Title: Characteristics of soil phosphorus in different aged stands of Chinese fir plantations in Huitong,Hunan Province
Abstract: Phosphorus( P) is an essential element for growth and development of plants. At cellular and sub-cellular levels,P plays a vital role in various important metabolic processes,such as protein synthesis,cell division,newborn tissues development and energy transformations. In terrestrial ecosystems,P is often the most limiting nutrient. This is particularly the case for some regions where nitrogen( N) in the soils is likely saturated due to high N deposition,extensive N fertilizer application and fossil fuel combustion. In this study,changes in P formations( total P,available P,inorganic P and organic P) in soils were investigated in three aged stands of Chinese fir plantations( 7-,17-and 25-year-old stands) in Huitong County,Hunan Province,China. The fractions of inorganic P in soils were also determined in the studied plantations. The purpose of this project is to examine the alterations of soil P in different aged Chinese fir forests. The resultsshowed that the total P content ranged from 317.06 to 398.56 mg / kg and available P content from 0.82 to 1.38 mg / kg,in the three examined aged stands. The total P and available P contents were in a relative low level when compared with the corresponding values derived from the national soil survey. But the total P and available P contents in soils significantly increased with the aged stands. The average total P content in soils was about 19.68% and 15.75% higher in 17-year-old stands and 25-year-old stands than in 7-year-old stands. Available P content was about 45.55% higher in the 17- and 25-year-old stands than in the 7-year-old stands. P activation coefficient in the soils was low( 2.0%) in the three aged stands of Chinese fir forests,which suggested that the transformation of organic P to available P was restricted,even certain mineralization indeed occurred in the studied site. The concentration of inorganic phosphorus was 169. 50,182. 03 and175. 94 mg / kg in the 7-,17- and 25-year-old stands,respectively. On average,the amount of inorganic P fractions in the studied soils was in an order: occluded bound P( O-P) iron bound P( Fe-P) calcium bound P( Ca-P) aluminum bound P( Al-P). Significant changes in the patterns of absorption of inorganic phosphorus fraction occurred in different growth and developmental stages of Chinese fir forests. Typically,the Al-P fraction was the major component of the inorganic P absorbed by the tree in the 7- and 17-year-old plantations. But the Fe-P and Ca-P fractions became the most assimilated inorganic P in 25-year-old Chinese fir stands. It was found that there was a close relationship between the available P and organic P in soils with a correlation coefficient of 0. 667 in the studied stands,which implied that the organic P was the main source of soil available P in Chinese fir plantations in the study region. The results suggested that it was likely an important management practice to increase the transform rate of inorganic P to available P in the younger stands in order to improve soil fertility and promote forest productivity. Our study provided a scientific basis and reference for better understanding of P storage and cycling in Chinese fir forests.
Publication Year: 2014
Publication Date: 2014-01-01
Language: en
Type: article
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