In a time of rapid global change, the question of what determines patterns in species abundance d... more In a time of rapid global change, the question of what determines patterns in species abundance distribution remains a priority for understanding the complex dynamics of ecosystems. The constrained maximization of information entropy provides a framework for the understanding of such complex systems dynamics by a quantitative analysis of important constraints via predictions using least biased probability distributions. We apply it to over two thousand hectares of Amazonian tree inventories across seven forest types and thirteen functional traits, representing major global axes of plant strategies. Results show that constraints formed by regional relative abundances of genera explain almost ten times more of local relative abundances than constraints based on either directional or stabilizing selection for specific functional traits, although the latter does show clear signals of environmental dependency. These results provide a quantitative insight by inference from large-scale dat...
Forest structure, function and dynamics in Western Amazonia, 2016
Floodplain forests comprise some of the defining and most enigmatic habitats of Western Amazonia.... more Floodplain forests comprise some of the defining and most enigmatic habitats of Western Amazonia. This chapter provides an overview of the multi-directional relationships between: forest structure and carbon stocks; fruit production and phenology; and frugivores and seed dispersal services, paying particular attention throughout to the role of the flood pulse by examining areas of adjacent varzea and terra firme forest. Examining the impact of the seasonal flood on plant communities and phenological patterns in fruit production, and the relative importance of different seed dispersal modes, helps interpret the respective frugivore communities of terra firme and varzea forests. Contrasting the differences found between these adjacent forest types adds an important perspective to the individual assessments of above-ground biomass, phenological patterns and fruit-frugivore interactions, and these multiple components also combine in speculation over the possible implications of an ‘empty flooded forest’. This research helps to address the shortage of such studies in Western Amazonia to date.
Research Highlights: Rare, or sparsely distributed, species drive the floristic diversity of upla... more Research Highlights: Rare, or sparsely distributed, species drive the floristic diversity of upland, terra firme and seasonally flooded forests in the central Juruá—a remote and hitherto floristically poorly known area in the Brazilian Amazon. Background and Objectives: Floristic inventories are critical for modelling and understanding the role of Amazonian forests in climate regulation, for sustainable management of forest resources and efficient conservation planning. Yet, detailed information about the often complex spatial distributions of many Amazonian woody plants is limited. Here, we provide information about forest structure and species composition from a remote terra firme forest and an adjacent floodplain forest in the western Brazilian Amazon. More specifically, we ask (1) how floristically different are the terra firme and floodplain forests? and (2) how variable is species composition within the same forest type? Materials and Methods: Between September 2016 and Octobe...
Understanding how ecological communities are structured is a major goal in ecology. Ecological ne... more Understanding how ecological communities are structured is a major goal in ecology. Ecological networks representing interaction patterns among species have become a powerful tool to capture the mechanisms underlying plant-animal assemblages. However, these networks largely do not account for inter-individual variability and thus may be limiting our development of a clear mechanistic understanding of community structure. In this study, we develop a new individual-trait based approach to examine the importance of individual plant and pollinator functional size traits (pollinator thorax width and plant nectar holder depth) in mutualistic networks. We performed hierarchical cluster analyses to group interacting individuals into classes, according to their similarity in functional size. We then compared the structure of bee-flower networks where nodes represented either species identity or trait sets. The individual trait-based network was almost twice as nested as its species-based equ...
Patterns of habitat selection are influenced by local productivity, resource availability, and pr... more Patterns of habitat selection are influenced by local productivity, resource availability, and predation risk. Species have taken millions of years to hone the macro- and micro-habitats they occupy, but these may now overlap with contemporary human threats within natural species ranges. Wattled Curassow (), an endemic galliform species of the western Amazon, is threatened by both hunting and habitat loss, and is restricted to white-water floodplain forests of major Amazonian rivers. In this study conducted along the Juruá River, Amazonas, Brazil, we quantified the ranging ecology and fine-scale patterns of habitat selection of the species. We estimated the home range size of using conventional VHF telemetry. To estimate patterns of habitat selection, we used geo-locations of day ranges to examine the extent and intensity of use across the floodplain, which were then compared to a high-resolution flood map of the study area. We captured two females and one male, which we monitored fo...
The PREDICTS project-Projecting Responses of Ecological Diversity In Changing Terrestrial Systems... more The PREDICTS project-Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)-has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in answering a range of questions in ecology and conservation biology. To our knowledge, this is the largest and most geographically and taxonomically representative database of spatial comparisons of biodiversity that has been collated to date; it will be useful to researchers and international effort...
Predicting the functional consequences of biodiversity loss in realistic, multitrophic communitie... more Predicting the functional consequences of biodiversity loss in realistic, multitrophic communities remains a challenge. No existing biodiversity-ecosystem function study to date has simultaneously incorporated information on species traits, network topology, and extinction across multiple trophic levels, while all three factors are independently understood as critical drivers of post-extinction network structure and function. We fill this gap by comparing the functional consequences of simulated species loss both within (monotrophic) and across (bitrophic) trophic levels, in an ecological interaction network estimated from spatially explicit field data on tropical fecal detritus producer and consumers (mammals and dung beetles). We simulated trait-ordered beetle and mammal extinction separately (monotrophic extinction) and the coextinction of beetles following mammal loss (bitrophic extinction), according to network structure. We also compared the diversity effects of bitrophic exti...
1. Quantifying the impact of habitat disturbance on ecosystem function is critical to understandi... more 1. Quantifying the impact of habitat disturbance on ecosystem function is critical to understanding and predicting the future of tropical forests. Many studies have examined post-disturbance changes in animal traits related to mutualistic interactions with plants, but the effect of disturbance on plant traits in diverse forests has received much less attention. 2. Focusing on two study regions in the eastern Brazilian Amazon, we used a traitbased approach to examine how seed dispersal functionality within tropical plant communities changes across a landscape-scale gradient of human modification, including both regenerating secondary forests and primary forests disturbed by burning and selective logging. 3. Surveys of 230 forest plots recorded 26,533 live stems from 846 tree species. Using herbarium material and literature, we compiled trait information for each tree species, focusing on dispersal mode and seed size. 4. Disturbance reduced tree diversity and increased the proportion of lower wood density and small-seeded tree species in study plots. Disturbance also increased the proportion of stems with seeds that are ingested by animals and reduced those dispersed by other mechanisms (e.g. wind). Older secondary forests had functionally similar plant communities to the most heavily disturbed primary forests. Mean seed size and wood density per plot were positively correlated for plant species with seeds ingested by animals. 5. Synthesis. Anthropogenic disturbance has major effects on the seed traits of tree communities, with implications for mutualistic interactions with animals. The important role of animal-mediated seed dispersal in disturbed and recovering forests highlights the need to avoid defaunation or promote faunal recovery. The changes in mean seed width suggest larger vertebrates hold especially important functional roles in these human-modified forests. Monitoring fruit and seed traits can provide a valuable indicator of ecosystem condition, emphasizing the importance of developing a comprehensive plant traits database for the Amazon and other biomes.
Little is known about consumer productivity in the tropics despite the key feedbacks that animals... more Little is known about consumer productivity in the tropics despite the key feedbacks that animals impose on primary productivity. In the Amazon basin, seasonally flooded and unflooded forests exist side by side, and ants (Formicidae) dominate animal biomass. Although flooding has a direct negative effect on soil-dwelling ants, it is less clear whether flooding has indirect effects on arboreal ants via associated changes in tree communities. To test whether seasonal inundation by whitewater affects arboreal ants, we investigated ant communities in adjacent flooded and unflooded forests along a major whitewater river in central-western Amazonia. Whitewater-flooded forest exhibits higher primary productivity than unflooded forest. We thus hypothesized that forest type would affect the productivity and the foraging traits of arboreal ants and that these changes would be mediated by increases in plant-derived food for ants in flooded forest. We compared ant and plant communities between flooded-and unflooded-forest transects along the Juru a River in Amazonas, Brazil. We collected, identified, and counted terrestrial and arboreal ants, and we measured ant traits with putative relationships to foraging strategy. We also identified plant stems to characterize the abundance of ant food rewards. Flooding negatively affected the diversity and abundance of terrestrial ants but did not change the diversity of arboreal ants. Arboreal ants were more abundant and exhibited higher biomass in flooded forest than in unflooded forest. Arboreal ant traits also suggested that ants may rely more heavily on plant-derived food in flooded forest than in unflooded forest. These differences were associated with a higher abundance of plant stems predicted to contain ant food rewards in flooded forest than in unflooded forest. Our results indicate that the productivity of arbo-real ants is affected by that of the underlying forest. Such effects may be mediated by the predominantly herbivorous foraging strategy of canopy ants, which would link ant populations closely to primary production and stoichiometry. Given ants' important functional roles, these differences in ant productivity between forest types may have consequences for other arthropods and feedbacks to plants throughout the Amazon basin.
In a time of rapid global change, the question of what determines patterns in species abundance d... more In a time of rapid global change, the question of what determines patterns in species abundance distribution remains a priority for understanding the complex dynamics of ecosystems. The constrained maximization of information entropy provides a framework for the understanding of such complex systems dynamics by a quantitative analysis of important constraints via predictions using least biased probability distributions. We apply it to over two thousand hectares of Amazonian tree inventories across seven forest types and thirteen functional traits, representing major global axes of plant strategies. Results show that constraints formed by regional relative abundances of genera explain almost ten times more of local relative abundances than constraints based on either directional or stabilizing selection for specific functional traits, although the latter does show clear signals of environmental dependency. These results provide a quantitative insight by inference from large-scale dat...
Forest structure, function and dynamics in Western Amazonia, 2016
Floodplain forests comprise some of the defining and most enigmatic habitats of Western Amazonia.... more Floodplain forests comprise some of the defining and most enigmatic habitats of Western Amazonia. This chapter provides an overview of the multi-directional relationships between: forest structure and carbon stocks; fruit production and phenology; and frugivores and seed dispersal services, paying particular attention throughout to the role of the flood pulse by examining areas of adjacent varzea and terra firme forest. Examining the impact of the seasonal flood on plant communities and phenological patterns in fruit production, and the relative importance of different seed dispersal modes, helps interpret the respective frugivore communities of terra firme and varzea forests. Contrasting the differences found between these adjacent forest types adds an important perspective to the individual assessments of above-ground biomass, phenological patterns and fruit-frugivore interactions, and these multiple components also combine in speculation over the possible implications of an ‘empty flooded forest’. This research helps to address the shortage of such studies in Western Amazonia to date.
Research Highlights: Rare, or sparsely distributed, species drive the floristic diversity of upla... more Research Highlights: Rare, or sparsely distributed, species drive the floristic diversity of upland, terra firme and seasonally flooded forests in the central Juruá—a remote and hitherto floristically poorly known area in the Brazilian Amazon. Background and Objectives: Floristic inventories are critical for modelling and understanding the role of Amazonian forests in climate regulation, for sustainable management of forest resources and efficient conservation planning. Yet, detailed information about the often complex spatial distributions of many Amazonian woody plants is limited. Here, we provide information about forest structure and species composition from a remote terra firme forest and an adjacent floodplain forest in the western Brazilian Amazon. More specifically, we ask (1) how floristically different are the terra firme and floodplain forests? and (2) how variable is species composition within the same forest type? Materials and Methods: Between September 2016 and Octobe...
Understanding how ecological communities are structured is a major goal in ecology. Ecological ne... more Understanding how ecological communities are structured is a major goal in ecology. Ecological networks representing interaction patterns among species have become a powerful tool to capture the mechanisms underlying plant-animal assemblages. However, these networks largely do not account for inter-individual variability and thus may be limiting our development of a clear mechanistic understanding of community structure. In this study, we develop a new individual-trait based approach to examine the importance of individual plant and pollinator functional size traits (pollinator thorax width and plant nectar holder depth) in mutualistic networks. We performed hierarchical cluster analyses to group interacting individuals into classes, according to their similarity in functional size. We then compared the structure of bee-flower networks where nodes represented either species identity or trait sets. The individual trait-based network was almost twice as nested as its species-based equ...
Patterns of habitat selection are influenced by local productivity, resource availability, and pr... more Patterns of habitat selection are influenced by local productivity, resource availability, and predation risk. Species have taken millions of years to hone the macro- and micro-habitats they occupy, but these may now overlap with contemporary human threats within natural species ranges. Wattled Curassow (), an endemic galliform species of the western Amazon, is threatened by both hunting and habitat loss, and is restricted to white-water floodplain forests of major Amazonian rivers. In this study conducted along the Juruá River, Amazonas, Brazil, we quantified the ranging ecology and fine-scale patterns of habitat selection of the species. We estimated the home range size of using conventional VHF telemetry. To estimate patterns of habitat selection, we used geo-locations of day ranges to examine the extent and intensity of use across the floodplain, which were then compared to a high-resolution flood map of the study area. We captured two females and one male, which we monitored fo...
The PREDICTS project-Projecting Responses of Ecological Diversity In Changing Terrestrial Systems... more The PREDICTS project-Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)-has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in answering a range of questions in ecology and conservation biology. To our knowledge, this is the largest and most geographically and taxonomically representative database of spatial comparisons of biodiversity that has been collated to date; it will be useful to researchers and international effort...
Predicting the functional consequences of biodiversity loss in realistic, multitrophic communitie... more Predicting the functional consequences of biodiversity loss in realistic, multitrophic communities remains a challenge. No existing biodiversity-ecosystem function study to date has simultaneously incorporated information on species traits, network topology, and extinction across multiple trophic levels, while all three factors are independently understood as critical drivers of post-extinction network structure and function. We fill this gap by comparing the functional consequences of simulated species loss both within (monotrophic) and across (bitrophic) trophic levels, in an ecological interaction network estimated from spatially explicit field data on tropical fecal detritus producer and consumers (mammals and dung beetles). We simulated trait-ordered beetle and mammal extinction separately (monotrophic extinction) and the coextinction of beetles following mammal loss (bitrophic extinction), according to network structure. We also compared the diversity effects of bitrophic exti...
1. Quantifying the impact of habitat disturbance on ecosystem function is critical to understandi... more 1. Quantifying the impact of habitat disturbance on ecosystem function is critical to understanding and predicting the future of tropical forests. Many studies have examined post-disturbance changes in animal traits related to mutualistic interactions with plants, but the effect of disturbance on plant traits in diverse forests has received much less attention. 2. Focusing on two study regions in the eastern Brazilian Amazon, we used a traitbased approach to examine how seed dispersal functionality within tropical plant communities changes across a landscape-scale gradient of human modification, including both regenerating secondary forests and primary forests disturbed by burning and selective logging. 3. Surveys of 230 forest plots recorded 26,533 live stems from 846 tree species. Using herbarium material and literature, we compiled trait information for each tree species, focusing on dispersal mode and seed size. 4. Disturbance reduced tree diversity and increased the proportion of lower wood density and small-seeded tree species in study plots. Disturbance also increased the proportion of stems with seeds that are ingested by animals and reduced those dispersed by other mechanisms (e.g. wind). Older secondary forests had functionally similar plant communities to the most heavily disturbed primary forests. Mean seed size and wood density per plot were positively correlated for plant species with seeds ingested by animals. 5. Synthesis. Anthropogenic disturbance has major effects on the seed traits of tree communities, with implications for mutualistic interactions with animals. The important role of animal-mediated seed dispersal in disturbed and recovering forests highlights the need to avoid defaunation or promote faunal recovery. The changes in mean seed width suggest larger vertebrates hold especially important functional roles in these human-modified forests. Monitoring fruit and seed traits can provide a valuable indicator of ecosystem condition, emphasizing the importance of developing a comprehensive plant traits database for the Amazon and other biomes.
Little is known about consumer productivity in the tropics despite the key feedbacks that animals... more Little is known about consumer productivity in the tropics despite the key feedbacks that animals impose on primary productivity. In the Amazon basin, seasonally flooded and unflooded forests exist side by side, and ants (Formicidae) dominate animal biomass. Although flooding has a direct negative effect on soil-dwelling ants, it is less clear whether flooding has indirect effects on arboreal ants via associated changes in tree communities. To test whether seasonal inundation by whitewater affects arboreal ants, we investigated ant communities in adjacent flooded and unflooded forests along a major whitewater river in central-western Amazonia. Whitewater-flooded forest exhibits higher primary productivity than unflooded forest. We thus hypothesized that forest type would affect the productivity and the foraging traits of arboreal ants and that these changes would be mediated by increases in plant-derived food for ants in flooded forest. We compared ant and plant communities between flooded-and unflooded-forest transects along the Juru a River in Amazonas, Brazil. We collected, identified, and counted terrestrial and arboreal ants, and we measured ant traits with putative relationships to foraging strategy. We also identified plant stems to characterize the abundance of ant food rewards. Flooding negatively affected the diversity and abundance of terrestrial ants but did not change the diversity of arboreal ants. Arboreal ants were more abundant and exhibited higher biomass in flooded forest than in unflooded forest. Arboreal ant traits also suggested that ants may rely more heavily on plant-derived food in flooded forest than in unflooded forest. These differences were associated with a higher abundance of plant stems predicted to contain ant food rewards in flooded forest than in unflooded forest. Our results indicate that the productivity of arbo-real ants is affected by that of the underlying forest. Such effects may be mediated by the predominantly herbivorous foraging strategy of canopy ants, which would link ant populations closely to primary production and stoichiometry. Given ants' important functional roles, these differences in ant productivity between forest types may have consequences for other arthropods and feedbacks to plants throughout the Amazon basin.
The complex web of inter-relationships observed in nature that confronted early natural historian... more The complex web of inter-relationships observed in nature that confronted early natural historians on their voyages to the tropics, inspired not only the theory of evolution by natural selection but also the development of ecology as a scientific discipline and set the foundation for the study of ecological networks. Modern network analyses owe much to these early observations of species interactions but also to pioneering advances in the fields of mathematics and social sciences. In this chapter, we review the history of ecological network studies, documenting their background in the fields of natural history, mathematics and social sciences, along with the most influential players and the ideas that they introduced. We continue the story up to the present day, documenting developments within ecology including food web models and mutualistic networks, and emerging concepts such as individual-based, trait-based and multi-layer networks. Following generations of detailed observations and theoretical development, modern network ecologists now have both the data and the analytical techniques to advance our understanding of nature’s interdependencies, particularly in the diverse tropical environments that so captivated early naturalists.
Floodplain forests comprise some of the defining and most enigmatic habitats of Western Amazonia.... more Floodplain forests comprise some of the defining and most enigmatic habitats of Western Amazonia. This chapter provides an overview of the multi-directional relationships between: forest structure and carbon stocks; fruit production and phenology; and frugivores and seed dispersal services, paying particular attention throughout to the role of the flood pulse by examining areas of adjacent varzea and terra firme forest. Examining the impact of the seasonal flood on plant communities and phenological patterns in fruit production, and the relative importance of different seed dispersal modes, helps interpret the respective frugivore communities of terra firme and varzea forests. Contrasting the differences found between these adjacent forest types adds an important perspective to the individual assessments of above-ground biomass, phenological patterns and fruit-frugivore interactions, and these multiple components also combine in speculation over the possible implications of an ‘empty flooded forest’. This research helps to address the shortage of such studies in Western Amazonia to date.
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Papers by Joseph Hawes
2. Focusing on two study regions in the eastern Brazilian Amazon, we used a traitbased approach to examine how seed dispersal functionality within tropical plant communities changes across a landscape-scale gradient of human modification, including both regenerating secondary forests and primary forests disturbed by burning and selective logging.
3. Surveys of 230 forest plots recorded 26,533 live stems from 846 tree species. Using herbarium material and literature, we compiled trait information for each tree species, focusing on dispersal mode and seed size.
4. Disturbance reduced tree diversity and increased the proportion of lower wood density and small-seeded tree species in study plots. Disturbance also increased the proportion of stems with seeds that are ingested by animals and reduced those dispersed by other mechanisms (e.g. wind). Older secondary forests had functionally similar plant communities to the most heavily disturbed primary forests. Mean seed size and wood density per plot were positively correlated for plant species with seeds ingested by animals.
5. Synthesis. Anthropogenic disturbance has major effects on the seed traits of tree communities, with implications for mutualistic interactions with animals. The important role of animal-mediated seed dispersal in disturbed and recovering forests highlights the need to avoid defaunation or promote faunal recovery. The changes in mean seed width suggest larger vertebrates hold especially important functional roles in these human-modified forests. Monitoring fruit and seed traits can provide a valuable indicator of ecosystem condition, emphasizing the importance of developing a comprehensive plant traits database for the Amazon and other biomes.
2. Focusing on two study regions in the eastern Brazilian Amazon, we used a traitbased approach to examine how seed dispersal functionality within tropical plant communities changes across a landscape-scale gradient of human modification, including both regenerating secondary forests and primary forests disturbed by burning and selective logging.
3. Surveys of 230 forest plots recorded 26,533 live stems from 846 tree species. Using herbarium material and literature, we compiled trait information for each tree species, focusing on dispersal mode and seed size.
4. Disturbance reduced tree diversity and increased the proportion of lower wood density and small-seeded tree species in study plots. Disturbance also increased the proportion of stems with seeds that are ingested by animals and reduced those dispersed by other mechanisms (e.g. wind). Older secondary forests had functionally similar plant communities to the most heavily disturbed primary forests. Mean seed size and wood density per plot were positively correlated for plant species with seeds ingested by animals.
5. Synthesis. Anthropogenic disturbance has major effects on the seed traits of tree communities, with implications for mutualistic interactions with animals. The important role of animal-mediated seed dispersal in disturbed and recovering forests highlights the need to avoid defaunation or promote faunal recovery. The changes in mean seed width suggest larger vertebrates hold especially important functional roles in these human-modified forests. Monitoring fruit and seed traits can provide a valuable indicator of ecosystem condition, emphasizing the importance of developing a comprehensive plant traits database for the Amazon and other biomes.