Effect Of Black Carbon Addition After Fire On Decomposition Of Fine Roots Of Larix Gmelinii

Fine root decomposition,as a key link in terrestrial chemical cycling,is an important source of soil nutrients.As an important influencing factor in ecosystem succession,fire has significantly changed the carbon and nitrogen distribution pattern in ecosystems.Black carbon,as one of the main products of fire,has the characteristics of high aromatization and stable properties,and can be stored on the surface and soil for a long time.Black carbon and fire change the ability of plants to transport nutrients to the soil,affecting underground chemical cycling.However,little is currently known about the mechanism of root decomposition caused by fire and black carbon.This article takes the fine roots of Larix gmeliniiforest in the Bila River Nature Reserve of the Daxing’an Mountain range in Inner Mongolia as the research object,and compares the effects of control plots,fire disturbance plots,and post fire black carbon addition plots on fine root decomposition;Reveal the mechanism of the combined effect of fire interference and black carbon addition on fine root decomposition,and use the residual rate of fine root mass as a characterization of the fine root decomposition rate.The main research is as follows:(1)Fire and black carbon addition had no significant effect on soil temperature,while the soil moisture content significantly increased by 29.61% after fire.Compared with the control plot,the content of soil SOC and MBC showed an upward trend after fire,with a significant increase of 14.55% in soil SOC;Compared with the burnt sample plot,the addition of black carbon increased the content of soil SOC and MBC.Burning and high-level black carbon addition significantly reduced soil MBN content(15.57% and 23.92%)in the sample plots.(2)In the change of root C content,compared with the control plot,the fine root C content of 0-0.5mm after fire significantly decreased by 9.63%,and the fine root C content in the black carbon addition treatment increased by 10.43% and 8.43% compared to the fire plot,respectively;After burning,the content of fine root C in the 0.5-2mm sample increased significantly by 14.62%,and the content of fine root C in the high-level black carbon sample plot was significantly higher than that in the burned sample plot by 5.70%;There was no significant change in roots larger than 2mm during the treatment.In the variation of fine root N content,compared with the initial N content,the overall trend shows an upward trend.Compared with the control plot,the N content of the three diameter classes of roots after fire significantly increased by 7.77%,12.24%,and 27.90%.Compared with the fire plot,the N content of fine roots in the 0-0.5mm and 0.5-2mm samples with black carbon addition showed a significant downward trend,while the N content of fine roots in the 0-0.5mm samples decreased by 7.47% and 6.36%;The N content of 0.5-2mm fine roots significantly decreased by 37.51% and 43.35%;The N content in roots larger than 2mm significantly increased by23.15% and 33.12% in the black carbon addition treatment.(3)Compared with the control plot,the residual weight of fine roots of Larix gmelinii larch with a thickness of 0-0.5mm in both fire and black carbon treatments showed a decreasing trend(11.234%,8.511%,and 8.233%);Compared with it,the residual mass rate of fine roots with a thickness of 0.5-2mm decreased after fire,but it was not significant;The addition of black carbon showed an inhibitory effect on the decomposition of 0.5-2mm fine roots;The residual rate of root mass greater than 2mm showed no significant change after fire,while the residual rate of root mass in the sample plots with high-level black carbon addition significantly increased by 8.69% after fire.Overall,the residual mass rates of fine roots from 0to 0.5mm and 0.5-2mm decreased significantly after fire and black carbon addition treatments,with fire having the most significant promoting effect on the decomposition of fine roots from0 to 0.5mm;The residual rate of root mass greater than 2mm was significantly inhibited by the addition of high-level black carbon after fire,resulting in a significantly higher residual rate of root mass than other treatment results.