Resorption Patterns Of 10 Nutrient Elements In Leaves Of Woody Plants In Northern China

As a crucial mechanism of nutrient conservation,nutrient resorption helps maintain elemental balance in plant tissues.Perennial plants withdraw nutrients from senesced-leaves and shuttle them to seeds,roots and other live parts of plants,increasing the residence time of nutrients within plants and reducing the cost of absorbing nutrients from soil.This study aims to investigate resorption patterns of ten mineral nutrients[i.e.,nitrogen(N),phosphorus(P),potassium(K),magnesium(Mg),calcium(Ca),manganese(Mn),zinc(Zn),aluminium(Al),iron(Fe),and copper(Cu)]in leaves of 70 woody plants in north of China,including Greater Khingan,Lesser Khingan,Changbai Mountain,around Beijing,Hebei Saihanba,Taihang mountains,Yin mountains,Shannxi Ziwu mountain and ten sites in northern Xinjiang Uygur Autonomous Region(including Gurbantunggut Desert).As a crucial mechanism of nutrient conservation,nutrient resorption is affected by many factors,we try to explore effect of nutrient status(leaf nutrient and soil nutrient),plant life form,nutrient storage size and phylogeny,geography and climate(longtitude,latitude,altitude,MAP,MAT and aridity)on ten nutrients resorption efficiencies,and we also tried to explore nutrient resorption in community level.Based on this,we also gave synthetically discussion.The main conslusions in this study are as follows:1)The mean mass loss correction factor(MLCF)for conifers is 0.8983,and for deciduous broadleaf species is 0.8246.The mean nutrient resorption efficiencies(NuRE)varied greatly among ten mineral nutrients and followed the rank order that phosphorus resprption efficiency(PRE)(63.58%)>nitrogen resprption efficiency(NRE)(56.84)>potassium resprption efficiency(KRE)(50.73%)>copper resprption efficiency(CuRE)(35.95%)>magnesium resprption efficiency(MgRE)(18.54%)>zinc resprption efficiency(ZnRE)(-7.78%)>manganese resprption efficiency(MnRE)(-16.54%)>calcium resprption efficiency(CaRE)(-18.50)>iron resprption efficiency(FeRE)(-50.09%)>aluminum resprption efficiency(AIRE)(-61.0%).NuRE of all elements were positively correlated with concentrations of corresponding nutrients in green-leaves,and negatively correlated with concentrations in senesced-leaves.2)Concentrations in soil of most mineral nutrients(N,P,Mg,Mn,Zn and Fe)showed significantly positive correlations with concentrations of corresponding nutrients in green-and senesced-leaves.NuRE of N,P,K,Cu,Al,Fe were significantly negative correlated with concentrations of corresponding nutrients in soil,but MgRE and CaRE showed reverse trend.It shows the trade-off of plants between nutrient resorption and asorbing nutrient from soil,which means plants usually resorb less nutrient before leaves falling when soil is rich.3)NRE,KRE and CuRE were signifcantly higher in trees than in shrubs.MgRE,MnRE,CaRE and AIRE were significantly higher in shrubs.No signifcant difference in PRE was observed between trees and shrubs.NRE,PRE,KRE,CuRE and ZnRE were higher in conifers than in deciduous broadleaf species.NRE,PRE,KRE and CuRE of all species showed significantly positive correlations with height,diameter at breast height(DBH)and aboveground biomass,same with trees.However,shrubs had reverse trend.It may show that palnts with strong sink strength have higher nutrient resorption efficiency.4)Latitude and mean annual precipitation(MAP)had non-significant effect on most NuRE.Longitude had negative effect on most NuRE.Altitude and mean annual temperature(MAT)had significantly negative effect on NRE,PRE,KRE and CuRE,both for trees and ahrubs.NRE,PRE and KRE significantly decreased with aridity,while MgRE,MnRE,CaRE and ZnRE significantly increased with aridity when the degree of aridity(1-AI,AI was defined as the ratio of precipitation to potential evapotranspiration)higher than 0.5.We observed signifcant phylogenetic signals for Mg,Al and Fe concentrations in green-leaves,but non-signifcant phylogenetic signals for NuREof all mineral nutrients and their concentrations in senesced-leaves,suggesting that NuREs were not phylogenetically conservative,namely NuREs were not regulated by their evolutionary history in north of China.5)In community level,except Cu and Ca,the other NuREs had no significant difference with individual level.NuRE of most mineral nutrients had no significant correlation with nutrient status,neither geographic and climatic factors,and relations between NuREs and all factors are weaker than individual level.In summary,this study answered the effects of nutrient status,life forms and nutrient pool,geographic,climatic factors and phylogeny on nutrient resortion,and explored how repsorption works in community level in the north of China.Macroelemnts and Cu were resorbed during leaf senescence,Ca and other microelments tended to be accumulated in senesced leaves.Nutrient status had negative effect on nutrient resorption efficiency.Most NuREs were negatively realted with Longtitude,MAT;relations between NuREs and all factors are weaker than individual level.Considering all factors,we found nutrient staus had most contribution for NuREs.