A two-part study looking at how changes in soil salinity affect tamarisk growth and how beetle-induced defoliation affects tamarisk growing in soils with different salinities. Results showed that tamarisk plants grow better in soils with a similar salinity to their own origin site and that lower salinity does not benefit tamarisk plants adapted to higher saline conditions. Tamarisk beetles caused a significantly greater reduction in total biomass in the high salinity plants than the low salinity ones (averages of 63% and 32% respectively), likely due to increased water stress and reduced resources to enable regrowth. Although plants compensated for herbivory by regrowing foliage over three defoliation events and maintained similar leaf biomass through regrowth, they ultimately had a reduced basal area and 62% lower root biomass compared to the controls. Thus, herbivory caused a shift in plant allocation of resources from overall growth to compensation, reducing root and stem investment.
Long, R.W., D’Antonio, C.M., Dudley, T.L. et al. Salinity driven interactions between plant growth and a biological control agent. Biol Invasions 23, 3161–3173 (2021). https://doi.org/10.1007/s10530-021-02556-x