外源性氮和磷添加对藜蒴林土壤养分及生化特性的影响

目前全球性的氮沉降和施磷肥不断增加对森林土壤产生重要影响。藜蒴(Castanopsis fissa)是我国南方重要的用材树种之一,研究外源性氮和磷对藜蒴林土壤养分和生化特性的影响,可以为藜蒴人工林的可持续经营提供理论指导。针对广东省云勇林场一片立地条件相似的14年生黎蒴人工林进行为期2年的模拟氮和磷沉降,设置不施肥(对照)、施N肥、施P肥、施N+P肥4种处理,对应的氮和磷施用量分别为0,200 kg N,80 kg P and200 kg N+80 kg P(hm-2·a-1),每种处理有8个重复。结果表明,加N减少了土壤全P、全K和速效K含量,增加了土壤碱解N含量;加P提高了土壤有机质、全N、全P、速效P和速效K含量,减少了土壤全K含量;加N+P提高了土壤有机质、全N、全P、碱解N和速效P含量,减少了土壤全K含量。加N、加P和加N+P处理增加了土壤细菌、真菌数量及磷酸酶和过氧化氢酶活性。加P处理还增加了土壤放线菌数量及土壤脲酶活性,加N+P处理也提高了脲酶活性。

Effects of N and P addition on soil nutrient and biochemical characteristics in a Castanopsis fissa plantation

An ever-increasing of atmospheric N deposition and P fertilization in the world significantly affect forest soils. Castanopsis fissa is one of the important timber species in southern China. Elucidation of the effects of N and P addition on C. fissa plantation ecosystems can provide theoretical guidance for the sustainable management of C. fissa plantations. In this paper, a field experiment was conducted to investigate the response of forest ecosystem to the increased N and P deposition in a 14-year-old Castanopsis fissa plantation in Yunyong Forest Farm, Guangdong province. Treatments included CK, N, P, and N+ P addition groups at doses of 0, 200 kg N, 80 kg P and 200 kg N+80 kg P (hm^-2·a^-1), respectively, with eight replicates per treatment. The results indicated that N addition decreased the total P, total K and effective K and increased the alkalized N in the soil. Addition of P increased soil organic matter, total N, total P, effective P, and effective K and decreased total K. Addition of N+P increased soil organic matter, total N, total P, alkalized N, and effective P and decreased total K. Addition of N, P, and N+P increased the number of soil bacteria and fungi and the activities of soil urease and acid phosphatase. Moreover, addition of P increased the number of soil actinomycetes and urease activity and addition of N+P also increased soil urease activity.