模拟氮沉降对典型阔叶红松林土壤有机碳和养分的影响

Response of Soil Organic Carbon and Nutrients to Simulated Nitrogen Deposition in Typical Mixed Broadleaved-Korean Pine Forest

为探讨氮沉降对典型阔叶红松（Pinus koraiensis）林的影响，从2008年6月－2010年8月进行了人工模拟氮沉降实验，实验分为对照、低N、中N、高N4个处理，每个处理3个重复。所施氮肥为CO（NH，）。以溶液的形式喷施，4个处理浓度分别为0、30、60、120kg·hm^-2·a^-1。在氮沉降进行1年后，采集各处理0～20、20～40和40～60em的土壤样品，测定其土壤有机C、全N、碱解N和速效P、速效K。结果表明：相同处理下，有机C和全N含量随土层的加深均逐渐减少。总体上低、中N处理显著增加了土壤有机C、碱解N和速效K含量，中、高N处理显著降低了土壤速效P含量（P〈0．05），而对全N含量影响不显著（P〉0．05）。土壤有机C与土壤全N、碱解N、速效P、速效K之间存在极显著正相关关系（P〈0．001）。有机C和土壤养分对氮沉降的响应说明氮沉降在短期内可能影响阔叶红松林土壤碳库积累和土壤肥力水平。

In order to determine the effects of increased nitrogen deposition on soil organic carbon and nutrients in mixed broadleaved-Korean pine forest in Xiaoxing＇ an Mountains, China, a simulated nitrogen deposition field experiment was conducted from June 2008 to August 2010. Four nitrogen treatments （ control, low, medium and high nitrogen） used CO（NH2）2 solution of 0, 30, 60 and 120 kg ·hm^-2·a^-1. We collected 0 -20, 20 -40, 40 - 60 cm soil samples and measured soil organic carbon （ SOC ）, total nitrogen （ TN）, alkali-hydrolyzable N （HN）, available phosphorus （AP） and available potassium （AK） in June and October, 2009 and 2010. For two years experiments, we found that SOC and TN contents decreased with the increase of soil depth. Low and medium nitrogen treatments significantly increased SOC, HN and AK contents （P 〈 0.05）. While, medium, high nitrogen treatments significantly reduced AP content （ P 〈 0.05 ）, and there was no significant changes of the TN before and after simulated nitrogen deposition field experiment （ P 〉 0.05 ）. Regression analysis showed that significant positive associations were found between the SOC and TN, HN, AP, AK （P 〈 0. 001 ）. The study suggests that continuous nitrogen deposition may increase the soil organic carbon pool and soil fertility in the mixed broadleaved-Korean pine forest ecosystem.