Classification of Taiwan forest vegetation

Abstract

Aim We identify the main forest vegetation types in Taiwan, provide their formal definitions and describe their species composition, habitat affinities and distribution. Location Taiwan. Methods A data set of 9822 vegetation plots with environmental characteristics recorded in the field or derived from digital maps in GIS was compiled from historical literature and an extensive field survey. Using expert knowledge, 6574 of these plots were used to build a classification into broad vegetation types. The units of the resulting classification were formally defined using a Cocktail determination key, which can be used for the automatic assignment of new vegetation plots to these vegetation types. Results Twelve vegetation types of zonal forests and nine types of azonal forests were distinguished. Zonal types in the subtropical region, from high mountains to foothills, are Juniperus subalpine coniferous woodland, Abies–Tsuga upper‐montane coniferous forest, Chamaecyparis montane mixed cloud forest, Fagus montane deciduous broad‐leaved cloud forest, Quercus montane evergreen broad‐leaved cloud forest, Machilus–Castanopsis sub‐montane evergreen broad‐leaved forest, Phoebe–Machilus sub‐montane evergreen broad‐leaved forest and Ficus–Machilus semi‐evergreen foothill forest. Zonal types in the tropical region, from high mountains to foothills, are Pasania–Elaeocarpus montane evergreen broad‐leaved cloud forest, Drypetes–Helicia sub‐montane evergreen broad‐leaved forest, Dysoxylum–Machilus foothill evergreen broad‐leaved forest and Aglaia–Ficus foothill evergreen broad‐leaved forest. Azonal types are Illicium–Cyclobalanopsis tropical winter monsoon forest, Pyrenaria–Machilus subtropical winter monsoon forest, Diospyros–Champereia tropical rock‐outcrop forest, Zelkova–Quercus subtropical rock‐outcrop forest, Pinus successional woodland, Alnus successional woodland, Trema–Mallotus successional woodland, Scaevola–Hibiscus seashore woodland and Kandelia mangrove. Conclusions The diversity of forest vegetation in Taiwan is strongly structured by the temperature and moisture gradient. Along the temperature gradient, five altitudinal zones can be recognized. Azonal forest types develop at sites affected by the winter monsoon, on steep slopes, rocky soils, in seashore saline habitats and in places disturbed by fire, landslides and human activities. Zonal vegetation contains a higher ratio of endemic and Pacific species and occurs in wetter habitats, whereas azonal vegetation contains co‐existing species from different regions and usually occurs in drier habitats.

Variation in Mountain Vegetation Composition between the East and the West Sides of Southern Taiwan

“…Steep and fragile slopes are common, and landslides frequently occur following heavy rains, road construction, or earthquakes. Temperature mostly corresponds with altitude, with a mean altitudinal lapse rate of 0.55 • C per 100 m, whereas differences in precipitation are caused primarily by monsoon exposure, particularly the northeastern monsoon in winter [1]. In summer, the warm southwestern monsoons and typhoons lead to abundant precipitation across the entire island.…”

“…Temperature in January was calculated from the monthly mean temperatures computed from satellite images with a resolution of 1 km × 1 km. Temperature data derived from satellite images were more sensitive to topography than the temperature data calculated from the regression model of weather stations [1]. Winter precipitation (the ratio of the sum of precipitation of December, January and February divided by the annual precipitation) was taken as interpolated values from the WorldClim database [29].…”

“…Its mountainous topography (highest peak: 3952 m a.s.l.) forms distinct altitudinal vegetation zones, with vegetation corresponding to several latitudinal zones from subarctic to tropical [1] and different geographic areas that vary by precipitation and temperature. Based on climatic data, Taiwan has been classified into seven ecoregions [2].…”

“…To describe and parameterize recognized vegetation types, formalization can be achieved using supervised classification methods that create unequivocal rules and criteria for determining vegetation types. An example is the cocktail determination key [18][19][20][21], which describes each vegetation type using a logical formula that combines statements concerning the presence or absence of typical or dominant species [1]. The cocktail determination key was developed by combining the presence or absence of specific ecologically meaningful species groups [18] that provide unequivocal rules for assigning relevés to vegetation types [20][21][22][23].…”

Detection of ground fog in mountainous areas from MODIS (Collection 051) daytime data using a statistical approach

“…While cloud forest areas of Taiwan are already the subject of intensive research (cf., e.g., Mildenberger et al, 2009;Chu et al, 2012), Taiwan's cloud forest has never been completely mapped on a country-wide scale. The most comprehensive information about the extent of cloud forest in Taiwan available today is given by Li et al (2013), based on the National Vegetation Database of Taiwan. Since these data are based on field surveys, they are highly reliable but only cover the area of 9822 plots (each with an area of 400-2000 m 2 ) distributed over the whole country.…”