Native and planted forest species determine different carbon and nitrogen pools in Arenosol developed on Holocene deposits from a costal Mediterranean area (Tuscany, Italy)

Abstract

In a coastal Mediterranean area, the effects of two native [Quercus ilex (Holm), Alnus glutinosa and Fraxinus oxycarpa (Hygro)] and one planted [Pinus pinaster (Pine)] forest species on both content and quality of organic C and total N pools in Arenosols was assessed. Three soil profiles per each forest cover were opened and sampled. Total N in the organic layers was not affected by forest covers, whereas total organic C ranged from 36.1 to 63.2 Mg ha−1, being organic layers under Hygro those with the highest contents. Total organic C in the first 50 cm of mineral soil was 64 Mg ha−1 under Holm and 36.7 and 37.6 Mg ha−1 under Pine and Hygro, respectively. Soil covered by Holm and Hygro stored, respectively, 5.2 and 3.2 Mg ha−1 of total N. Soils under Pine showed the lowest values of total N, extractable C and N, microbial biomass C and N and microbial quotient. Also the quality of the organic layers was lowest under Pine, as evidenced by the highest values of TOC/TN ratio. Forest covers affected size and quality of organic C and total N pools in Arenosols. Arenosols stored from 73.7 to 127.2 Mg ha−1 of organic C and from 3.9 to 7.1 Mg ha−1 of total N. The organic layers could accumulate even the same amount of organic C and up to 50 % of the total N stored in the first 50 cm of mineral soils. Pine cover worsened the quality of soil organic matter.