加勒比松林分改造对土壤化学性质和酶活性的影响

【目的】通过引入阔叶树种对加勒比松Pinus caribaea林进行林分改造,为科学经营加勒比松人工林提供科学依据。【方法】在一部分加勒比松林的株间和行间插种黎蒴Castanopsis fissa、大叶相思Acacia mangium、红桂木Artocarpus nitidus ssp.Lingnanensis和油茶Camellia oleifera(简称P1样地),在一部分加勒比松林的株间和行间插种荷木Schima superba、光叶山矾Symplocos lancifolia、竹节树Carallia brachiata和油茶(简称P2样地),同时,保留一块加勒比松林作为对照样地(CK)。在3个样地分别以五点取样法采集0~20和20~40 cm土层的土壤样品,用常规方法测定土壤的p H、有机质、全氮、全磷、全钾、碱解氮、速效磷和速效钾含量,分别用比色法、磷酸苯二钠比色法和高锰酸钾滴定法测定过氧化氢酶酶、磷酸酶及脲酶活性。【结果】3个样地0~20和20~40 cm土层的土壤有机质、全氮、土壤碱解氮和有效磷含量均为P2样地P1样地CK样地,0~20 cm土层的土壤养分含量均显著大于20~40 cm土层土壤;3个样地0~20 cm土层的土壤全磷含量均较低,全钾含量为CK样地P1样地P2样地;样地土壤的过氧化氢酶活性与p H及有机质、全氮、碱解氮、全钾和速效磷含量显著相关;磷酸酶活性与p H及有机质、全氮、碱解氮、速效磷和全钾含量显著相关;脲酶活性与土壤有机质、全氮、全磷、碱解氮、速效磷和速效钾含量显著相关。【结论】林分改造明显提高了森林的土壤肥力,且P2样地的树种组合模式优于P1样地,具有较好的土壤改造效果,可用于林分改造。

Impacts of stand transformation on soil chemical properties and enzyme activities in a Pinus caribaea stand

Objective Stand transformation was studied in a Pinus caribaea stand by introducing broad-leaved tree species to provide a scientific basis for rational management of P. caribaea stands.Method Castanopsis fissa, Acacia mangium, Artocarpus nitidus ssp. Lingnanensis and Camellia oleifera were planted among rows and lines of one part of the P. caribaea stand (P1), Schima superba, Symplocos lancifolia, Carallia brachiata and C. oleifera were planted among rows and lines of another part of the P. caribaea stand (P2), and one part of the remaining the P. caribaea stand was used as the control (CK). Five-point sampling method was used to collect soil samples from 0-20 and 20-40 cm depth soil layers respectively at three sample plots. Soil pH, organic matter, total nitrogen, total phosphorus, total potassium, alkalized nitrogen, avaiable phosphorus and avaiable potassium were determined by routine methods. Activities of catalase, phosphatase and urease were determined by colorimetry, disodium phenyl phosphate colorimetric method and titration with potassium permanganate, respectively.Result The contents of soil organic matter, total nitrogen, alkalized nitrogen and available phosphorus in 0-20 and 20-40 cm depth soil layers of three sample plots decreased in the order of P2, P1 and CK. The soil nutrient contents in 0-20 cm depth soil layers of the three sample plot was significantly higher than those in corresponding 20-40 cm depth soil layers. The total phosphorus contents were low in 0-20 cm depth soil layer of three sample plots, and the content of soil total potassium decreased in the order of CK, P1 and P2. Soil catalase activity was significantly related to pH and the contents of organic matter, total nitrogen, alkalized nitrogen, total potassium and alkalized phosphorus. Phosphatase activity was significantly related to pH and the contents of organic matter, total nitrogen, alkalized nitrogen, available phosphorus and total potassium. Urease activity was significantly related to soil contents of organic matter, total nitrogen, total phosphorus, alkalized nitrogen, avaiable phosphorus and avaiable potassium.Conclusion Stand transformation significantly improved the soil fertility of P. caribaea stand. The effect of mixed pattern at P2 plot was better than those at P1 plot. Mixed pattern at P2 plot can be used in stand transformation.