Thu, Aug 18, 2022: 8:30 AM-8:45 AM
513D
Background/Question/MethodsLong-term spatial point analysis can provide the spatial information of different species at different times to understand the species’ demographic dynamic and density-dependent. Density-dependent is one of the processes in intraspecific competition, which can cause high individual mortality and be detected by the spatial point analysis. Lanjenchi Forest Dynamic plot is a tropical forest with high stem density caused by the Northeast monsoon wind in the winter. According to previous research, species can be classified into windward, intermediate (including mid-windward and mid-leeward), and leeward species. Besides, in four times census data of the Lanjenchi plot, the mortality rate became higher from 1997 to 2019. To understand the changes in the density-dependent of dead trees for each species through time. We collected the survey data on all free-standing trees ≥ 1 cm diameter at breast height (DBH), identified, measured, and mapped in 1997, 2005, 2013, and 2019. Used the pair-correlation functions with 999 times random labeling null model to test the impact of density-dependent for each species over three periods. And to explore whether different distributed species types were affected by the difference of the density-dependent effect and tested between two classes of tree sizes (small trees and big trees).
Results/ConclusionsOur results demonstrated that 69.3-79.7% of small trees for each species suffered density-dependent, but its effect fluctuated over three periods. The number of windward species that did not suffer any density-dependent effect decreased (46-30%). Most windward species suffered negative density dependence (34%, 26%, 46%), and some windward species suffered only negative density dependence over three periods. Their population density gradually decreased because of intense intraspecific competition—Eurya nitida var. nanjenshanensis, which is endemic. On the other hand, the leeward species mainly suffered from positive density-dependent effects, and its effect was increased (33-66%)—for example, Ardisia quinquegona increased its population density. On the other hand, the density-dependent effect of the intermediate species does not have a trend. In addition, the pioneer species (e.g., Melastoma candidum) mainly suffered negative density-dependent. The result of their short life history and easily influenced by disturbances (e.g., typhoons, heavy rain). Overall, we found some spatial information on density-dependent for each species to detect its distribution changes. Expect our results to provide information for future forest management policies under climate change.
Results/ConclusionsOur results demonstrated that 69.3-79.7% of small trees for each species suffered density-dependent, but its effect fluctuated over three periods. The number of windward species that did not suffer any density-dependent effect decreased (46-30%). Most windward species suffered negative density dependence (34%, 26%, 46%), and some windward species suffered only negative density dependence over three periods. Their population density gradually decreased because of intense intraspecific competition—Eurya nitida var. nanjenshanensis, which is endemic. On the other hand, the leeward species mainly suffered from positive density-dependent effects, and its effect was increased (33-66%)—for example, Ardisia quinquegona increased its population density. On the other hand, the density-dependent effect of the intermediate species does not have a trend. In addition, the pioneer species (e.g., Melastoma candidum) mainly suffered negative density-dependent. The result of their short life history and easily influenced by disturbances (e.g., typhoons, heavy rain). Overall, we found some spatial information on density-dependent for each species to detect its distribution changes. Expect our results to provide information for future forest management policies under climate change.