Soil taxonomy physicochemical characteristics and mineralogy associated with the critically endangered endemic tree Syzygium travancoricum in the Western Ghats of India

Soil properties are important indicators of plant growth as well as soil health. A study has been conducted related to the properties of soil under Syzygium travncorium is an indigenous tree to the South Western Ghats, India. The current study was conducted at Kalasamala, a temple grove lying at Thrissur district, Kerala, this study was to compare the soil taxonomy, physicochemical properties, and mineralogy under Syzygium travancoricum (profile A) and adjacent heterogeneous vegetation (profile B) to evaluate whether the edaphic environment effects the persistence of this endangered tree species grown there by taking soil profiles at depth 1.5m. The soils under two types of vegetations were classified under the order Ultisol and sub-classified as as Ustic Palehumults (profile A) and Typic Haplustult. Profile A, has quartz in the sand fractions; chlorite mica, kaolinite, gibbsite and quartz in silt fractions; chlorite, kaolinite, gibbsite and quartz in clay fractions. In contrast profile B, exhibits quartz and feldspars in sand fractions; chlorite, Hydroxy Interlayered Vermiculate, mica, kaolinite, gibbsite, and quartz in silt fractions; chlorite, Hydroxy Interlayered Vermiculate, kaolinite, gibbsite, and quartz in clay fractions. Profile A has three classes of soil textures; sandy loam, sandy clay loam, sandy clay, whereas only two textural classes, sandy loam and sandy clay loam were found in profile B. Furthermore, it has been observed that the process of illuviation results accumulation of clays at the bottom horizons in these systems, thus enhancing Cation Exchange Capacity (CEC), Total Exchangeable Acidity (TEA) and Soil Organic Carbon (SOC) except the illuvial layer (Bt2) of profile B. This study recognized typical characteristics of tropical humid soils, including leaching, low nutrient levels, and acidity. The decline of Syzygium travancoricum , by low seedling and poor regeneration, may be partly due to these limiting edaphic conditions along with anthropogenic pressures such as over exploitation and habitat destruction.