Impacts Of Two Year's Fertilization On Root Morphological Characters And Nutrient Contents Of Fine Roots In Japanese Larch (Larix Kaempferi) Plantation

Fine roots are the most sensitive part in forest root system. They play an important role in exchanging nutrient from roots to soil in forest ecosystem. Fine roots have different architecture, morphology and function, especially for low order root, which have plasticity and are susceptible to soil environment. Effects of two-year fertilization on fine root morphology (length, diameter, specific root length and surface area), nutrient (C, N, P, C∶N, C∶P and N∶P) and soil nutrient were studied in Japanese larch (Larix kaempferi) plantation. The results showed that:Different fertilizered treatments affected differently on root length, diameter, specific root length and surface area. N fertilized decreased root length and surface area of 1 to 5 order root, but increased root diameter and specific root length (SRL). However, P fertilized decreased root length, while increased root diameter, SRL and surface are. N+P fertilized decreased root length and SRL, increased root diameter and surface area. However, all of the differences were not significant.Different fertilization affected on fine root biomass. N fertilized decreased 1 to 5 order root biomass. However, P and N+P fertilized increased them. N and N+P fertilized increased fine root tissue nitrogen concentration, but P fertilization decreased lower root (1 and 2 order root) tissue nitrogen. N fertilized decreased 1 to 4 order root carbon concentration, but increased 5 order root carbon concentration. N+P fertilized and P fertilized decreased 1 order root carbon, increased 2 to 5 order root carbon concentration. N fertilized decreased fine root biomass, but increased root nitrogen concentration. The reasons may be increased fine root tissue concentration and root respiration, which cost root carbon concentration. P availability illustrated there was copulated among C and N in root physiological process.Fertilization could affect the proportion among C, N and P. Comparison with control (C∶N∶P=45.4∶4.1∶1), the proportion among C, N and P, on which effected by N (C∶N∶P=48.1∶4.2∶1) and N+P (C∶N∶P=51.3∶4.4∶1) were higher, however which effected by P (C∶N∶P = 43.8∶3.8∶1) was lower. N fertilized decreased C∶N of 1 to 5 oder root, N+P fertilized decreased C∶N of 1 to 4 order root but increased C∶N of 5 order root. P fertilized increased C∶N of 1 to 5 order root. The reductions resulted from N fertilized were above 1%, while others were below 0.1%. Fine root C∶N was increased, while soil C∶N was decreased affected by N and N+P fertilized. However P fertilized decreased soil C∶N but increased root C∶N. The reasons may be ascribe to changed level of supply of soil nutrients, which would change root absorbency to N and P, as a result of fertilization. Fine root absorbency to N would increased, which was affected by mutual developed restraints of root absorbency to C, N and P. These results ware an important in understanding effects of soil nutrients on fine root morphology and nutrient concentrations, recognizing despondences of different order root to nutrient changed and finding out the relationships between root elements and changed soil nutrient resources. These would be propitious to interpret the respondence of fine root biomass, production, turnover and lifespan to nutrient availability and understand fine root physiecological function.