氮添加对华西雨屏区常绿阔叶林土壤团聚体稳定性及养分含量的影响
Effects of nitrogen addition on soil aggregate stability and nutrient contents in an evergreen broad-leaved forest in the Rainy Area of Western China
[目的]大气氮沉降显著影响了森林生态系统的土壤养分循环。土壤团聚体是森林土壤最具代表性的基本结构单元，对保护和稳定储存土壤养分具有重要意义。然而，氮沉降对森林土壤团聚体稳定性及养分含量的影响还不明确。[方法]基于此，在华西雨屏区常绿阔叶林中进行了为期 5年的野外氮添加试验，设置了对照(CK，0 kg hm-2 a-1)、低氮添加(LN，50 kg hm-2 a-1)和高氮添加(HN，100 kg hm-2 a-1)3个处理，测定了4种粒级土壤团聚体(˃ 5 mm、2-5 mm、0.25-2 mm和＜0.25 mm)的平均重量直径(MWD)、几何平均直径(GMD)、分形维数(D)以及团聚体中有机碳(SOC)、全氮(TN)、铵态氮(NH4+-N)、硝态氮(NO3--N)、全磷(TP)和有效磷(AP)含量。[结果]N添加显著提高了 ˃ 5 mm土壤团聚体质量占比，且HN处理的促进作用更明显;N添加显著增加了土壤团聚体MWD和GMD，增幅分别介于 1 6%-20%和 18%-27%之间，显著促进了小粒级土壤团聚体向大粒级土壤团聚体的转化;HN添加显著提高了土壤团聚体内SOC含量，增幅介于 26.7%-47.9%之间;N添加显著提高了土壤团聚体内TN和NO3--N含量，增幅分别介于 8.4%-46.4%和 36.0%-102.4%之间，显著降低了土壤团聚体内TP含量;N添加显著提高了土壤团聚体C/P和N/P。[结论]N添加提高了华西雨屏区常绿阔叶林土壤团聚体的稳定性和固碳能力，加剧了土壤磷限制。
[Objectives]Atmospheric nitrogen deposition significantly affects soil nutrient cycling in forest ecosystems.Soil aggregates are the most representative basic structural units of forest soils,which are of great significance for the protection and stable storage of soil nutrients.However,the effects of nitrogen(N)deposition on the stability and nutrient contents of forest soil aggregates are still unclear.[Methods]Based on this,a 5-year field N addition experiment was executed in an evergreen broad-leaved forest in the Rainy Area of Western China.Three treatments were set as follows:control(CK,0 kg hm-2 a-1),low N addition(LN,50 kg hm-2 a-1),and high N addition(HN,100 kg hm-2 a-1).The mean weight diameter(MWD),geometric mean diameter(GMD),fractal dimension(D)and the contents of soil organic carbon(SOC),total N(TN),ammonium nitrogen(NH4+-N),nitrate nitrogen(NO3--N),total phosphorus(TP)and available phosphorus(AP)of four soil aggregates grain size(˃ 5 mm,2-5 mm,0.25-2 mm,and＜0.25 mm)were determined.[Results]The results showed that N addition significantly enhanced the quality of the soil aggregate ˃ 5 mm proportion,and the enhancement in HN was stronger than that in LN treatment.N addition significantly increased the soil aggregates MWD and GMD by 16%-20%and 18%-27%,respectively.N addition significantly facilitated the transformation of small-grained soil aggregates to large-grained soil aggregates.HN addition significantly increased the contents of SOC in soil aggregates by 26.7%-47.9%.N addition significantly increased the contents of TN and NO3--N in soil aggregates by 8.4%-46.4%and 36.0%-102.4%,respectively,with significantly decreasing TP contents in soil aggregates.N addition significantly increased soil aggregate C/P and N/P.[Conclusions]The above results indicated that N addition can improve the stability of soil aggregates and enhance the C pool in soil aggregates while aggravating the soil P limitation in this evergreen broad-leaved forest in the Rain Area of Western China.
司澳;肖永翔;陈俊;杜美霖;胡峻嶍;邹星丞;万仁平;蒋明朱;李哲;周世兴;黄从德;
四川农业大学林学院 成都 611130;四川省林业和草原调查规划院 成都 610081;四川农业大学林学院 成都 611130;四川农业大学林学院 成都 611130;四川农业大学林学院 成都 611130;四川农业大学林学院 成都 611130;四川农业大学林学院 成都 611130;四川农业大学林学院 成都 611130;四川农业大学林学院 成都 611130;四川农业大学林学院 成都 611130;四川农业大学林学院 成都 611130;
Q958.15;S154.5
N addition soil aggregate evergreen broad-leaved forest soil nutrients aggregate stability
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