Phenological Patterns Of Native Species And Their Relationships With Ecological Factors On Karst Mountainous Area In The Stone Forest, Yunnan

There are close relationships between the phenological pattern and ecological factors during the period of growth and development of plants. A variety of environment factors are regarded as the main driving forces for the appearance of certain phenophases. At the Stone Forests World Geo-Park in Yunnan Province, SW China, the investigation of phenology of 250 individual plants (35 indigenous plant species from 25 families) including arbor, shrubs and liana was executed. Phenophases involving bud-burst, leaf flushing, flowering, fruiting, leaf coloration and leaf shedding were assessed for 5~8 individuals of each species at 10 d intervals from January 2003 to March 2005. The composition and quantity of litterfall, and standing crop and water holding capacity of litter on forest floor of natural forest and plantations on the Karst mountainous area were also investigated form 2003 to 2004. The results were as follows:1. Bud burst and leaf flushing of most plants species peaked only once a year, and occurred at the end of dry season before the first spring rainfall(February to April). While bud burst occurred in February for 46% of the total plants observed when the air temperature was 10℃. 57% species of them flushed when the air temperature rising and exceeded 15℃in March. The peak of leaf coloration and leaf shedding occurred at the end of rainy season and beginning of dry season (November to January of next year). Flowering period lasted from the end of dry season to the beginning of rainy season, but peaked at the dry season too (April). Fruiting occurred at the rainy season (May to October), and peaked in July.2. The mean temperature and≥5℃accumulation qir temperature of different penological periods obviously influenced the phenological performance of the native plants. There were close relationship between the flowering and fruiting of plants and light and temperature in the area. The principal component analysis (PCA)showed that temperature and sunshine duration influence all phenophases. Furthermore, the latter was more important to trigger bud burst and leaf flushing. It implied that solar irradiation and temperature and their combined effects were the most crucial environment conditions affecting the time of vegetative and reproductive phenology in the evolution. In addition, 4 phenological types for flowering and fruiting, and 3 phenological types for bud burst, leaf flushing, leaf coloration and leaf shedding were classified respectively based on the hierarchical cluster analysis. The bud burst and lead flushing were influenced by water availability in the end of dry season. Inducing of spring flushing by increasing photoperiod assured that a full complement of young, photosynthetically efficient leaves was in time when the rainy season was about to begin, yet avoided prolonged exposure of young leaves to severe drought. The flowering peaked in dry season for successful pollination and the fruiting pattern supported the hypothesis that high water availability was necessary at the time of fruiting to enhance fruit maturation and seed germination success.3. The variation in phenological patterns of indigenous plants provided diversity of landscape clusters and scenic spots for people at both space and time scales. This suggested that conservation and planning for the World Natural Heritage would need to be considered at landscape scale, in order to best conserve biodiversity at the SFWGP.4. Based on the phenological characteristics of the native plants, the natural landscape and vegetation construction of the Karst area, the principle of"the harmony collocation between the stone and the woody plants"was proposed. It was also suggested that some ornamental plants with adapting to the Karst environment at temporal and spatial patterns should be selected to make suitable vegetation landscape, in order to increase landscape and ecological values, as well as the meaning of the Stone Forest Scenic Spot.5. The annual litterfall of natural Cyclobalanopsis glaucoides forest was 7.26 t?hm-2, while it was 1.98 t?hm-2, 2.49 t? hm-2 and 4.07 t? hm-2 in the secondary forest of Neolitsea homiantha, Pinus yunnanensis plantation and Cupressus duclouxiana Plantation, respectively. The seasonality of litterfall was bimodal in all the forests. The order of the standing crop of litter on forest was C. duclouxiana Plantation (13.59 t?hm-2) > C. glaucoides forest (7.57 t? hm-2) > N. homiantha, secondary forest (5.02 t? hm-2) > P. yunnanensis plantation (4.83 t? hm-2). The pattern of water holding capacity of litter on forest floor of different forests was similar to the order of the standing crop. Based on the quantitative relationship of litterfall and litter on forest floor, it showed that the decomposition quotient of litter on forest floor was faster in the natural forest dominated by C. glaucoides than other forests in the area. Therefore, it was suggested that attention should be paid to conservation of the natural forest, and introduction of some suitable species to the monoculture plantation and also to protection of cover plants and litter on forest floor so as to regulate the composition and structure of the community and improve the integrative effect of the plantations.