Effects Of N And P Addition On The Stoichiometry Of Three Grassland Plants N And P

Since the beginning of the 20 th century,the rapid increase in human activities has accelerated the change of climate,which has accelerated the process of nitrogen conversion into the biosphere in the atmosphere,resulting in a significant increase in the available N in the ecosystem.Due to the influence of nitrogen deposition,the balance of demand for P in the biosphere will be broken,so that the terrestrial ecosystem will be restricted by N,P or N and P,and the physiological functions and characteristics of plants will also change accordingly.At present,a large part of domestic nutrient addition tests for grassland and grassland ecosystems are carried out by simulating nitrogen deposition.There are few tests for adding phosphate fertilizer alone or for simultaneous addition of phosphate fertilizer and nitrogen fertilizer.In fact,in order to verify whether nitrogen deposition can lead to phosphorus limitation,whether the soil’s nitrogen and phosphorus stoichiometry characteristics affect the individual levels,individual species and communities of plants,only the addition of phosphorus can be verified..In addition,at present,most of the research on the ecological stoichiometric characteristics of plants and the response of plants to nitrogen addition mainly study the above-ground parts of plants,in which plant leaves are the main research objects,while in the underground part of plants,ie the roots.Research is quite rare.But in fact,the feedback of different functions and different physiological characteristics of plants is determined by different organs,and different organs have distinct structural differences,so different plant parts respond to different changes in different environments and Its ecological stoichiometry is completely different,and the coordinated adaptation mechanisms of different plant organs within different environmental changes are present in these differences.Therefore,if you want to find different coordination mechanisms of different plant organs to cope with environmental changes,you can not ignore the differences in the corresponding patterns between different plant organs and their corresponding ecological stoichiometry,and finally can discover and predict the individual plants and the whole community.Based on this conclusion,this study used the three dominant species of forest grassland,Potentilla tanacetifolia,Lespedeza daurica,and Festuca elata,as the research materials.A plant carried out four nitrogen gradients(0,10,20,40 kg N hm-2yr-1)and three phosphorus gradients(4,6,8 kg P hm-2yr-1)and their interaction test treatment(12 in total)The treatment,4 replicates per treatment),studied the characteristics and stoichiometry of nitrogen and phosphorus uptake by three plants.Experimental results show:1.The effect of N addition on the increase of N content in the three plants was not obvious,but the addition of P increased the N content.This may be due to the addition of P to limit the uptake of N by the aboveground parts of the plant or to allow more transfer of N to the roots of the plant.At the same time,the effect of P addition on the increase of plant P content was not obvious,but the effect of N addition on plant P content was significant.2.The effects of nitrogen and phosphorus on the N content in Potentilla and Tall Fescue were not significant,and the N content in the soil of S.chinensis was significantly increased,and the N content increased with the increase of P content.3.In this experiment,the P content of the three plant soils decreased significantly under the N20 and N40 N gradients.Comparing the aboveground P content of the plants,it was found that the P20 absorption and transformation efficiency were greatly improved in the N20 and N40 gradient plants.,resulting in a decrease in the P content in the soil.4.The addition of N and P resulted in a significant increase in the ammoniation rate of Potentilla chinensis and Xing’an Lespede,and the rate of ammoniation in tall fescue soil decreased.At the same time,the soil nitrification rate of S.chinensis and Tall Fescue was high N(There is a significant improvement under N40)treatment.