Martinelli L A, Victoria R L, Trivelin P C O, Devol A H, Richey J E
School of Oceanography, University of Washington, WB-10, 98105, Seattle, WA, USA.
Departmento de Física e Meteorologia, Escola Superior de Agricultura "Luiz de Queiroz", CP 9, CEP 13400, Piracicaba, SP, Brazil.
Oecologia. 1992 Jul;90(4):591-596. doi: 10.1007/BF01875455.
TheN natural abundance values of various Amazon floodplain (várzea) plants was investigated. Samples of young leaf tissues were collected during three different periods of the river hydrography (low water, mid rising water and high water) and during one period in the Madeira River (high water). A large variation ofN abundance was observed, both among the different plant types and between the different flood stages. This variation probably, reflected, in part, the highly variable nature of the floodplain, sometimes dry and oxygenated and at other times inundated and anaerobic and, in part, changes in plant nitrogen metabolism. Comparison of the nitrogen isotopic composition of leguminous plants with that of non-leguminous plants showed that, on average, theN abundance was lower in the legumes than non-legumes, suggesting active N-fixation. Also, theN natural abundance in aquatic grasses of the generaPaspalum, was in general, lower than theN abundance of aquatic grasses of the generaEchinochloa. As both of these grasses grow in the same general habitat, it appears thatPaspalum grasses may also be nitrogen fixers.
对亚马逊河漫滩（várzea）各种植物的氮自然丰度值进行了调查。在河流不同水文时期（枯水期、涨水期和高水位期）以及马德拉河的一个时期（高水位期）采集了幼叶组织样本。观察到不同植物类型之间以及不同洪水阶段之间氮丰度存在很大差异。这种差异部分可能反映了河漫滩高度可变的性质，有时干燥且有氧，有时被淹没且厌氧，部分反映了植物氮代谢的变化。豆科植物与非豆科植物氮同位素组成的比较表明，平均而言，豆科植物中的氮丰度低于非豆科植物，这表明存在活跃的固氮作用。此外，雀稗属水生草类的氮自然丰度总体上低于稗属水生草类的氮丰度。由于这两种草都生长在相同的一般生境中，似乎雀稗属草类也可能是固氮植物。
