A Study On The Species Diversity And Distribution Pattern Of Understory Plants In Phyllostachys Pubescens Forest Along Altitudinal Gradient

The species diversity and distribution pattern along an altitudinal gradient of understory plants were studied in Baoshan Phyllostachys pubescens forest in Shunchang County,Fujian Province.This study aimed to demonstrate patterns of species diversity along an altitudinal gradient and to explore its causes.Through quantitative approaches to study the species composition,αdiversity andβdiversity, the different species composition, floristic composition and diversity in different elevation segments of bamboo forest were analysed in the study. Meanwhile, Detrended Canonical Correspondence Analysis(DCCA) was used to detect the correlates between species diversity and the environmental factors. The results were as follows:(1)The difference of floristic composition and species along an altitudinal gradientBased on a 6 400 m2 survery area in Baoshan, vascular plants belong to 93 families, 211 genera, 330 species. Tropical elements dominate in family, genus and species. In the family level, pantropic sub-type was the main distribution type, but there were still some northern temperate sub-type composition. The predominant component of genera flora belonged to the tropical distribution type, with a certain amount of transitive character. From an elevation of 450 m to 1 200 m, the types and quantities of plants and the dominant species were obvious differences in different plots. The low elevation segment and the high elevation segment owned fewer species, the middle elevation segment owned more species.(2)Changes in life-form taxa of species along an altitudinal gradientThere was abundance of life forms in bamboo understory plants. Phanerophytes predoninate in each elevation segment, chamaephytes and geopnytes followed. According to the results of cluster analysis of life-form spectrum, the composition of Baoshan bamboo understory plants could be divided into four elevation segments: the low elevation segment(450 m-600 m), the mid-low elevation segment(650 m-800 m), the mid-high elevation segment(850 m-1 000 m) and the high elevation segment(1 050 m-1 200 m).(3) Changes in species richness along an altitudinal gradientThe species number, individual number and species richness showed the regular pattern that first increased and then decreased along an altitudinal gradient, but the trend showed insignificant difference with increasing elevation(p>0. 10) .(4) Changes in species diversity along an altitudinal gradientBothαdiversity index andβdiversity index did not change significantly with increasing elevation.(5) The results of DCCA ordinationDetrended Canonical Correspondence Analysis(DCCA) was used to detect species diversity and its environmental correlates, the results showed that shrub layer, meso-layer and herb layer Axes1efficient was significant, so as the overall efficient, cumulative percentage variance of species-environment relation of the first two axises is 65.1%, 65.6%, 62.6%, respectively. Correlation coefficients matrix of environment variables with the first two axes of DCCA showed that elevation was the most important factor impacting species diversity, aspect followed, slope gradient and slope position had no significant relationg with species distribution.Baoshan Phyllostachys pubescens forest understory community was full of species. The dominant species showed significant difference along an altitudinal gradient, and elevation was the most important environmental factor impacting species diversity, but the structure of plant communities was still stability.The all results would provided scientific basis for the reasonable management of bamboo plantation, protection for the integrity of the bamboo ecosystem and the selection of associated plants for bamboo forest.