Contents of Some Mineral Elements and Their Resorption Efficiencies in Casuarina equisetifolia Branchlets Across a Coastal Gradient

Abstract

对福建东山赤山林场不同海岸梯度上短枝木麻黄小枝中的钾(k)、钙(CA)、镁(Mg)、钠(nA)、铁(fE)、锰(Mn)和锌(zn)元素含量及其再吸收率动态进行了研究.结果表明,海岸梯度对短枝木麻黄小枝中各元素含量及其再吸收率均具有显著影响.在各海岸梯度上,k再吸收率为正值,且基干林带的再吸收率显著低于其它样地,fE和zn为负值,CA、Mg和nA再吸收率在防护林带前沿为负值,而在后沿林为正值,Mn则相反.这表明,基干林带严重的环境胁迫显著降低了短枝木麻黄小枝的养分再吸收率.短枝木麻黄成熟小枝中的k、Mg含量与其再吸收率存在显著正相关,而nA和fE与其再吸收率存在显著负相关,其它元素与其再吸收率之间没有显著相关性.除k外,各元素在衰老小枝中的含量与相应元素再吸收率之间均存在显著负相关,表明元素再吸收程度越高,其再吸收率就越高.CA、Mg、nA和fE再吸收率之间具有显著的正相关关系(P<0.01),zn除与Mn再吸收率呈显著正相关外,与其它元素均表现为负相关,Mn则与其它元素再吸收率之间没有显著相关性.因而短枝木麻黄小枝中不同类型的养分状况对其再吸收率具有不同的影响.表5参42Contents of some mineral elements and their resorption efficiencies in Casuarina equisetifolia branchlets across a coastal gradient were studied at the Chishan Forestry Center of Dongshan County,Fujian Province,China.The results showed that the distance to coast had a significant effect on the contents of mineral elements and their resorption efficiencies.Resorption efficiencies of K element(REK) were all positive across the coastal gradient,with the lowest value found at the coastline sampling site,while Fe and Zn resorption efficiencies(REFe and REZn) were all negative across the coastal gradient.Ca,Mg and Na resorption efficiencies(RECa,REMg and RENa),which were contrary to Mn(REMn),were negative in seaward plantations and positive in inland plantations.It was suggested that the resorption efficiencies of the mineral nutrients significantly decreased with severer environmental stresses.There were also significant positive correlations between the K and Mg content and their resorption efficiencies in mature branchlets while the correlations between the Na and Fe content and their resorption efficiencies were significantly negative.In senescent branchlets,the content of all the elements and their resorption efficiencies except for K were negatively correlated.In addition,the correlation was positive between REZn and REMn,while negative between REZn and resorption efficiencies of other elements.No correlation was found between REMn and resorption efficiencies of other elements.These results showed that nutrient conditions in branchlets had different effects on their resoption efficiencies for different mineral nutrients.Tab 5,Ref 42国家“十一五”重大科技支撑计划项目(No.2009BADB2B0302)资助---