Study On The Natural Reg+eneration, Litter Decomposition And Allelopathy Of Manchurian Ash (Fraxinus Mandshrrica Rupr.)

The natural regeneration of Pinus koraiensis, Pinus sylvestris var. mongolica and Larix plantations and Fraxinus mandshrrica natural forest were surveyed in Mao'er Mountain Experimental Station of Northeast Forestry University. The results showed that the regeneration of Pinus koraiensis, Pinus sylvestris var. mongolica and Larix plantations were better than that of Fraxinus mandshrrica natural forest. In Pinus koraiensis, Pinus sylvestris var. mongolica and Larix plantations, the amount of regenerating seedlings was more than 16000stem.hm-2, but in Fraxinus mandshrrica natural forest, it was less than 5000 stem.hm-2.After a year of decomposition, the percent of weight lost of Fraxinus mandshrrica and larix litter were 67.0% and 26.55%, respectively. The percent of weight lost of Fraxinus mandshrrica litter was significantly higher than that of larix litter. During the decomposition, Fraxinus mandshrrica was more than larix in nutrient release of P, K, Ca, Mg except for N. The initiative values of nutrient in Fraxinus mandshrrica litter were higher than those of larix litter. Therefore, nutrient return of Fraxinus mandshrrica to soil by litter was more than that of larix.Radish seed was used to study the allelopathy of Fraxinus mandshrrica and Larix. The results showed that the aqueous extract of Fraxinus mandshrrica and Larix fresh leaves had significant inhibiting effect on the seed sprout and the growth of radish. The inhibiting effect of aqueous extract of Fraxinus mandshrrica fresh leaves was higher than that of Larix. In the un-decomposing and decomposing litter, there was different performance between the aqueous extract of Fraxinus mandshrrica and that of Larix. Fraxinus mandshrrica had the general inhibiting effects on the seed sprout and the growth of radish in all the treatments, while Larix showed the effects only in the treatments of 1:30 and 1:100. Moreover, in the decomposing litter, the magnitude of habiting effects of Fraxinus mandshrrica and Larix decreased significantly. The reason that the regeneration capacity of Fraxinus mandshrrica in natural forests was lower than that of in Larix might be related with the different allelopathy of Fraxinus mandshrrica and Larix in fresh and un-decomposing leaves.