The Fundamental Features of Zonal Vegetation in Jiangsu Province and Its Distribution Pattern
Liu Fangxun, Huang Zhiyuan
Chin J Plan Ecolo. 1982, 6 (3):
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Jiangsu Province is situated at the sea board of Yellow sea, in latitute 30?46′—35?07′ north, longitude 116?22′—121 ?55′ east. It lies on the transitional area of warm temperate and subtropic zones, extending across southern temperate, northern subtropic and central subtropic bioclimatic belts. The annual mean temperature is 13–16℃, annual mean precipitation is 800–1200mm. There are uplifted hills and low mountains, which occupy about 5% of the total area, majority of them has an elevation of 200--300m. in general. The highest mountain in the area, Yun Tai Shan is mere at an elevation of 625m.By analysing the data, chiefly obtained by our own field survey, we recognize that, the basic characteristics of zonal vegetation in Jiangsu Province and its distribution pattern may be briefly summarized as follows:There are three typical zonal vegetation types in Jiangsu Province:1. The deciduous broad-leaved forestIt is mainly distributed in the north warm temperate region of the province and also may be seen in northern subtropic region. The basic constructive species for deciduous broad-leaved forest belong to the family Fagaceae, including Quercus variabilis, Q. fabri, Q. acutissima, Q. serrata var. brevipetiolata etc. In the calcareous hills, the species of Ulmaceae, such as Celtis bungeana, C. biondii, Ulmus pumila, U. parvifolia etc. are the characteristic species. 2. The deciduous and evergreen mixed forest It is widely distributed in the northern subtropic region of the province, but the typical form occupies the dotting hills along the edges of Taihu lake and the low mountains of Yixing and Liyang Districts, mainly in the central subtropic region. The basic constructive species for deciduous and evergreen mixed forest also belong to the family Fagaceae. The deciduous species are Quercus variabilis, Q. fabri, Q. acutissima, Q. serrata var. brevipetiolata etc. while the evergreen species are Castanopsis sclerophylla, Cyclobalanopsis glauca etc. Some calciphilous species such as Ulmus spp., Celtis spp., Zelkova schneideriana, Aphananthe aspera, Pteroceltis tatarinowii etc occurred on the calcareous hills. We consider that the deciduous and evergreen mixed forest type is a transitional form. This type is distributed overwhelmingly in the transitional area, the northern subtropic zone between warm temperate and subtropic zones of China, consequently it is distinguished with transitional characteristics, which are remarkably reflected by the development of mixed forest formation and its wide occurrence. 3. The evergreen broad-leaved forestIt is merely distributed in the central subtropic region of the province mainly in the mountainous regions of Yixing and Liyang Districts. The basic constructive species for evergreen broad-leaved forest are the evergreen trees of the family Fagaceae, such as Castanopsis sclerophylla, C. carlesii, Cyclobalanopsis glauca. C. myrsinaefolia, Lithocarpus glabra etc. In this forest, the deciduous spices are usually more in number than the evergreens, but the abundance and coverage of the latter are certainly dominant, therefore we consider that the evergreen broad-leaved forest type at the northern fringe of central zone is usually ,with some transitional characteristics. The principal types of three typical zonal vegetation types mentioned above are tabulated in detail. According to data of many plots, the dominant and frequent species, crown density distribution and habitat of all communities have been respectively generalized. Owing to having no high mountains the vertical zonation of vegetation does not exist. But the zonal vegetation types extending across three bioclimatic belts appear evidently. From north to south, the floristic component of zonal vegetation are gradually becoming multified, the number of vegetation types is increasing and zonal vegetation patterns occur successively in the order of the deciduous broad-leaved forest type, the deciduous and evergreen mixed forest type and the evergreen broad-leaved forest type. The typical zonal vegetation types of southern temperate, northern subtropic and central subtropic belts of China are tentatively designated as deciduous broad-leaved forest type, deciduous and evergreen mixed forest type and evergreen broad-leaved forest type respectively. The preceding two types containing the secondary vegetation, may also occur in northern and central subtropic belts respectively.