中亚热带森林更新方式对土壤磷素的影响

为了深入了解磷(P)在中亚热带森林生态系统内的有效性,在三明市梅列区陈大采育场黄坑工区,选择天然林采伐后采取不同更新方式的多种森林,以米槠天然林为对照,研究森林不同更新方式对中亚热带森林土壤全磷、有效磷及可溶性有机磷的影响。结果显示:在0—100 cm土层,(1)土壤全磷平均含量大小顺序依次为米槠天然林(NF)(0.49±0.09)g/kg,米槠轻度干扰人促更新林(LAR)(0.35±0.04)g/kg,米槠强度干扰人促更新林(HAR)(0.34±0.03)g/kg,马尾松人工林(PIM)(0.32±0.02)g/kg,杉木人工林(CUL)(0.3±0.03)g/kg,人促更新林比人工林高,NF显著高于其它的林分(P0.05);(2)土壤有效磷(Na HCO3提取)平均含量大小顺序依次为NF(0.41±0.39)mg/kg,LAR(0.26±0.2)mg/kg,HAR(0.23±0.16)mg/kg,PIM(0.17±0.05)mg/kg,CUL(0.13±0.06)mg/kg,NF显著高于其它林分,LAR显著比人工林高(P0.05)。(3)在0—10 cm土层,各林分可溶性有机磷含量在夏季最高,冬季最低,温度和降水量的季节变化是影响其重要因子之一;同一季节,人促更新林比人工林高,NF显著高于人工林(P0.05)。结果表明,全磷、有效磷和可溶性有机磷含量随人为干扰强度的增强呈降低趋势,其与年凋落物量和土壤有机碳储量呈显著正相关,与土壤容重呈显著负相关,全磷和有效磷在土壤剖面呈表聚性特征。相比于人工林经营,采取人促天然更新的方式,更有利于中亚热带森林养分的贮存和转化,有利于森林的长期经营和管理。

Effect of forest regeneration on soil phosphorus in mid-subtropical area

To better understand the availability of phosphorus (P) in mid-subtropical forest ecosystems, various forests that originated from natural tree felling were selected in the Huangkeng work area of the Chenda state-owned forestry farm, and the effect of different regeneration patterns on soil total, available, and dissolved organic P were studied. The results indicated that, in the 0-100 cm soil layer, (1) Average soil total P content from highest to lowest was (0.49±0.09) g/kg in the Castanopsis carlesii forest (NF), (0.35±0.04) g/kg in the mild disturbance forest with natural regeneration (LAR), (0.34±0.03) g/kg in the intensive disturbance forest with natural regeneration (HAR), (0.32±0.02) g/kg in the Pinus massoniana plantation (PIM), and (0.3±0.03) g/kg in the Cunninghamia lancealata plantation. Natural regeneration forests had higher total P than plantations, and total P for NF was significantly higher than that of the plantations (P < 0.05). (2) Average soil available P content (NaHCO₃ extraction) from highest to lowest was (0.41±0.39) mg/kg for NF, (0.26±0.2) mg/kg for LAR, (0.23±0.16) mg/kg for HAR, (0.17±0.05) mg/kg for PIM, and (0.13±0.06) mg/kg for CUL. Available P of LAR was significantly higher than that of plantations (P < 0.05). (3) In the 0-10 cm soil layer, dissolved organic P content was highest in summer and lowest in winter for every forest type, which was probably caused by seasonal changes in temperature and precipitation. In the same season, dissolved organic P from NF was significantly higher than that of plantations (P < 0.05), and dissolved organic P is natural regeneration forests was higher than in plantations. Correlation analysis showed total P, available P, and dissolved organic P were significantly positively correlated with litterfall and soil organic carbon storage, but had a significant negative correlation with soil bulk density, and exhibited a declining trend with increasing human disturbance. Total P and available P in the soil profile exhibited characteristics of surface accumulation. Compared to plantation management, natural forest regeneration was more conducive to storage and transformation of nutrients, and for the long-term management of the mid-subtropical forests.