不同海岸梯度下木麻黄防护林生态化学计量特征

摘要

以海坛岛沿海防护林主要树种木麻黄(Casuarina equisetifolia)为研究对象,对不同海岸梯度下木麻黄土壤与小枝C、N、P含量及其生态化学计量特征进行分析,结果表明: (1)木麻黄土壤全C、全N含量,N/P、C/P离海岸越远值越高,全P、C/N相对稳定;小枝的全N、全P整体呈现随海岸距离的增加含量减小的递变规律,全C呈现"V"字型变化趋势,在梯度4达到最小值,C/N、N/P、C/P比值整体从梯度1到梯度6呈现上升趋势. (2)木麻黄内稳性指数HC(90.91)>HN(19.61)>HC/N(10.31)>HN/P(3.91)>HC/P(3.77)>HP(3.33),即内稳性C>N>C/N>N/P>C/P>P;(3)土壤N/P、C/P与pH值、全盐存在极显著的负相关关系(P<0.01),与土壤容重没有相关性(P>0.05),C/N与土壤容重呈显著负相关关系(P<0.05),pH值、全盐、土壤容重是生态化学计量的主要影响因子;磷是限制木麻黄生长的营养元素.%Changes in the element stoichiometry characteristics of Casuarina equisetifolia branchlets and soil across a coastal gradient were studied at Haitan Island Shelter Forest.Results show that:(1)Total carbon, total nitrogen,N/P ratios,C/P ratios but total phosphorus and C/N ratios in soil and C/N ratios,N/P ratios,C/P ratios of branchlets were more and more higher across a coastal gradient, but branchlets of total N, total P and its stoichiometric ratios have the opposite response;branchlets of total C increased after slightly decreasing likes "V",and the minimum value in the gradient 4.(2)The stoichiometric homeostasis of branchlets HC(90.91)>HN(19.61)>HC/N(10.31)>HN/P(3.91)>HC/P(3.77)>HP(3.33), strictlyhomeostatic C>N>C/N>N/P>C/P>P;(3)The correlation analysis indicated that soil N/P,C/P were negatively correlated with pH and salinity significantly (P<0.01),while no correlation with soil bulk density(P>0.05),besides, significantly negative correlation between C/N and soil bulk density(P<0.05),so the main factors that pH, salinity, soil bulk density influence ecological stoichiometry;the significant linear relationships between total soil P content and branchlets P content to ensure that P was the limiting nutrient.