Topographic Influence on Plant Nitrogen and Phosphorus Stoichiometry in a Temperate Forested Watershed
Topographic Influence on Plant Nitrogen and Phosphorus Stoichiometry in a Temperate Forested Watershed
复制标题
DOI：
10.1007/s11270-015-2701-2
复制
发表时间：
2015
期刊：
影响因子：
--
通讯作者：
M. Chiwa;S. Ikezaki;Ayumi Katayama;T. Enoki
中科院分区：
文献类型：
--
作者：
M. Chiwa;S. Ikezaki;Ayumi Katayama;T. Enoki
植物化学计量学已被用于诊断大气氮沉积增加引起的磷限制。森林流域内N/P化学计量学的空间变异性尚未得到评估。本研究在低磷有效性岩石(蛇纹岩)上对27个样地的叶片进行了天气取样，以评估空间地形变化对N/P化学计量学的影响。对日本柏叶N、P浓度和N/P比值进行了测定，并对其在不同流域的空间变异进行了评价。各站点平均叶片P浓度较低(0.66 ± 0.16 mg/g−1)，而叶片N浓度较高(13.0 ± 1.5 mg/g−1)，N/P比值较高(21 ± 5)。此外，柏树地上部分生物量的增长与凋落物P呈正相关，表明研究地点柏树的P限制。叶片P浓度对凸度指数(IC)的响应大于N，N/P比值与IC相关，表明N/P比值受地形因素的影响。部分原因可能是由于大气氮沉降增加，与P相比，N有效性的空间变异性较小。因此，在诊断氮沉积引起的磷限制时，应考虑地形因素。
Plant stoichiometry has been used to diagnose phosphorus (P) limitation caused by increased atmospheric nitrogen (N) deposition. Spatial variability of N/P stoichiometry within a forested watershed has not yet been evaluated. This study conducted synoptic sampling of leaf matter in 27 plots within a temperate forested watershed on low P availability rock (serpentine bedrock) with a moderately high atmospheric N deposition (16 kg N ha−1year−1) to assess the effects of spatial topographic variation on N/P stoichiometry. Leaf N and P concentrations and N/P ratios of Japanese cypress were assessed, and their spatial variations were evaluated across a catchment. Average leaf P concentration was low (0.66 ± 0.16 mg g−1) across the sites, while leaf N concentration was high (13.0 ± 1.5 mg g−1); subsequently, N/P ratios were high (21 ± 5). In addition, the aboveground biomass growth of Japanese cypress positively correlated with litter P, implying the P limitation of Japanese cypress at the study site. Leaf P concentrations responded to the index of convexity (IC) values more than those of N. Subsequently, the N/P ratio correlated with IC, suggesting that N/P ratios are susceptible to topographic features. This could be partly caused by smaller spatial variability of N availability compared with P, owing to increased atmospheric N deposition. Thus, topography should be taken into consideration when diagnosing P limitation caused by N deposition.