Ecological restoration of mined-out areas of dry tropical environment, India Nimisha Tripathi & Raj Shekhar Singh Received: 15 April 2007 / Accepted: 12 November 2007 / Published online: 13 December 2007 # Springer Science + Business Media B.V. 2007 Abstract The objective of the present study was to evince the long-term changes after natural revegeta- tion and experimental revegetation of the coal mine spoils with respect to total plant biomass, available plant nutrients, nitrogen transformation and microbial biomass N (MBN) in dry tropical environment of India. Total plant biomass (above- and below- ground), plant available nitrogen, soil nitrogen min- eralization and microbial biomass N (MBN) were studied for 2 years in 5 and 10 years old naturally vegetated and revegetated coal mine spoils, and dry tropical forest ecosystem of India. In forest ecosys- tem, the above ground biomass values ranged from 3,520 to 3,630 kg ha -1 and belowground from 6,280 to 6,560 kg ha -1 . Plant available nitrogen ranged from 16.76 to 23.21 μgg -1 , net N-mineralization from 9.8 to 48.53 μgg -1 month -1 and MBN from 26.4 to 80.02 μgg -1 . In naturally revegetated mine spoil, the above ground biomass values ranged from 1,036 to 1,380 kg ha -1 and belowground from 2,538 to 3,380 kg ha -1 . Plant available nitrogen ranged from 7.33–17.14 μgg -1 , net N-mineralization from 3.1 to 12.46 μg g -1 month -1 and MBN from 14.2 to 35.44 μgg -1 . In revegetated mine spoil, the above ground biomass values ranged from 1,224 to 1,678 kg ha -1 and belowground from 2,870 to 4,130 kg ha -1 . Plant available nitrogen ranged from 9.4 to 18.83 μg g -1 , net N-mineralization from 4.2 to 16.2 μgg -1 month -1 and MBN from 21.6 to 42.6 μgg -1 . The mean plant biomass values in 5 and 10 years mine spoils was lower compared to forest ecosystem by 2.5 and 2 times, respectively. N-mineralization value in 5 year mine spoil was 3.5 times lower and in 10 years mine spoil 2 times lower compared to forest ecosys- tem. The MBN value was about 2 times lower in both 5 and 10 year mine spoils compared to native forest. MBN was positively related to the re-vegetation age of the mine spoil. Keywords Mineral-N . Nitrification . N-mineralization . Microbial-N . Naturally vegetated mine spoil . Revegetated mine spoil . Forest ecosystem Introduction During the excavation of coal or surface mining, the overlying soil is removed and rock debris gets deposited in the form of overburden. These over- burdens are mostly acidic in nature with very scarce organic matter contents. The mine spoils are not fit for plant growth, as they possess either very coarse Environ Monit Assess (2008) 146:325–337 DOI 10.1007/s10661-007-0083-7 N. Tripathi (*) : R. S. Singh Central Mining Research Institute, Barwa Road, Dhanbad 826 001 Jharkhand, India e-mail: nymphaea7@yahoo.com R. S. Singh e-mail: rss_60@yahoo.com