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• 1. [Article] Independent effects of habitat loss and fragmentation on pollination : tropical forest fragmentation alters hummingbird movements and pollination dynamics

  A growing body of work reveals that animal-mediated pollination is negatively affected by anthropogenic disturbance. Landscape-scale disturbance results in two often inter-related processes: (1) habitat ...

  Citation × Citation Citation Abstract Copy Title: Independent effects of habitat loss and fragmentation on pollination : tropical forest fragmentation alters hummingbird movements and pollination dynamics Author: Hadley, Adam S. A growing body of work reveals that animal-mediated pollination is negatively affected by anthropogenic disturbance. Landscape-scale disturbance results in two often inter-related processes: (1) habitat loss, and (2) disruptions of habitat configuration (i.e. fragmentation). Understanding the relative effects of such processes is critical in designing effective management strategies to limit pollination and pollinator decline. I reviewed existing published work from 1989 to 2009 and found that only six of 303 studies separated the effects of habitat loss from fragmentation. I provide a synthesis of the current landscape, behavioral, and pollination ecology literature in order to present preliminary multiple working hypotheses to explain how these two landscape processes might independently influence pollination dynamics (Chapter 2). Despite the potential importance of independent effects of habitat fragmentation, effects on pollination remain largely untested. Studies designed to disentangle the independent effects of habitat loss and fragmentation are essential for gaining insight into landscape-mediated pollination declines. I also found that the field of landscape pollination ecology could benefit from quantification of the matrix, landscape functional connectivity, and pollinator movement behavior. To test the hypothesis that pollinator movement can be influenced by landscape configuration, I translocated radio-tagged hummingbirds across agricultural and forested landscapes near Las Cruces, Costa Rica (Chapter 3). I found return paths were on average more direct in forested than in agricultural landscapes. In addition, movement paths chosen in agricultural landscapes were more forested than the most direct route suggesting that hummingbirds avoided crossing open areas when possible. To determine if differences in pollinator movement translated to differences in plant reproduction, I tested the relative importance of landscape composition versus configuration on the reproductive success of Heliconia tortuosa, a hummingbird-pollinated forest herb (Chapter 4). I used a stratified random sampling design to select sites across orthogonal gradients in patch size, amount of forest, and elevation. I tested four landscape change hypotheses (i.e., local, landscape composition, landscape fragmentation, and fragmentation threshold). I found that Heliconia reproduction supported both the local site and landscape fragmentation hypotheses. Seed set increased with increasing forest patch size independent of amount of forest in the surrounding landscape. I also found that increasing patch size positively influenced the relative abundance of pollinators. The observed differences in seed set likely resulted from differences in hummingbird movements (Chapter 3) and/or abundance under different landscape configurations. Title: Independent effects of habitat loss and fragmentation on pollination : tropical forest fragmentation alters hummingbird movements and pollination dynamics Author: Hadley, Adam S. A growing body of work reveals that animal-mediated pollination is negatively affected by anthropogenic disturbance. Landscape-scale disturbance results in two often inter-related processes: (1) habitat loss, and (2) disruptions of habitat configuration (i.e. fragmentation). Understanding the relative effects of such processes is critical in designing effective management strategies to limit pollination and pollinator decline. I reviewed existing published work from 1989 to 2009 and found that only six of 303 studies separated the effects of habitat loss from fragmentation. I provide a synthesis of the current landscape, behavioral, and pollination ecology literature in order to present preliminary multiple working hypotheses to explain how these two landscape processes might independently influence pollination dynamics (Chapter 2). Despite the potential importance of independent effects of habitat fragmentation, effects on pollination remain largely untested. Studies designed to disentangle the independent effects of habitat loss and fragmentation are essential for gaining insight into landscape-mediated pollination declines. I also found that the field of landscape pollination ecology could benefit from quantification of the matrix, landscape functional connectivity, and pollinator movement behavior. To test the hypothesis that pollinator movement can be influenced by landscape configuration, I translocated radio-tagged hummingbirds across agricultural and forested landscapes near Las Cruces, Costa Rica (Chapter 3). I found return paths were on average more direct in forested than in agricultural landscapes. In addition, movement paths chosen in agricultural landscapes were more forested than the most direct route suggesting that hummingbirds avoided crossing open areas when possible. To determine if differences in pollinator movement translated to differences in plant reproduction, I tested the relative importance of landscape composition versus configuration on the reproductive success of Heliconia tortuosa, a hummingbird-pollinated forest herb (Chapter 4). I used a stratified random sampling design to select sites across orthogonal gradients in patch size, amount of forest, and elevation. I tested four landscape change hypotheses (i.e., local, landscape composition, landscape fragmentation, and fragmentation threshold). I found that Heliconia reproduction supported both the local site and landscape fragmentation hypotheses. Seed set increased with increasing forest patch size independent of amount of forest in the surrounding landscape. I also found that increasing patch size positively influenced the relative abundance of pollinators. The observed differences in seed set likely resulted from differences in hummingbird movements (Chapter 3) and/or abundance under different landscape configurations. Close

• 2. [Article] How sweet is the land? Modeling caloric landscapes for tropical hummingbirds

  Pollination is a critical ecosystem function for sustaining biodiversity. However, pollinators and the services they provide are threatened by landscape-altering anthropogenic activities across the globe. ...

  Citation × Citation Citation Abstract Copy Title: How sweet is the land? Modeling caloric landscapes for tropical hummingbirds Author: Birkett, Christina Nozomi Pollination is a critical ecosystem function for sustaining biodiversity. However, pollinators and the services they provide are threatened by landscape-altering anthropogenic activities across the globe. Habitat loss and fragmentation, introduction of invasive species, chemical use, and urbanization have been shown to impact pollination. Pollinator foraging behavior is thought to be largely a function of available floral rewards, therefore, understanding the role of resource distributions in pollinator abundance and behavior within disturbed landscapes is a key piece of information for conservation. Fine scale information on floral resource distribution across disturbed landscapes is lacking in most systems. Here we demonstrate how existing presence-only species distribution modeling techniques (i.e., Maximum entropy modeling [MaxEnt]) can be combined with widely available environmental information to create resource landscapes for both pollinator communities and specific pollinators of interest. This model is the first of its kind, making possible simultaneous visualization of fine-scale resource configuration and quantity across abroad spatial extent. We tested this method to build caloric landscapes using tropical hummingbird-plant system in Costa Rica. We found that our MaxEnt models performed well on independent data for all 13 flower species we examined. Our landscape-scale caloric map showed that available calories within each 35m² pixel ranged from 0 to greater than 30,000 across our study region. Our model provides the possibility of predicting pollinator movement and abundance based upon resource supply. As its parameters are flexible, it is broad in its potential applications. The flexibility in calibration to desired resource landscapes permits applying the model to other pollinator-plant systems. We hope that this model will complement the current ecologist’s toolbox, aiding in ensuring the continuation and health of pollinator systems. Title: How sweet is the land? Modeling caloric landscapes for tropical hummingbirds Author: Birkett, Christina Nozomi Pollination is a critical ecosystem function for sustaining biodiversity. However, pollinators and the services they provide are threatened by landscape-altering anthropogenic activities across the globe. Habitat loss and fragmentation, introduction of invasive species, chemical use, and urbanization have been shown to impact pollination. Pollinator foraging behavior is thought to be largely a function of available floral rewards, therefore, understanding the role of resource distributions in pollinator abundance and behavior within disturbed landscapes is a key piece of information for conservation. Fine scale information on floral resource distribution across disturbed landscapes is lacking in most systems. Here we demonstrate how existing presence-only species distribution modeling techniques (i.e., Maximum entropy modeling [MaxEnt]) can be combined with widely available environmental information to create resource landscapes for both pollinator communities and specific pollinators of interest. This model is the first of its kind, making possible simultaneous visualization of fine-scale resource configuration and quantity across abroad spatial extent. We tested this method to build caloric landscapes using tropical hummingbird-plant system in Costa Rica. We found that our MaxEnt models performed well on independent data for all 13 flower species we examined. Our landscape-scale caloric map showed that available calories within each 35m² pixel ranged from 0 to greater than 30,000 across our study region. Our model provides the possibility of predicting pollinator movement and abundance based upon resource supply. As its parameters are flexible, it is broad in its potential applications. The flexibility in calibration to desired resource landscapes permits applying the model to other pollinator-plant systems. We hope that this model will complement the current ecologist’s toolbox, aiding in ensuring the continuation and health of pollinator systems. Close