The Fine-root Morphological And The Distribution Pattern Of Carbon,Nitrogen Of Alnus Formosana Burk-grass Compound Model

The fine-root had different morphology,nutriention structure and physiological function.low-level root morphogical plasticity,it is very sensitive to the changes of resource availability of the surrounding soil. With the diversification of nutrient availability change their morphology,nutriention structure and physiological function, to adapt to the soil environment.this study carried out in return farmland to forest zone of danling county, with the Alnus formosana Burk-Lolium multiflorum Lam fertilization (ALF) model, the Alnus formosana Burk-Lolium multiflorum Lam (AL)model Alnus formosana Burk-natural grass(A)model as the object.Mainly studied the effection of morphology, carbon,nitrogen content of Alnus formosana Burk fine-root by planted Lolium multiflorum Lam and fertilization, Provided theoretical basis of the sustainable development of Alnus formosana Burk-grass compound model.The results showed that:(1) Alnus formosana Burk fine-root mean diameter increased with the rise of root order in each model.In the surface soil layer(0-10cm), The mean diameter of fine-root was in the range of0.25-1.42mm、0.32-1.17mm、0.27-1.44mm in each model,and in the subsurface(10-20cm) the mean diameter of fine-root in the range of0.26-1.2mm、0.27-1.25mm、0.28-1.36mm. The mean diameter of ALF compound model was the smallest, the mean diameter of the2th and3th order in natural grass model was smaller than AL model, the mean diameter of the lth,4th and5th order in AL model was smaller than A model. Planting Lolium multiflorum Lam and fertilization reduced the mean diameter of fine-root, which promoted the fine-root absorption of soil nutrients and moisture(2) The Alnus formosana Burk fine-root SRL and surface area had significant level. surface soil fine-root SRL was larger than the sub-surface soil(expect the SRL of A model), and the fine-root SRL decreased with the rise of root order in each model. the fine-root surface area of ALF AL A model changed just like this:"∧","M" and rising with the rise of root order. In the subsurface, the fine-root surface area showed increase trendence with the rise of root order in each compound model(except the2th fine-root in ALF). The1-5th fine-root SRL of surface soil:ALF>AL>A, and the1th-5th fine-root SRL of ALF and AL is significant larger than A compound model.In sub-surface,the lth and2th fine-root: A>ALF>AL,the3th:ALF>A>AL,the4th and5th:ALF>AL>A.The fine-root surface area of the lth-4th order showed that A<ALF<AL in the surface and subsurface soil;the5th order showed that ALF<AL<A (surface soil),ALF<A<AL(subsurface soil).which indicated that planting Lolium multiflorum Lam increased the fine-root surface area, increased the contact area between fine-root and soil,thus improved the ability of fine-root absorbed water and nutrients from soil, it was beneficial to the sustainable management of forest-grass model.(3) The biomass of1th to5th order fine-root in surface soil was significant higher than subsurface soil(p<0.05). The fine-root biomass increased with the rise of root order in each model (expect the5th fine-root of surface of ALF treatments model). The biomass of the lth-3th order fine-root showed that A<ALF<AL; In the surface soil,The biomass of the4th and5th order fine-root showed that AL<A<ALF; The biomass of the4th and5th order fine-root respectively showed that A<ALF<AL and ALF<AL<A. Relatived to the A model,planting Lolium multiflorum Lam (ALF and AL model) significantly increased the fine-root biomass of the surface and subsurface soil (expect the4th and5th fine-root of ALF model). Planting Lolium multiflorum Lam and fertilization treatment lower the fine-root biomass of the surface and subsurface soil of ALF model.(4) The carbon and nitrogen content of all model in surface was more than subsur-face,the C and N content of the lower fine-root increased as the rise of root order, and senior fine-root didn’t followed this trend.In the surface soil of summer of2010,winter and spring and in the subsurface soil of fall and the summer of2011, the C content of ALF treatments and AL model was more than the C content of A model.In the surface soil of fall and spring of2011,and in the subsurface soil of winter and spring, the C content of ALF treatments and AL model was more than the C content of A model. which accounted for planting Lolium multiflorum Lam and fertilization treatments enhance the fine-root absorp-tion ability. The annual variation of C content of the1th-5th fine-root generally had the increase-reduce trendence, the least C content happened in winter, which was identical with the relative change of the fine root absorbed and consumption of organic nutrients. From the winter of2010to the summer of2011, the fine-root carbon of ALF and AL model was more than A model, and the increasing rate of fine-root carbon was,which indicated that planting Lolium multiflorum Lam was positive to promote the winter recovery of Alnus formosana Burk fine-root. The1th-5th fine-root N increased in a year of surface and subsurface soil of ALF model,the2th-5th fine-root N of winter was the maximum.In AL model, the most N content of the lth-3th fine-root was in winter, while the4th and5th fine-root N content was the least one.In the A model,the lth-3th fine-root had the most N content in summer of2010,while the most N of the4th and5th was in winter and fall respectively.(5) In generally, the fine-root C/N of the all model increased as the rise of root order (expected the3th or4th or5th fine-root in some model), the C/N of low-level fine-root (the lth-2th or lth-3th fine-root) had less annual fluctuations in ALF treatments and AL model,while the C/N of senior fine-root (the4th and5th order fine-root)had larger luctuations of the C/N range. The lth-3th fine-root had more volatility in A model than the lth-3th of other model, but the4th and5th had less volatility. The low-level root of the plots which planted Lolium multiflorum Lam had the smallest C/N in spring, while the senior fine-root had the smallest C/N in winter(expect the subsurface soil of ALF treatments).The C/N of1th-5th fine-root of surface soil was smallest in winter in A model, the C/N of low-level fine-root was smallest in surface soil and the C/N of senior fine-root was smallest in subsurface. Fine-root C/N is consistent to the fine-root seasonal physiological change(organic matter accumulation and respiration consumes) because of planting Lolium multiflorum Lam, which could promoted the growth of Alnus formosana Burk.(6) The relativity presents in the fine-root surface area and root order,C content, N content,C/N ratio, mean diameter, SRL, biomass didn’t exist. while the relativity presents between the fine-root C contnt and biomass also didn’t.The other factors were significantly correlated to each other.