Population dynamics of natural regeneration of rattan in secondary lowland rain forest in Hainan Island, southern China

ObjectiveThis paper analyzes the population dynamics and undulation periods of rattan populations in Ganshiling tropical secondary lowland rain forest, Hainan Island of southern China, explores the growth dynamic regularity of rattan populations, and provides a theoretical basis for resource protection and later restoration for rattan.

MethodThe Daemonorops jenkinsiana (DJ), Calamus rhabdocladus (CR), C. walkeri (CW) and C. tetradactylus (CT) distributing in Ganshiling tropical secondary lowland rainforest were chosen for the objects in this paper. We used the method of substituting space for time to compile and analyze life tables, matching surviving curve for each species according to power function and exponential function.The study also established 3 kinds of function for predicting the survival probability, and analyzed rattan's periodic fluctuation law by spectral method.

ResultThe results showed that the main constituents of rattan populations were seedling and young vines which accounted for 90.1%-97.7% of total samples, only a few of adults were tracked in the region. The interval period mortality and average survival numbers of CT and CR decreased with growing. Meanwhile, CW and DJ increased firstly and then decreased. The life expectancy of CT would be maximized at 2.5-4.5 m, CW, DJ and CR of which would be maximized at 4.5-6.5 m, 6.5-8.5 m and 8.5-10.5 m, respectively. The survival curve of CR was more closed to exponential function (Deevey-Ⅱ type, R²=0.840, P=0.000 < 0.01) than power function, and the others were more closed to power function (Deevey-Ⅲ type, R²>0.910, P=0.000 < 0.01). All rattans had a high survival rate at early stage, and then reduced with growing. The others had a sharp decline to steady situation in death density except for CW, with high mortality in early stage than the later. The spectral analysis results indicated that wave amplitudes had significant differences among DJ, CR and CW except of CT, CR and CW had the biggest amplitude fluctuation at 4.5-6.5 m, and DJ had the biggest amplitude fluctuation at 2.5-4.5 m.

ConclusionOur results indicated that natural regeneration of rattan in Ganshilin Region had characteristics of high breeding potential and low survival rate, which revealed the adaptive strategy of rattans in this region, in other words, making up insufficient of survival rate by means of high reproductive rate to increase the odds of species preservation. Meanwhile, survival ability is powerful before rattan climbing to the canopy, and the others relative to CT are more affected by external environment. Therefore, the measures increasing regenerate seedling survival rate by improving environment and manual plant strong seedling will be available for the protection of rattan resources.