Data from: strawberry guava invasion of a Hawaiian rainforest: changing population pattern

Strawberry guava (waiawī, Psidium cattleyanum O. Deg., Myrtaceae) is a
small tree invasive on oceanic islands where it may alter forest ecosystem
processes and community structure. To better understand the dynamics of
its invasion in Hawaiian rainforests in anticipation of the release of a
biocontrol agent, we measured growth and abundance of vertical stems
>= 0.5 cm DBH for 16 years (2005-2020) in an intact
Metrosideros-Cibotium rainforest on windward Hawai'i Island.
Specifically, we compared the growth and abundance of both shoots
(originating from seed or from the root mat) and sprouts (originating
above ground from established stems) in four replicate study sites. Mean
stem density increased from 9562 stems/ha in 2005 to 26,595 stems/ha in
2020, the majority of which were stems < 2 cm DBH. Mean annual
rates of population growth (lambda) varied between 1.03 and 1.17. Early in
the invasion, both density and per capita recruitment of shoots was
greater than that of sprouts, but as overall stem density increased over
time, sprout abundance and recruitment came to surpass that of shoots.
Relative growth rates among small stems < 2 cm DBH declined over
time for both shoots and sprouts, but relative growth rates of sprouts
were consistently greater than that of shoots after the first 3 years. The
capacity of strawberry guava to recruit from both rooted shoots and
vegetative sprouts contributes to the facility with which it can invade
intact rainforest, persist in the forest understory, and respond to canopy
opening. Strawberry guava thus poses a considerable risk of stand
replacement for Hawaiian rainforests. Stand management will require
perpetual efforts of guava control at high priority sites as extreme
weather events associated with climate change bring canopy-opening events
due to storms, drought and pathogens.