Fire disturbance belowground: untangling consequences for soil food webs and organic matter
| dc.contributor.author | Pressler, Yamina, author | |
| dc.contributor.author | Moore, John C., advisor | |
| dc.contributor.author | Cotrufo, M. Francesca, advisor | |
| dc.contributor.author | Knapp, Alan K., committee member | |
| dc.contributor.author | Balgopal, Meena M., committee member | |
| dc.date.accessioned | 2019-06-14T17:05:33Z | |
| dc.date.available | 2020-06-10T17:05:25Z | |
| dc.date.issued | 2019 | |
| dc.description.abstract | Soils and the ecological communities they house provide a diverse array of ecosystem services including the provisioning of food and fiber, decomposition and nutrient cycling, water filtration, and the maintenance of terrestrial biodiversity. These complex belowground communities, and therefore the ecosystem processes they regulate, are increasingly threatened by fire due to climate, land use, and management changes. Fires can have profound effects on the physical and chemical soil environment, with consequences for soil biological communities. Fires cause mortality of soil organisms during the disturbance event, change the soil pH, and alter the quantity and quality of soil organic matter (SOM). In particular, fires transform organic matter into pyrogenic carbon (PyC), a recalcitrant material with a dense aromatic structure and long residence times in soils. In natural ecosystems, soil food webs interact with PyC produced after a fire. In agroecosystems, PyC, in the form of biochar, is also used as a tool to manage soil carbon and fertility. Given the widespread effects of fire on biological, chemical, and physical components of the soil, and the importance of soil communities for the provisioning of ecosystem services, understanding the consequences of fire disturbance for soil food webs and organic matter is an important research objective. My dissertation leverages several different scientific inquiry approaches to understand the consequences of disturbance and management for the ecology of soils. I take a multifaceted approach by considering soil organisms, food webs, and organic matter in the context of fire disturbance and agricultural management. I begin by presenting results from a meta-analysis investigating the effect of fire on soil biota biomass, abundance, richness, evenness, and diversity. Overall, I found a pervasive negative effect of fire on soil microorganisms and conclude that soil fauna are more resistant to fire than soil microorganisms. Then, I present results from a field study investigating the effect of fire frequency on soil food web structure, function, stability, and resilience in an oak-pine savanna. Here, I found that while soil biota biomass and food web function did not differ with fire frequency, food web structure, stability, and resilience did. In particular, soil food webs at intermediate fire frequencies (4-year fire return interval) were the least stable and least resilient to fire. Thereafter, I consider the consequences of fire for SOM composition through the lens of PyC. I seek to understand where and why PyC persists in soils at a continental scale by using multiple analytical techniques to quantify PyC across Europe. I found that PyC may contribute a smaller component of soil organic carbon than previously thought and that organic carbon is the best predictor of PyC at a continental scale. I then consider how agricultural management and PyC in the form of biochar, impacts soil food webs in a semi-arid corn agroecosystem. I did not find any measurable effects of biochar on soil food web structure or function. I conclude that the long-term impact of historical land management on soil food webs far outweighs any impact of short-term management practices involving biochar. I then use this field study as an opportunity to integrate scientific inquiry in middle school classrooms. I present a collection of classroom activities co-developed with secondary educators that lead students to investigate the effect of biochar on soils and plants. I conclude by discussing the themes, patterns, and ideas that emerge from the preceding chapters. I found that the responses of soil ecological communities to disturbance are highly context dependent. This context dependency leads to hidden, unexpected, and even contradictory patterns. I end by reflecting on how completing this work has informed my non-linear approach to science. | |
| dc.format.medium | born digital | |
| dc.format.medium | doctoral dissertations | |
| dc.identifier | Pressler_colostate_0053A_15306.pdf | |
| dc.identifier.uri | https://hdl.handle.net/10217/195271 | |
| dc.language | English | |
| dc.language.iso | eng | |
| dc.publisher | Colorado State University. Libraries | |
| dc.relation.ispartof | 2000-2019 | |
| dc.rights | Copyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright. | |
| dc.subject | disturbance | |
| dc.subject | pyrogenic carbon | |
| dc.subject | soil food webs | |
| dc.subject | fire | |
| dc.subject | biochar | |
| dc.subject | soil fauna | |
| dc.title | Fire disturbance belowground: untangling consequences for soil food webs and organic matter | |
| dc.type | Text | |
| dcterms.embargo.expires | 2020-06-10 | |
| dcterms.embargo.terms | 2020-06-10 | |
| dcterms.rights.dpla | This Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). | |
| thesis.degree.discipline | Ecology | |
| thesis.degree.grantor | Colorado State University | |
| thesis.degree.level | Doctoral | |
| thesis.degree.name | Doctor of Philosophy (Ph.D.) |
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