Precise Fertilization Regime For Young Betula Platyphylla Plantation Forest Stand

Taking 11-year-old of young Betula platyphylla plantation forest stand as the research object,the recommended fertilizer application amount was calculated based on the management unit division,nutrition diagnosis and combined with the gradient distribution of available nutrients in soil in the Northeast China Transect(NECT).Based on the part of"3414" experiment design(1-N0P0K0,2-N0P2K2,3-N1P2K2,4-N2P0K2,5-N2P0K2,6-N2P2K2,7-N2P3K2,8-N2P2K0,9-N2P2K1,10-N2P2K3,11-N3P2K2),the precision fertilization experiment was carried out for two consecutive years,and the comprehensive response of growth physiological index of trees and soil nutrition index after fertilization was tested by principal component analysis,and aim to discussed the precise fertilization technology of young Betula platyphylla plantation forest stand.Compared the differences of forest soil,forest leaves and spring xylem sap flow(sap flow)in four kinds of microtopography and their correlation with tree morphological indexes,and to explore the possibility of asp flow as nutrient diagnostic material.The results show that:(1)After precise fertilization,the comprehensive response of all fertilization treatments except treatment 2 and 5 was higher than that of control cheeck(CK).The results of comprehensive response of fertilization were consistent with the results of nutritional diagnosis.The nutritional diagnosis showed that the low yield group was deficient in soil K,tree N and tree K,and the order of tree fertilizer requirement was K>N>P.The comprehensive response score of treatment 10(excessive K application)ranked first;The comprehensive response score of treatment 6(recommended amount of fertilizer application)ranked the second;The comprehensive response of treatment 1(CK)ranked 9th;The comprehensive response score of treatment 2(N0P2K2)ranked 11th.(2)In the second year of precise fertilization,the effect on tree DBH was small,and the effect on AR/TR was large.In the second year,the relative increase of DBH of treatment 4,6 and 11 were 125%,116%and 125%.Treatment 10 showed inhibition of DBH growth,which relative increase 24%.The relative increase of tree DBH in June accounted for 50～98%of the whole year.AR/TR of excessive fertilization treatment was significantly higher than that of treatment 1(p<0.05).AR/TR of treatment 4,6,8 and 9 was higher than that of treatment 1,but the difference was not significant.(3)Precise fertilization has no obvious effect on the seasonal change of physiological and biochemical indexes of leaves,but significantly increases the nutrient concentration of leaves.From June to August,the leaf N,P concentration of each treated showed a v-shaped change trend of decreasing first and then increasing.The C concentration in the leaves showed an overall upward trend.Except for treatment 10,the chlorophyll concentration showed an overall rising trend.In the early stage of leaf development(June),all indexes of treatment 6 and 10 were higher than that of treatment 1.(4)Compared with the leaf and soil nutrients in the early stage of leaf spreading,the sap flow is more suitable for the nutritional diagnosis of trees before full leaf spreading.There were significant differences in the height and DBH of trees in different microtopography(p<0.05),significant differences in the concentration of C3,N3,P3 and K3 in liquid flow(p<0.05),significant differences in the concentration of soil nutrients(TNi,TC1,TP1,TKi,AP and AK),and no significant differences in the concentration of C2,N2 and K2 in leaves(p<0.05).The tree height was positively correlated with the concentration of C in the flow(p<0.01),and positively correlated with the concentration of TN1,TC1,TP1 and C2 in the leaves(p<0.05).There was a significant positive correlation between DBH and concentration of N and P of sap flow(P<0.01).Above all:Accurate fertilization techniques of young Betula platyphylla plantation forest stand include management unit division,nutrition diagnosis,determination of recommended fertilizer application rate,and fertilization response test.The comprehensive response score of the fertilizer application amount(treatment 6)determined by this technology ranks the second,which provides scientific reference for the study of forest tree fertilization in the later period.The sap flow can be used as the nutrient diagnostic material before leaf spreading,which can advance the time of nutrition diagnosis and enrich the theory of forest nutrition diagnosis.