Forest Fire Severity Affects Host Plant Quality and Insect Herbivore Damage

Abstract

Climate change models predict increased forest fire occurrence and severity in the near future. Forest fire disturbance affects multiple ecological interactions, but there is little evidence for how naturally-occurring fires affect plant quality and herbivore damage, which is important because plants and herbivorous insects comprise most of the diversity in natural ecosystems and are responsible for a variety of ecosystem services. We surveyed three fires in the Rocky Mountains to investigate the effects of fire severity on wax currant (Ribes cereum), an important source of food and cover for wildlife in Colorado. We measured plant quality and herbivore damage; we found that fire severity had a significant negative effect on both measures. Notably, high severity fires decreased herbivore damage by about 50%. Furthermore, we found that the effect of fire on insect herbivore damage is mostly direct, but that indirect effects mediated through changes in plant quality are also significant. Our results have important implications for the effects of climate-driven increases in fire severity on plant-insect interactions, illustrating strong direct and weaker indirect negative effects of fire severity in a forest ecosystem.

Fire affects galling insect communities through vegetation changes in a subtropical seasonally semiarid forest

“…In particular, the diet breadth of an insect herbivore could be influencing its vulnerability to fire. Unlike generalists, specialist insects are expected to be more sensitive to fire‐induced changes in vegetation due to their higher dependency on a particular plant resource (Murphy et al, 2018; Pearse & Altermatt, 2013). Most available studies addressing the resilience of insects to fire are focused on generalist herbivore species (Lopes & Vasconcelos, 2011; García et al, 2016; Andrade et al, 2019), whereas specialist herbivores have been less frequently investigated (Murphy et al, 2018; Pearse & Altermatt, 2013).…”

“…Unlike generalists, specialist insects are expected to be more sensitive to fire‐induced changes in vegetation due to their higher dependency on a particular plant resource (Murphy et al, 2018; Pearse & Altermatt, 2013). Most available studies addressing the resilience of insects to fire are focused on generalist herbivore species (Lopes & Vasconcelos, 2011; García et al, 2016; Andrade et al, 2019), whereas specialist herbivores have been less frequently investigated (Murphy et al, 2018; Pearse & Altermatt, 2013). Some studies have demonstrated that fire affects herbivory (Murphy et al, 2018) and species richness and composition in communities of specialist insects (Kaynaş & Gürkan, 2008; Kim & Holt, 2012; Mutz et al, 2017).…”

“…Most available studies addressing the resilience of insects to fire are focused on generalist herbivore species (Lopes & Vasconcelos, 2011; García et al, 2016; Andrade et al, 2019), whereas specialist herbivores have been less frequently investigated (Murphy et al, 2018; Pearse & Altermatt, 2013). Some studies have demonstrated that fire affects herbivory (Murphy et al, 2018) and species richness and composition in communities of specialist insects (Kaynaş & Gürkan, 2008; Kim & Holt, 2012; Mutz et al, 2017). However, the effect triggered by fire on specialist herbivores, both directly or indirectly, remains unknown.…”

Wildfires change plant scents but not pollinator attraction in a Mediterranean palm

“…Drought and variation in soil nutrient content can induce changes on floral scents and pollinator attraction (Burkle and Runyon, 2016; Majetic et al, 2017; Glenny et al, 2018). In addition, antagonistic pressures modify plant fragrances (Kessler et al, 2011; Burkle and Runyon, 2016), and these pressures can be altered by wildfires (Knight and Holt, 2005; García et al, 2016; Murphy et al, 2018). At a broader scale, recent studies have pointed out the importance of plant chemical-signaling on pollination at the community level (Kantsa et al, 2017; Burkle and Runyon, 2019).…”

Sample Size Calculations for Vegetation Studies

“…The statistical methods presented in this paper for calculating sample size assume a normal distribution of vegetation data (except the Chi-square test which is a non-parametric statistic also called a distribution free test). Although some studies have indicated that vegetation characteristics such as biomass, density, production, plant height and seed production are normally distributed (Rosner & Rose 2006;Hoch & Korner 2009;Giannini et al 2018), some others have revealed that distribution of these characteristics is not normal (Mascaro & Schnitzer 2011;Murphy et al 2018;Bisi et al 2018).Therefore, it is recommended to test the distribution of vegetation data before selection of a statistical test using Kolmogorov-Smirnov or Shapiro-Wilk test. If the data are not normally distributed, transformation methods such as log, square root, and angular transformation can be used to normalize the distribution of data.…”