Effect of drought on plant physiology, disease susceptibility and insect herbivory in rainforest saplings

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Dmitry Grishin
Lillian Green
Maxwell Etherington
Ellie Lambden
Jaiden Lane
Lachlan Read
Hannah Peryman
Laura Bailey
Lillian Burless

Keywords

throughfall infrastructure, reduced rainfall, in situ, natural ecosystems, severity, pathogens, herbivory

Abstract

Two rainforest canopy tree species were sampled as saplings in June of 2022 in a cross-sectional study to compare the effect of drought on physiological performance, insect herbivory and leaf disease damage. Throughfall infrastructure was utilised to simulate drought in field conditions. A strong effect of drought was found across all physiological measures, with drought being correlated with lower leaf chlorophyll content, stomatal conductance, and photosystem 2 efficiency. Plant health was assessed at the leaf-level using a 0-5 visual scale. No significant effect of drought on insect herbivory of disease damage was found, except for in Argyrodendron peralatum. Correlation of physiological performance and individual health assessments revealed several trends in susceptibility. Chlorophyll content was found to be more steeply correlated to insect damage severity in drought treatments than in control treatments, the effect of stomatal water conductance was investigated, and reduction in efficiency of photosystem 2 was correlated to higher severity of affliction. Mechanisms behind trends in susceptibility were investigated but the inference power of this study was limited by the cross-sectional nature. A longitudinal study tracking the progression of plant health metrics, physiological performance, and development was suggested for future research in conjunction with studies that analyse drought impact on invertebrate communities.    

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