Although Yangmingshan National Park is situated in the sub-tropical zone, the distribution of the Park’s vegetation differs from that of other areas at similar latitudes for the following two reasons: firstly, due to the post-volcanic activity, the soil temperature in the park is relatively warm, lacking in calcium and strongly acidic; secondly, the north-east monsoons during winter bring abundant rainfall and markedly lower temperatures, which means that in addition to vegetation like sub-tropical rainforest, temperate evergreen broad-leaved forests and short grassy plains on mountain ridges, even alpine plants that normally grow in the Central Mountain Range at an average height of 2,500 meters above sea level can be found here in the Park.
Due to the unique distribution of vegetation, the signature plant species in the park include the following: Bretschneider’s tree, Taiwan maackia and common euscaphis. The Park also features plant species that typically grow in medium elevations such as the Hairy Japanese-maple, weelstamen tree, griffith wood sorrel, Thalictrum urbanini, Formosan gentian, oriental poison oak, Henery''s monachosorum, stipellate acrophorus and Blechnum hancockii Hance, to name a few. Other rare or special species such as Anoectochilus formosanus, octagon mayapple, Taiwanese holly-grape, kousa dogwood, and red-spotted rhododendron can also be found in the Park.
The plant biomes in the Park included aquatic and terrestrial environments. The terrestrial plant biomes can roughly be divided into grassy plains, arrow bamboo forest, broad-leaved forest and afforestation zones.
Due to the erosion by high temperatures and strong acidity of the volcanic terrains, the top soil in some parts of the Park is loose and thin; only species that are hardy and can tolerate strong acidity can survive here. An example is silvergrass (Miscanthus sinensis Anderss var.glaber), an off-shoot of Miscanthus sinensis, and a hardy member of the Poaceae (or Gramineae). This species can grow in terrains and topography that are otherwise not tolerated by other plant species. Its germination and growth require ample exposure to sunlight, both of which are made available by the exposed terrains of the various landslide areas, and therefore plains of silvergrass thrive on slopes covered in mist.
Silvergrass blooming (photo by Chieh An Ko)
Arrow bamboo typically grows to a height of just one or two meters. Its stem is slender rigid, was used by indigenous people to make arrow shafts, hence the name given to this species. The type of arrow bamboo grows in Yangmingshan is the usawa crane, one of the three types of arrow bamboo species in Taiwan. They are mainly distributed on the sheltered slopes at elevations of 800 meters above sea level, such as the ridgelines of Mt. Zhuzi, Mt. Xiaoguanyin, Mt. Datun and Mt. Qixing. It is one of the park’s important dominant plant species.
The broad-leaved forests are found in areas between 500 and 900 meters above sea level, and are composed mainly of tall members of the Laurel family, such as the commonly found red nanmu and large-leaved machilus; various arboreal trees like the wheelstamen tree, Formosan sweet gum, Taiwan cherry, tailleaved adinandra and wild cherry; various shrubberies like the common eurya, purple woodnettle, narrow-petaled hydrangea, and rough-leaved holly. The forests are also interspersed with lianas and herbaceous plants, which altogether form a plant world with considerable vertical variation, providing many kinds of birds, insects, mammals and amphibians excellent habitats for nesting, foraging and activities.
The aquatic plants in the Park are mostly found in crater marshes and ponds, such as the Datun Pond, Erziping, Menghuan Pond, Xiangtian Pond, Huangzui Pond and the Mt. Daijianhou marshes. The most well-known pond among these is the Menghuan Pond on the mountainside of Mt. Qixing (at an elevation of approximately 850 meters). The bottom of the pond is covered in a thick layer of humus soil. Among its many types of aquatic plants, the pond is noted for having one of the rarest types of aquatic fern – Isoetes taiwanesnsis. Its look is similar to the edible Chinese chives, but smaller in dimension. Other companion plants include the pipewort, Japanese spikerush, rough-seed bulrush and Chinese water chestnut. The water levels in these ponds varied significantly with changes in seasonal rainfall, therefore it is difficult to classify the aquatic plants into submerged, emerged or hygrophytes, as the plants in these locations often combine features from two or three ecological niches.
Common euscaphis (photo by Chih Wu Han)