间伐和凋落物处理对华北落叶松人工林土壤磷形态的影响

Effects of thinning and litter manipulation on soil phosphorus dynamicsin a Larixprincipis-rupprechtii plantation

土壤磷在维持生态系统功能稳定性中发挥重要作用,研究间伐和凋落物处理下的土壤磷组分特征及转化机理,对森林生态系统磷素管理和可持续发展具有重要意义。采用Tiessen改良的Hedley分级方法,探究了不同间伐强度(未间伐、轻度间伐、中度间伐、重度间伐)和凋落物处理(对照、加倍、去凋、切根去凋)下土壤磷形态的变化特征及其驱动因子。结果显示:随着间伐强度的增大,土壤活性磷(Resin Pi、NaHCO3 Pi和NaHCO3 Po)、土壤微生物量磷和酸性磷酸酶活性呈先增加后降低的趋势,且在中度间伐最高。凋落物加倍(DL)显著增加了土壤活性磷(Resin Pi、NaHCO3 Pi和NaHCO3 Po)、土壤微生物量磷和酸性磷酸酶活性。稳定态磷(HCl Pi、浓HCl Pi和浓HCl Po)、残留态磷(Residual P)不受间伐和凋落物处理的影响。冗余分析(RDA)显示,土壤微生物量磷、酸性磷酸酶活性和土壤有机碳是引起华北落叶松人工林表层土壤磷组分变化的重要因子。研究表明,适度的间伐和增加凋落物能够显著提高华北落叶松人工林表层土壤磷素的活化能力。本研究为华北落叶松人工林的可持续经营提供依据。

Soil phosphorus(P)plays an important role in maintaining the stability of ecosystem functions.Understanding the effects of forest management practices(e.g.,thinning)on soil phosphorus fractions is important for soil phosphorus management for sustainable development in forest ecosystems.In this paper,a modified Hedley phosphorus fractionation method was used to sequentially extract soil samples and investigate the characteristics of soil phosphorus fractions with different thinning intensities(control,T0;Low thinning,T15;Moderate thinning,T35;Heavy thinning,T50)and litter manipulation(control,CK;exclusion litter,NL;addition litter,DL;exclusion litter and roots,NRL)in a Larixprincipis rupprechtii plantation and addressed its determining factors.The results showed that soil labile phosphorus(Resin Pi,NaHCO3 Pi and NaHCO3 Po),soil microbial biomass phosphorus,and acid phosphatase activity increased first and then decreased with the increase of thinning intensity,and the maximum appeared in T35.DL treatment significantly increased soil labile phosphorus(Resin Pi,NaHCO3 Pi and NaHCO3 Po),soil microbial biomass phosphorus,and acid phosphatase activity.No labile phosphorus(HCl Pi,concentrated HCl Pi and concentrated HCl Po)and residual phosphorus(Residual P)were not affected by thinning or litter treatments.The redundancy analysis(RDA)indicated that the changes in phosphorus fractions were mainly driven by soil microbial biomass phosphorus,acid phosphatase activity,andsoil organic carbon in the surface soil of the Larixprincipis rupprechtii plantation.The results suggested that moderate thinning and increased litter could significantly improve the activation of phosphorus in the surface soil of the Larixprincipis rupprechtii plantation.