Nutrient Input via Incident Rainfall in a Eucalyptus dunnii Stand in the Pampa biome

ABSTRACT We evaluated the nutrient input via incident rainfall in a Eucalyptus dunnii stand in the Brazilian Pampa biome. During the two-year study, we analyzed nutrient concentrations in incident rainfall (P), throughfall via drip (Pi), and stemflow (Et). Ion concentrations (NO2-, NO3-, PO43- , SO42-, Cl-, K+, Ca2+ , and Mg2+) were determined from the aqueous solution, and based on the water volume, the quantity per hectare (kg ha-1) was estimated for each element. Statistical differences observed by ANOVA and separation of means contrasts were subjected to Tukey’s test (5%), adopting a completely randomized design. Higher concentrations of SO4 2- in P; NO3- in Pi solution, and K+, Ca2+ , Mg2+, and Cl- in Et were observed. Greater amounts of nutrients such as Cl-, K+, Ca2+, and SO42 were incorporated via Pi.

摘要 本研究在巴西潘帕（Pampa）生物群落的邓恩桉（Eucalyptus dunnii）人工林样地中，评估了自然降雨（incident rainfall）携带的养分输入通量。在为期两年的研究周期内，我们分别测定了自然降雨（记为P）、林冠穿透雨（记为Pi）以及树干茎流（记为Et）中的养分浓度。我们对水溶液中的NO₂⁻、NO₃⁻、PO₄³⁻、SO₄²⁻、Cl⁻、K⁺、Ca²⁺及Mg²⁺等离子浓度进行了定量分析，并结合水样体积，估算得到各元素每公顷的养分输入量（单位：kg·ha⁻¹）。本研究采用完全随机试验设计，通过方差分析（ANOVA）检测各组间的统计学差异，并采用显著性水平为5%的Tukey检验开展均值多重比较。结果表明：自然降雨（P）中SO₄²⁻浓度最高，林冠穿透雨（Pi）溶液中NO₃⁻浓度最高，而树干茎流（Et）中则以K⁺、Ca²⁺、Mg²⁺及Cl⁻浓度为最高。林冠穿透雨（Pi）携带的养分输入总量最高，其中以Cl⁻、K⁺、Ca²⁺及SO₄²⁻最为突出。