| Ecological stoichiometry is an important part of biogeochemical research.It mainly studies the changes in nutrient contents and C:N:P ratios in soils and in various organs of plants.It helps to reveal the status of nutrient allocation and limiting factors for plant growth,and the relationship between plants and soil.This study focused on(Eucalyptus grandis ×E.urophylla),the most widely grown fast-growing species in Guangxi,and Castanopsis hystrix,the native species in Guangxi.In this study,four treatments including compound fertilizer(H),compound fertilizer+biochar(HC),compound fertilizer+nitrogen(HN)and blank control(CK)were set up to study the effects of these fertilization measures on the biomass of(Eucalyptus grandis ×E.urophylla)× Castanopsis hystrix mixed forests and the ecological and ecological stoichiometry characteristics of undergrowth plants and soils,which could provide a theoretical basis for the operation of a large area of(Eucalyptus grandis×E.urophylla)× Castanopsis hystrix mixed forests.The main findings are as follows:(1)H,HC and HN treatments all increased the biomass of(Eucalyptus grandis ×E.urophylla)× Castanopsis hystrix mixed forest.With manual ground clearance,the biomass of(Eucalyptus grandis ×E.urophylla)× Castanopsis hystrix mixed forest in various treatments from high to low were:HC>H>HN>CK.With controlled burning,the biomass of(Eucalyptus grandis xE.urophylla)× Castanopsis hystrix mixed forest in various treatments from high to low were:H>HC>HN>CK,manual ground clearance of HC fertilization method was better than other fertilization methods,H treatment under controlled burning was better than other fertilization methods.The increase in trunk biomass was greatest in all fertilization treatments,followed by tree roots;different fertilization treatment,organ allocation pattern of(Eucalyptus grandis ×E.urophylla)biomass was as follows:stem>root>rind>branch>leaf,and Castanopsis hystrix was as follows:stem>root>branch>leaf,the trunk had the largest proportion.Compared with the manual clearance method,controlled burning increased the biomass of various organs of eucalyptus.The proportion of stems and leaves in the biomass of individual trees was increased,the proportion of roots was decreased,and the proportion of skin and branches was basically unchanged.Controlled burning significantly reduced biomass of herb layer and significantly increased biomass of litter layer.(2)H,HC,and HN treatments generally increased C,N,P of Plant leaf.Under manual ground clearance,the responses of Plant leaves to fertilizer application measures were as follows:HC>H>HN>CK,and the HC fertilization method was superior;under the controlled burning method,(Eucalyptus grandis ×E.urophylla)× Castanopsis hystrix mixed forest had a lower response to HN treatment and more obvious response to H treatment,C,N,P in the tree layer and the undergrowth layer increased significantly under H treatment;compared with the manual ground clearance,the controlled burning improved the Plant leaf of C,P as whole,but Plant leaf of N decreased.Under the manual ground clearance,leaf C:N,N:P,C:P ratio of shrub layer,herb layer and litter layer underwent H,HC,and HN treatment decreased overall,but leaf N:P ratio of tree layer increased,leaf C:N,C:P ratio of tree layer decreased.Under controlled burning,leaf N:P ratio of shrub layer and herb layer under different fertilization increased generally,while leaf C:N,N:P and C:P ratio of tree layer and litter layer decreased or did not change significantly,and the ecological stoichiometry ratio of plant leaf was more Sensitive to H treatment.(3)Soil C,N,P was concentrated in the soil surface.Under manual ground clearance,H,HC,and HN treatment increased soil C,N,P in 0-60cm,and the effect of different fertilization methods on soil was:HC>H>HN>CK.HC treatment significantly increased soil nutrients.HC treatment of soil N:P,C:P ratio in 0-10 cm decreased significantly,the three fertilization methods significantly reduced soil C:N,N:P,C:P ratio.Under controlled burning,H treatment significantly increased soil C,N in 0-60 cm soil layer,significantly increased the soil P in 0-10 and 20-40 cm soil layers,and had no significant effect on other soil layers.HC treatment significantly increased soil C,N of 0-10 and 10-20 cm soil layers,and there was no significant effect on the depth of 20-40 and 40-60 cm in the deep soil layers.HN treatment significantly increased soil N of 10-20 cm,but there was no significant effect to other soil layers;different fertilization methods had an increase effect on soil N:P,C:P ratio on the soil layer of 10-20 cm,other soil layers C:N,N:P and C:P ratio had no significant response to fertilization.Compared with the manual ground clearance,soil C,P increased with controlled burning,but soil N decreased in contrast.(4)Plant leaf C:N,C:P ratio was negatively correlated with plant biomass,but tree layer plant N:P ratio was positively correlated with plant biomass,and N:P ratio of Undergrowth plants was negatively correlated with plant biomass,Controlled burning weakened the correlation between plant leaf C:N:P ratio and biomass,and the correlation between N:P ratio and biomass of shrub layer,herb layer leaf was changed from negative correlation under manual ground clearance to positive correlation under controlled burning.(5)Under Manual clearance the surface soil(0-10 cm,10-20 cm)was positively correlated with the ecological stoichiometry ratio of the plant,but negatively correlated with the deep soil layer(20-40 cm,40-60 cm).Under controlled burning,there was a negative correlation between soil and plant ecological stoichiometry ratio or no significant correlation. |
PDF Full Text Request