氮磷添加对黄土丘陵区撂荒草地优势植物功能性状的影响

Effects of Nitrogen and Phosphorus Addition on Functional Traits of Dominant Plant Species in Abandoned Grasslands of Loess Hilly Region

在陕北黄土丘陵区开展野外撂荒草地氮、磷添加控制试验,并选取3种典型优势种铁杆蒿(Artemisia sacrorum)、达乌里胡枝子(Lespedeza davurica)和芦苇(Phragmites australis)为研究对象,探讨不同优势种的功能性状和土壤理化性质在短期氮、磷添加处理下的响应规律,并探讨其与土壤养分的关系。结果表明:磷添加总体上促进了达乌里胡枝子和铁杆蒿对磷元素的吸收,并导致叶片氮磷比下降,但芦苇叶片磷含量变化不显著;达乌里胡枝子比叶面积在氮添加后表现为增加的趋势,芦苇和铁杆蒿表现为降低的趋势;氮添加使达乌里胡枝子茎叶比下降,而芦苇和铁杆蒿茎叶比增加。芦苇和铁杆蒿功能性状指标可塑性指数在氮添加下更高,而达乌里胡枝子则在磷添加下更高,且在不同处理下达乌里胡枝子功能性状可塑性指数均高于芦苇和铁杆蒿。氮、磷添加后土壤养分的变化对植物功能性状变化的解释率均高于50%;氮、磷添加处理下达乌里胡枝子比叶面积、茎叶比等性状受土壤全磷、速效磷等指标影响较大;而芦苇和铁杆蒿的功能性状整体上与氮相关的指标相关性更高。以上结果表明,不同优势种由于自身的遗传特性、环境耐受性不同,故其功能性状对氮、磷添加的响应具有差异。

The objective of this study was to investigate the effects of short-term nitrogen and phosphorus addition on functional traits of three dominant plant species(Artemisia sacrorum,Lespedeza davurica and Phragmites australis)and soil physicochemical properties,as well as to examine the potential correlations between them in abandoned grasslands located in the Loess Hilly Region of northern Shaanxi Province.The results showed that phosphorus addition promoted the absorption of phosphorus in L.davurica and A.sacrorum,resulting in a reduction of the leaf nitrogen phosphorus ratio.However,the change in phosphorus content of Ph.australis was not statistically significant.There was an observed increase in the specific leaf area(SLA)of L.davurica after nitrogen addition,whereas the SLA of Ph.australis and A.sacrorum demonstrated a decreasing trend.The addition of nitrogen also resulted in a decrease in the stem leaf ratio(S/L)of L.davurica,while causing an increase in the S/L of A.sacrorum and Ph.australis.The plasticity index of functional traits was higher in Ph.australis and A.sacrorum under nitrogen addition,while L.davurica exhibited higher plasticity index under phosphorus addition.Additionally,the plasticity index of functional traits of L.davurica was found to be higher than that of observed in Ph.australis and A.sacrorum.Changes in soil nutrient levels after nitrogen and phosphorus addition explained over 50%of the variation in plant functional traits.The SLA and S/L of L.davurica were found to be greatly affected by soil total phosphorus and available phosphorus levels under the nitrogen and phosphorus addition treatments.While the functional traits of Ph.australis and A.sacrorum were more correlated with soil nitrogen-related indices.In conclusion,different dominant plant species differed in their functional traits in response to nitrogen and phosphorus addition due to their unique genetic characteristics and environmental tolerances.