Abstract:

Consecutive investigations in 1994, 1996, 1998, and 2002 in the permanent plots established in Futian Mangrove Reserve of Shenzhen, Guangdong Province, revealed that the breaking, drying and death of the individual plants or branches in the mangrove communities were significant and the number of plants in plots covering an area of 200 m² was 417, 341, 196 and 132; the average density of population per square meter is 2.08, 1.70, 0.98 and 0.66; the death rate between the interval of two investigations is 18.2%, 42.5% and 32.6% respectively. The individuals of population exhibit an obvious diameter at breast height (DBH) growth. For example, the maximum increment of individual DBH was up to 3.63, 2.45, and 4.52 cm in the dominant populations Aegiceras corniculatum (L.) Blanco (Ac), Kandelia candel (L.) Druce (Kc), and Avicennia marina (Forsk.) Vierh. (Am), respectively. At the same time, growth of individual height was also prominent. In the second investigation, 233 out of the 341 individuals exhibit a height growth; whereas the number under the third and fourth investigations was 127 out of 196 and 74 out of 132, respectively. During a 2-year interval, the maximum height growth was 1.5 m in Ac, 1.9 m in Kc, and 1.8 m in Am. The biomass also showed a relative change in the mangrove communities. The total biomass of stems and leaves decreased with time but occasionally an increase was found in the second and third investigations and finally a decrease in the fourth investigation. However, the average biomass of the survived individuals usually increased with time. In terms of the total biomass, the results of the four investigations were similar to the previous research in which the data were calculated by the methods of standardized timbers, etc. being 7.57, 8.36, 5.15 and 7.71 kg/m² during 1994, 1996, 1998 and 2002, respectively. The above analysis indicates that self-thinning of mangrove communities is an important evolutionary process, characterized by drying, breaking, and death of individuals/ramifications. During the process of evolution, fewer new seedlings developed, and individual height growth, DBH growth, breaking and death from dryness maybe closely related to the composition, structure, and density of population in the mangrove communities.

Key words: Mangrove, Aegiceras corniculatum , Kandelia candel , Avicennia marina , self-thinning, growth dynamic