Growth Cycle And Dynamic Analysis Of Spatial Structure In Moso Bamboo Stand

Research on moso bamboo stand structure has long been focused on exploration of its non-spatial structure, and recent study has shifted to analyze spatial structure of moso bamboo stands, but on the basis of static analysis. Rarely has research explored the dynamic changes of moso bamboo stand spatial structures. This paper takes the near-natural moso bamboo stands in Tianmu Mountain National Nature Reserve in Zhejiang province as a case study. Based on 6 times survey data from 2009 to 2014, the time series spectrum analysis and spatial structure indices were used to study the growth cycle of the live bamboo number and the cycle of dynamic changes of moso bamboo stand spatial structures. The dynamic relationships between the stand average competition index, the stand age mingling, the stand aggregation index and the number of live bamboo were analyzed to reveal the growth cycle and the characteristics of spatial structure dynamic of moso bamboo stand, providing the theoretic basis for sustainable management of moso bamboo stand. To achieve this target, dimensional coordinates(X, Y, Z), diameter at breast height(DBH), bamboo height, clear bole height, crown size and growth status were measured within a permanent sample plot with a size of 100 m×100 m using adjacent grid investigation method. This permanent sample plot has been investigated annually in last six years. The results were summarized as following:(1) There is a wide age range of moso bamboo stand, from 1~19 years. The age diversity increases over time. The number of moso bamboo in each age is unevenly distributed, with obvious on-year and off-year, for example, the years of 1998, 2004 and 2010 have higher numbers than other years.(2) Spectrum analysis results show that no growth cycle for the number changes of live bamboo, and 2-year and 6-year cycles of the number growth with different years of live bamboo shoot emergency. By contrast, 3-year cycle is not significant.(3) Spectrum analysis of stand spatial structure shows no obvious cycles of spatial structure dynamic of moso bamboo stand.(4) Spectrum analysis of total competition index dynamic changes with different years of live bamboo shoot emergency shows obvious 2-year cycle and 6-year cycle. At the same time, the cycle of average competition index dynamic changes with different years of live bamboo shoot emergency is 2 years, and average age mingling and average aggregation index with different years of live bamboo shoot emergency are not significant.(5) During the period between 2009 and 2014, the stand average competition index in on-year is bigger than that in off-year. As time goes, the stand average competition index and the number of live bamboo have the same trend with on-year and off-year changes. The stand average competition index is closely related with the number of live bamboo, with R2 of 0.8430. The stand aggregation index declines with values of less than 1, and shows clustered distribution. The stand aggregation index and the number of live bamboo have high relationship with R2 of 0.8598. The stand age mingling increases slowly over time. The relationship between the stand age mingling and the number of live bamboo(R2 of 0.7089) is lower than that between the stand average competition index and the stand aggregation index.