CAJ | 학술논문

大气氮沉降的增加对森林土壤的影响是近来生态学研究的重要课题。以鼎湖山季风常绿阔叶林（以下简称为“阔叶林”）、马尾松（Pinus massoniana）林、针阔叶混交林（以下简称为“混交林”）和增城木荷（Schima superba）人工幼林等4种林型土壤为研究对象，采用野外原位模拟大气氮沉降的方法，设置3种模拟氮沉降量，即N0（对照，N：0 g·m-2·a-1）、N5（N：5 g·m-2·a-1）、N10（N：10 g·m-2·a-1），在模拟氮沉降时间分别为42个月（阔叶林）、31个月（马尾松林）、50个月（混交林）、20个月（人工幼林）后，采集0~20 cm土层的林地土壤，分析土壤的化学性质，探讨不同氮沉降量对不同林型土壤化学性质的影响。结果表明，（1）模拟氮沉降对鼎湖山阔叶林、马尾松林、混交林土壤pH值的影响基本一致，均使pH值下降。其中，当氮沉降量达到N10时，阔叶林土壤pH值降为3.97，与对照相比下降了0.11 pH单位，差异达显著性水平（p<0.05）。而人工幼林土壤pH值未随着氮沉降量的不同而有明显的变化。（2）模拟氮沉降在近2年至4年的时间内，对阔叶林、混交林、人工幼林的土壤有机质、全氮、全磷、全钾、水解性氮、速效磷、速效钾含量的影响均不明显，马尾松林土壤有机质、全氮、全磷、速效磷、速效钾含量也没有明显变化，但模拟氮沉降导致了马尾松林土壤水解性氮含量明显下降，从95.12 mg·kg-1降至84.39 mg·kg-1，差异达显著性水平（p<0.05）。（3）模拟氮沉降对鼎湖山阔叶林、马尾松林、混交林等3种林型土壤盐基饱和度、盐基离子Ca2+、Mg2+、K+含量的影响未达显著水平，而对这3种林型土壤交换性Na+含量的影响则较明显且影响趋势基本一致，即氮沉降的增加导致了土壤交换性Na+含量明显下降。在N10处理下，与对照相比，这3种林型的土壤交换性Na+含量分别下降了40.0%、68.4%、50.0%，差异达显著性水平（p<0.05）。氮沉降对人工幼林土壤盐基离子含量无明显的影响。由此可得出结论：在近2年至4年的时间内，氮沉降的增加能引起鼎湖山3种林型土壤尤其是阔叶林土壤加速酸化，引起交换性Na+明显淋失，以及马尾松林土壤水解性氮含量明显下降；但氮沉降的增加对木荷人工幼林土壤化学性质暂无明显的影响。后者可能与该林型模拟氮沉降时间较短、林龄较轻而处于快速生长期等因素有关。大氣氮沉降的增加對森林土壤的影響是近來生態學研究的重要課題。以鼎湖山季風常綠闊葉林（以下簡稱為“闊葉林”）、馬尾鬆（Pinus massoniana）林、針闊葉混交林（以下簡稱為“混交林”）和增城木荷（Schima superba）人工幼林等4種林型土壤為研究對象，採用野外原位模擬大氣氮沉降的方法，設置3種模擬氮沉降量，即N0（對照，N：0 g·m-2·a-1）、N5（N：5 g·m-2·a-1）、N10（N：10 g·m-2·a-1），在模擬氮沉降時間分彆為42箇月（闊葉林）、31箇月（馬尾鬆林）、50箇月（混交林）、20箇月（人工幼林）後，採集0~20 cm土層的林地土壤，分析土壤的化學性質，探討不同氮沉降量對不同林型土壤化學性質的影響。結果錶明，（1）模擬氮沉降對鼎湖山闊葉林、馬尾鬆林、混交林土壤pH值的影響基本一緻，均使pH值下降。其中，噹氮沉降量達到N10時，闊葉林土壤pH值降為3.97，與對照相比下降瞭0.11 pH單位，差異達顯著性水平（p<0.05）。而人工幼林土壤pH值未隨著氮沉降量的不同而有明顯的變化。（2）模擬氮沉降在近2年至4年的時間內，對闊葉林、混交林、人工幼林的土壤有機質、全氮、全燐、全鉀、水解性氮、速效燐、速效鉀含量的影響均不明顯，馬尾鬆林土壤有機質、全氮、全燐、速效燐、速效鉀含量也沒有明顯變化，但模擬氮沉降導緻瞭馬尾鬆林土壤水解性氮含量明顯下降，從95.12 mg·kg-1降至84.39 mg·kg-1，差異達顯著性水平（p<0.05）。（3）模擬氮沉降對鼎湖山闊葉林、馬尾鬆林、混交林等3種林型土壤鹽基飽和度、鹽基離子Ca2+、Mg2+、K+含量的影響未達顯著水平，而對這3種林型土壤交換性Na+含量的影響則較明顯且影響趨勢基本一緻，即氮沉降的增加導緻瞭土壤交換性Na+含量明顯下降。在N10處理下，與對照相比，這3種林型的土壤交換性Na+含量分彆下降瞭40.0%、68.4%、50.0%，差異達顯著性水平（p<0.05）。氮沉降對人工幼林土壤鹽基離子含量無明顯的影響。由此可得齣結論：在近2年至4年的時間內，氮沉降的增加能引起鼎湖山3種林型土壤尤其是闊葉林土壤加速痠化，引起交換性Na+明顯淋失，以及馬尾鬆林土壤水解性氮含量明顯下降；但氮沉降的增加對木荷人工幼林土壤化學性質暫無明顯的影響。後者可能與該林型模擬氮沉降時間較短、林齡較輕而處于快速生長期等因素有關。
대기담침강적증가대삼림토양적영향시근래생태학연구적중요과제。이정호산계풍상록활협림（이하간칭위“활협림”）、마미송（Pinus massoniana）림、침활협혼교림（이하간칭위“혼교림”）화증성목하（Schima superba）인공유림등4충림형토양위연구대상，채용야외원위모의대기담침강적방법，설치3충모의담침강량，즉N0（대조，N：0 g·m-2·a-1）、N5（N：5 g·m-2·a-1）、N10（N：10 g·m-2·a-1），재모의담침강시간분별위42개월（활협림）、31개월（마미송림）、50개월（혼교림）、20개월（인공유림）후，채집0~20 cm토층적임지토양，분석토양적화학성질，탐토불동담침강량대불동림형토양화학성질적영향。결과표명，（1）모의담침강대정호산활협림、마미송림、혼교림토양pH치적영향기본일치，균사pH치하강。기중，당담침강량체도N10시，활협림토양pH치강위3.97，여대조상비하강료0.11 pH단위，차이체현저성수평（p<0.05）。이인공유림토양pH치미수착담침강량적불동이유명현적변화。（2）모의담침강재근2년지4년적시간내，대활협림、혼교림、인공유림적토양유궤질、전담、전린、전갑、수해성담、속효린、속효갑함량적영향균불명현，마미송림토양유궤질、전담、전린、속효린、속효갑함량야몰유명현변화，단모의담침강도치료마미송림토양수해성담함량명현하강，종95.12 mg·kg-1강지84.39 mg·kg-1，차이체현저성수평（p<0.05）。（3）모의담침강대정호산활협림、마미송림、혼교림등3충림형토양염기포화도、염기리자Ca2+、Mg2+、K+함량적영향미체현저수평，이대저3충림형토양교환성Na+함량적영향칙교명현차영향추세기본일치，즉담침강적증가도치료토양교환성Na+함량명현하강。재N10처리하，여대조상비，저3충림형적토양교환성Na+함량분별하강료40.0%、68.4%、50.0%，차이체현저성수평（p<0.05）。담침강대인공유림토양염기리자함량무명현적영향。유차가득출결론：재근2년지4년적시간내，담침강적증가능인기정호산3충림형토양우기시활협림토양가속산화，인기교환성Na+명현림실，이급마미송림토양수해성담함량명현하강；단담침강적증가대목하인공유림토양화학성질잠무명현적영향。후자가능여해림형모의담침강시간교단、림령교경이처우쾌속생장기등인소유관。
The effects of the increasing atmospheric nitrogen deposition on forest soils have become one of the major issues in ecological research recently. The authors used the method of simulating atmospheric nitrogen deposition in situ, set up three levels of nitrogen deposition:N0 (CK, N:0 g·m-2·a-1), N5(N:5 g·m-2·a-1), and N10(N:10 g·m-2·a-1)for a monsoon evergreen broad-leaved forest (called“broad-leaved forest”for short in the following), a Pinus massoniana forest, and a coniferous and broad-leaved mixed forest (called “mixed forest” for short in the following) in Dinghushan Mountain, and for a young Schima superba plantation in Zengcheng, Guangdong province, China, collected the soil samples of 0~20 cm soil layer after simulating atmospheric nitrogen deposition for 42 months (broad-leaved forest), 31 months (Pinus massoniana forest), 50 months (mixed forest), and 20 months (the young plantation), and analysed the soil properties, to discuss the effects of different nitrogen deposition levels on the soil properties of different forest types. The results showed that, (1) the simulated nitrogen deposition appeared the similar tendency towards the effects on soil pH values of the broad-leaved forest, Pinus massoniana forest, and mixed forest in Dinghushan Mountain, forcing the pH values to drop. Among them, when the nitrogen deposition was at N10 level, the soil pH value of the broad-leaved forest decreased to 3.97 by falling off 0.11 pH value unit compared with CK, and the difference reached significant level (p<0.05). But there was no evident change of pH value with the nitrogen deposition levels in the young plantation. (2) Within the nearly 2 years to 4 years, the simulated nitrogen deposition did not evidently affect the contents of soil organic matter, total nitrogen, total phosphorus, total potassium, hydrolysable nitrogen, rapidly available phosphorus and rapidly available potassium in the broad-leaved forest, mixed forest and young plantation, but led to a marked decrease in contents of soil hydrolysable nitrogen in Pinus massoniana forest, from 95.12 mg·kg-1 to 84.39 mg·kg-1, with a significance level of 0.05. (3) The effects of the simulated nitrogen deposition on soil base-saturation percentage, and contents of base-exchangeable ion Ca2+, Mg2+and K+in the broad-leaved forest, Pinus massoniana forest, and mixed forest in Dinghushan Mountain, were no significant difference, but the effects on contents of soil exchangeable ion Na+in these three forest types were evident and appeared the similar tends, i. e., the increase in nitrogen deposition brought about the evident decrease in contents of soil exchangeable ion Na+. At N10 level and compared with CK, contents of soil exchangeable ion Na+in these three forest types decreased by 40.0%, 68.4%and 50.0%, respectively, with a significance level of 0.05. There was no evident effect on contents of soil exchangeable ions in the young plantation under nitrogen deposition. It is concluded that within the nearly 2 years to 4 years, the increasing nitrogen deposition could lead to accelerating soil acidification and evident leaching of soil exchangeable ion Na+ in the three forest types in Dinghushan Mountain, and lead to evident decrease in the content of soil hydrolysable nitrogen in Pinus massoniana forest, but it could not evidently affect soil chemical properties of young Schima superba plantation. And the latter might be related to that there was less time for simulating nitrogen deposition in the plantation, and the plantation was at the stage of rapid growth, and so on.