The effects of fire and drought on plant-soil feedbacks of a nonnative invasive grass in southern Illinois

Non-native plants can disrupt ecosystem functioning and internally reinforce their dominance over native species by altering soil nutrient availability (i.e. resource-mediated feedbacks) and by modifying fire regimes (i.e. disturbance-mediated feedbacks). While fire and other disturbances are shown to promote further invasions, there is a limited understanding of their effects on invader-driven biogeochemical impacts. In this thesis, I examine how climate-mediated disturbances including fire and drought affect invader impacts on soil carbon (C) and nitrogen (N) cycling. Working in temperate deciduous forests in southern Illinois, I quantified the effects of fire and drought on belowground soil organic matter pools, microbial biomass, extracellular enzyme activities, and soil respiration in stands invaded by the C4 exotic grass Microstegium vimineum. I used a manipulative field experiment conducted across two invaded sites with contrasting fire history to determine the effects of prescribed burning and growing season drought imposed using rainout shelters. I found that invaded plots exposed to repeated burning had lower invasive grass productivity, higher root:shoot ratio, and higher C:N ratio in plant tissues and soil microbial biomass. The results presented here suggest that invasion by grasses like M. vimineum may increase the potential for N loss during fire, leading to a progressive depletion of N availability through repeated burning, which may weaken the positive resource-mediated feedbacks initiated by non-native plants. I also found that drought may further contribute to the weakening of invasive plant-soil feedbacks through co-limitation with N. Though climate change is generally predicted to facilitate the spread and establishment of invasive plants in the future, increases in fire and drought frequency may weaken the self- reinforcing feedbacks and ecosystem impacts of non-native invasive plants.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Natural Res & Env Sciences

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2019

Author dc:creator

• Rembelski, Mara Kathleen

Contributors dc:contributor

• Fraterrigo, Jennifer M

• Invasive grasses
• Repeated fire
• Drought
• Nitrogen
• Soil organic matter
• Plant-soil feedbacks
• Temperate forests
• Microstegium vimineum
• Biogeochemical cycles

Statement dc:rights

• Copyright 2019 Mara Rembelski

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/105613

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/105613