Retention of Nitrogen by a Nitrogen‐Loaded Scotch Pine Forest
Retention of Nitrogen by a Nitrogen‐Loaded Scotch Pine Forest
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DOI：
10.2136/sssaj1999.03615995006300020017x
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发表时间：
1999-03
影响因子：
2.9
通讯作者：
C. Johannisson;P. Högberg;D. Myrold
中科院分区：
文献类型：
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作者：
C. Johannisson;P. Högberg;D. Myrold
森林储存添加氮的能力以及这些多余的氮如何与其他营养物质相互作用尚不清楚。我们研究了苏格兰松（Pinus sylvestris L.）森林中氮的保留情况，该森林接受了20年以四种速率（N0-N3，相当于0、36、72和108 kg N /公顷-1年-1年）每年添加氮，并补充和不补充P和k。最高氮处理（N3）在本研究前3年暂停。在有和没有活树根的溶渗仪下测量无机氮的淋溶，并通过采样林下植被、20 cm深度土壤和渗滤液来追踪注入更多层的15n的去向。无机氮的淋溶随施氮量的增加而增加，且在施氮地块上以no3为主。悬浮N3处理的N浸出量低于N2处理。在添加了NH + 4标记的渗滤仪下，出现了标记的NO - 3，表明硝化作用在N2处理中很重要，但在N1处理中不重要，这表明需要添加bbb10 - 30 kg N / h -1年-1才能在该地点诱导更大的净硝化作用。我们的数据表明：(i)树木是一个重要的氮汇，（ii） P和K的添加对氮保持有边际的积极影响，（iii）当氮负荷被去除时，以前含氮的森林的淋滤迅速减少。
The capacity of forests to store added N and how this excess N might interact with other nutrients is not well understood. We studied N retention in a Scotch pine (Pinus sylvestris L.) forest that had received two decades of annual additions of N as NH 4 NO 3 at four rates (N0-N3, equivalent to 0, 36, 72 and 108 kg N ha -1 yr 1 ), with and without supplementary additions of P and K. The highest N treatment (N3) was suspended three years before this study. Leaching of inorganic N was measured beneath lysimeters with and without living tree roots inside them, and the fate of 15 N injected into the mor layer was traced by sampling understory vegetation, soil to 20-cm depth, and leachates. Leaching of inorganic N increased with increasing N dose and was dominated by NO 3 on plots to which N had been added. In the suspended N3 treatment, leaching of N was lower than in the N2 treatment. The presence of tree roots greatly reduced leaching of N. The occurrence of labeled NO - 3 under lysimeters to which labeled NH + 4 had been added showed that nitrification was important in treatment N2, but not in N1, suggesting that additions of >30 kg N ha -1 yr -1 are needed to induce larger net nitrification at this site. Our data showed (i) that trees were an important sink for N, (ii) that additions of P and K had a marginal positive effect on N retention, and (iii) that leaching from previously N-loaded forest rapidly decreased when the N load was removed.