亚热带米槠天然林凋落物和根系输入变化对土壤磷组分的影响

Effects of litter and root inputs changes on soil phosphorus fractions in a subtropical natural forest of Castanopsis carlesii

植物残体添加和去除试验(The Detritus Input and Removal Treatments,DIRT)是研究地上凋落物以及植物根系对土壤营养物质循环过程及机制探究的一种试验设计。于2012年6月选择福建省三明森林生态系统与全球变化研究站的米槠常绿阔叶天然林,设置5种处理:对照(CT)、去除凋落物(NL)、去除根系(NR)、去除凋落物与根系(NI)、添加双倍凋落物(DL),在2018年12月对各处理不同土层(0—10cm、10—20cm)土壤磷组分及其影响因子进行研究,结果表明:(1)在0—10cm土层中DL处理总磷含量显著大于NL处理,NI处理无机磷含量最低,在10—20cm中DL处理有机磷含量显著大于其他处理;(2)DL处理活性磷(Resin⁃P、NaHCO^(3)⁃Pi、NaHCO^(3)⁃Po)含量在0—10cm土层中显著大于其他处理。在10—20cm土层中NR处理活性磷以及中等活性磷显著大于NL处理。残留态磷(Residual⁃P)含量最高,但在各处理与土层之间并没有明显差异;(3)酸性磷酸酶在0—10 cm土层不同处理间的变化趋势明显,CT处理活性最高,NI处理活性最低。NR与NL处理在10—20cm土层的差异并不明显。冗余分析表明,土壤磷组分的变化主要受酸性磷酸酶、土壤含水率、可溶性有机氮以及总氮的影响。凋落物的输入对促进土壤磷素增加,改善土壤质量具有重要意义;植物根系则对土壤磷的活化与稳定具有关键作用。

The detritus input and removal treatment is an experimental design to study the effects of aboveground litter and plant roots on soil nutrient cycling process and mechanism.In June 2012,we set up five treatments,viz.control(CT),no litter(NL),no roots(NR),no input(NI),and double litter(DL),in a natural evergreen broad⁃leaved forest of Castanopsis carlesii in Sanming,Fujian Province.Soil phosphorus fractions and their influencing factors in different soil layers(0—10 cm and 10—20 cm)of each treatment were studied in December 2018.The results showed that:(1)in the 0—10 cm soil layer,the total phosphorus content in DL treatment was significantly higher than that in NL treatment.The inorganic phosphorus content in NI treatment was the lowest,The organic phosphorus content in DL treatment was significantly higher than other treatments in 10—20 cm soil layer;(2)The contents of easily⁃available phosphorus fractions(Resin⁃P,NaHCO^(3)⁃Pi,NaHCO^(3)⁃Po)in DL treatment were significantly higher than those in other treatments in 0—10 cm soil layer.In 10—20 cm soil layer,the easily⁃available phosphorus and moderately⁃available phosphorus in NR treatment were significantly higher than those in NL treatment.The content of residual⁃P was the highest,but there was no significant difference between the treatment and soil layer;(3)The change trend of acid phosphatase in 0—10 cm soil layer was obvious among different treatments.CT treatment had the highest activity and NI treatment had the lowest activity.The difference between NR and NL treatments was not obvious in 10—20 cm soil layer.Redundancy analysis showed that the changes of soil phosphorus fractions were mainly affected by acid phosphatase,soil moisture content,dissolved organic nitrogen,and total nitrogen.Adding litter could mineralize organic phosphorus by increasing soil microbial biomass and enhancing soil acid phosphatase activity,promote the transformation of soil organic phosphorus to inorganic phosphorus,and improve the availability of soil phosphorus.However,root system could absorb soil active phosphorus and mineralize other phosphorus fractions.It had positive significance to improve the structure of P in soil.