Species Diversity, Stand Structure, and Species Distribution across a Precipitation Gradient in Tropical Forests in Myanmar

Abstract

An understanding of how species diversity, structural pattern, and species distribution vary across different environmental regions is crucially important for tropical ecology. In this study, we explored how these ecological parameters vary across various rainfall regions in the tropics with annual rainfall levels ranging from 843 to 2035 mm. Diversity, similarity, structure, and forest classification, and their correspondence with rainfall regions were tested. We found that species diversity, site class, and structural complexity increased with rainfall, with differences of 1000 mm having significant effects on diversity. The structure and heterogeneity of forests were higher in the high rainfall regions than the low rainfall regions. The forest structure was significantly correlated with rainfall, and the structure differed substantially where annual rainfall differed among sites by approximately 200 or 400 mm. Forests could be classified into two types according to whether they had high annual rainfall (1411-2035 mm) or low annual rainfall (843-1029 mm). In addition, the dominance of species changed noticeably from high-to low-rainfall regions, with Tectona hamiltoniana and Terminalia oliveri only being abundant in the low rainfall region. Species diversity and richness were significantly correlated with rainfall and average temperature. These findings will provide invaluable information for forest management and ecological phytogeography.

Factors Affecting Natural Regeneration of Tropical Forests across a Precipitation Gradient in Myanmar

“…Xylia dolabriformis Benth. was one of the most dominant species at sites 1-5 [31], although it was not found at site 6. The dominant species at site 1 were Xylia dolabriformis, Tectona grandis L.f., Protium serratum (Wall.…”

“…Three parameters, namely, species diversity, species richness, and density of overstory structure of sites 1-5, were obtained from our previously published research conducted at the same sample plots [31]. These parameters for site 6, and other parameters of overstory structure for all sites, were calculated in this study.…”

“…Kurz, Terminalia tomentosa, Shorea oblongifolia Thw., and Dipterocarpus tuberculatus Roxb., and those at site 5 were Tectona hamiltoniana Wall., X. dolabriformis, Terminalia oliveri Brandis, T. tomentosa, and Anogeissus acuminate (Roxb. ex Candolle) Guillemin et al [31]. At site 6, the dominant species were Morinda tinctorial Roxb., Acacia leucophloea (Roxb.)…”

“…All trees greater than 5 cm in diameter at breast height (dbh) in the 50 m × 50 m sample plots were recorded as the overstory structure in this study. Some of the overstory structure data were obtained from our former published research, Khaine et al [31], because the same study sites were used. Within each sample plot (50 m × 50 m), two subsample plots of 20 m × 20 m, i.e., 400 m 2 each, were laid out in diagonally opposite corners of the plot (see Plot B in Figure 1).…”

Riparian vegetation in production forest at Cemoro-Modang River, Cepu, Central Java

“…In tropical regions, species diversity was significantly correlated with rainfall and average temperature, while forest structure was significantly correlated with rainfall. The species richness, stand structure, species dominance, basal area, and size class consistently decreased from high to low rainfall regions (Khaine et al, 2017). The results of species diversity index on each tree life stages in the riparian zone at Cemoro-Modang river ranged from 0.24 to 2.03 (Table 3).…”