Abstract:

Maoershan forestry centre lies in Zhangguangcai Mountain of Changbai Mountain range. Main forest types are plantation (Pinus sylvestris var.mongolica, Pinus koraiensis and Larix gmelinii )and natural secondary forests(Fraxinus mandshurica, Quercus mongolica and Populus davidiana) in Maoershan region. Fine roots have enormous surface, growing and turning over quickly, playing an important role in terms of substance cycle and energy flow in forestry ecosystem. This experiment was studied on dynamics of live, dead and total fine roots (≤5mm) biomass of 0～30cm soil layer by soil core method and the differences between the six stands in Maoershan region. The results showed: 1) The fine roots biomass in different stands had obvious differences. Total fine roots biomass of six stands from high to low were F.mandshurica(1030.0g·m^-2)>Q.mongolica(973.4g·m^-2)>P.koraiensis(780.9g·m^-2)>L.gmelinii(718.2g·m^-2)>P.davidiana(709.1g·m^-2 )> P.sylvestris var. mongolica (470.4g·m^-2);2) Except L.gmelinii, the trend of live fine roots biomass was in accord with the trend of total fine roots biomass. The maximum biomass of live fine roots in P.koraiensis or L.gmelinii' stand appeared in May, others in June; In F.mandshurica stand, the minimum biomass of live fine roots appeared in September, others in July or August; 3) The proportions of dead fine roots biomass were different in different stands; 4) Fine roots vertical distribution was affected by temperature, water and nutrient, the proportion of fine roots biomass centralized in 0～10cm soil layer. Fine roots biomass of six sands in 0～10 cm soil layer was over 40% of the total fine roots biomass, the proportion of F.mandshurica was 60.3%. Space-time dynamics of different stands had different characteristics. When researching on substance cycle and energy flow of all forest ecosystems, we should consider the characteristics of different stands in order to improve estimative precision.

Key words: Maoershan, fine roots, biomass, plantation, natural secondary forest