Decreased Soil Microbial Biomass and Changed Microbial Community Composition following a Defoliation Event by the Forest Tent Caterpillar
With climate change projected to increase the frequency and severity of episodic insect outbreak events, assessing potential consequences for soil microbial communities and nutrient dynamics is of importance for understanding forest resilience. The forest tent caterpillar (<i>Malacosoma disstr...
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-04-01
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| Series: | Forests |
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| Online Access: | https://www.mdpi.com/1999-4907/14/4/792 |
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| author | Éléonore Dansereau-Macias Emma Despland Ira Tanya Handa |
| author_facet | Éléonore Dansereau-Macias Emma Despland Ira Tanya Handa |
| author_sort | Éléonore Dansereau-Macias |
| collection | DOAJ |
| description | With climate change projected to increase the frequency and severity of episodic insect outbreak events, assessing potential consequences for soil microbial communities and nutrient dynamics is of importance for understanding forest resilience. The forest tent caterpillar (<i>Malacosoma disstria)</i> is an important defoliator of deciduous tree species in temperate and mixed forests of eastern North America with an invasion cycle every 10–12 years and outbreak events that can last 3–6 years. Following a defoliation episode on trembling aspen (<i>Populus tremuloides)</i> from 2015 to 2017 in Abitibi-Témiscamingue, QC, Canada, we sought to test if defoliation resulted in changes to soil bacterial and fungal communities. We hypothesized an increase in soil microbial biomass due to increased caterpillar frass inputs and potential changes in community structure following the event. Soils were sampled in August 2018, May 2019 and July 2019 from sites that had been subjected to defoliation during the outbreak and from sites where no defoliation had been recorded. We assessed soil microbial biomass and fungal to total microbial activity ratio on all sampling dates, and Community Level Physiological Profiles (CLPPs) for 2018 only using a substrate-induced respiration method. Contrary to our hypothesis, we observed a significant 50% decrease in microbial biomass (μg biomass-C g<sup>−1</sup> soil hour<sup>−1</sup>) in defoliated stands, suggesting tree carbon normally allocated towards root exudates was reallocated towards foliage regeneration. We noted a differentiated carbon-based substrate usage following defoliation, but no change in the fungal to total microbial activity ratio. The observed changes in the two years following the defoliation event suggest that defoliation episodes above-ground could trigger changes in soil chemistry below-ground with effects on soil microbial communities that may, in turn, feedback to influence forest plant dynamics. |
| first_indexed | 2024-03-11T05:01:13Z |
| format | Article |
| id | doaj.art-805903b5ddf64532bfb2e27d59b4b568 |
| institution | Directory Open Access Journal |
| issn | 1999-4907 |
| language | English |
| last_indexed | 2024-03-11T05:01:13Z |
| publishDate | 2023-04-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Forests |
| spelling | doaj.art-805903b5ddf64532bfb2e27d59b4b5682023-11-17T19:17:57ZengMDPI AGForests1999-49072023-04-0114479210.3390/f14040792Decreased Soil Microbial Biomass and Changed Microbial Community Composition following a Defoliation Event by the Forest Tent CaterpillarÉléonore Dansereau-Macias0Emma Despland1Ira Tanya Handa2Département des Sciences Biologiques, Université du Québec à Montréal, 141 President-Kennedy Ave., Montreal, QC H2X 1Y4, CanadaBiology Department, Concordia University, 7141 Sherbrooke West, Montreal, QC H4B 1R6, CanadaDépartement des Sciences Biologiques, Université du Québec à Montréal, 141 President-Kennedy Ave., Montreal, QC H2X 1Y4, CanadaWith climate change projected to increase the frequency and severity of episodic insect outbreak events, assessing potential consequences for soil microbial communities and nutrient dynamics is of importance for understanding forest resilience. The forest tent caterpillar (<i>Malacosoma disstria)</i> is an important defoliator of deciduous tree species in temperate and mixed forests of eastern North America with an invasion cycle every 10–12 years and outbreak events that can last 3–6 years. Following a defoliation episode on trembling aspen (<i>Populus tremuloides)</i> from 2015 to 2017 in Abitibi-Témiscamingue, QC, Canada, we sought to test if defoliation resulted in changes to soil bacterial and fungal communities. We hypothesized an increase in soil microbial biomass due to increased caterpillar frass inputs and potential changes in community structure following the event. Soils were sampled in August 2018, May 2019 and July 2019 from sites that had been subjected to defoliation during the outbreak and from sites where no defoliation had been recorded. We assessed soil microbial biomass and fungal to total microbial activity ratio on all sampling dates, and Community Level Physiological Profiles (CLPPs) for 2018 only using a substrate-induced respiration method. Contrary to our hypothesis, we observed a significant 50% decrease in microbial biomass (μg biomass-C g<sup>−1</sup> soil hour<sup>−1</sup>) in defoliated stands, suggesting tree carbon normally allocated towards root exudates was reallocated towards foliage regeneration. We noted a differentiated carbon-based substrate usage following defoliation, but no change in the fungal to total microbial activity ratio. The observed changes in the two years following the defoliation event suggest that defoliation episodes above-ground could trigger changes in soil chemistry below-ground with effects on soil microbial communities that may, in turn, feedback to influence forest plant dynamics.https://www.mdpi.com/1999-4907/14/4/792forest tent caterpillar (<i>Malacosoma disstria)</i>insect outbreakdefoliation eventMicroRespsoil microbial activity |
| spellingShingle | Éléonore Dansereau-Macias Emma Despland Ira Tanya Handa Decreased Soil Microbial Biomass and Changed Microbial Community Composition following a Defoliation Event by the Forest Tent Caterpillar Forests forest tent caterpillar (<i>Malacosoma disstria)</i> insect outbreak defoliation event MicroResp soil microbial activity |
| title | Decreased Soil Microbial Biomass and Changed Microbial Community Composition following a Defoliation Event by the Forest Tent Caterpillar |
| title_full | Decreased Soil Microbial Biomass and Changed Microbial Community Composition following a Defoliation Event by the Forest Tent Caterpillar |
| title_fullStr | Decreased Soil Microbial Biomass and Changed Microbial Community Composition following a Defoliation Event by the Forest Tent Caterpillar |
| title_full_unstemmed | Decreased Soil Microbial Biomass and Changed Microbial Community Composition following a Defoliation Event by the Forest Tent Caterpillar |
| title_short | Decreased Soil Microbial Biomass and Changed Microbial Community Composition following a Defoliation Event by the Forest Tent Caterpillar |
| title_sort | decreased soil microbial biomass and changed microbial community composition following a defoliation event by the forest tent caterpillar |
| topic | forest tent caterpillar (<i>Malacosoma disstria)</i> insect outbreak defoliation event MicroResp soil microbial activity |
| url | https://www.mdpi.com/1999-4907/14/4/792 |
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