The replacement of native dry forests by commercial (exotic) tree plantations could generate changes in rainfall partitioning, which further affects the water cycle. In this study, we determined (i) the rainfall partitioning into interception, throughfall and stemflow, (ii) the role of rainfall event size on rainfall partitioning, (iii) the pH of water channelized as throughfall and stemflow, and (iv) the runoff in Lithraea molleoides (a native species) and Pinus elliottii (an exotic species) stands in the dry Chaco mountain forests, central Argentina. On average, interception, throughfall and stemflow accounted for 19.3%, 79.5% and 1.2% of the gross rainfall in L. molleoides stand, and 32.6%, 66.7% and 0.7% of the gross rainfall in P. elliottii stand, respectively. Amounts of interception, throughfall and stemflow presented positive linear relationships with the increment of rainfall event size for both tree species (P<0.01 in all cases). Percentages of interception, throughfall and stemflow were all related to the increment of rainfall event size, showing different patterns. With increasing rainfall event size, interception exponentially decreased, throughfall asymptotically increased and stemflow linearly increased. Both P. elliottii and L. molleoides stands presented significant differences in the pH values of water channelized as throughfall (6.3 vs. 6.7, respectively; P<0.01) and stemflow (4.5 vs. 5.8, respectively; P<0.01). Runoff occupied only 0.3% of the gross rainfall in P. elliottii stand and was zero in L. molleoides stand. Our results showed that the native species L. molleoides presented 13.6% more water reaching the topsoil (i.e., net rainfall; net rainfall=gross rainfall—interception—runoff) than the exotic species P. elliottii. This study improves our understanding of the effects of native vegetation replacement on the local water balance in the dry forest ecosystems.

中文翻译：

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在阿根廷中部干燥的查科山林中，由外来的松树人工林取代原始干燥的 Lithraea molleoides 森林引起的降雨分配变化

用商业（外来）人工林取代原生干旱森林可能会导致降雨分配发生变化，从而进一步影响水循环。在这项研究中，我们确定了 (i) 降雨划分为截留、直通和茎流，(ii) 降雨事件大小对降雨划分的作用，(iii) 通道化为直通和茎流的水的 pH 值，以及 (iv) Lithraea molleoides（一种本地物种）和 Pinus elliottii（一种外来物种）的径流位于阿根廷中部干燥的 Chaco 山林中。平均而言，截流、贯流和茎流分别占 L. molleoides 林分总降雨量的 19.3%、79.5% 和 1.2%，分别占 P. elliottii 林分总降雨量的 32.6%、66.7% 和 0.7%。拦截量，两种树种的降雨量和茎流均与降雨事件大小的增量呈正线性关系（在所有情况下均 P <0.01）。截留百分比、贯流百分比和茎流百分比都与降雨事件规模的增加有关，呈现出不同的模式。随着降雨事件规模的增加，截获量呈指数下降，通过量渐近增加，茎流线性增加。P. elliottii 和 L. molleoides 林分在作为直通流（分别为 6.3 对 6.7； P < 0.01）和茎流（分别为 4.5 对 5.8； P < 0.01）的渠道化水的 pH 值方面存在显着差异。径流仅占 P. elliottii 林分总降雨量的 0.3%，而 L. molleoides 林分则为零。我们的结果表明，本地物种 L. molleoides 呈现 13。到达表土的水量（即净降雨量；净降雨量 = 总降雨量 - 截留量 - 径流）比外来物种 P. elliottii 多 6%。这项研究提高了我们对原生植被替代对干燥森林生态系统中当地水平衡的影响的理解。