Forest Floor Dynamics and its Management Options in Mixed Old Grown Pinus Roxburghii Sargent. Plantation of Doon Valley

Present paper deals with patterns in litter fall, decomposition, nutrient return, release and accumulation in 57 year old chir pine plantation of Doon-valley. Initially, the plantation was raised as monoculture but later on stand was invaded by broad-leaf species like Michelia champaca , Cinnamomum camphora and Mallotus philippensis. Needles contributed 49.41% (4780.82 kg ha^-1 y^-1 ) to the total litter fall (9675.89 kg ha^-1 y^-1). The peak period of leaf fall in pine is -1 -1 during April-May. The other invaded species of the plantation contributed 4124.22 kg ha^-1 y^-1 , which was 42.62% of the total litter fall. The value of decomposition constant (k) was 1.35 for leaf litter while it was 0.865 for twig litter. Leaching losses were low during the first month of the decomposition rate. It was 2.59 % of the annual decomposition. Higher values for decomposition rate, was recorded during rainy season. Temperature, rainfall and number of rainy days were positively related with decomposition rate. Nutrient concentration is generally higher in needle litter than of twig litter. Ca and N contributed higher proportion in total nutrient return, release and accumulation. In general, the magnitude of total nutrient return followed the magnitude of total litter fall. The higher nutrient return was associated with higher -1 -1 litter fall and nutrient concentrations. Further, the order of importance in terms of magnitude ( kg ha^-1 y^-1 ) of total nutrient return was :Ca (77.46) > N (57.63)> K (51.70)> Mg (11.74)>P(7.14). The broad leaves contributed in total return -1 -1 magnitude (kg ha^-1 y^-1 )as Ca (43.21) > N (28.46) > K (23.05) > Mg (4.72) > P (2.93). It was 55.78%, 55.05%, 44.58%%, 40.20%%, 40.86% respectively, for Ca, N, K, Mg and P. Significant variations in all the nutrients were noticed. N and P showed higher variations. These variations are non-significantly correlated with magnitude of leaf fall showing inefficient biochemical cycling, except for nitrogen.