不同林龄无瓣海桑人工林土壤生态化学计量特征

Characterization of Soil Ecological Stoichiometry in Plantation Forests of Different Stand Ages of Sonneratia apetala

为探究不同林龄无瓣海桑林土壤养分及其生态化学计量特征变化,通过测定10,15,22 a共3个林龄无瓣海桑林0~30 cm土层土壤的pH值、含盐量(TDS)、有机碳(SOC)、全氮(TN)、碱解氮(AN)、全磷(TP)、有效磷(AP)、全钾(TK)和速效钾(AK)含量,计算化学计量比,并分析各指标间的相关性。结果表明:1)造林后,土壤pH值表现为先上升后下降,土壤养分明显增加,土壤SOC,TN含量高于全国土壤平均水平,TP含量略低于全国土壤平均水平;2)不同林龄土壤理化性质及生态化学计量比均存在显著差异,随林龄的增加,土壤pH值先增加后降低,SOC,TN,AN,TP和AK含量先降低后增加,TK和AP变化不明显;3)无瓣海桑林的生长发育可能受到氮(N)的限制,尤其是林龄幼中期影响较大。无瓣海桑人工林对红树林湿地土壤养分的恢复具有明显的调节作用。

To investigate the changes in soil physicochemical properties and its ecological stoichiometric characteristics in different stand ages,the contents of pH,total dissolved salt(TDS),organic carbon(SOC),total nitrogen(TN),available nitrogen(AN),total phosphorus(TP),available phosphorus(AP),total potassium(TK),and available potassium(AK)of the 0~30 cm soil layer of three stand ages of 10,15,and 22 a were measured,the stoichiometric ratios were calculated,and the correlation between each index was analyzed.The results showed that:1)After afforestation,soil pH showed a decrease followed by an increase and then a decrease,soil nutrients increased significantly,SOC and TN were higher than the national soil average,and TP was slightly lower than the national soil average,indicating that the soil C and N content in the study area was relatively high;2)there were significant differences in soil physicochemical properties and ecological stoichiometric ratios among different stand ages;with the increase of stand age,soil pH increased and then decreased,SOC,TN,AN,TP and AK contents decreased and then increased,and the changes of TK and AP were not obvious;3)The growth and development of Sonneratia apetala forest may be limited by N,especially in the period of young and middle stand age.The plantation of Sonneratia apetala forest had a significant regulatory effect on the restoration of soil nutrients in mangrove wetlands.