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2. Pest Control in Coffee: A Tri-trophic Comparison between a Mainland and an Island Agroecosystem

Author

Vandermeer, John, Hajian-Forooshani, Zachary, Rivera-Salinas, Iris Saraeny, Perfecto, Ivette, Wardle, David A., Series Editor, Canadell, Josep G., Series Editor, Díaz, Sandra, Series Editor, Heldmaier, Gerhard, Series Editor, Jackson, Robert B., Series Editor, Levia, Delphis F., Series Editor, Schulze, Ernst-Detlef, Series Editor, Sommer, Ulrich, Series Editor, Moreira, Xoaquín, editor, and Abdala-Roberts, Luis, editor more...

Published
2024
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4. The interplay of extinction and synchrony in the dynamics of metapopulation formation

Author

Vandermeer, John and Hajian-Forooshani, Zachary

Subjects
Quantitative Biology - Populations and Evolution, 92.10
Abstract

The idea of a metapopulation has become canonical in ecology. Its original mean field form provides the important intuition that migration and extinction interact to determine the dynamics of a population composed of subpopulations. From its conception, it has been evident that the very essence of the metapopulation paradigm centers on the process of local extinction. We note that there are two qualitatively distinct types of extinction, gradual and catastrophic, and explore their impact on the dynamics of metapopulation formation using discrete iterative maps. First, by modifying the classic logistic map with the addition of the Allee effect, we show that catastrophic local extinctions in subpopulations are a pre-requisite of metapopulation formation. When subpopulations experience gradual extinction, increased migration rates force synchrony and drive the metapopulation below the Allee point resulting in migration induced destabilization of the system across parameter space. Second, a sawtooth map (an extension of the Bernoulli bit shift map) is employed to simultaneously explore the increasing and decreasing modes of population behavior. We conclude with four generalizations. 1. At low migration rates, a metapopulation may go extinct faster than completely unconnected subpopulations. 2. There exists a gradient between stable metapopulation formation and population synchrony, with critical transitions from no metapopulation to metapopulation to synchronization, the latter frequently inducing metapopulation extinction. 3. Synchronization patterns emerge through time, resulting in synchrony groups and chimeric populations existing simultaneously. 4. There are two distinct mechanisms of synchronization: i. extinction and rescue and, ii.) stretch reversals in a modification of the classic chaotic stretching and folding., Comment: 35 pages, 21 figures more...

Published
2021

6. New forms of structure in ecosystems revealed with the Kuramoto model

Author

Vandermeer, John, Hajian-Forooshani, Zachary, Medina, Nicholas, and Perfecto, Ivette

Subjects
Quantitative Biology - Populations and Evolution, Nonlinear Sciences - Adaptation and Self-Organizing Systems
Abstract

Ecological systems, as is often noted, are complex. Equally notable is the generalization that complex systems tend to be oscillatory, whether Huygens simple patterns of pendulum entrainment or the twisted chaotic orbits of Lorenz convection rolls. The analytics of oscillators may thus provide insight into the structure of ecological systems. One of the most popular analytical tools for such study is the Kuramoto model of coupled oscillators. Using a well-studied system of pests and their enemies in an agroecosystem, we apply this model as a stylized vision of the dynamics of that real system, to ask whether its actual natural history is reflected in the dynamics of the qualitatively instantiated Kuramoto model. Emerging from the model is a series of synchrony groups generally corresponding to subnetworks of the natural system, with an overlying chimeric structure, depending on the strength of the inter-oscillator coupling. We conclude that the Kuramoto model presents a novel window through which interesting questions about the structure of ecological systems may emerge., Comment: 18 pages, 5 figures more...

Published
2020

11. The Community Ecology of Herbivore Regulation in an Agroecosystem: Lessons from Complex Systems

Author

Vandermeer, John, Armbrecht, Inge, de la Mora, Aldo, Ennis, Katherine K, Fitch, Gordon, Gonthier, David J, Hajian-Forooshani, Zachary, Hsieh, Hsun-Yi, Iverson, Aaron, Jackson, Douglas, Jha, Shalene, Jiménez-Soto, Estelí, Lopez-Bautista, Gustavo, Larsen, Ashley, Li, Kevin, Liere, Heidi, MacDonald, Andrew, Marin, Linda, Mathis, Kaitlyn A, Monagan, Ivan, Morris, Jonathan R, Ong, Theresa, Pardee, Gabriella L, Rivera-Salinas, Iris Saraeny, Vaiyda, Chatura, Williams-Guillen, Kimberly, Yitbarek, Senay, Uno, Shinsuke, Zemenick, Ash, Philpott, Stacy M, and Perfecto, Ivette more...

Subjects
agroecosystems, ecology, complex systems, Environmental Sciences, Biological Sciences, Ecology
Abstract

Abstract: Whether an ecological community is controlled from above or below remains a popular framework that continues generating interesting research questions and takes on especially important meaning in agroecosystems. We describe the regulation from above of three coffee herbivores, a leaf herbivore (the green coffee scale, Coccus viridis), a seed predator (the coffee berry borer, Hypothenemus hampei), and a plant pathogen (the coffee rust disease, caused by Hemelia vastatrix) by various natural enemies, emphasizing the remarkable complexity involved. We emphasize the intersection of this classical question of ecology with the burgeoning field of complex systems, including references to chaos, critical transitions, hysteresis, basin or boundary collision, and spatial self-organization, all aimed at the applied question of pest control in the coffee agroecosystem. more...

Published
2019

12. The population dynamics of clustered consumer-resource spatial patterns: Insights from the demographics of a Turing mechanism.

Author

Hajian-Forooshani, Zachary, Rivera-Salinas, Iris Saraeny, Perfecto, Ivette, and Vandermeer, John

Subjects
*POPULATION dynamics, *FIELD research, *AGRICULTURAL ecology, *DEMOGRAPHIC surveys, *TREND analysis
Abstract

In ecology, Alan Turing's proposed activation-inhibition mechanism has been abstracted as corresponding to several ecological interaction types to explain pattern formation in ecosystems. Consumer-resource interactions have strong theoretical arguments linking them to both the Turing mechanism and pattern formation, but there is little empirical support to demonstrate these claims. Here, we connect several lines of evidence to support the proposition that consumer-resource interactions can create empirically observed spatial patterns through a mechanism similar to Turing's theory. We propose the existence of a fine-scale demographic spatial pattern (DSP), in which the youngest resources are located at the periphery and oldest in the center of clusters. We find evidence of a DSP in the spatially clustered distribution of arboreal ant nests, whose large-scale spatial patterning has previously been hypothesized to be driven by ant parasitoids. Through a combination of field surveys and analysis of demographic trends, we demonstrate how the DSP structures the interactions between the ant and its parasitoid. To explore the implications of DSP for consumer-resource pattern forming systems generally, we use a spatially explicit consumer-resource model to show how relative diffusion rates of the system shape multiscale spatial patterns that structure the demographic trends of the resource population in predictable ways. This work provides both empirical support for consumer-resource spatial patterns as well as a multiscale approach to understand their spatially explicit population dynamics. [ABSTRACT FROM AUTHOR] more...

Published
2025
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13. Crop pests and predators exhibit inconsistent responses to surrounding landscape composition.

Author

Karp, Daniel S, Chaplin-Kramer, Rebecca, Meehan, Timothy D, Martin, Emily A, DeClerck, Fabrice, Grab, Heather, Gratton, Claudio, Hunt, Lauren, Larsen, Ashley E, Martínez-Salinas, Alejandra, O'Rourke, Megan E, Rusch, Adrien, Poveda, Katja, Jonsson, Mattias, Rosenheim, Jay A, Schellhorn, Nancy A, Tscharntke, Teja, Wratten, Stephen D, Zhang, Wei, Iverson, Aaron L, Adler, Lynn S, Albrecht, Matthias, Alignier, Audrey, Angelella, Gina M, Zubair Anjum, Muhammad, Avelino, Jacques, Batáry, Péter, Baveco, Johannes M, Bianchi, Felix JJA, Birkhofer, Klaus, Bohnenblust, Eric W, Bommarco, Riccardo, Brewer, Michael J, Caballero-López, Berta, Carrière, Yves, Carvalheiro, Luísa G, Cayuela, Luis, Centrella, Mary, Ćetković, Aleksandar, Henri, Dominic Charles, Chabert, Ariane, Costamagna, Alejandro C, De la Mora, Aldo, de Kraker, Joop, Desneux, Nicolas, Diehl, Eva, Diekötter, Tim, Dormann, Carsten F, Eckberg, James O, Entling, Martin H, Fiedler, Daniela, Franck, Pierre, Frank van Veen, FJ, Frank, Thomas, Gagic, Vesna, Garratt, Michael PD, Getachew, Awraris, Gonthier, David J, Goodell, Peter B, Graziosi, Ignazio, Groves, Russell L, Gurr, Geoff M, Hajian-Forooshani, Zachary, Heimpel, George E, Herrmann, John D, Huseth, Anders S, Inclán, Diego J, Ingrao, Adam J, Iv, Phirun, Jacot, Katja, Johnson, Gregg A, Jones, Laura, Kaiser, Marina, Kaser, Joe M, Keasar, Tamar, Kim, Tania N, Kishinevsky, Miriam, Landis, Douglas A, Lavandero, Blas, Lavigne, Claire, Le Ralec, Anne, Lemessa, Debissa, Letourneau, Deborah K, Liere, Heidi, Lu, Yanhui, Lubin, Yael, Luttermoser, Tim, Maas, Bea, Mace, Kevi, Madeira, Filipe, Mader, Viktoria, Cortesero, Anne Marie, Marini, Lorenzo, Martinez, Eliana, Martinson, Holly M, Menozzi, Philippe, Mitchell, Matthew GE, Miyashita, Tadashi, Molina, Gonzalo AR, and Molina-Montenegro, Marco A more...

Subjects
Animals, Crops, Agricultural, Ecosystem, Pest Control, Biological, Models, Biological, agroecology, biodiversity, biological control, ecosystem services, natural enemies, Crops, Agricultural, Pest Control, Biological, Models
Abstract

The idea that noncrop habitat enhances pest control and represents a win-win opportunity to conserve biodiversity and bolster yields has emerged as an agroecological paradigm. However, while noncrop habitat in landscapes surrounding farms sometimes benefits pest predators, natural enemy responses remain heterogeneous across studies and effects on pests are inconclusive. The observed heterogeneity in species responses to noncrop habitat may be biological in origin or could result from variation in how habitat and biocontrol are measured. Here, we use a pest-control database encompassing 132 studies and 6,759 sites worldwide to model natural enemy and pest abundances, predation rates, and crop damage as a function of landscape composition. Our results showed that although landscape composition explained significant variation within studies, pest and enemy abundances, predation rates, crop damage, and yields each exhibited different responses across studies, sometimes increasing and sometimes decreasing in landscapes with more noncrop habitat but overall showing no consistent trend. Thus, models that used landscape-composition variables to predict pest-control dynamics demonstrated little potential to explain variation across studies, though prediction did improve when comparing studies with similar crop and landscape features. Overall, our work shows that surrounding noncrop habitat does not consistently improve pest management, meaning habitat conservation may bolster production in some systems and depress yields in others. Future efforts to develop tools that inform farmers when habitat conservation truly represents a win-win would benefit from increased understanding of how landscape effects are modulated by local farm management and the biology of pests and their enemies. more...

Published
2018

15. Mexico ants : incidence and abundance along the Nearctic–Neotropical interface

Author

Dáttilo, Wesley, Vásquez-Bolaños, Miguel, Ahuatzin, Diana A., Antoniazzi, Reuber, Chávez-González, Edgar, Corro, Erick, Luna, Pedro, Guevara, Roger, Villalobos, Fabricio, Madrigal-Chavero, Ricardo, de Faria Falcão, Jéssica C., Bonilla-Ramírez, Adrián, Romero, Agustín Rafael García, de la Mora, Aldo, Ramírez-Hernández, Alfredo, Escalante-Jiménez, Ana Leticia, Martínez-Falcón, Ana P., Villarreal, Andrés I., Sandoval, Ashley García Colón, Aponte, Bolívar, Juárez-Juárez, Brenda, Castillo-Guevara, Citlalli, Moreno, Claudia E., Albor, Cristopher, Martínez-Tlapa, Dora Luz, Huber-Sannwald, Elisabeth, Escobar, Federico, Montiel-Reyes, Fernando J., Varela-Hernández, Fernando, Castaño-Meneses, Gabriela, Pérez-Lachaud, Gabriela, Pérez-Toledo, Gibrán Renoy, Alcalá-Martínez, Irene, Rivera-Salinas, Iris Saraeny, Chairez-Hernández, Isaías, Chamorro-Florescano, Ivette A., Hernández-Flores, Jaime, Toledo, Javier Martínez, Lachaud, Jean-Paul, Reyes-Muñoz, Jesús Lumar, Valenzuela-González, Jorge E., Horta-Vega, Jorge Víctor, Cruz-Labana, José Domingo, Reynoso-Campos, José Javier, Navarrete-Heredia, José L., Rodríguez-Garza, Juan Antonio, Pérez-Domínguez, Juan Francisco, Benítez-Malvido, Julieta, Ennis, Katherine K., Sáenz, Laura, Díaz-Montiel, Luis A., Tarango-Arámbula, Luis Antonio, Quiroz-Robedo, Luis N., Rosas-Mejía, Madai, Villalvazo-Palacios, Margarita, Gómez-Lazaga, María, Cuautle, Mariana, Aguilar-Méndez, Mario J., Baena, Martha L., Madora-Astudillo, Martha, Rocha-Ortega, Maya, Pale, Michel, García-Martínez, Miguel A., Soto-Cárdenas, Miguel Angel, Correa-Ramírez, Miguel Mauricio, Janda, Milan, Rojas, Patricia, Torres-Ricario, René, Jones, Robert W., Coates, Rosamond, Gómez-Acevedo, Sandra Luz, Ugalde-Lezama, Saúl, Philpott, Stacy M., Joaqui, Tatiana, Marques, Tatianne, Zamora-Gutierrez, Veronica, Martínez Mandujano, Viviana, Hajian-Forooshani, Zachary, and MacGregor-Fors, Ian more...

Published
2020

16. MEXICO’S ANTS : WHO ARE THEY AND WHERE DO THEY LIVE?

Author

Dáttilo, Wesley, Vásquez-Bolaños, Miguel, Ahuatzin, Diana A., Antoniazzi, Reuber, Chávez-González, Edgar, Corro, Erick, Luna, Pedro, Guevara, Roger, Villalobos, Fabricio, Madrigal-Chavero, Ricardo, de Faria Falcão, Jéssica C., Bonilla-Ramírez, Adrián, Romero, Agustín Rafael García, de la Mora, Aldo, Ramírez-Hernández, Alfredo, Escalante-Jiménez, Ana Leticia, Martínez-Falcón, Ana P., Villarreal, Andrés I., Sandoval, Ashley García Colón, Aponte, Bolívar, Juárez-Juárez, Brenda, Castillo-Guevara, Citlalli, Moreno, Claudia E., Albor, Cristopher, Martínez-Tlapa, Dora Luz, Huber-Sannwald, Elisabeth, Escobar, Federico, Montiel-Reyes, Fernando J., Varela-Hernández, Fernando, Castaño-Meneses, Gabriela, Pérez-Lachaud, Gabriela, Pérez-Toledo, Gibrán Renoy, Alcalá-Marínez, Irene, Rivera-Salinas, Iris Saraeny, Chairez-Hernández, Isaías, Chamorro-Florescano, Ivette A., Hernández-Flores, Jaime, Toledo, Javier Martínez, Lachaud, Jean-Paul, Reyes-Muñoz, Jesús Lumar, Valenzuela-González, Jorge E., Horta-Vega, Jorge Víctor, Cruz-Labana, José Domingo, Reynoso-Campos, José Javier, Navarrete-Heredia, José L., Rodríguez-Garza, Juan Antonio, Pérez-Domínguez, Juan Francisco, Benítez-Malvido, Julieta, Ennis, Katherine K., Sáenz, Laura, Díaz-Montiel, Luis A., Tarango-Arámbula, Luis Antonio, Quiroz-Robedo, Luis N., Rosas-Mejía, Madai, Villalvazo-Palacios, Margarita, Gómez-Lazaga, María, Cuautle, Mariana, Aguilar-Méndez, Mario J., Baena, Martha L., Madora-Astudillo, Martha, Rocha-Ortega, Maya, Pale, Michel, García-Martínez, Miguel A., Soto-Cárdenas, Miguel Angel, Correa-Ramírez, Miguel Mauricio, Janda, Milan, Rojas, Patricia, Torres-Ricario, René, Jones, Robert W., Coates, Rosamond, Gómez-Acevedo, Sandra Luz, Ugalde-Lezama, Saúl, Philpott, Stacy M., Joaqui, Tatiana, Marques, Tatianne, Zamora-Gutierrez, Veronica, Mandujano, Viviana Martínez, Hajian-Forooshani, Zachary, and MacGregor-Fors, Ian more...

Published
2020

17. High intermediary mutualist density provides consistent biological control in a tripartite mutualism

Author

Rivera-Salinas, Iris Saraeny, Hajian-Forooshani, Zachary, Jiménez-Soto, Esteli, Cruz-Rodríguez, Juan Antonio, and Philpott, Stacy M

Subjects
Zoology, Biological Sciences, Agroecology, Biological control, Ecosystem services, Mutualisms, Context dependency, Coffee, Entomology
Abstract

Understanding the ecology of mutualisms becomes a particularly important task when considering agroecosystems, as many ecosystem services are associated with mutualistic interactions. Here we report on experiments associated with an indirect pest control mutualism between the arboreal nesting ant Azteca sericeasur and coffee. This system is particularly interesting because the indirect Azteca-Coffea mutualism emerges from an Azteca-scale insect mutualism that takes place on the coffee plant. We describe this interaction structure as a mutualism-dependent mutualism and ask whether the density of intermediary mutualist (scale insects, Coccus) that benefits Azteca also influences the benefits provided to coffee plants. We found that indeed Azteca’s benefit to Coffea is consistent when Coccus density is high. Furthermore, we also found that at low Coccus density Azteca only benefits Coffea in the beginning of the rainy season, and this effect is likely due to the fact that Coccus produces less sugars with higher precipitation. We suggest a framework for thinking about context-dependency in agroecosystem mutualisms that may provide a more mechanistic way to tease apart the prevalent context-dependent results in ecological literature. Finally, we address some past recommendations as it pertains to the management of the Azteca-Coffea-Coccus complex in coffee agroecosystems. more...

Published
2018

27. Tree effects on coffee leaf rust at field and landscape scales

Author

Avelino, Jacques, Gagliardi, Stephanie, Perfecto, Ivette, Isaac, Marney E., Liebig, Theresa, Vandermeer, John, Merle, Isabelle, Hajian-Forooshani, Zachary, Motisi, Natacha, Avelino, Jacques, Gagliardi, Stephanie, Perfecto, Ivette, Isaac, Marney E., Liebig, Theresa, Vandermeer, John, Merle, Isabelle, Hajian-Forooshani, Zachary, and Motisi, Natacha more...

Abstract

While integrating trees into agricultural systems (i.e., agroforestry systems) provides many valuable ecosystem services, they can also interact with plant diseases. We demonstrate that a detailed understanding of how plant diseases interact with trees in agroforestry systems is necessary to identify key tree canopy characteristics, leaf traits, spatial arrangements, and management options that can help control plant diseases at different spatial scales. We focus our analysis on how trees affect coffee leaf rust, a major disease impacting one of the world's most significant crop commodities. We show that trees can both promote and discourage the development of coffee leaf rust at the plot scale via microclimate modifications in the understory. Based on our understanding of the role of tree characteristics in shaping the microclimate, we identify several canopy characteristics and leaf traits that can help manage coffee leaf rust at the plot scale: namely, thin canopies with high openness, short base height, horizontal branching, and small, dentate leaves. In contrast, at the edge of coffee farms, having large trees with high canopy volume and small, thick, waxy leaves is more useful to reduce throughflow wind speeds and intercept the airborne dispersal of urediniospores, an important consideration to control disease at the landscape scale. Seasonal pruning can help shape trees into the desired form, and trees can be spatially arranged to optimize desired effects. This case study demonstrates the added value of combining process-based epidemiology studies with functional trait ecology to improve disease management in agroforestry systems. more...

Published
2023

30. Supplementary material: Literature references for figure 1. from New forms of structure in ecosystems revealed with the Kuramoto model

Author

Vandermeer, John, Hajian-Forooshani, Zachary, Medina, Nicholas, and Perfecto, Ivette

Abstract

Ecological systems, as is often noted, are complex. Equally notable is the generalization that complex systems tend to be oscillatory, whether Huygens' simple patterns of pendulum entrainment or the twisted chaotic orbits of Lorenz’ convection rolls. The analytics of oscillators may thus provide insight into the structure of ecological systems. One of the most popular analytical tools for such study is the Kuramoto model of coupled oscillators. We apply this model as a stylized vision of the dynamics of a well-studied system of pests and their enemies, to ask whether its actual natural history is reflected in the dynamics of the qualitatively instantiated Kuramoto model. Emerging from the model is a series of synchrony groups generally corresponding to subnetworks of the natural system, with an overlying chimeric structure, depending on the strength of the inter-oscillator coupling. We conclude that the Kuramoto model presents a novel window through which interesting questions about the structure of ecological systems may emerge. more...

Published
2021
Full Text
View/download PDF

35. Crop pests and predators exhibit inconsistent responses to surrounding landscape composition

Author

Karp, Daniel S., Chaplin-Kramer, Rebecca, Meehan, Timothy D., Martin, Emily A., DeClerck, Fabrice, Grab, Heather, Gratton, Claudio, Hunt, Lauren, Larsen, Ashley E., Martinez-Salinas, Alejandra, O'Rourke, Megan E., Rusch, Adrien, Poveda, Katja, Jonsson, Mattias, Rosenheim, Jay A., Schellhorn, Nancy A., Tscharntke, Teja, Wratten, Stephen D., Zhang, Wei, Iverson, Aaron L., Adler, Lynn S., Albrecht, Matthias, Alignier, Audrey, Angelella, Gina M., Anjum, Muhammad Zubair, Avelino, Jacques, Batary, Peter, Baveco, Johannes M., Bianchi, Felix J.J.A., Birkhofer, Klaus, Bohnenblust, Eric W., Bommarco, Riccardo, Brewer, Michael J., Caballero-López, Berta, Carrière, Yves, Carvalheiro, Luísa G., Cayuela, Luis, Centrella, Mary, Cetkovic, Aleksandar, Henri, Dominic Charles, Chabert, Ariane, Costamagna, Alejandro C., De la Mora, Aldo, De Kraker, Joop, Desneux, Nicolas, Diehl, Eva, Diekötter, Tim, Dormann, Carsten F., Eckberg, James O., Entling, Martin H., Fiedler, Daniela, Franck, Pierre, van Veen, Frank, Frank, Thomas, Gagic, Vesna, Garratt, Michael P.D., Getachew, Awraris, Gonthier, David J., Goodell, Peter B., Graziosi, Ignazio, Groves, Russell L., Gurr, Geoff M., Hajian-Forooshani, Zachary, Heimpel, George E., Herrmann, John D., Huseth, Anders S., Inclán, Diego J., Ingrao, Adam J., Iv, Phirun, Jacot, Katja, Johnson, Gregg A., Jones, Laura, Kaiser, Marina, Kaser, Joe M., Keasar, Tamar, Kim, Tania N., Kishinevsky, Miriam, Landis, Douglas A., Lavandero, Blas, Lavigne, Claire, Le Ralec, Anne, Lemessa, Debissa, Letourneau, Deborah K., Liere, Heidi, Lu, Yanhui, Lubin, Yael, Luttermoser, Tim, Maas, Bea, Mace, Kevi, Madeira, Felipe, Mader, Viktoria, Cortesero, Anne-Marie, Marini, Lorenzo, Martinez, Eliana, Martinson, Holly M., and Menozzi, Philippe more...

Subjects
F08 - Systèmes et modes de culture, H10 - Ravageurs des plantes
Abstract

The idea that noncrop habitat enhances pest control and represents a win–win opportunity to conserve biodiversity and bolster yields has emerged as an agroecological paradigm. However, while noncrop habitat in landscapes surrounding farms sometimes benefits pest predators, natural enemy responses remain heterogeneous across studies and effects on pests are inconclusive. The observed heterogeneity in species responses to noncrop habitat may be biological in origin or could result from variation in how habitat and biocontrol are measured. Here, we use a pest-control database encompassing 132 studies and 6,759 sites worldwide to model natural enemy and pest abundances, predation rates, and crop damage as a function of landscape composition. Our results showed that although landscape composition explained significant variation within studies, pest and enemy abundances, predation rates, crop damage, and yields each exhibited different responses across studies, sometimes increasing and sometimes decreasing in landscapes with more noncrop habitat but overall showing no consistent trend. Thus, models that used landscape-composition variables to predict pest-control dynamics demonstrated little potential to explain variation across studies, though prediction did improve when comparing studies with similar crop and landscape features. Overall, our work shows that surrounding noncrop habitat does not consistently improve pest management, meaning habitat conservation may bolster production in some systems and depress yields in others. Future efforts to develop tools that inform farmers when habitat conservation truly represents a win–win would benefit from increased understanding of how landscape effects are modulated by local farm management and the biology of pests and their enemies. more...

Published
2018

44. Emergent Spatial Heterogeneity Structures the Assembly and Functioning of Ecological Communities: An Agroecological Perspective

Author

Hajian-Forooshani, Zachary

Subjects
Agroecology, Community Ecology, Spatial Ecology, Ecology
Abstract

Heterogeneity is a ubiquitous feature of ecosystems and perhaps an important contributing factor to the oft noted difficulties associated with making generalizations in community ecology. Our answers to questions regarding the origins and consequences of various types of heterogeneity in ecological systems have long been met with contingencies and context dependency, highlighting the need to continually revisit our organizing metaphors. The work presented in this dissertation is concerned with these metaphors and especially those associated with the ecological processes that generate spatial heterogeneity in ecosystems. In eleven case studies, we attempt to understand the generation and subsequent implications of spatial heterogeneity for the assembly and functioning of ecological communities in agroecosystems. We first address how ecological interactions create spatial pattern in Chapter 1 by presenting a novel demographic framework for understanding consumer-resource generated spatial patterns. We then explore how spatial heterogeneity influences ecological interactions in Chapter 2 and Chapter 3. Whereas in the former we ask how basic ecological interactions are influenced by dynamic patterns of heterogeneity in ecosystems, in the later we ask how changes in spatial structure influences pathogen epidemics. Chapter 4 then empirically explores how dispersal differentially alters community structure in leaf-litter metacommunities and Chapter 5 explores the use of coupled oscillators as a metaphor for ecological communities. These first five chapters represent an attempt to understand the feedbacks between ecological interactions that create spatial heterogeneity and how spatial heterogeneity structures ecological communities. The dissertation then shifts focus to a fungal pathogen of coffee, the coffee leaf rust, and uses its community of consumers as a model system to understand how spatial heterogeneity influences community structure and how community structure influences biological control of the pathogen. Chapter 6 gives a brief overview of the history and ecology of the pathogen and its community, and Chapters 7-9 explore the assembly and organization of these communities, highlighting their interactions with the pathogen as well as among themselves. Finally, Chapters 10 and 11 are concerned with the structure of interaction networks associated with the coffee leaf rust and the provisioning of top-down control of the coffee leaf rust pathogen in both Mexico and Puerto Rico. Taken together, this dissertation contributes to our understanding of how ecological communities create and are impacted by the heterogeneous environments they occupy. Furthermore, this work attempts to highlight the importance of such concepts in an agroecological context where questions of community structure and population regulation have the potential for practical significance. more...

Published
2022