近自然化改造对马尾松人工林土壤团聚体有机磷组分含量变化的影响

Effects of close-to-nature transformation on content of soil organic phosphorus fractions in soil aggregates of Pinus massoniana plantations

关键词:  马尾松人工林, 土壤团聚体, 有机磷组分, 近自然化改造, 亚热带

Key words:  Pinus massoniana plantations, soil aggregates, organic phosphorus fractions, close-to-nature transformation, subtropics

摘要:

有机磷(Po)是土壤磷库的重要组成部分。为探究马尾松人工林近自然化改造对土壤团聚体Po分布特征的影响,该研究以南亚热带的马尾松纯林(PP)和近自然化改造后的马尾松-阔叶树种混交林(CP)为对象,采集0～10 cm土样后利用干筛法将其筛分为>2 mm、0.25～2 mm和<0.25 mm三部分粒径团聚体,并测定原土及各粒径团聚体中各Po组分、微生物生物量磷(MBP)含量和酸性磷酸酶(ACP)活性。结果表明:(1)CP的土壤Po组分与PP相比发生了变化,高稳定性有机磷(HRO-P)和中度活性有机磷(MLO-P)在原土以及各团聚体径级中均显著高于PP(P<0.05),而活性有机磷(LO-P)和中度稳定性有机磷(MRO-P)在CP和PP中并无显著差异,PP和CP各组分Po在原土和各团聚体径级中无明显变化规律。(2)各形态Po在PP中占比大小为HRO-P>MRO-P>MLO-P>LO-P,而在CP中为HRO-P>MLO-P>MRO-P>LO-P。(3)CP中的MBP含量和ACP活性在原土及各团聚体径级中均显著高于PP,并且随着团聚体径级的减小,ACP活性上升。(4)冗余分析发现,土壤有效磷(AP)、土壤团聚体平均重量直径(MWD)、MBP和全氮(TN)为土壤Po组分的主要驱动因子。综上认为,近自然化改造有利于马尾松人工林土壤中磷的积累与转化,该研究结果为马尾松人工林土壤质量和生产力的提升提供了理论依据。

Abstract:

Organic phosphorus(Po)is an important part of soil phosphorus reservoir. In order to investigate the effects of soil aggregate Po distribution properties in Pinus massoniana plantations after close-to-nature transformation, the pure P. massoniana plantations(PP)and P. massoniana-broad-leaved mixed plantations(CP)after close-to-nature transformation were investigated in southern subtropical China. Soil samples collected from 1-10 cm were screened into >2 mm, 0.25-2 mm and <0.25 mm three-part aggregates using the dry-sieving method. The Po fraction, microbial biomass phosphorus(MBP)content and acid phosphatase(ACP)activity in the bulk soil and aggregates were measured to understand the distribution of the Po fraction and its drivers. The results were as follows:(1)Soil Po fractions changed in CP compared to PP, with highly recalcitrant organic phosphorus(HRO-P)and moderately labile organic phosphorus(MLO-P)significantly greater in the bulk soil and soil aggregates than in PP(P<0.05), while labile organic phosphorus(LO-P)and moderately recalcitrant organic phosphorus(MRO-P)were not significantly different in CP and PP. In addition, there was no consistent pattern of change in Po fractions in the bulk soil and soil aggregates between PP and CP.(2)The size of the proportion of each form of Po in PP was HRO-P>MRO-P>MLO-P>LO-P, while CP was HRO-P>MLO-P>MRO-P>LO-P.(3)The MBP content and ACP activity in CP were significantly greater than that of PP in the bulk soil and soil aggregates, and there was a tendency for the ACP activity to increase with the decrease in the size of aggregates.(4)Redundancy analysis revealed that soil available phosphorus(AP), soil aggregate mean weight diameter(MWD), MBP and total nitrogen(TN)were the main drivers of soil Po fractions. In conclusion, the close-to-nature transformation is beneficial to the accumulation and transformation of soil phosphorus in P. massoniana plantation. This study provides a theoretical reference for the improvement of soil quality and productivity in P. massoniana plantations.