Choosing Plant Introductions: Needs of Graziers

Forage plants introduced to Hawai`i have come from both temperate and tropical areas of the world. Although introduced species have changed the face of the landscape, they have often failed to provide long-term benefits to the livestock industry. Proper management of rangelands can result in increased livestock productivity and reduce the need for further introductions of forage plants. Almost from the start of the cattle grazing industry, graziers in Hawai`i have been introducing new forage plants. Native Hawai`ian grasses evolved without grazing pressure, so when subjected to ruminants and overgrazing, they soon made room for introduced species better adapted to grazing. Today it is difficult to find indigenous and endemic grasses in a sward or grassland. Alien plants have been introduced both intentionally and unintentionally, most flourishing for a number of years then decreasing and giving way to less palatable, and in a few cases hardier, plants. As the early grazing industry needed improved varieties, it initially drew upon proven forage plants that were available from temperate areas. In general, these plants did not do well at lower elevations but improved the forage in the cooler regions of Hawai`i. It would be difficult to imagine what Mauna Kea would look like without sweet vernalgrass (Anthoxanthum odoratum), or what Ka`u would be like without meadow ricegrass (Ehrharta stipoides) or kikuyu grass (Pennisetum clandestinum). They have become part of the landscape along with many other introduced plants. In more recent times some of the forage plant introductions have come from tropical areas and are thus well adapted to the conditions in the lower and drier areas in Hawai`i. Some of the best examples of these highly adapted grasses are buffelgrass (Cenchrus ciliaris) in dry areas, and green panic (Panicum maximum var. trichylum) and Guinea grass (Panicum maximum var. maximum) in slightly wetter areas.