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Soil Nitrogen Nutrition Habitat Characteristics Of The Severe Fire Area In Larix Gmelinii Forests

Posted on:2020-06-06Degree:MasterType:Thesis
Country:ChinaCandidate:C B LiFull Text:PDF
GTID:2370330578976081Subject:Soil science
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Forest fire disturbance is an important factor leading to the change of soil nitrogen nutrient habitat in boreal forest.The study focused on soil nitrogen under typical Larix gmelinii forest in the north of Great Xing'an,and continuous fixed-point monitoring was used to analyze the characteristics and formation mechanism of soil nitrogen nutrient habitats in burned sites under different intensity forest fires in time series to better recognize the dynamic of forest soil nitrogen nutrition habitat after fire disturbance and provide reference for improvement and ecological restoration in the burned forest.The results were showed as follows:1)In recovery time series of,the contents of NH4+-N,NO3--N and mineral nitrogen(NH4+-N+NO3--N)in the surface soil of Fire-burned areas of Ledum palustre-Larix gmelinii and Rhododendron simsii-Larix gmelinii all increased immediately after fire and then decreased gradually.2)In sampling time series,the contents of NH4+-N and mineral nitrogen in the surface soil of Fire-burned areas of Ledum palustre-Larix gmelinii and Rhododendron simsii-Larix gmelinii decreased in the growing season and then increased,but there was no significant difference in the contents of NO3--N.3)The contents of NO3--N,NH4+-N and mineral nitrogen in Surface soil samples from Ledum palustre-Larix gmelinii and Rhododendron simsii-Larix gmelinii were higher than those in the subsoil.4)In general,the contents of NH4+-N,NO3--N and mineral nitrogen in the areas of Ledum palustre-Larix gmelinii are higher than those in the areas of Rhododendron simsii-Larix gmelinii.5)The contents of NH4+-N dominated in all the samples.The contents of NH4+-N obviously improved in the forest of Ledum palustre-Larix gmelinii and gradually declined with the recovery of revegetation.6)The rate of ammonia,nitrification,and mineralization rates in the unburned forest land and various fire sites of Ledum palustre-Larix gmelinii,Rhododendron simsii-Larix gmelinii forests have changed from negative to positive in July;In general,the rate of ammonia,nitrification and mineralization in each fire burned site during the growing season was significantly higher than that in the unburned site.At the end of the growth season,the rate of ammonia,nitrification,and mineralization of the soil in the early and mid-burning areas(except for the Rhododendron simsii-Larix gmelinii from September to October)increased compared with the growth season.7)Soil temperature,humidity and redox potential were elosely related to soil nitrogen nutrition level in the burn site of heavy larch forest in the greater hinggan mountains.Soil NH4+-N content was significantly positively correlated with soil temperature and soil moisture.Soil NO3--N content was negatively correlated with soil temperature and positively correlated with soil humidity and redox potential.Soil mineral nitrogen content was positively correlated with soil moisture and redox potential.and negatively correlated with soil temperature.
Keywords/Search Tags:Larix gmelinii, Severe fire, Soil, Mineral nitrogen nutrition
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