红松、白桦的氮营养行为及其种间分异

对红松、白桦的吸收空间和吸收N素的时间(季节)、数量、形态的研究表明,在混交情况下,白桦表现出较典型的浅根性特征,吸收根主要集中在土壤表层;红松则具有深根性趋势,其吸收根在下层土壤空间的分布明显增加.白桦吸收N素养分的季节比较集中,具有明显的峰期;而受白桦庇荫的红松则在整个生长季中一直比较平缓地吸收N素,峰期不甚明显.白桦对N的消耗量较大;而红松对N的消耗量则相对较小,N利用效率比白桦高34%.在对N素养分化学形态的偏向选择性方面,白桦较喜NO₃^--N,而红松则较偏好NH₄⁺-N.

Behaviors of nitrogen nutrition of Pinus koraiensis and Betula platyphylla and their interspecific differentiation

Studies on the spatial, temporal, quantitative, and form aspects of nitrogen uptake by Pinus koraiensis and Betula platyphylla showed that in pine-birch mixed forest, birch tree was characterized by typical shallow-roots, and its nutrient-seeking roots were largely distributed in topsoil; while pine tree was characterized by deep roots, and its nutrient seeking roots were obviously increased in deep soil. As for seasonal dynamics of Nuptake, birch showed an intensive uptake with a remarkable peak period, while pine shadowed by birch performed gently in the whole growing season without any significant peak period. In the quantitative aspect, birch consumed relatively larger amount of N, while pine only required relatively smaller amount of it and the Nuse efficiency was 34% higher than that of birch. As for the selective uptake of chemical Nforms, birch tended to select NO₃^--N, while pine preferred to NH₄⁺-N.