Pre‐damage biomass allocation and not invasiveness predicts tolerance to damage in seedlings of woody species in Hawaii

Abstract

Plant-herbivore interactions have been predicted to play a fundamental role in plant invasions, although support for this assertion from previous research is mixed. While plants may escape from specialist herbivores in their introduced ranges, herbivory from generalists is common. Tolerance traits may allow non-native plants to mitigate the negative consequences of generalist herbivory that they cannot avoid in their introduced range. Here we address whether tolerance to herbivory, quantified as survival and compensatory growth, is associated with plant invasion success in Hawaii and investigate traits that may enhance tolerance in seedlings, the life stage most susceptible to herbivory. In a greenhouse experiment, we measured seedling tolerance to simulated herbivory through mechanical damage (50% leaf removal) of 16 non-native woody plant species differing in invasion status (invasive vs. non-invasive). Seedlings were grown for 2 weeks following damage and analyzed for biomass to determine whether damaged plants could fully compensate for the lost leaf tissue. Over 99% of all seedlings survived defoliation. Although species varied significantly in their levels of compensation, there was no consistent difference between invasive and non-invasive species. Seedlings of 11 species undercompensated and remained substantially smaller than control seedlings 2 weeks after damage; four species were close to compensating, while one species overcompensated. Across species, compensation was positively associated with an increased investment in potential storage reserves, specifically cotyledons and roots, suggesting that these organs provide resources that help seedlings re-grow following damage. Our results add to a growing consensus that pre-damage growth patterns determine tolerance to damage, even in young seedlings which have relatively low biomass. The lack of higher tolerance in highly invasive species may suggest that invaders overcome herbivory barriers to invasion in other ways, such as resistance traits, or that herbivory does not play an important role in the seedling invasion dynamics of these woody species in Hawaii.

Lineage and latitudinal variation in Phragmites australis tolerance to herbivory: implications for invasion success

“…We implemented an artificial folivory treatment to simulate the effects of heavy folivory, a common approach in the study of tolerance to herbivory (Marquis , Tiffin and Inouye , Ashton and Lerdau , Vergés et al , Lurie et al ). Phragmites australis lineages vary widely in resistance to folivory (Cronin et al , Bhattarai et al ) and, consequently, it would have been difficult to achieve a standardized level of herbivory among source populations without varying herbivore density and/or exposure time.…”

“…The mechanisms underlying tolerance to herbivory are varied but relatively understudied (Tiffin , Moreira et al , Siddappaji et al , Krimmel and Pearse , Quijano‐Medina et al ). Plant traits like high photosynthetic rates, growth rates, belowground storage and branching are thought to promote compensatory growth, and therefore tolerance (Meyer , Strauss and Agrawal , Tiffin , Lurie et al ). Life‐history traits like longer lifespan and investment in belowground also have been linked to tolerance (Krimmel and Pearse ).…”

Overcompensation: a 30‐year perspective

“…In this Special Feature, Lurie et al. () investigate plant traits associated with the seedling tolerance of invasive and noninvasive tree species in Hawaii, and demonstrate that predamage growth patterns determine tolerance independent of species’ invasiveness status. Their finding supports the view that the same tolerance mechanism may act early in life for both invasive and noninvasive woody species, and might be generalizable to some extent across species.…”

“…Regardless of the evolution of increased competitive ability (EICA) hypothesis (Blossey and N€ otzold 1995) stating that invasive species have improved their competitive ability because of changes in resource allocation as a response to lack of native herbivores, surprisingly little is known about tolerance relative to species invasiveness. In this Special Feature, Lurie et al (2017) investigate plant traits associated with the seedling tolerance of invasive and noninvasive tree species in Hawaii, and demonstrate that predamage growth patterns determine tolerance independent of species' invasiveness status. Their finding supports the view that the same tolerance mechanism may act early in life for both invasive and noninvasive woody species, and might be generalizable to some extent across species.…”

The effect of allometric partitioning on herbivory tolerance in four species in South China

“…Numerous studies have indicated that the biomass allocation patterns of plant organs are size‐dependent (McConnaughay & Coleman, ; Niinemets, ; Wright & McConnaughay, ). However, many other studies have used proportional changes to reflect herbivory tolerance or compare the tolerances of different species (Araminiene, Varnagiryte‐Kabašinskiene, & Stakenas, ; Lurie, Barton, & Daehler, ; Stevens et al, ; Wang, Bezemer, van der Putten, Brinkman, & Biere, ; Wang et al, ; Zvereva, Lanta, & Kozlov, ). The ratios used to test biological hypotheses may change with plant size and cannot accurately measure the relationship between herbivory tolerance and biomass allocation.…”