Spatial Heterogeneity in Tree Diversity and Forest Structure of Evergreen Broadleaf Forests in Southern China along an Altitudinal Gradient

Abstract

Abstract:We studied the influence of altitude on the spatial heterogeneity of tree diversity and forest structure in a subtropical evergreen broadleaf forest in southern China. Significant positive correlation was found between tree species diversity, basal area and altitude, but negative correlation between slenderness of trunks and altitude. According to topography, tree species diversity, diameter at breast height, height and basal area increased from ridges to valleys, while slenderness and stem density did not differ significantly with topography. Redundancy analysis (RDA) was employed to clarify relationships between tree species diversity and environmental factors (topography and soil water holding capacity). Topography and water conditions jointly explained 57.8% of the diversity variation. Tree species diversity was significantly correlated with altitude, slope and bulk density (Monte Carlo permutation test with 999 permutations, p < 0.05). A positive relationship existed between altitude, soil non-capillary porosity and diversity, while slope, aspect and soil water content were the opposite. Our results show that soil water holding capacity has a positive effect on maintaining species diversity. When comparing with topographic factors-the main driving forces affecting the pattern of tree species diversity-the effect of soil water holding capacity was weak.

Topographic variables to determine the diversity of woody species in the exclosure of Northern Ethiopia

“…agreement with this study,Cui and Zheng (2016) also reported Shannon diversity index increased with altitude, with the highest diversity being recorded in the highest altitude in evergreen broadleaf forests in southern China. Zhang et al (2013) found the highest species diversity appeared in the middle elevation and under medium disturbance intensity in the Baihua Mountain Reserve, Beijing, China.…”

“…The present study revealed that altitude has a significant effect on species diversity and richness. Altitude is a key variable affecting species diversity in mountains, as observed in numerous studies (Rahbek, 2005;Fetene et al, 2006;Muhumuza and Byarugaba, 2009;Kebede et al, 2013;Cui and Zheng, 2016). Similarly, a study by Kebede et al (2013) reported that aspect, slope and altitudinal variation in Ethiopian landscapes has influenced the existence of varied vegetation types and floristic diversity.…”

“…With increasing elevation, the total number of species recorded in each plot decreased linearly in Temperate Mountain Forests of Northern China (Zhang et al, 2016b). The difference in species richness and diversity among the altitudinal gradient is due to the variation in climate variables, deforestation, human interaction, encroachment pressure and soil erosion (Amjad et al, 2013;Bertuzzo et al, 2016;Cui and Zheng, 2016). Climate is a visible factor affecting species distribution and richness in many areas (Fang and Lechowicz, 2006).…”

“…The present study also revealed that slope has a significant effect on species diversity and richness. Slope has been recognized as an effective factor on diversity and richness (Boll et al, 2005;Cui and Zheng, 2016). Wolf et al (2012) argued that slope has a significant effect on woody species diversity, because they determine water availability.…”

Assessing Biotic and Abiotic Effects on Biodiversity Index Using Machine Learning

“…As seen in the results of this study, elevation was the main influential factor in RF models. This variable is a significant predictor affecting species diversity, as observed in previous studies [81,82]. Similarly, aspect, slope and altitudinal variation in Ethiopian landscapes have influenced the existence of varied vegetation types and diversity [83].…”