The Effects On Microbial Biomass In Soil Aggregates Of Burned Area Under Different Restoration

In order to explore the effects of different vegetation restoration approaches on soil aggregates'formation and it's cycle carbon and nitrogen of severely burned area in Greater Xing'an Mountains,we chose the artificial restoration?Larix gmelini plantation and Pinus sylvestris var.mongolica plantation?,the artificial promoting nature regeneration and the natural regeneration of forest soil in Greater Xing'an Mountains after the severely burned in may 6,1987 respectively as the research object.The soil aggregates of>2 mm,2¹ mm,1⁰.5mm,0.5⁰.25 mm and<0.25 mm were respectively obtained by dry sieving method and the distribution features of the soil microbial biomass carbon?MBC?,the soil microbial biomass nitrogen?MBN?,the soil organic carbon?SOC?,the soil dissolved organic carbon?DOC?,the soil total nitrogen?STN?and the soil K₂SO₄-extractable nitrogen in total soil and soil aggregates were determined.Our studies have important significance to provide scientific basis of forest ecosystem restoration and reconstruction.?1?The contents of MBC,MBN,SOC,DOC,STN and soil K₂SO₄-extractable nitrogen presented an decreasing trend along with the increase of soil depth,furthermore,The SOC mainly distribution in the surface soil layer.Except soil K₂SO₄-extractable nitrogen,the other carbon and nitrogen indexes were all highest in Artificial promotion regeneration forest and were lowest in Pinus sylvestris var.mongolica plantation.Show that the effect of the artificial promoting nature regeneration approaches on soil quality recovery is better than others.?2?The soil aggregate contents presented an first decrease then increase reduced finally trend along with the decrease of size fraction.The soil aggregate>2 mm were predominant in Larix gmelini plantation,Pinus sylvestris var.mongolica plantation and Artificial promotion regeneration forest and 1⁰.5 mm were predominant in the surface soil of Natural secondary forest.Show that the aggregating of surface soil of the artificial restoration forest and the artificial promoting nature regeneration forest was better than the natural regeneration forest.?3?Under different vegetation restorations,the contens of MBC,MBN,SOC and STN in soil aggregates presented an decreasing trend along with the increase of soil depth and increasing trend along with the particle size of aggregate increases,the large aggregates were significant higher than the micro aggregates.The distribution features of the soil K₂SO₄-extractable nitrogen contents in the aggregate with differences between different layers,in0⁵cm soil layer,the soil K₂SO₄-extractable nitrogen presented an first decrease then increase trend along with the particle size of aggregate decreases,in 5¹0cm and 10²0cm soil layer,the soil K₂SO₄-extractable nitrogen presented an decreases trend along with the particle size of aggregate decreases.Furthermore,The DOC mainly distributed in the 1⁰.5 mm particle size and larger size aggregate.Show that the soil organic carbon and nitrogen cycle of the large aggregates more active than the small aggregates.?4?The MBC and MBN had significant positive correlations with the SOC,STN and DOC,but which uncorrelations with the soil K₂SO₄-extractable nitrogen.