areas of Peninsular Malaysia

Non-volant mammals in Peninsular Malaysia face numerous threats, primarily driven by habitat loss, fragmentation and illegal hunting. These threats highlight the importance of conducting wildlife surveys in the available forested areas to enhance the current strategies for conservation and management, particularly for a threatened taxon like non-volant mammals. This study aimed to document and update information of non-volant mammals from four areas: Tasik Bera (Pahang state); Tasik Kenyir, Pulau Redang and Universiti Malaysia Terengganu (UMT) Campus (Terengganu state). Cage traps and Visual Encounter Survey methods were utilised to record non-volant mammals from August 2022 until March 2023. This study successfully documented 123 individuals from 27 non-volant mammal species, representing 11 families from 6 orders. Tasik Bera demonstrated the highest species count at 18, followed by UMT Campus with 6, while Tasik Kenyir and Pulau Redang each recorded 4 species. The species diversity was the highest at Tasik Bera (H' = 2.65) and the lowest at Pulau Redang (H' = 1.01). Macaca fascicularis, Tupaia glis and Paradoxurus hermaphroditus were recorded from three of four sites. This study has added new geographically recorded species for Tasik Bera (11 species) and UMT Campus (4 species). This study has advanced our knowledge of the diversity and distribution of non-volant mammals, enhancing our understanding in this field. This understanding is crucial for implementing efficient conservation and management strategies, aiding in the development of targeted conservation strategies to protect these species and their habitats.

Strontium isotope mapping of elephant enamel supports an integrated microsampling-modeling workflow to reconstruct herbivore migrations

Strontium isotope ratios (87Sr/86Sr) in dental tissues are widely used to study animal and human migration. However, questions remain regarding how different biological processes and sampling methods influence measured 87Sr/86Sr and subsequent interpretations. We present a unique experiment with the known relocation history of a zoo elephant to evaluate the influence of biological turnover, tissue type, and sampling methods. We collected 87Sr/86Sr data from the elephant's tusk and molar enamel using in-situ laser ablation microsampling, conventional drilling, and micromilling techniques. Our data comparisons show that the innermost enamel best records the primary 87Sr/86Sr turnover history, while enamel maturation affects outer enamel 87Sr/86Sr. Conventional drilling and micromilling show attenuated 87Sr/86Sr records due to enamel maturation and sample averaging. To effectively account for 87Sr/86Sr signal attenuation due to turnover, we demonstrated a microsampling-modeling workflow using our tusk and enamel data. This recommended workflow can facilitate geospatially explicit interpretations of seasonal migration.

Integrating Network and Meta-Ecosystem Models for Developing a Zoogeochemical Theory

Human activities have caused significant changes in animal abundance, interactions, movement and diversity at multiple scales. Growing empirical evidence reveals the myriad ways that these changes can alter the control that animals exert over biogeochemical cycling. Yet a theoretical framework to coherently integrate animal abundance, interactions, movement and diversity to predict when and how animal controls over biogeochemical cycling (i.e., zoogeochemistry) change is currently lacking. We present such a general framework that provides guidance on linking mathematical models of species interaction and diversity (network theory) and movement of organisms and non-living materials (meta-ecosystem theory) to account for biotic and abiotic feedback by which animals control biogeochemical cycling. We illustrate how to apply the framework to develop predictive models for specific ecosystem contexts using a case study of a primary producer-herbivore bipartite trait network in a boreal forest ecosystem. We further discuss key priorities for enhancing model development, data-model integration and application. The framework offers an important step to enhance empirical research that can better inform and justify broader conservation efforts aimed at conserving and restoring animal populations, their movement and critical functional roles in support of ecosystem services and nature-based climate solutions.

Preventing extinction in an age of species migration and planetary change

International and national conservation policies almost exclusively focus on conserving species in their historic native ranges, thus excluding species that have been introduced by people and some of those that have extended their ranges on their own accord. Given that many of such migrants are threatened in their native ranges, conservation goals that explicitly exclude these populations may overlook opportunities to prevent extinctions and respond dynamically to rapidly changing environmental and climatic conditions. Focusing on terrestrial mammals, we quantified the number of threatened mammals that have established new populations through assisted migration (i.e., introduction). We devised 4 alternative scenarios for the inclusion of assisted-migrant populations in mainstream conservation policy with the aim of preventing global species extinctions. We then used spatial prioritization algorithms to simulate how these scenarios could change global spatial conservation priorities. We found that 22% (70 species out of 265) of all identified assisted-migrant mammals were threatened in their native ranges, mirroring the 25% of all mammals that are threatened. Reassessing global threat statuses by combining native and migrant ranges reduced the threat status of 23 species (∼33% of threatened assisted migrants). Thus, including migrant populations in threat assessments provides a more accurate assessment of actual global extinction risk among species. Spatial prioritization simulations showed that reimagining the role of assisted-migrant populations in preventing species extinction could increase the importance of overlooked landscapes, particularly in central Australia, Europe, and the southwestern United States. Our results indicated that these various and nonexhaustive ways to consider assisted-migrant populations, with due consideration of potential conservation conflicts with resident taxa, may provide unprecedented opportunities to prevent species extinctions.

Habitat quality outweighs the human footprint in driving spatial patterns of Cetartiodactyla in the Kunlun-Pamir Plateau

The Human Footprint (HFP) and Habitat Quality (HQ) are critical factors influencing the species' distribution, yet their relation to biodiversity, particularly in mountainous regions, still remains inadequately understood. This study aims to identify the primary factor that affects the biodiversity by comparing the impact of the HFP and HQ on the species' richness of Cetartiodactyla in the Kunlun-Pamir Plateau and four protected areas: The Pamir Plateau Wetland Nature Reserve, Taxkorgan Wildlife Nature Reserve, Middle Kunlun Nature Reserve and Arjinshan Nature Reserve through multi-source satellite remote sensing product data. By integrating satellite data with the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST)HQ model and utilizing residual and linear regression analysis, we found that: (1) The Wildness Area (WA) predominantly underwent a transition to a Highly Modified Area (HMA) and Intact Area (IA), with a notable 12.02% rise in stable regions, while 58.51% rather experienced a negligible decrease. (2) From 1985 to 2020, the Kunlun-Pamir Plateau has seen increases in the forestland, water, cropland and shrubland, alongside declines in bare land and grassland, denoting considerable land cover changes. (3) The HQ degradation was significant, with 79.81% of the area showing degradation compared to a 10.65% improvement, varying across the nature reserves. (4) The species richness of Cetartiodactyla was better explained by HQ than by HFP on the Kunlun-Pamir Plateau (52.99% vs. 47.01%), as well as in the Arjinshan Nature Reserve (81.57%) and Middle Kunlun Nature Reserve (56.41%). In contrast, HFP was more explanatory in the Pamir Plateau Wetland Nature Reserve (88.89%) and the Taxkorgan Wildlife Nature Reserve (54.55%). Prioritizing the restoration of degraded habitats areas of the Kunlun Pamir Plateau could enhance Cetartiodactyla species richness. These findings provide valuable insights for the biodiversity management and conservation strategies in the mountainous regions.

Wild Ungulates and Cattle Have Different Effects on Litter Decomposition as Revealed by Fecal Addition in a Northeast Asian Temperate Forest

Litter decomposition is critical for maintaining productivity and nutrient cycling in forest ecosystems. Large herbivores play an essential role in determining the processes of nutrient cycling. Asian temperate forests are becoming degraded and fragmented by the widespread intensification of anthropogenic activities, including excessive livestock grazing. However, the effects of livestock grazing and wild ungulates on forest litter decomposition remain less explored. In this study, we used a litterbag experiment to investigate the effects of the addition of cattle (Bos taurus) and sika deer (Cervus nippon) feces on litter decomposition. The study was conducted in Northeast China from July 2022 to October 2023. We found that the addition of deer feces significantly reduced litter decomposition, but the addition of cattle feces greatly increased litter decomposition. The presence of cattle and deer excrement significantly accelerated the release of C after 1 year of litter decomposition. Compared with the results of the control group (no addition of feces), the addition of cattle and sika deer feces increased C release by 37.45% and 22.69%, respectively. Fecal addition increased the release of N; however, for the three treatment groups, the maximum accumulation of N occurred in the middle of litter decomposition, which may have been due to the initial chemical quality of the leaves and snow melt as well as nutrient limitations at the sites. Compared with the results of the control group, P release in the feces of cattle increased by 4.35%, but P release in the feces of deer decreased by 27.55%. This work highlights that feces deposition by large herbivores (e.g., wild or domestic) in the forest has nonequivalent effects on litter decomposition. Such effects may further alter the nutrient cycling in temperate forest ecosystems, with far-reaching effects on the ecosystem that deserve closer attention. We suggest that conservation managers should seek evidence-based interventions to optimize livestock use of forest habitats shared with wildlife.

Effects of multiple mammalian herbivores and climate on grassland-shrubland transitions in the Chihuahuan Desert

The replacement of grasses by shrubs or bare ground (xerification) is a primary form of landscape change in drylands globally with consequences for ecosystem services. The potential for wild herbivores to trigger or reinforce shrubland states may be underappreciated, however, and comparative analyses across herbivore taxa are sparse. We sought to clarify the relative effects of domestic cattle, native rodents, native lagomorphs, and exotic African oryx (Oryx gazella) on a Chihuahuan Desert grassland undergoing shrub encroachment. We then asked whether drought periods, wet season precipitation, or interspecific grass-shrub competition modified herbivore effects to alter plant cover, species diversity, or community composition. We established a long-term experiment with hierarchical herbivore exclosure treatments and surveyed plant foliar cover over 25 years. Cover of honey mesquite (Prosopis glandulosa) proliferated, responding primarily to climate, and was unaffected by herbivore treatments. Surprisingly, cattle and African oryx exclusion had only marginal effects on perennial grass cover at their current densities. Native lagomorphs interacted with climate to limit perennial grass cover during wet periods. Native rodents strongly decreased plant diversity, decreased evenness, and altered community composition. Overall, we found no evidence of mammalian herbivores facilitating or inhibiting shrub encroachment, but native small mammals interacting with climate drove dynamics of herbaceous plant communities. Ongoing monitoring will determine whether increased perennial grass cover from exclusion of native lagomorphs and rodents slows the transition to a dense shrubland.

The influence of vertebrate scavengers on leakage of nutrients from carcasses

The decomposition of carcasses by scavengers and microbial decomposers is an important component of the biochemical cycle that can strongly alter the chemical composition of soils locally. Different scavenger guilds are assumed to have a different influence on the chemical elements that leak into the soil, although this assumption has not been empirically tested. Here, we experimentally determine how different guilds of vertebrate scavengers influence local nutrient dynamics. We performed a field experiment in which we systematically excluded different subsets of vertebrate scavengers from decomposing carcasses of fallow deer (Dama dama), and compared elemental concentrations in the soil beneath and in the vegetation next to the carcasses over time throughout the decomposition process. We used four exclusion treatments: excluding (1) no scavengers, thus allowing them all; (2) wild boar (Sus scrofa); (3) all mammals; and (4) all mammals and birds. We found that fluxes of several elements into the soil showed distinct peaks when all vertebrates were excluded. Especially, trace elements (Cu and Zn) seemed to be influenced by carcass decomposition. However, we found no differences in fluxes between partial exclusion treatments. Thus, vertebrate scavengers indeed reduce leakage of elements from carcasses into the soil, hence influencing local biochemical cycles, but did so independent of which vertebrate scavenger guild had access. Our results suggest that carcass-derived elements are dispersed over larger areas rather than locally leak into the soil when vertebrate scavengers dominate the decomposition process.

Behavioural responses to mammalian grazing expose insect herbivores to elevated risk of avian predation

Large mammalian herbivores (LMH) are important functional components and drivers of biodiversity and ecosystem functioning in grasslands. Yet their role in regulating food-web dynamics and trophic cascades remains poorly understood. In the temperate grasslands of northern China, we explored whether and how grazing domestic cattle (Bos taurus) alter the predator-prey interactions between a dominant grasshopper (Euchorthippus unicolor) and its avian predator the barn swallow (Hirundo rustica). Using two large manipulative field experiments, we found that in the presence of cattle, grasshoppers increased their jumping frequency threefold, swallows increased foraging visits to these fields sixfold, and grasshopper density was reduced by about 50%. By manipulatively controlling the grasshoppers' ability to jump, we showed that jumping enables grasshoppers to avoid being incidentally consumed or trampled by cattle. However, jumping behaviour increased their consumption rates by swallows 37-fold compared with grasshoppers that were unable to jump. Our findings illustrate how LMH can indirectly alter predator-prey interactions by affecting behaviour of avian predators and herbivorous insects. These non-plant-mediated effects of LMH may influence trophic interactions in other grazing ecosystems and shape community structure and dynamics. We highlight that convoluted multispecies interactions may better explain how LMH control food-web dynamics in grasslands.

The Protection and Management of Wapiti in Desert Oases: Bare Land Poses a Limitation to Wapiti Conservation

The Helan Mountains, situated in the heart of the desert, act as a dividing line between China's arid and semi-arid zones. Often referred to as a "desert oasis", they create an ecological island with a uniquely distinctive geographical location, making this area a focal point of contemporary research. Ungulates play a critical role in this ecosystem. The Alashan wapiti (Cervus canadensis alashanicus), an isolated population of China's smallest wapiti (Cervus canadensis) subspecies, is found exclusively within the Helan Mountains Nature Reserve. The conservation of this isolated population is fraught with challenges, particularly during winter, the harshest season for northern ungulates. Winter habitats are crucial for ensuring population stability. Therefore, we used certain methods, such as factor screening and model parameter optimization to assess habitat suitability using multi-scale species distribution models. The optimized results show that suitable habitats overlap with areas of high vegetation coverage in the Helan Mountains, covering just 588.32 km2, which is less than a quarter of the reserve's total area. The bare land area and winter NDVI are the two primary factors influencing habitat suitability, with other factors having minimal impact, underscoring the critical importance of food resources for the Alashan wapiti. The limited availability of these resources poses significant conservation challenges. Our findings provide a more precise foundation for targeted habitat protection and restoration efforts. We recommend enhancing the protection and restoration of food resources, effectively conserving vegetated areas, and preventing desertification.

Body size modulates the extent of seasonal diet switching by large mammalian herbivores in Yellowstone National Park

Prevailing theories about animal foraging behaviours and the food webs they occupy offer divergent predictions about whether seasonally limited food availability promotes dietary diversification or specialization. Emphasis on how animals compete for food predominates in work on the foraging ecology of large mammalian herbivores, whereas emphasis on how the diversity of available foods generally constrains dietary opportunity predominates work on entire food webs. Reconciling predictions about what promotes dietary diversification is challenging because species' different body sizes and mobilities modulate how they seek and compete for resources-the mechanistic bases of common predictions may not pertain to all species equally. We evaluated predictions about five large-herbivore species that differ in body size and mobility in Yellowstone National Park using GPS tracking and dietary DNA. The data illuminated remarkably strong and significant correlations between body size and five key indicators of diet seasonality (R 2 = 0.71-0.80). Compared to smaller species, bison and elk showed muted diet seasonality and maintained access to more unique foods when winter conditions constrained food availability. Evidence from GPS collars revealed size-based differences in species' seasonal movements and habitat-use patterns, suggesting that better accounting for the allometry of foraging behaviours may help reconcile disparate ideas about the ecological drivers of seasonal diet switching.

Environmental DNA metabarcoding reveals temporal dynamics but functional stability of arthropod communities in cattle dung

Terrestrial invertebrates are highly important for the decomposition of dung from large mammals. Mammal dung has been present in many of Earth's ecosystems for millions of years, enabling the evolution of a broad diversity of dung-associated invertebrates that process various components of the dung. Today, large herbivorous mammals are increasingly introduced to ecosystems with the aim of restoring the ecological functions formerly provided by their extinct counterparts. However, we still know little about the ecosystem functions and nutrient flows in these rewilded ecosystems, including the dynamics of dung decomposition. In fact, the succession of insect communities in dung is an area of limited research attention also outside a rewilding context. In this study, we use environmental DNA metabarcoding of dung from rewilded Galloway cattle in an experimental set-up to investigate invertebrate communities and functional dynamics over a time span of 53 days, starting from the time of deposition. We find a strong signal of successional change in community composition, including for the species that are directly dependent on dung as a resource. While several of these species were detected consistently across the sampling period, others appeared confined to either early or late successional stages. We believe that this is indicative of evolutionary adaptation to a highly dynamic resource, with species showing niche partitioning on a temporal scale. However, our results show consistently high species diversity within the functional groups that are directly dependent on dung. Our findings of such redundancy suggest functional stability of the dung-associated invertebrate community, with several species ready to fill vacant niches if other species disappear. Importantly, this might also buffer the ecosystem functions related to dung decomposition against environmental change. Interestingly, alpha diversity peaked after approximately 20-25 days in both meadow and pasture habitats, and did not decrease substantially during the experimental period, probably due to preservation of eDNA in the dung after the disappearance of visiting invertebrates, and from detection of tissue remains and cryptic life stages.

The impact of insect herbivory on biogeochemical cycling in broadleaved forests varies with temperature

Herbivorous insects alter biogeochemical cycling within forests, but the magnitude of these impacts, their global variation, and drivers of this variation remain poorly understood. To address this knowledge gap and help improve biogeochemical models, we established a global network of 74 plots within 40 mature, undisturbed broadleaved forests. We analyzed freshly senesced and green leaves for carbon, nitrogen, phosphorus and silica concentrations, foliar production and herbivory, and stand-level nutrient fluxes. We show more nutrient release by insect herbivores at non-outbreak levels in tropical forests than temperate and boreal forests, that these fluxes increase strongly with mean annual temperature, and that they exceed atmospheric deposition inputs in some localities. Thus, background levels of insect herbivory are sufficiently large to both alter ecosystem element cycling and influence terrestrial carbon cycling. Further, climate can affect interactions between natural populations of plants and herbivores with important consequences for global biogeochemical cycles across broadleaved forests.

Validating the concept of top scavenger: the Andean Condor as a model species

Vultures provide the key ecosystem service of quickly removing carrion, so they have recently been assumed to be top scavengers. To challenge the concept of top scavenger (i.e. the most influential in the scavenging community and process), between 2012 and 2019, we recorded the consumption of 45 equine carcasses available for two different avian scavenger guilds in the Tropical Andes; each guild included the Andean Condor, the alleged top scavenger. The carcasses eaten by Andean Condors were consumed, on average, 1.75 times faster than those they did not eat. Furthermore, the greater abundance of feeding condors shortened carcass consumption time more than a greater abundance of any other species by 1.65 to 5.96 times, on average. These findings support the hypothesis that the Andean Condor significantly drives scavenging dynamics and is, therefore, an unrestricted top scavenger. Additionally, we established a gradient of tolerance of avian scavengers to domestic dog disturbance at carcasses, from highest to lowest: vultures > caracaras > condors. Our study framework holds great potential for advancing in food webs' comprehension through quantifying the relative functional role of scavenging communities' members and for guiding efforts to weigh up the ecological contributions of top scavengers and foster their conservation.

Grazing herbivores reduce herbaceous biomass and fire activity across African savannas

Fire and herbivory interact to alter ecosystems and carbon cycling. In savannas, herbivores can reduce fire activity by removing grass biomass, but the size of these effects and what regulates them remain uncertain. To examine grazing effects on fuels and fire regimes across African savannas, we combined data from herbivore exclosure experiments with remotely sensed data on fire activity and herbivore density. We show that, broadly across African savannas, grazing herbivores substantially reduce both herbaceous biomass and fire activity. The size of these effects was strongly associated with grazing herbivore densities, and surprisingly, was mostly consistent across different environments. A one-zebra increase in herbivore biomass density (~100 kg/km2 of metabolic biomass) resulted in a ~53 kg/ha reduction in standing herbaceous biomass and a ~0.43 percentage point reduction in burned area. Our results indicate that fire models can be improved by incorporating grazing effects on grass biomass.

Trophic rewilding as a restoration approach under emerging novel biosphere conditions

Rewilding is a restoration approach that aims to promote self-regulating complex ecosystems by restoring non-human ecological processes while reducing human control and pressures. Rewilding is forward-looking in that it aims to enhance functionality for biodiversity, accepting and indeed promoting the dynamic nature of ecosystems, rather than fixating on static composition or structure. Rewilding is thus especially relevant in our epoch of increasingly novel biosphere conditions, driven by strong human-induced global change. Here, we explore this hypothesis in the context of trophic rewilding - the restoration of trophic complexity mediated by wild, large-bodied animals, known as 'megafauna'. This focus reflects the strong ecological impacts of large-bodied animals, their widespread loss during the last 50,000 years and their high diversity and ubiquity in the preceding 50 million years. Restoring abundant, diverse, wild-living megafauna is expected to promote vegetation heterogeneity, seed dispersal, nutrient cycling and biotic microhabitats. These are fundamental drivers of biodiversity and ecosystem function and are likely to gain importance for maintaining a biodiverse biosphere under increasingly novel ecological conditions. Non-native megafauna species may contribute to these effects as ecological surrogates of extinct species or by promoting ecological functionality within novel assemblages. Trophic rewilding has strong upscaling potential via population growth and expansion of wild fauna. It is likely to facilitate biotic adaptation to changing climatic conditions and resilience to ecosystem collapse, and to curb some negative impacts of globalization, notably the dominance of invasive alien plants. Finally, we discuss the complexities of realizing the biodiversity benefits that trophic rewilding offers under novel biosphere conditions in a heavily populated world.

Wilder rangelands as a natural climate opportunity: Linking climate action to biodiversity conservation and social transformation

Rangelands face threats from climate and land-use change, including inappropriate climate change mitigation initiatives such as tree planting in grassy ecosystems. The marginalization and impoverishment of rangeland communities and their indigenous knowledge systems, and the loss of biodiversity and ecosystem services, are additional major challenges. To address these issues, we propose the wilder rangelands integrated framework, co-developed by South African and European scientists from diverse disciplines, as an opportunity to address the climate, livelihood, and biodiversity challenges in the world's rangelands. More specifically, we present a Theory of Change to guide the design, monitoring, and evaluation of wilder rangelands. Through this, we aim to promote rangeland restoration, where local communities collaborate with regional and international actors to co-create new rangeland use models that simultaneously mitigate the impacts of climate change, restore biodiversity, and improve both ecosystem functioning and livelihoods.

Resource partitioning in a novel herbivore assemblage in South America

Human-induced species declines and extinctions have led to the downsizing of large-herbivore assemblages, with implications for many ecosystem processes. Active reintroduction of extirpated large herbivores or their functional equivalents may help to reverse this trend and restore diverse ecosystems and their processes. However, it is unclear whether resource competition between native and non-native herbivores could threaten restoration initiatives, or to what extent (re)introduced species may influence local vegetation dynamics. To answer these questions, we investigated the diets of a novel South American herbivore assemblage that includes resident native species, reintroduced native species and introduced non-native species. We examined plant composition, diet breadth and the overlap between species to describe the local herbivory profile and the potential for resource competition. Using DNA metabarcoding on faecal samples (n = 465), we analysed the diets of the herbivore assemblage in the Rincón del Socorro rewilding area of Iberá National Park, Argentina. We compared the species richness of faecal samples, the occurrence of plant families/growth forms and the compositional similarity of samples (inter- and intraspecifically). Our results indicate species-level taxonomic partitioning of plant resources by herbivores in this system. Differences in sample richness, composition and diet breadth reflected a diverse range of herbivory strategies, from grazers (capybara) to mixed feeders/browsers (brocket deer, lowland tapir). Differences in diet compositional similarity (Jaccard) revealed strong taxonomic resource partitioning. The two herbivores with the most similar diets (Pampas deer and brocket deer) still differed by more than 80%. Furthermore, all but one species (axis deer) had more similar diet composition intraspecifically than compared to the others. Overall, we found little evidence for resource competition between herbivore species. Instead, recently reintroduced native species and historically introduced non-natives are likely expanding the range of herbivory dynamics in the ecosystem. Further research will be needed to determine the full ecological impacts of these (re)introduced herbivores. In conclusion, we show clear differences in diet breadth and composition among native, reintroduced and non-native herbivore species that may be key to promoting resource partitioning, species coexistence and the restoration of ecological function.

Meta-analysis shows that wild large herbivores shape ecosystem properties and promote spatial heterogeneity

Megafauna (animals ≥45 kg) have probably shaped the Earth's terrestrial ecosystems for millions of years with pronounced impacts on biogeochemistry, vegetation, ecological communities and evolutionary processes. However, a quantitative global synthesis on the generality of megafauna effects on ecosystems is lacking. Here we conducted a meta-analysis of 297 studies and 5,990 individual observations across six continents to determine how wild herbivorous megafauna influence ecosystem structure, ecological processes and spatial heterogeneity, and whether these impacts depend on body size and environmental factors. Despite large variability in megafauna effects, we show that megafauna significantly alter soil nutrient availability, promote open vegetation structure and reduce the abundance of smaller animals. Other responses (14 out of 26), including, for example, soil carbon, were not significantly affected. Further, megafauna significantly increase ecosystem heterogeneity by affecting spatial heterogeneity in vegetation structure and the abundance and diversity of smaller animals. Given that spatial heterogeneity is considered an important driver of biodiversity across taxonomic groups and scales, these results support the hypothesis that megafauna may promote biodiversity at large scales. Megafauna declined precipitously in diversity and abundance since the late Pleistocene, and our results indicate that their restoration would substantially influence Earth's terrestrial ecosystems.

The late-Quaternary megafauna extinctions: Patterns, causes, ecological consequences and implications for ecosystem management in the Anthropocene

Across the last ~50,000 years (the late Quaternary) terrestrial vertebrate faunas have experienced severe losses of large species (megafauna), with most extinctions occurring in the Late Pleistocene and Early to Middle Holocene. Debate on the causes has been ongoing for over 200 years, intensifying from the 1960s onward. Here, we outline criteria that any causal hypothesis needs to account for. Importantly, this extinction event is unique relative to other Cenozoic (the last 66 million years) extinctions in its strong size bias. For example, only 11 out of 57 species of megaherbivores (body mass ≥1,000 kg) survived to the present. In addition to mammalian megafauna, certain other groups also experienced substantial extinctions, mainly large non-mammalian vertebrates and smaller but megafauna-associated taxa. Further, extinction severity and dates varied among continents, but severely affected all biomes, from the Arctic to the tropics. We synthesise the evidence for and against climatic or modern human (Homo sapiens) causation, the only existing tenable hypotheses. Our review shows that there is little support for any major influence of climate, neither in global extinction patterns nor in fine-scale spatiotemporal and mechanistic evidence. Conversely, there is strong and increasing support for human pressures as the key driver of these extinctions, with emerging evidence for an initial onset linked to pre-sapiens hominins prior to the Late Pleistocene. Subsequently, we synthesize the evidence for ecosystem consequences of megafauna extinctions and discuss the implications for conservation and restoration. A broad range of evidence indicates that the megafauna extinctions have elicited profound changes to ecosystem structure and functioning. The late-Quaternary megafauna extinctions thereby represent an early, large-scale human-driven environmental transformation, constituting a progenitor of the Anthropocene, where humans are now a major player in planetary functioning. Finally, we conclude that megafauna restoration via trophic rewilding can be expected to have positive effects on biodiversity across varied Anthropocene settings.

Dead foundation species drive ecosystem dynamics

Foundation species facilitate communities, modulate energy flow, and define ecosystems, but their ecological roles after death are frequently overlooked. Here, we reveal the widespread importance of their dead structures as unique, interacting components of ecosystems that are vulnerable to global change. Key metabolic activity, mobility, and morphology traits of foundation species either change or persist after death with important consequences for ecosystem functions, biodiversity, and subsidy dynamics. Dead foundation species frequently mediate ecosystem stability, resilience, and transitions, often through feedbacks, and harnessing their structural and trophic roles can improve restoration outcomes. Enhanced recognition of dead foundation species and their incorporation into habitat monitoring, ecological theory, and ecosystem forecasting can help solve the escalating conservation challenges of the Anthropocene.

When function, not origin, matters

Native and introduced megaherbivores similarly affect plant diversity and abundance.

Functional traits-not nativeness-shape the effects of large mammalian herbivores on plant communities

Large mammalian herbivores (megafauna) have experienced extinctions and declines since prehistory. Introduced megafauna have partly counteracted these losses yet are thought to have unusually negative effects on plants compared with native megafauna. Using a meta-analysis of 3995 plot-scale plant abundance and diversity responses from 221 studies, we found no evidence that megafauna impacts were shaped by nativeness, "invasiveness," "feralness," coevolutionary history, or functional and phylogenetic novelty. Nor was there evidence that introduced megafauna facilitate introduced plants more than native megafauna. Instead, we found strong evidence that functional traits shaped megafauna impacts, with larger-bodied and bulk-feeding megafauna promoting plant diversity. Our work suggests that trait-based ecology provides better insight into interactions between megafauna and plants than do concepts of nativeness.

Environmental context shapes the relationship between grass consumption and body size in African herbivore communities

Though herbivore grass dependence has been shown to increase with body size across herbivore species, it is unclear whether this relationship holds at the community level. Here we evaluate whether grass consumption scales positively with body size within African large mammalian herbivore communities and how this relationship varies with environmental context. We used stable carbon isotope and community occurrence data to investigate how grass dependence scales with body size within 23 savanna herbivore communities throughout eastern and central Africa. We found that dietary grass fraction increased with body size for the majority of herbivore communities considered, especially when complete community data were available. However, the slope of this relationship varied, and rainfall seasonality and elephant presence were key drivers of the variation-grass dependence increased less strongly with body size where rainfall was more seasonal and where elephants were present. We found also that the dependence of the herbivore community as a whole on grass peaked at intermediate woody cover. Intraspecific diet variation contributed to these community-level patterns: common hippopotamus (Hippopotamus amphibius) and giraffe (Giraffa camelopardalis) ate less grass where rainfall was more seasonal, whereas Cape buffalo (Syncerus caffer) and savanna elephant (Loxodonta africana) grass consumption were parabolically related to woody cover. Our results indicate that general rules appear to govern herbivore community assembly, though some aspects of herbivore foraging behavior depend upon local environmental context.

Towards a mechanistic understanding of animal-ecosystem interactions

Research Highlight: Ferraro, K. M., Welker, L., Ward, E. B., Schmitz, O. J., & Bradford, M. A. (2023). Plant mycorrhizal associations mediate the zoogeochemical effects of calving subsidies by a forest ungulate. Journal of Animal Ecology, https://doi.org/10.1111/1365-2656.14002. Animals play large roles in ecosystem elemental cycling but predicting effects in diverse contexts remains a substantial challenge. Fundamental to progress is (1) identifying mechanisms by which animals impact nutrient distribution and cycling, and (2) disentangling how environmental context mediates the operation of alternative mechanisms. In an elegant field experiment, Ferraro et al. (2023) provide the first detailed exploration of the impact of nutrient inputs from mammalian parturition on soil functioning and the stoichiometry of plant tissues. The authors find that nitrogen from experimental additions of ungulate parturition material (natal fluids) is rapidly incorporated into microsite soil organic pools and plant tissues. They also find that soil processes (soil microbial biomass, rates of carbon mineralization, nitrogen mineralization and nitrification) and the nitrogen content of plant tissues above- and belowground are increased by addition of parturition material. Notably, the authors identify that increases in some soil processes and plant tissue nitrogen are weaker in microsites dominated by ericoid mycorrhizal plants than those dominated by ectomycorrhizal plants. These findings demonstrate that parturition depositions, a ubiquitous but overlooked mechanism of mammalian impacts on ecosystems, impact ecosystem processes and plant tissue stoichiometry. Furthermore, plant-fungal associations are a predictive axis of context dependency mediating zoogeochemical effects at fine scales. Ferraro et al.'s (2023) novel approach simultaneously advances mechanistic understanding of animal-ecosystem interactions at fine scales and facilitates prediction of ungulate effects on nutrient availability at landscape extents.

Trait-based sensitivity of large mammals to a catastrophic tropical cyclone

Extreme weather events perturb ecosystems and increasingly threaten biodiversity1. Ecologists emphasize the need to forecast and mitigate the impacts of these events, which requires knowledge of how risk is distributed among species and environments. However, the scale and unpredictability of extreme events complicate risk assessment1-4-especially for large animals (megafauna), which are ecologically important and disproportionately threatened but are wide-ranging and difficult to monitor5. Traits such as body size, dispersal ability and habitat affiliation are hypothesized to determine the vulnerability of animals to natural hazards1,6,7. Yet it has rarely been possible to test these hypotheses or, more generally, to link the short-term and long-term ecological effects of weather-related disturbance8,9. Here we show how large herbivores and carnivores in Mozambique responded to Intense Tropical Cyclone Idai, the deadliest storm on record in Africa, across scales ranging from individual decisions in the hours after landfall to changes in community composition nearly 2 years later. Animals responded behaviourally to rising floodwaters by moving upslope and shifting their diets. Body size and habitat association independently predicted population-level impacts: five of the smallest and most lowland-affiliated herbivore species declined by an average of 28% in the 20 months after landfall, while four of the largest and most upland-affiliated species increased by an average of 26%. We attribute the sensitivity of small-bodied species to their limited mobility and physiological constraints, which restricted their ability to avoid the flood and endure subsequent reductions in the quantity and quality of food. Our results identify general traits that govern animal responses to severe weather, which may help to inform wildlife conservation in a volatile climate.

Strong above-ground impacts of a non-native ungulate do not cascade to impact below-ground functioning in a boreal ecosystem

1. Experimental studies across biomes demonstrate that herbivores can have significant effects on ecosystem functioning. Herbivore effects, however, can be highly variable with studies demonstrating positive, neutral or negative relationships between herbivore presence and different components of ecosystems. Mixed effects are especially likely in the soil, where herbivore effects are largely indirect mediated through effects on plants. 2. We conducted a long-term experiment to disentangle the effects of non-native moose in boreal forests on plant communities, nutrient cycling, soil composition and soil organism communities. 3. To explore the effect of moose on soils, we conduct separate analyses on the soil organic and mineral horizons. Our data come from 11 paired exclosure-control plots in eastern and central Newfoundland, Canada that provide insight into 22-25 years of moose herbivory. We fit piecewise structural equations models (SEM) to data for the organic and mineral soil horizons to test different pathways linking moose to above-ground and below-ground functioning. 4. The SEMs revealed that moose exclusion had direct positive impacts on adult tree count and an indirect negative impact on shrub percent cover mediated by adult tree count. We detected no significant impact of moose on soil microbial C:N ratio or net nitrogen mineralization in the organic or mineral soil horizon. Soil temperature and moisture, however, was more than twice as variable in the presence (i.e. control) than absence (i.e. exclosure) of moose. Overall, we observed clear impacts of moose on above-ground forest components with limited indirect effects below-ground. Even after 22-25 years of exclusion, we did not find any evidence of moose impacts on soil microbial C:N ratio and net nitrogen mineralization. 5. Our long-term study and mechanistic path analysis demonstrates that soils can be resilient to ungulate herbivore effects despite evidence of strong effects above-ground. Long-term studies and analyses such as this one are relatively rare yet critical for reconciling some of the context-dependency observed across studies of ungulates effects on ecosystem functions. Such studies may be particularly valuable in ecosystems with short growing seasons such as the boreal forest.

No plant is an island

Most of the world's ecosystems are dominated by plants, and preserving the natural and agricultural landscapes that we depend on therefore requires understanding plants and their interactions at local and global scales. This is challenging because plants' ways of perceiving each other and communicating with each other and with animals are so fundamentally different from the ways we animals communicate with, and manipulate, each other. The collection of articles in the present issue of Current Biology illustrates the progress being made in deciphering some of the processes and mechanisms involved in plant interactions at different scales. While the topic of interactions with plants is very broad, any overview will require covering chemical signals and their reception; mutualisms and symbioses; interactions with pathogens; and interactions in communities. Approaches taken in these fields range from molecular biology and physiology to ecology.