Ecosystem Research Articles

Large potential impacts of marine heatwaves on ecosystem functioning.

Ocean warming is driving significant changes in the structure and functioning of marine ecosystems, shifting species' biogeography and phenology, changing body size and biomass and altering the trophodynamics of the system. Particularly, extreme temperature events such as marine heatwaves (MHWs) have been increasing in intensity, duration and frequency. MHWs are causing large-scale impacts on marine ecosystems, such as coral bleaching, mass mortality of seagrass meadows and declines in fish stocks and other marine organisms in recent decades. In this study, we developed and applied a dynamic version of the EcoTroph trophodynamic modelling approach to study the cascading effects of individual MHW on marine ecosystem functioning. We simulated theoretical user-controlled ecosystems and explored the consequences of various assumptions of marine species mortality along the food web, associated with different MHW intensities. We show that an MHW can lead to a significant biomass reduction of all consumers, with the severity of the declines being dependent on species trophic levels (TLs) and biomes, in addition to the characteristics of MHWs. Biomass of higher TLs declines more than lower TLs under an MHW, leading to changes in ecosystem structure. While tropical ecosystems are projected to be sensitive to low-intensity MHWs, polar and temperate ecosystems are expected to be impacted by more intense MHWs. The estimated time to recover from MHW impacts is twice as long for polar ecosystems and one-third longer for temperate biomes compared with tropical biomes. This study highlights the importance of considering extreme weather events in assessing the effects of climate change on the structures and functions of marine ecosystems.

Tropical root responses to global changes: A synthesis.

Tropical ecosystems face escalating global change. These shifts can disrupt tropical forests' carbon (C) balance and impact root dynamics. Since roots perform essential functions such as resource acquisition and tissue protection, root responses can inform about the strategies and vulnerabilities of ecosystems facing present and future global changes. However, root trait dynamics are poorly understood, especially in tropical ecosystems. We analyzed existing research on tropical root responses to key global change drivers: warming, drought, flooding, cyclones, nitrogen (N) deposition, elevated (e) CO2, and fires. Based on tree species- and community-level literature, we obtained 266 root trait observations from 93 studies across 24 tropical countries. We found differences in the proportion of root responsiveness to global change among different global change drivers but not among root categories. In particular, we observed that tropical root systems responded to warming and eCO2 by increasing root biomass in species-scale studies. Drought increased the root: shoot ratio with no change in root biomass, indicating a decline in aboveground biomass. Despite N deposition being the most studied global change driver, it had some of the most variable effects on root characteristics, with few predictable responses. Episodic disturbances such as cyclones, fires, and flooding consistently resulted in a change in root trait expressions, with cyclones and fires increasing root production, potentially due to shifts in plant community and nutrient inputs, while flooding changed plant regulatory metabolisms due to low oxygen conditions. The data available to date clearly show that tropical forest root characteristics and dynamics are responding to global change, although in ways that are not always predictable. This synthesis indicates the need for replicated studies across root characteristics at species and community scales under different global change factors.

Emerging Hotspots of Surface Chlorophyll Trend in the Tropical Oceans

AbstractRecent studies show that climate change signals in the long‐term trend of the tropical ecosystems have emerged earlier than projected by climate models. However, it remains unclear whether tropical ocean surface chlorophyll (SChl) shows a robust trend in the available satellite data era, and what possible physical mechanisms can be responsible for this trend. Here, using combined data from observations, hindcast biogeochemical simulations, and climate model outputs, we document consistently decreasing trends of SChl in the three ocean basins (Indian Ocean, Pacific Ocean, and Atlantic Ocean) with varying magnitude from −1.6% to −10.0% per decade during 1998–2020, with tropical ocean SChl showing a decreasing trend of −7.1% per decade. In the Indo‐Pacific Ocean, mechanisms for the two hotspots with significantly decreasing SChl trends are identified. (a) In the northern tropical Pacific, under the anthropogenic forcing, enhanced stratification associated with frequent interannual surface warming overwhelms the Ekman pumping effect due to positive wind stress curl, leading to a decrease in SChl. (b) In the southern tropical Indian Ocean, the downwelling process dominates the decreasing SChl trend due to the Ekman pumping associated with the negative wind stress curl prevailing in the Indian Ocean, while the contribution from the stratification change is negligible. This study identifies two hotspots with consistently decreasing SChl trends in the tropical ocean which are influenced by the complex physical processes under a warmer climate and calls for more comprehensive understanding of the interactions between physical processes and biogeochemical cycles in the tropical ocean ecosystems.

Vegetation patterns associated with nutrient availability and supply in high-elevation tropical Andean ecosystems

Abstract. Plants absorb nutrients and water through their roots and modulate soil biogeochemical cycles. The mechanisms of water and nutrient uptake by plants depend on climatic and edaphic conditions, as well as the plant root system. Soil solution is the medium in which abiotic and biotic processes exchange nutrients, and nutrient concentrations vary with the abundance of reactive minerals and fluid residence times. High-altitude ecosystems of the tropical Andes are interesting for the study of the association between vegetation, soil hydrology, and mineral nutrient availability at the landscape scale for different reasons. First of all, because of low rock-derived nutrient stocks in intensely weathered volcanic soils, biocycling of essential nutrients by plants is expected to be important for plant nutrient acquisition. Second, the ecosystem is characterized by strong spatial patterns in vegetation type and density at the landscape scale and hence is optimal to study soil-water–vegetation interactions. Third, the area is characterized by high carbon stocks but low rates of organic decomposition that might vary with soil hydrology, soil development, and geochemistry, all interconnected with vegetation. The páramo landscape forms a vegetation mosaic of bunch grasses, cushion-forming plants, and forests. In the nutrient-depleted nonallophanic Andosols, the plant rooting depth varies with drainage and soil moisture conditions. Rooting depths were shallower in seasonally waterlogged soils under cushion plants and deeper in well-drained soils under forest and tussock grasses (>100 cm). Vegetation composition is a relevant indicator of rock-derived nutrient availability in soil solutions. The soil solute chemistry revealed patterns in plant-available nutrients that were not mimicking the distribution of total rock-derived nutrients nor the exchangeable nutrient pool but clearly resulted from strong biocycling of cations and removal of nutrients from the soil by plant uptake or deep leaching. Soils under cushion plants showed solute concentrations of Ca, Mg, and Na of about 3 times higher than forest and tussock grasses. Differences were even stronger for dissolved Si with solute concentrations that were 16 times higher than forest and 6 times higher than tussock grasses. Amongst the macronutrients derived from lithogenic sources, P was a limiting nutrient with very low solute concentrations (<1 µM) for all three vegetation types. In contrast K showed greater solute concentrations under forest soils with values that were 2 to 3 times higher than under cushion-forming plants or tussock grasses. Our findings have important implications for future management of Andean páramo ecosystems where vegetation type distributions are dynamically changing as a result of warming temperatures and land use change. Such alterations may lead not only to changes in soil hydrology and solute geochemistry but also to complex changes in weathering rates and solute export downstream with effects on nutrient concentrations in Andean rivers and high-mountain lakes.

Carbon isotope trends across a century of herbarium specimens suggest CO2 fertilization of C4 grasses.

Increasing atmospheric CO2 is changing the dynamics of tropical savanna vegetation. C3 trees and grasses are known to experience CO2 fertilization, whereas responses to CO2 by C4 grasses are more ambiguous. Here, we sample stable carbon isotope trends in herbarium collections of South African C4 and C3 grasses to reconstruct 13C discrimination. We found that C3 grasses showed no trends in 13C discrimination over the past century but that C4 grasses increased their 13C discrimination through time, especially since 1950. These changes were most strongly linked to changes in atmospheric CO2 rather than to trends in rainfall climatology or temperature. Combined with previously published evidence that grass biomass has increased in C4-dominated savannas, these trends suggest that increasing water-use efficiency due to CO2 fertilization may be changing C4 plant-water relations. CO2 fertilization of C4 grasses may thus be a neglected pathway for anthropogenic global change in tropical savanna ecosystems.

Spatial ecology of the Endangered and endemic Sagalla caecilian Boulengerula niedeni in the Eastern Arc Mountains of Kenya

Caecilians (Order Gymnophiona) are generalist predators of soil invertebrates, and may therefore play an important role in tropical soil ecosystems. However, their fossorial lifestyle and the associated difficulties in surveying them have caused a deficit in data for the majority of species. We applied a systematic approach and an intensive sampling strategy to an Endangered and evolutionarily distinct caecilian from the Eastern Arc Mountains, the Sagalla caecilian Boulengerula niedeni. We investigated the association between habitat type and caecilian occupancy across its entire range, the Sagalla Hill, Kenya, and explored the relationship between several variables (land use type, surface soil temperature, soil compactness and landowner prediction of caecilian presence) and its presence in different habitats. We found no significant effects of any of the investigated variables in predicting caecilian presence across the Sagalla landscape. Instead, our findings suggest that the species survives at least as well in agricultural landscapes as it does in areas with indigenous vegetation, with an estimated density of around 900 caecilians per hectare. A bimodal distribution of sizes and weights of captured specimens suggests ongoing successful breeding and recruitment. This suggests that there is a case for cautious optimism with regard to the status of B. niedeni. Our work could act as a useful pilot for further, improved caecilian surveys in the Eastern Arc Mountains and beyond, to improve our understanding and conservation of these overlooked fossorial amphibians. Keywords: amphibian, Gymnophiona, Herpelidae, soil ecology, amphibian conservation, Taita Hills

Woody flora of Karumpuliyuthu Hill, Tenkasi, Tamil Nadu, India: a checklist

Qualitative field surveys were conducted to record the woody plant (tree, shrub, and liana) wealth in Karumpuliyuthu Hill, Tenkasi district, Tamil Nadu. All the recorded species were confirmed with regional floras. The qualitative field survey allowed us to record 42 species in 32 genera and 19 families. The family Fabaceae had a large number of species (13 species) in the study area. The present study adds valuable information about the occurrence of 42 woody plant species in a tropical thorn forest ecosystem. The woody plant community is dominated by native plants, and only three are introduced. Nearly half of the recorded species produce fleshy fruits, thus providing food to small mammals and birds.

Reassembly of ground-dwelling ant communities in reforestation plots in SW Costa Rica

Due to agriculture and logging, Costa Rica has lost many primary forests, making reforestation an important task. To judge the progress of reforestation, it is important to follow the reassembly of organismal communities within restored habitats. The COBIGA project near La Gamba, in the Golfo Dulce region of Costa Rica, aims at reforestation of lowland sites with native tree species. Ants, as ubiquitous and highly abundant terrestrial organisms, have a substantial influence on tropical ecosystems. The multiple roles include scavenging, predation, herbivory, and mutualistic interactions. We examined ant community responses to reveal the status of community regeneration and functional integrity. We compared the composition and diversity of the ant assemblages at three different age reforestation sites (2, 8, and 10 years old) with those at an old-growth forest as a reference site. By offering canned tuna fish at ground level along replicated transects, we observed 43 ant species representing six functional groups during the 2 months of sampling. Most of the observed ant species were omnivorous, but old-growth forests harbored a substantial number of other functional groups, such as generalized predators, arboreal predators, and arboreal omnivores. In contrast, the youngest reforestation site harbored a severely impoverished ant assemblage comprising mostly generalized polygynous and polydomous ant species from lower trophic levels. The within-site heterogeneity of the ant assemblages increased from the youngest to the oldest forest. In addition, our results show the importance of monitoring the progress of forest recovery to avoid the spread of invasive species into primary habitats.

Co-occurrence of two invasive plants in a tropical savanna ecosystem: a top priority for management

In this study, we assessed the co-occurrence influence of Hyptis suaveolens and Urena lobata on native plant species and soil properties in a guinea savanna vegetation in Nigeria. We sampled 120 plots of 10 × 10 m2 with 30 plots each in sites invaded by H. suaveolens, U. lobata, mixed site and in sites with none of the species (control). A sparse partial least square discriminant analysis was used to assess the effect of invasive plant treatments on the plant diversity and soil properties, whereas the relationships between the soil properties, plant diversity and invasive species treatments were assessed using the canonical correspondence analysis. The indices of diversity of the control were significantly higher than all the other treatments (p < 0.001) with the mixed site having the lowest. There were significant differences in phosphorus, calcium, aluminium, soil alkalinity and diversity indices among the treatments. The results also indicated that the diversity indices and some soil properties were negatively associated with the mixed site. The negative impacts on the native diversity and change in the soil properties caused by the co-invasion of these two plants are more additive than non-additive. Therefore, priority should be placed on the management of co-invaded sites.

Modeling drought mortality and resilience of savannas and forests in tropical Asia

The projected increase of drought occurrence in many tropical and sub-tropical regions globally under future climates will affect terrestrial ecosystems, particularly by increasing drought-induced plant mortality. The capacity to simulate drought mortality in vegetation models is therefore essential to understand future ecosystem dynamics. Using the trait-based vegetation model aDGVM2, we assessed drought mortality and resilience in tropical Asia under climate change. We conducted model simulations for ten sites in tropical Asia, representing a biogeographic gradient. Responses of vegetation attributes and mortality rates were simulated until 2099 for hypothetical drought scenarios and recovery times were calculated. Model simulations showed biomass dieback during drought due to increased plant mortality, primarily among tall and old trees. Drought responses were related to hydraulic traits and associated ecological strategies. Despite severe drought impacts, recovery was possible, but recovery times differed between ecosystem attributes. We conclude that the aDGVM2 enhances our ability to understand drought impacts in tropical ecosystems. The model can simulate increased mortality during drought in a trait- and individual-based modeling framework. It indicated drought resilience of forests and adaptation to drought by changes in community trait composition and the demographic structure. Yet, further model improvements are required to better represent drought impact and recovery.

An inadequate sampling of the soundscape leads to over-optimistic estimates of recogniser performance: a case study of two sympatric macaw species

ABSTRACT Passive acoustic monitoring (PAM) – autonomously recording ambient sound – could dramatically increase the scale and robustness of species monitoring in rainforest ecosystems. PAM generates large volumes of data that require automated methods of target species detection. Species-specific recognisers, which often use supervised machine learning, can achieve this goal. However, they require a large training dataset of target and non-target signals, which is time-consuming and challenging to create. Unfortunately, very little information about creating training datasets for supervised machine learning recognisers is available, especially for tropical ecosystems. Here, we show an iterative approach to creating a training dataset that improved recogniser precision from 0.12 to 0.55. By sampling background noise using an initial small recogniser, we can address one of the significant challenges of training dataset creation in acoustically diverse environments. Our work demonstrates that recognisers will likely fail in real-world settings unless the training dataset size is large enough and sufficiently representative of the ambient soundscape. We outline a workflow that can provide users with an accessible way to create a species-specific PAM recogniser that addresses these issues for tropical rainforest environments. Our work provides important lessons for PAM practitioners wanting to develop species-specific recognisers for acoustically diverse ecosystems.

Seasonal dynamics and habitat preferences of juvenile fish assemblages in the Wanquan Estuary, South China: Implications for conservation and management

Tropical estuaries encompass diverse habitats, which are crucial for supporting juvenile fish by providing nurseries, refuges, and migration routes. In the present study, we investigated the seasonal and spatial dynamics of juvenile fish assemblages in the Wanquan Estuary, Hainan Island, China, examining variations during the wet and dry seasons across four types of habitats. Our research aimed to test the hypotheses: (1) the wet season supports a greater abundance and species richness of juvenile fish compared to the dry season, and (2) juvenile fish showed varying habitat preferences across seasons. We recorded a total of 3617 individuals belonging to 33 families, 50 genera, and 78 taxa. Our findings revealed significant seasonal fluctuations in the assemblage structure, with peak abundance during the wet season in August, primarily consisting of diadromous species. A notable shift towards marine species was observed in March. Spatially, juvenile fish exhibited significant habitat preferences, with a strong preference for sand substrates for most species. Contrary to common expectations, mangrove fringe habitats were not identified as the primary nursery grounds for juvenile fish. Instead, our study highlights the importance of habitat diversity and connectivity in enhancing nursery functions. Water temperature and salinity were the key drivers influencing the seasonal and temporal patterns of juvenile fish assemblages in the Wanquan River estuary The pronounced temporal dynamics of these assemblages, driven by seasonal environmental alterations affecting water variations and habitat connectivity, were more significant than spatial differences. The findings emphasize the need for focused connectivity of various habitats to support the conservation of diverse fish communities in tropical estuarine ecosystems.

Climate sensitive tree growth modelling of Myrocarpus frondosus in Southern Brazil using tree-ring time series and distributed generalized additive lag models

Abstract Climate change is expected to strongly affect the functioning of tropical and subtropical forest ecosystems around the globe, and tree-ring analysis is proving increasingly useful for understanding the changing dynamics in these environments. However, traditional dendroecological methods were not originally designed to jointly consider inter-annual and inter-tree variations, often assuming linear growth-climate relationships, and limiting the potential to address in-deep questions regarding the tree growth sensitivity to environmental drivers. In the present study, we applied a flexible generalized additive model to assess the climate-sensitivity of the species Myrocarpus frondosus Allemão growing in a subtropical Atlantic Forest (AF) site in southern Brazil. Tree-ring width time series from 117 stem cores together with monthly climate data of temperature and precipitation covering the period from 1968 to 2021 were used for model construction. The model was designed to simultaneously encompass detrending, to capture nonlinear effects of climate variables and their interactions and to predict mean tree-ring widths for the species. Based on a distributed lag model approach, we also tested the influence of different lengths of lagged climate series over the model accuracy. Both precipitation and temperature proved to be strong drivers of M. frondosus radial growth in the subtropical AF. An interaction effect between these regressor variables revealed a likely water stress scenario arising from warm and dry summer conditions, with strongly negative impacts for the species. Detrimental impacts on tree dormancy period can also be expected due to milder winters, with legacy effects on the radial increments across two subsequent years. In addition to monitoring, the approach applied here meets the needs for more robust predictions of the impacts of future climate conditions on species and communities, contributing to efforts aimed at the management and conservation in tropical and subtropical ecosystems, particularly in the AF.

Species diversity of fish at the Wuzhizhou Island, South China Sea, based on environmental DNA.

Wuzhizhou Island (WZZ) is located in Haitang Bay in the northern region of Sanya, Hainan Island. The sea area surrounding WZZ represents a typical tropical marine ecosystem, characterised by diverse and complex habitats. Therefore, there is a rich variety of marine fish species at WZZ. The marine ecosystem of WZZ was seriously destroyed initially in the 1970s-1980s and recovered in the 1990s, then constructed as the first national tropical marine ranch demonstration area of China in 2019. As fish is an important high trophic vertebrate in the marine ecosystem, understanding the composition and distribution of fish species could help us to recognise the status of the ecosystem of WZZ and supply scientific data for construction of the national marine ranch demonstration area. This study used eDNA technology to investigate the composition of fish community surrounding WZZ and provided a scientific basis for realising and protecting the marine ecosystem of the South China Sea. The WZZ is an offshore island in the South China Sea, harbouring abundant marine fish resources. Although previous research investigated fish species of WZZ, the data were, however, still incomplete due to limitation of sampling methods and survey seasons. In this study, we intended to take advantage of eDNA and supplement data of fish species at WZZ as much as possible. Based on eDNA, this study provided the data on 188 fish species (including nine undetermined species denoted by genus sp.) belonging to 17 orders, 63 families and 124 genera and they were the more comprehensive records of fish species surrounding WZZ. In addition, the information on Molecular Operational Taxonomic Units (MOTUs) for taxon identification was also provided, aiming to contribute to the establishment of a specific eDNA taxon database for fish of the South China Sea. This study included two datasets, which were occurrences of fish taxa at WZZ, as well as MOTUs sequences and geographical coordinate information of sampling sites. The "fish taxon occurrences" dataset presented records on taxonomic, distribution and habitat conditions of 188 fish species detected using eDNA, as well as the latitude and longitude information of the sampling sites, the "MOTUs information" dataset provided the MOTUs sequences, source of sequences, abundance of sequences for 188 fish species, also included the species matched in NCBI and the best NCBI BLAST sequence similarity.

Exploring uncharted territory: new frontiers in environmental DNA for tropical fisheries management.

Tropical ecosystems host a significant share of global fish diversity contributing substantially to the global fisheries sector. Yet their sustainable management is challenging due to their complexity, diverse life history traits of tropical fishes, and varied fishing techniques involved. Traditional monitoring techniques are often costly, labour-intensive, and/or difficult to apply in inaccessible sites. These limitations call for the adoption of innovative, sensitive, and cost-effective monitoring solutions, especially in a scenario of climate change. Environmental DNA (eDNA) emerges as a potential game changer for biodiversity monitoring and conservation, especially in aquatic ecosystems. However, its utility in tropical settings remains underexplored, primarily due to a series of challenges, including the need for a comprehensive barcode reference library, an understanding of eDNA behaviour in tropical aquatic environments, standardized procedures, and supportive biomonitoring policies. Despite these challenges, the potential of eDNA for sensitive species detection across varied habitats is evident, and its global use is accelerating in biodiversity conservation efforts. This review takes an in-depth look at the current state and prospects of eDNA-based monitoring in tropical fisheries management research. Additionally, a SWOT analysis is used to underscore the opportunities and threats, with the aim of bridging the knowledge gaps and guiding the more extensive and effective use of eDNA-based monitoring in tropical fisheries management. Although the discussion applies worldwide, some specific experiences and insights from Indian tropical fisheries are shared to illustrate the practical application and challenges of employing eDNA in a tropical context.

GROWTH AND YIELD OF BRAZILIAN SPINACH UNDER DIFFERENT SHADING INTENSITIES AND HARVESTING PERIODS IN A TROPICAL LOWLAND URBAN ECOSYSTEM

Brazilian spinach (Alternanthera sissoo) is a less prominent perennial leafy vegetable growing in the tropical ecosystem. Therefore, this research aimed to investigate the effects of different shading intensities and harvesting periods on the growth and yield of Brazilian spinach in a tropical lowland urban ecosystem. The investigation used a split-plot design, with different shading intensities (no-shading, 45%, 55%, and 80% shading) as the main plot and harvesting periods (every 2, 3, and 4 weeks) as the subplot. The results showed that Brazilian spinach growth was significantly enhanced under no-shading conditions compared to shading treatments. Furthermore, 80% shading negatively impacted plant growth during early stages, as evidenced by alterations in parameters including canopy area (26.47 cm2), diameter (7.98 cm), and index (0.52), as well as Soil Plant Analysis Development (SPAD) values. This led to reduced branch elongation, marketable yield (14.76 g), and non-marketable yield (4.68), along with a decreased dry weight of stems (0.25 g), branches (0.40 g), leaves (0.85 g), and roots (0.44 g). However, marketable leaves from unshaded plants had higher carbon content (34.64%) and lower nitrogen content (2.83%). More frequent harvesting every 2 weeks elevated marketable yield (67.22 g) but suppressed the growth of stems (1.05 g), branches (4.39 g), and roots (1.73 g). Based on these observations, the cultivation of Brazilian spinach in unshaded areas with a biweekly harvesting routine was recommended

Seeding success: Integrating seed dispersal networks in tropical forest restoration

AbstractWhile the reassembly of fruit‐frugivore interactions remains at the forefront of tropical forest restoration, seed dispersal networks emerge as a potential approach to enhance restoration success. This review explores the integration of seed dispersal networks in tropical forest restoration, with the aims of (1) synthesizing important findings in the literature, (2) detailing potential biases in utilizing network theory, and (3) addressing current knowledge gaps and future directions for the field. We first highlight the importance of combining phytocentric and zoocentric approaches when sampling for seed dispersal interactions, as different methodologies have varying effects on network measures, and combining approaches can foster a more comprehensive understanding of dispersal interactions. Furthermore, when integrating seed dispersal networks into restoration goals, we suggest a highly connected and species‐rich network is desirable for earlier stages of forest succession where community turnover and transient interactions are pivotal. Nested patterns may emerge throughout varying stages of forest succession, and identifying generalist species that make up nested patterns may be useful for restoration practitioners in both early and later stages of forest regeneration. Modularity should be highest at later stages of succession to maintain community structure and stability, and connector species may play important roles in facilitating seed dispersal across temporal scales. Finally, we emphasize the importance of site‐specific long‐term datasets, chronosequences, and studies at large spatial scales to continue to understand network reassembly as a function of tropical forest succession and to develop effective strategies that enhance the recovery of tropical forest ecosystems.

Seeing the forest through the palms: developments in environmentally sustainable palm oil production and zero-deforestation efforts

Palm oil is produced on plantations primarily in Indonesia and Malaysia, which, historically, have been responsible for significant tropical deforestation and ecosystem loss. Driven by a shift away from hydrogenated vegetable oils and its high productivity, palm oil is now part of more than half of all packaged consumer products. Given its centrality across many supply chains, certification schemes have sought to improve environmental sustainability in the palm oil industry. Increasingly, there is an intersection between certification schemes and regulatory drivers. The recent 2023 European Union regulation on deforestation-free products has implications for palm oil and many other forest products. Environmental certification schemes, such as the one developed by the Roundtable on Sustainable Palm Oil, have the potential to play a critical role in the implementation of this recent policy for palm oil and can serve as model for many other commodities subject to the new Directive.

Pastures as natural climate solutions: A socioecological study of tree carbon and beef production trade-offs

Sustainable management strategies that facilitate the incorporation of trees into cattle pastures are widely recognized as emerging natural climate solutions. However, their potential to dually improve ecological functioning and human livelihoods has yet to be evaluated across regions on local scales, utilizing both ecological and sociological data. Further, the relationship between landowner participation in conservation management programs (CMPS) and their management priorities (i.e. production vs sustainability) also remains unclear. Therefore, the aims of this study were to evaluate the accuracy of past global-scale remote estimations of aboveground biomass and derived tree carbon density (MgC ha−1) within pasturelands at the local scale in both temperate and tropical regions. We also sought to analyze how participation in CMPs related to the perceptions of stakeholders toward the ecological health of their system. We compared findings between farms in temperate (n = 26) and tropical (n = 16) ecosystems. We found that discrepancies exist between previous remote studies and current field estimations of tree carbon in the farms, and these differences were not regionally uniform. In contrast, stakeholders enrolled in CMPs had a higher value of trees in both regions. CMPs participants also had lower annual stocking rates than those that practiced conventional management but no differences in woody species diversity (H’) or tree carbon (MgC ha−1). We demonstrate the urgent need for local-scale studies to accurately estimate tree carbon in mosaic pasture systems and the importance of conservation management in shifting the priorities of landowners, which could eventually lead to more sustainable systems.

Coastal dolphins provide foraging opportunities to benthic-feeding seabirds in a tropical seagrass ecosystem

Abstract In marine ecosystems, predators can affect community and ecosystem dynamics through a variety of processes such as foraging facilitation. Here, we report evidence of foraging facilitation between common bottlenose dolphins (Tursiops truncatus) and double-crested cormorants (Nannopterum auritum) in the Caribbean seagrass-dominated atoll of Turneffe, Belize using aerial drone observations conducted in 2015-2017. While dolphins exhibited occasional aggressive behaviours toward the cormorants, the latter frequently followed dolphin movements, suggesting opportunistic pursuit of dolphins for prey access during dolphin bottom foraging activity. Our observations underscore the intricate ecological relationships among marine predators and highlight the need to quantify the mutual benefits and costs of such interactions as coastal ecosystems are rapidly changing.