Small‐scale indirect plant responses to insect herbivory could have major impacts on canopy photosynthesis and isoprene emission

Visakorpi, Kristiina; Gripenberg, Sofia; Malhi, Yadvinder; Bolas, Conor G.; Oliveras, Imma; Harris, Neil; Rifai, Sami W.; Riutta, Terhi

doi:10.1111/nph.15338

Cited by 34 publications

(38 citation statements)

References 98 publications

(151 reference statements)

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“…Although herbivory was generally low, values were within the range registered by other studies in grasslands (e.g., Scherber et al 2006) and were in agreement with the patterns observed in recent reviews of insect herbivory (Zhang et al 2016, Kozlov andZvereva 2018). It has been observed that even low levels of leaf area removed can trigger alterations in plant physiology and nutritional quality (Kerchev et al 2012, Visakorpi et al 2018) and in turn affect plant population dynamics (Stein et al 2010, Allan andCrawley 2011).…”

Section: Discussionsupporting

confidence: 89%

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Insect and plant traits drive local and landscape effects on herbivory in grassland fragments

et al. 2019

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Herbivory is one of the most important antagonistic insect–plant interactions and can be influenced by factors at local and landscape scales. Landscape fragmentation may reduce herbivory directly (i.e., decreasing abundance and species richness of herbivores), but also indirectly increase herbivory (i.e., releasing herbivores from top‐down control). At a local scale, reduced plant diversity may enhance herbivory through lessened associated resistance, while resource availability (i.e., higher vegetation height and cover) may promote herbivory. Few studies have simultaneously considered the influence of local and landscape variables on insect herbivory. We evaluate effects of landscape (fragment size, connectivity, and arable land percentage) and local factors (plant cover and height and plant species richness) on insect herbivory in fragmented calcareous grasslands. Further, we ask whether these effects depend on feeding traits of herbivores (chewers vs. suckers) and habitat specialization of plants (specialists vs. generalists). Results show that herbivory was best explained by models including variables at both local and landscape scales. However, local factors were more important than landscape variables. Herbivory was in all cases positively related to height of herbs (i.e., taller and more heterogeneous food resources), whereas the effect of plant species richness varied with feeding traits of herbivores. Herbivory by chewers, which are commonly more generalist feeders, was negatively affected by plant species richness, supporting the idea of associated plant resistance. In contrast, herbivory by suckers, which tend to be more specialized, increased with plant richness. Although there was little influence of landscape scale, herbivory on specialist plants was significantly higher in smaller grasslands probably as a consequence of herbivore release from natural enemies. Functional redundancy among herbivore species would allow to maintain overall herbivory in fragmented calcareous grasslands. This study highlights the need to consider different herbivore and plant traits for a better understanding of herbivory responses to local and landscape factors.

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Section: Discussionsupporting

confidence: 89%

“…, Visakorpi et al. ) and in turn affect plant population dynamics (Stein et al. , Allan and Crawley ).…”

Section: Discussionmentioning

confidence: 99%

Insect and plant traits drive local and landscape effects on herbivory in grassland fragments

et al. 2019

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“…FORCAsT employs a half‐hourly timestep. Our simulations therefore focused on the emissions of isoprene, which are calculated in FORCAsT by summing the contributions from 10 leaf angle classes in each crown‐space model level, following the algorithms of Guenther et al ():

ER = LAI \cdot ε \cdot γ_{iso},

where ER is the total emission rate (mg m −2 hr −1 ), LAI (m 2 /m 2 ) is the leaf area index and ε is a site‐ and species‐specific emission factor (1.20 mg m −2 hr −1 for Q. robur ; Visakorpi et al, ) which represents the emission rate of isoprene into the canopy at standard conditions of 30°C and 1,000 µmol m −2 s −1 . LAI was taken as the maximum reported for the site (3.6 m 2 /m 2 ; Herbst, Rosier, Morecroft, & Gowing, ) throughout this study which coincides with the period of peak growth.…”

Section: Methodsmentioning

confidence: 99%

“…The simulated exchange of heat and trace gases is further improved by constraining the friction velocity (u*) and the standard deviation of the vertical wind component (σ w ) following Bryan et al (2012). As u* and σ w were not measured at Wytham, we estimated each from the horizontal wind speed (u) following Makar et al (2017), Equation (1), and Shuttleworth and Wallace (1985), Equation (2) where ER is the total emission rate (mg m −2 hr −1 ), LAI (m 2 /m 2 ) is the leaf area index and ε is a site-and species-specific emission factor (1.20 mg m −2 hr −1 for Q. robur; Visakorpi et al, 2018) which represents the emission rate of isoprene into the canopy at standard conditions of 30°C and 1,000 µmol m −2 s −1 . LAI was taken as the maximum reported for the site (3.6 m 2 /m 2 ; Herbst, Rosier, Morecroft, & Gowing, 2008) throughout this study which coincides with the period of peak growth.…”

Section: Model Descriptionmentioning

confidence: 99%

Modelling the effect of the 2018 summer heatwave and drought on isoprene emissions in a UK woodland

Otu‐Larbi

Bolas

Ferracci

et al. 2020

Global Change Biology

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Projected future climatic extremes such as heatwaves and droughts are expected to have major impacts on emissions and concentrations of biogenic volatile organic compounds (bVOCs) with potential implications for air quality, climate and human health. While the effects of changing temperature and photosynthetically active radiation (PAR) on the synthesis and emission of isoprene, the most abundant of these bVOCs, are well known, the role of other environmental factors such as soil moisture stress are not fully understood and are therefore poorly represented in land surface models. As part of the Wytham Isoprene iDirac Oak Tree Measurements campaign, continuous measurements of isoprene mixing ratio were made throughout the summer of 2018 in Wytham Woods, a mixed deciduous woodland in southern England. During this time, the United Kingdom experienced a prolonged heatwave and drought, and isoprene mixing ratios were observed to increase by more than 400% at Wytham Woods under these conditions. We applied the state‐of‐the‐art FORest Canopy‐Atmosphere Transfer canopy exchange model to investigate the processes leading to these elevated concentrations. We found that although current isoprene emissions algorithms reproduced observed mixing ratios in the canopy before and after the heatwave, the model underestimated observations by ~40% during the heatwave–drought period implying that models may substantially underestimate the release of isoprene to the atmosphere in future cases of mild or moderate drought. Stress‐induced emissions of isoprene based on leaf temperature and soil water content (SWC) were incorporated into current emissions algorithms leading to significant improvements in model output. A combination of SWC, leaf temperature and rewetting emission bursts provided the best model‐measurement fit with a 50% improvement compared to the baseline model. Our results highlight the need for more long‐term ecosystem‐scale observations to enable improved model representation of atmosphere–biosphere interactions in a changing global climate.

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“…785–798). Finally, Visakorpi et al . (in this issue, pp. 799–810), found that herbivory reduced photosynthesis dramatically across a whole canopy level and increased isoprene emission.…”

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confidence: 96%

Introduction to a special feature issue – New insights into plant volatiles

Kessler

2018

New Phytologist

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This article is an Editorial on the special feature issue ‘New insights into plant volatiles’, which is published in this issue and which includes the following articles: Ameye et al., pp. 666–683; Sharifi et al. pp. 684–691; Moreira et al., pp. 703–713; Pichersky & Raguso, pp. 692–702; Chen et al., pp. 714–725; Danner et al., pp. 726–738; Junker et al., pp. 739–749; Rering et al., pp. 750–759; Eberl et al., pp. 760–772; Fernández‐Martínez et al., pp. 773–784; Glenny et al., pp. 785–798 and Visakorpi et al., pp. 799–810.

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Small‐scale indirect plant responses to insect herbivory could have major impacts on canopy photosynthesis and isoprene emission

Cited by 34 publications

References 98 publications

Insect and plant traits drive local and landscape effects on herbivory in grassland fragments

Insect and plant traits drive local and landscape effects on herbivory in grassland fragments

Modelling the effect of the 2018 summer heatwave and drought on isoprene emissions in a UK woodland

Introduction to a special feature issue – New insights into plant volatiles

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