Final Report: Predicting the Effects of Climate Change on the Spread of Fire-Promoting Plants in Hawai‘i: Assessing Emerging Threats to Rare Native Plants and Ecosystems

This project aimed to identify non-native plants in Hawai‘i that are likely to pose a high wildfire risk now or in the future, and to create resources useful to conservation and fire managers in Hawai‘i regarding wildfire risk and highly flammable non-native and invasive plant species. To do this, a screening tool was developed to assess wildfire risk of any introduced plant in Hawai‘i, and wildfire risk scores were generated for over 360 plant species that have been introduced to Hawai‘i. To identify new plant introductions that may pose high wildfire risk in the future, botanical surveys were conducted across the Hawaiian Islands, and the distribution of fire-promoting species (principally grasses) were mapped,...

A screening system to predict wildfire risk of invasive plants

Globally, invasive plant-fueled wildfires have tremendous environmental, economical, and societal impacts, and the frequencies of wildfires and plant invasions are on an upward trend globally. Identifying which plant species tend to increase the frequency or severity of wildfire is important to help manage their impacts. We developed a screening system to identify introduced plant species that are likely to increase wildfire risk, using the Hawaiian Islands to test the system and illustrate how the system can be applied to inform management decisions. Expert-based fire risk scores derived from field experiences with 49 invasive species in Hawai′i were used to train a machine learning model that predicts expert fire...

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Updates to the Hawaiian grass flora and selected keys to species: Part 2

This paper continues work by Faccenda (2022) to revise the introduced grass flora of Hawaiʻi and expands upon it by visiting and critically reviewing specimens from the remainder of the herbaria located in Hawaiʻi, including HALE, HAVO, and PTBG. The US herbarium was not visited, but all photographed specimens of Hawaiian grasses at US were examined, and selected specimens were loaned and examined in Hawaiʻi. As part of this work, a database of all Poaceae specimens from Hawaiʻi was created by combining digitized collection data from BISH, HALE, HAVO, PTBG, US, and various herbaria that have contributed data to GBIF (gbif.org 2022). This database was compared to the published island distribution of all grasses to...

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Spontaneous hybridization among invasive Poaceae in Hawai‘

During grass surveys across the islands of Hawai‘i in 2022, two novel hybrids among non-native Poaceae were found growing on roadsides. Spontaneous hybridization was observed among Chloris barbata and C. divaricata on O‘ahu and among Cenchrus clandestinus and C. setaceus on Hawai‘i island. Morphological evidence initially suggested these plants may be hybrids and molecular analysis using the ITS and rpl32-trnL regions confirmed that the plants are hybrids and identified their parentage. These hybrids are named Chloris × pseudosagrana nothosp. nov. and Cenchrus × peregrinus nothosp. nov. No developed seeds could be found on either of these hybrids and they are suspected to be sterile F1 hybrids. The occurrence of...

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