The effects of anthropogenic change on pollination in plant-pollinator communities Open Access

Loy, Xingwen (Spring 2021)

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Pollinators facilitate reproduction in ~80% of global plant species, making them integral to many agricultural and natural ecosystems. For over 200 years, western scientists have been fascinated by the intimate partnerships between pairs of plant and pollinator species. However, current pollinator declines and biodiversity loss have brought to attention the ecology of multi-species plant-pollinator communities. Now more than ever, we need to understand how diverse communities of plants and pollinators sustain one another, and how human activities threaten them. To this end, we must first have clarity on how pollinator diversity benefits plant pollination. Numerous studies have shown that increasing pollinator diversity improves pollination function. Yet this positive relationship is not always detectable, and even when it is, we are often unable to definitively explain why it manifests. In Chapter 2, I synthesized current empirical evidence of pollinator diversity-function relationships, highlighting problems, pitfalls and possibilities for advancing enquiry. Following this in-depth analysis of the value of pollinator diversity, I then examined two ways in which humans can impact natural pollination: i) through changes in pollinator diversity, and ii) through changes in plant- pollinator interactions. Chapter 3 examines how changes to land-use in the southeastern United States may affect the diversity of bees, a globally important insect pollinator. The U.S. government aims to convert the country’s southeastern pine plantations from producing timber to bioenergy feedstock. I showed how changing the management of pine plantations from to bioenergy feedstock could have drastic effects on local bee communities. Nevertheless, results suggest that some methods of bioenergy pine production may be less detrimental. Furthermore, pine plantations collectively support more bee diversity than corn, an alternative bioenergy crop. I then focused on how human-induced changes to plant-pollinator interactions could affect plant community pollination. In Chapter 4, I examined how earlier flowering phenology (flowering time), a hallmark of climate change, impacted pollen limitation and plant fecundity. Using a field experiment conducted on montane meadow communities the Colorado Rocky Mountains, I showed that human-induced early blooming can change the pollination success and fecundity of different plant species, in ways that may affect future plant co-existence and diversity. 

Table of Contents

Table of Contents

Chapter 1: Introduction

1.1. Overview

1.2. Chapter 2: The effects of pollinator diversity on pollination function

1.3. Chapter 3: Anthropogenic effects on pollinator communities

1.4. Chapter 4: Anthropogenic effects on plant community pollination

Chapter 2: The effects of pollinator diversity on pollination function

2.1. Introduction

2.2. Canonical mechanisms of diversity-function relationships

2.3. Differentiating community and ecosystem function

2.4. Canonical diversity-function mechanisms in pollination function

2.5. Functional enhancement: a novel diversity-function mechanism

2.6. Future research into diversity-function in inter-trophic interactions

2.7. Conclusion

2.8. References

Chapter 3: The impacts of bioenergy pine plantation management practices on bee communities

3.1. Introduction

3.2. Materials and Methods

3.3. Results

3.4. Discussion

3.5. Conclusions

3.6. References

Chapter 4: Species-dependent effects on plant fecundity in a large-scale, community phenology manipulation experiment

4.1. Introduction

4.2. Methods

4.3. Results

4.4. Discussion

4.5. Conclusion

4.6. References

Chapter 5 : Conclusions & Future Directions

Introduction and Conclusion References

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