Hölscher D, Sá T D A, Möller R F, Denich M, Fölster H
Institute of Soil Science and Forest Nutrition, University of Göttingen, Büsgenweg 2, D-37077 Göttingen, Germany, , , , , , DE.
Empresa Brasileira de Pesquisa Agropecuária/Centro de Pesquisa Agroflorestal da Amazônia Oriental, Caixa Postal 48, 66095-100 Belém, Pará, Brazil, , , , , , BR.
Oecologia. 1998 Apr;114(2):251-257. doi: 10.1007/s004420050443.
Rainfall partitioning into throughfall and stemflow was studied in a diverse and in a mono specific stand of secondary vegetation in Eastern Amazonia. The nutrient concentrations in the water were analysed in order to quantify the related hydrochemical fluxes. Secondary vegetation forms the fallow in the local shifting cultivation system and is usually dominated by shrubs and trees. Phenakospermum guyannense (Strelitziaceae), a banana-like herb, is one of the predominant non-woody species. The study was conducted during an 18-month period in a 2.5-year-old relatively species-rich stand and a 10-year-old stand dominated by P. guyannense. In a year with 1956 mm of rainfall 65% (1281 mm) of this quantity reached the soil as throughfall in the diverse stand and 38% (743 mm) in the mono specific stand. Stemflow was estimated to be 23% and 41% respectively. P. guyannense and Banara guianensis (Flacourtiaceae), a tree species, were causing these high funnelling effects. In the young diverse stand B. guianensis had a stemflow of more than 200 l year and P. guyannense had a median flux of 77 l year per pseudostem. In the older stand the taller plants of P.␣guyannense collected 644 l year per pseudostem on the median. The reason for these high values could be the banana-like growth form of P. guyannense and the crown morphology of B. guianensis, which has inclined branches. The low proportion of throughfall and the high stemflow values differ from all previous studies in Amazonian primary forests. The proximity to the Atlantic Ocean strongly influenced the nutrient fluxes via rainfall at our study site. This becomes obvious from the high Na and Cl fluxes with rainfall (19.7 kg Na ha year, 37.2 kg Cl ha year) which were approximately equal to the Na and Cl fluxes with the sum of throughfall and stemflow for both stands. K fluxes in throughfall and stemflow in both stands were higher than in rainfall by a factor of 8. The high K enrichment during the crown passage is assumed to be caused by a␣high K concentration in the leaf tissue resulting in enhanced leaching from the leaves. In months with low␣rainfall the concentrations of Ca, Mg, S and Cl in throughfall of the diverse stand were significantly higher than in months with high rainfall. This was mainly due to vegetation burns in the dry period, which resulted in ash deposition on the canopy and subsequent wash-off and solution of ash particles.
在亚马孙东部次生植被的一个多样化群落和一个单物种群落中，对降雨分配为穿透雨和树干流的情况进行了研究。分析了水中的养分浓度，以量化相关的水化学通量。次生植被构成了当地轮作耕种系统中的休耕地，通常以灌木和树木为主。圭亚那叶籽棕（旅人蕉科），一种类似香蕉的草本植物，是主要的非木本物种之一。该研究在一个2.5年生、物种相对丰富的群落和一个以圭亚那叶籽棕为主的10年生群落中进行，为期18个月。在年降雨量为1956毫米的一年中，在多样化群落中，65%（1281毫米）的降雨量以穿透雨的形式到达土壤，在单物种群落中为38%（743毫米）。树干流估计分别为23%和41%。圭亚那叶籽棕和圭亚那巴拿拉树（大风子科）这一树种造成了这些高汇集效应。在年轻的多样化群落中，圭亚那巴拿拉树的树干流超过200升/年，圭亚那叶籽棕每个假茎的通量中位数为77升/年。在较老的群落中，较高的圭亚那叶籽棕植株每个假茎的中位数收集量为644升/年。这些高值的原因可能是圭亚那叶籽棕类似香蕉的生长形态以及圭亚那巴拿拉树倾斜树枝的树冠形态。穿透雨的低比例和高树干流值与之前在亚马孙原始森林中的所有研究不同。靠近大西洋强烈影响了我们研究地点通过降雨的养分通量。这从降雨中的高钠和氯通量（19.7千克钠/公顷·年，37.2千克氯/公顷·年）中可以明显看出，这大约等于两个群落中穿透雨和树干流总和中的钠和氯通量。两个群落中穿透雨和树干流中的钾通量比降雨中的高8倍。树冠截留期间的高钾富集被认为是由于叶片组织中高钾浓度导致叶片淋溶增强所致。在降雨量低的月份，多样化群落中穿透雨中的钙、镁、硫和氯浓度显著高于降雨量高的月份。这主要是由于干旱期的植被燃烧，导致灰烬沉积在树冠上，随后灰烬颗粒被冲刷和溶解。
