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Diversity And Distribution Of Vascular Epiphytes Of Tropical Forests In Hainan Island, China

Posted on:2011-03-05Degree:DoctorType:Dissertation
Country:ChinaCandidate:G F LiuFull Text:PDF
GTID:1100360308482288Subject:Ecology
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Epiphytes are autotrophic plants which growing upon another plants, not parasitically upon but solely for mechanical support. Their whole life history or some stage is in the air, not attacting the earth. They derive moisture and nutrients from the air and rain and sometimes from debris accumulating around it. They are an important characteristic component in tropical forests, and play important roles in maintaining biodiversity and ecosystem functioning of the tropical forests.Currently, the ecological study on epiphytes including vascular epiphytes is still infancy in China. There are few studies concerning ecological characteristic of epiphytes in the tropical forest in China, but so far there are no systematic on diversity and distribution in Hainan Island, the largest areas of tropical forests in China.This study was conducted in Bawangling, where typical tropical forests of Hainan Island were distributed. The vascular epiphytes were surveyed in six forest types which are including the tropical monsoon forest, the tropical lowland rain forest, the tropical coniferous forest, the tropical montane rain forest, the tropical mountain evergreen forest and the tropical elfin forest. Species diversity, epiphyte type, life form and spatial distribution of vascular epiphytes in the six types of forest were analyzed. and characteristics of diversity and distribution pattern of vascular epiphytes in the tropical forests in this region were assessed. Tthe results were following:1. Characteristics of diversity of vascular epiphytes.There were 13,225 vascular epiphytes individuals in the 6 forest types in Bawangling, which were attributed to 61 genera,22 family. Epiphytic orchids were the dominant group in the region with 9,634 individuals, belonging to 60 species,26 genera. Among 26 genera in the Epiphytic orchids, Dendrobium had 10 species which was the most across all genera of epiphytic orchids, followed by Bulbophyllum with 7 species. Epiphytic pteridophytes were the second dominant group including 2,934 individuals,42 species,25 genera and 13 family. It was dominated by Polypodiaceae with 2,217 individuals,12 species. Except Orchidaceae, Asclepiadaceae was the dominance in Angiosperm with 434 individuals,5 species, followed by Araceae with 294 individuals,3 species, Moraceae with 13 individuals,5 species. There were few individuals and species in other Angiosperm. There were 18 species in the tropical monsoon forest,27 species in the tropical lowland rain forest,27 species in the tropical coniferous forest,57 species in the tropical montane rain forest,66 species in the tropical mountain evergreen forest and 52 species in the tropical elfin forest.2. Distribution patterns of vascular epiphytes in the different types of forests.There was apparent association between distribution pattern of vascular epiphytes and their forest types (i.e. the tropical monsoon forest, the tropical lowland rain forest, the tropical coniferous forest, the tropical montane rain forest, the tropical mountain evergreen forest and the tropical elfin forest). Species richness and abundance of vascular epiphytes in the region presented the feature of "increment from tropical monsoon forest to tropical mountain evergreen forest and decrement from tropical mountain evergreen forest to tropical elfin forest" with the elevation of the altitude, indicating that they were the highest in the tropical mountain evergreen forest. This feature differs from the characteristics that the biodiversity is the highest in the tropical montane rain forests in Bawangling Mountain and Wuzhishan Mountain, which is helpful for understanding the patterns of species diversity in Hainan Island.3. Spatial distribution of vascular epiphytes in the same type of forest.The abundance of vascular epiphytes is higher in the crown than in the trunk within the tropical monsoon forest and the tropical montane rain forest, and lower in the crown than in the trunk within the tropical lowland rain forest and the tropical elfin forest. while it presented little difference between trunk and crown in tropical mountain evergreen forest. Different patterns of spatial distribution of vascular epiphytes in the interior space of the forest are mainly attributed to different environmental factors (eg.,, temperature, moisture, light and winds)'which are different in the different height and level of the forest interior.4. Relationships between vascular epiphytes and size of phorophyte. In this region, except few species preferred to phorophyte (e.g. Dendrobium sinense), most of vascular epiphytes do not present the preference and selectivity to tree species. There was a significant positive relationship between abundance and species richness of vascular epiphytes and phorophyte size (DBH) in each type of forest, moreover, phorophyte size exerted greater impacts on abundance than species richness.5. Vascular epiphytes in logged forests were far lower than that in old-growth forest. Abundance and species richness of vascular epiphytes in the logged tropical montane rain forest were significantly lower than those in old-growth tropical montane rain forests neighboring to logged forests. Additionally, Abundance and species richness in the old-growth forest neighboring the logged forest were obviously lower than those in old-growth tropical montane rain forest which never experienced disturbance. Remnant with large DBH in the logged forests played vitally important roles in restoration and development of epiphyte population.6. Diversity and flora of vascular epiphytes in Hainan Island.There were rich vascular epiphytes in Hainan Island, which belong to 238 species (including variant and subspecies),91 genera and 28 family, based on data field investigation and literature survey. According to the analyses on flora of vascular epiphytes in Hainan Island, they were typical characterics and affinity of tropical flora.
Keywords/Search Tags:Epiphyte, vascular epiphyte, diversity, distribution, forest canopy, tropical forest, Hainan Island
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