Vázquez de Aldana B R, Geerts R H E M, Berendse F
Research Institute for Agrobiology and Soil Fertility, AB-DLO, P.O. Box 14, NL-6700 AA, Wageningen, The Netherlands.
Department of Terrestrial Ecology and Nature Conservation, Wageningen Agricultural University, Bornsesteeg 69, NL-6708 PD, Wageningen, The Netherlands.
Oecologia. 1996 Apr;106(2):137-143. doi: 10.1007/BF00328592.
Nitrogen losses from plants may occur through a variety of pathways, but so far, most studies have only quantified losses of nutrients by above-ground litter production. We used N pulse labelling to quantify total nitrogen losses from above- and below-ground plant parts. Using this method we were able to include also pathways other than above-ground litter production. To test the hypothesis that species from nutrient-poor habitats lose less nitrogen than species from more fertile soils, six perennial grasses from habitats with a wide range of nutrient availability were investigated: Lolium perenne, Arrhenatherum elatius, Anthoxanthum odoratum, Festuca rubra, F. ovina and Molinia caerulea. The results of an experiment carried out in pots in a green-house at two fertility levels show that statistically significant losses occur through pathways other than above-ground litter production. In the low fertility treatment, most (70%) losses from L. perenne occurred by litter production, but in Ar. elatius, F. rubra, F. ovina and M. caerulea, more than 50% of labelled N losses took place by root turn-over, leaching or exudation from roots. When nutrient supply increased, the N losses in above-ground dead material increased in all species and in Ar. elatius, A. odoratum and F. rubra the N losses via other pathways decreased. Ranked according to decreasing turnover coefficient the sequence of species was: L. perenne, A. odoratum, F. rubra, F. ovina, Ar. elatius, M. caerulea. These results suggest that species adapted to sites with low availability of nutrients lose less nitrogen (including above- and below-ground losses) than species adapted to more fertile soils.
植物的氮素损失可能通过多种途径发生，但到目前为止，大多数研究仅通过地上凋落物产量来量化养分损失。我们使用氮脉冲标记法来量化地上和地下植物部分的总氮损失。通过这种方法，我们还能够纳入除地上凋落物产量之外的其他途径。为了检验来自养分贫瘠生境的物种比来自更肥沃土壤的物种损失更少氮素这一假设，我们研究了来自养分可利用性范围广泛的生境的六种多年生禾本科植物：黑麦草、燕麦草、黄花茅、紫羊茅、羊茅和天蓝沼湿草。在温室中以两种肥力水平在花盆中进行的实验结果表明，除地上凋落物产量之外的其他途径也会发生具有统计学意义的损失。在低肥力处理中，黑麦草的大部分（70%）损失是通过凋落物产生的，但在燕麦草、紫羊茅、羊茅和天蓝沼湿草中，超过50%的标记氮损失是通过根系周转、淋溶或根系渗出发生的。当养分供应增加时，所有物种地上死亡物质中的氮损失都增加了，而在燕麦草、黄花茅和紫羊茅中，通过其他途径的氮损失减少了。按照周转系数递减排序，物种顺序为：黑麦草、黄花茅、紫羊茅、羊茅、燕麦草、天蓝沼湿草。这些结果表明，适应养分可利用性低的生境的物种比适应更肥沃土壤的物种损失的氮素（包括地上和地下损失）更少。
