EVENTS

Webinar overview:

Seedlings of native and invasive plants are not often studied, yet seedlings may be impacted by a variety of threats and may therefore offer a window into understanding the impacts that climate change will have on plant populations. Professor Kasey Barton from the the University of Hawaiʻi at Mānoa will share her experimental research, conducted in both the field and greenhouse, on the tolerance of both native and invasive plant seedlings to stress, including drought and salinity.

Research Question: How does tolerance of climate stress vary among and within species of native and invasive plants?

Webinar Abstract:

Invasive plants are widespread and abundant in the Hawaiian Islands and are increasing in diversity, abundance, and extent. Despite simultaneous declines in native island plants, however, there is limited direct evidence that competition is driving these patterns. Using functional traits to infer resource use strategies, we have detected vast overlap in strategies between native and invasive woody plants in Hawaiʻi. Moreover, functional strategies relate strongly to climate: native plants have more acquisitive leaf economics (meaning they have faster resource acquisition and are hence more competitive) in dry sites, and invasives have more acquisitive leaf economics in wet sites. Both native and invasive plants, however, converge on similar leaf economics in moderate climates. Considering this lack of evidence that invasive plants overall have more vigorous physiological strategies than native plants in Hawaiian forests, we predicted that competition may occur primarily during seedling establishment, and moreover, that climate change may be exacerbating these interactions.

Seedlings are often more sensitive to water limitation than older plants of the same species due to their small size, relatively limited stored reserves, and acquisitive growth strategy. Because climate change is not only reducing total incoming precipitation but also the timing, seedling recruitment is declining in many native Hawaiian plants, potentially providing opportunities for invasive plant spread if they have greater drought stress tolerance. Using experimental approaches in the field and greenhouse, combined with ecophysiological trait analysis, we have been investigating seedling drought tolerance across a diverse range of native and invasive Hawaiian plant species.

In coastal dune habitats, climate change is leading to increases in salinity as well as drought, with particularly strong effects predicted for seedling recruitment. We have been investigating salinity tolerance in native and invasive coastal dune species for insights into potential shifts in competition under climate change. We have detected considerable variability among species, with most experiencing reduced survival and growth under elevated salinity, indicating widespread vulnerability to climate change.

Speaker details:

Dr. Kasey Barton is a Professor at the University of Hawaiʻi at Mānoa in the School of Life Sciences. From Dr. Barton: “I grew up in Colorado. I got a B.S. in Biology from Stanford University. After college, I spent a year as a postbaccalaureate technician at Wesleyan University in Connecticut where I worked on experiments investigating maternal effects in seedling drought tolerance. This was my first introduction to seedling drought ecology, and also my first exposure to experimental approaches, both of which I still use today. I returned to Colorado for my Ph.D in Ecology and Evolutionary Biology, focusing on ontogenetic (developmental) patterns in plant chemical defenses. I received a NERC Postdoctoral Fellowship to get experience and training with research synthesis and meta-analysis at the University of London. Then, I moved to Hawaiʻi in 2010 to join the Botany faculty at UH-Mānoa where I have resided ever since. I love exploring the functional ecology of Hawaiʻi’s endemic plants and hopefully, contributing knowledge that contributes to their conservation and restoration. ”

Relevant Publications:

Walsh, S. K., D. Wolkis, R. M. Abbriano, and K. E. Barton. 2023. Variability in seed salinity tolerance in an island coastal community. Annals of Botany. https://doi.org/10.1093/aob/mcad129.

Barton, K. E. and C. Fortunel. 2023. Island plant functional syndromes and competition with invasive species. Journal of Biogeography 00: 1–13. https://doi.org/10.1111/jbi.14568.

Westerband, A. C., T. M. Knight, and K. E. Barton. 2021. Intraspecific trait variation and reversals of trait strategies across key climate gradients in native Hawaiian plants and non-native invaders. Annals of Botany 127: 553-564. (In special issue on “Intraspecific Variation in Plant Functional Traits”.) https://doi.org/10.1093/aob/mcaa050.