Fire-prone grasses, bushes, and trees

Fountain grasses

Fountain grasses, from the genus Cenchrus, are fire-adapted grasses: they ignite easily and burn well, but their roots are deep enough to survive and they are first to regrow in fire-damaged areas. They originate mostly from the savannas of East Africa and were introduced to the continental US and Hawaii (as well as Australia, Mexico, and other arid areas) for soil erosion control, cattle grazing, and decorative plantings. If left ungrazed or uncut, they can form deep mats of vegetation which provide ample fuel for large fires [JFSP].

The ranch has two main types of fountain grass. In the Heathers, the dominant species is buffel grass, Cenchrus ciliaris (edible by cattle, sheep, and goats, but toxic to horses [URL], and classified by several Australian provinces and the state of Arizona as a noxious weed [Wikipedia]). On the ranch, buffel grass displaced the native Hawaiian grass, pili (Heteropogon contortus) [Restoration Ecology]. In the Meadows, buffel grass gets mixed with the decorative crimson fountain grass, Cenchrus setaceus (indigestible even for goats, classified by the state of Hawaii as a noxious weed [DLNR]). The top of the Meadows and the Summit are free of buffel grass, but not of crimson fountain grass. Eradicating fountain grasses is not feasible, but it is important to keep the grass short and to rake away dead grass and clippings to reduce the fuel volume.

In the pictures below, the first is crimson fountain grass, the second pili grass, and the third buffel grass.

Bushes and trees

Koa haole (foreign koa), Leucaena leucocephala, is a bush or small tree native to southern Mexico and imported in the late 19th century to Hawaii for cattle fodder. It grows very fast and gets readily disseminated by birds (and by the cattle that feed on it), quickly forming dense thickets. Thickets of koa haole are growing throughout the ranch and large areas around Kona have been taken over by koa haole. Thickets on the Kohala coast get dessicated during prolonged droughts, creating a serious fire risk [URL]. Do not let koa haole grow within your defensible zone.

Kiawe, Prosopis pallida, is a type of mesquite that was first imported to Hawaii from Peru in 1828. A medium-sized tree with sharp spines and finely divided foliage, it is common throughout the Heathers, growing more densely in Heathers II. While not generally considered a serious fire risk [URL], kiawe trees can produce significant accumulations of dead wood -- and mesquite wood is prized for BBQ because it burns well, long, and hot! Trimming branches to keep them 8ft above ground and removing any dead wood helps reduce the risk.

Quoting from [Smith and Tunison]: "Koa haole and kiawe communities are frequently burned. The recovery rate of kiawe is approximately 20% and fountain grass and buffel grass rapidly invade or take over the area. In contrast, fire intensifies the cover of koa haole, which resprouts from the base and becomes established from seed."

Ironwood (also australian pine, horsehair tree), Casuarina equisetifolia, is a large upright tree growing to 100ft, with deep red bark and fine needle-like leaves. Native to Australia, it grows in most soils and thousands were planted in Hawaii at the beginning of the 20th century, including a continuous curtain along the Kohala crest road above the ranch. It is a favorite windscreen planting, but it drops large amounts of highly combustible leaves and twigs. Keeping its branches away from your home and keeping your roof, eaves, and porches free of leaves and twigs is crucial to keeping your house hardened against fire.

In the pictures below, the first is koa haole, the second kiawe, and the third ironwood.