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- All Subjects: psychology
- All Subjects: Interannual variability
- Status: Published
Description
Climate change will result not only in changes in the mean state of climate but also on changes in variability. However, most studies of the impact of climate change on ecosystems have focused on the effect of changes in the central tendency. The broadest objective of this thesis was to assess the effects of increased interannual precipitation variation on ecosystem functioning in grasslands. In order to address this objective, I used a combination of field experimentation and data synthesis. Precipitation manipulations on the field experiments were carried out using an automated rainfall manipulation system developed as part of this dissertation. Aboveground net primary production responses were monitored during five years. Increased precipitation coefficient of variation decreased primary production regardless of the effect of precipitation amount. Perennial-grass productivity significantly decreased while shrub productivity increased as a result of enhanced precipitation variance. Most interesting is that the effect of precipitation variability increased through time highlighting the existence of temporal lags in ecosystem response.
Further, I investigated the effect of precipitation variation on functional diversity on the same experiment and found a positive response of diversity to increased interannual precipitation variance. Functional evenness showed a similar response resulting from large changes in plant-functional type relative abundance including decreased grass and increased shrub cover while functional richness showed non-significant response. Increased functional diversity ameliorated the direct negative effects of precipitation variation on ecosystem ANPP but did not control ecosystem stability where indirect effects through the dominant plant-functional type determined ecosystem stability.
Analyses of 80 long-term data sets, where I aggregated annual productivity and precipitation data into five-year temporal windows, showed that precipitation variance had a significant effect on aboveground net primary production that is modulated by mean precipitation. Productivity increased with precipitation variation at sites where mean annual precipitation is less than 339 mm but decreased at sites where precipitation is higher than 339 mm. Mechanisms proposed to explain patterns include: differential ANPP response to precipitation among sites, contrasting legacy effects and soil water distribution.
Finally, increased precipitation variance may impact global grasslands affecting plant-functional types in different ways that may lead to state changes, increased erosion and decreased stability that can in turn limit the services provided by these valuable ecosystems.
Further, I investigated the effect of precipitation variation on functional diversity on the same experiment and found a positive response of diversity to increased interannual precipitation variance. Functional evenness showed a similar response resulting from large changes in plant-functional type relative abundance including decreased grass and increased shrub cover while functional richness showed non-significant response. Increased functional diversity ameliorated the direct negative effects of precipitation variation on ecosystem ANPP but did not control ecosystem stability where indirect effects through the dominant plant-functional type determined ecosystem stability.
Analyses of 80 long-term data sets, where I aggregated annual productivity and precipitation data into five-year temporal windows, showed that precipitation variance had a significant effect on aboveground net primary production that is modulated by mean precipitation. Productivity increased with precipitation variation at sites where mean annual precipitation is less than 339 mm but decreased at sites where precipitation is higher than 339 mm. Mechanisms proposed to explain patterns include: differential ANPP response to precipitation among sites, contrasting legacy effects and soil water distribution.
Finally, increased precipitation variance may impact global grasslands affecting plant-functional types in different ways that may lead to state changes, increased erosion and decreased stability that can in turn limit the services provided by these valuable ecosystems.
ContributorsGherardi Arbizu, Laureano (Author) / Sala, Osvaldo E. (Thesis advisor) / Childers, Daniel (Committee member) / Grimm, Nancy (Committee member) / Hall, Sharon (Committee member) / Wu, Jingle (Committee member) / Arizona State University (Publisher)
Created2014
Description
Animal psychology is the study of how animals interact with one another, their environment, and with humans. This can be done in two different settings, the wild and captivity, and through two different approaches, academic research and practice. Academic research relies primarily on behavioral observation for data collection. Practice uses behavioral observation as well, but allows for a more hands on experience and lets the practitioner make improvements in the quality of life. I interviewed two people, one who practices in captivity, and one who does research in the wild. Dr. David Bunn has done research on wild animals in Kruger National Park in South Africa for over twenty years, studying human-animal interactions. Hilda Tresz has worked in zoos nearly forty years and specializes in chimps. Working within the same field, but utilizing a different setting and approach makes a big difference in the feel of the job. Though I found many differences between the two by doing my own research and from conducting interviews, there are many similarities to note as well. The general field of animal psychology is very rewarding, requires a lot of patience, and leads to a better understanding of animal behavior and how to care for specific species of animals. Working with captive animals allows for the opportunity to make a big difference in animal's lives through behavioral enrichment and general care. Working in the wild allows us to understand the innate animal behaviors displayed. Through practice, people get more hands on experience; while through research, you get to observe animals in their native habitats. Each setting and approach has it's own benefits depending on what each person's goals are for their job.
ContributorsDaniel, Mckenna Lynne (Author) / Childers, Daniel (Thesis director) / Hall, Sharon (Committee member) / School of Social and Behavioral Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
The climate conversation is growing more important and necessary than ever. The media has a way of promoting a "doom and gloom" sentiment over conservation efforts and what the public has the power to do in terms of making a change. Now due to the effects of COVID-19 on the population's attention spans and memories, there is a need for a way to communicate climate science effectively and to encourage those who feel discouraged by climate change to find their inner power. The answer lies in photography. Making science accessible and intriguing through the art of photography is what can get people more interested and empowered to fight against climate change and alter their attitudes towards environmentalism. This thesis explains psychological research and the reasons why people feel helpless in terms of our global future. In then dives into human subjects research conducted on ASU's campus and how the survey results argue in favor of the paper's hypothesis. Additionally, ways to get involved and reasons why we need to remain hopeful are discussed.
ContributorsGorlick, Vanessa (Author) / Hall, Sharon (Thesis director) / Makings, Elizabeth (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor) / The Sidney Poitier New American Film School (Contributor) / Dean, W.P. Carey School of Business (Contributor)
Created2023-05