Disproportionate single-species contribution to canopy-soil nutrient flux in an Amazonian rainforest
Disproportionate single-species contribution to canopy-soil nutrient flux in an Amazonian rainforest
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DOI：
10.1016/j.foreco.2011.11.041
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发表时间：
2012-03
影响因子：
3.7
通讯作者：
S. Germer;A. Zimmermann;C. Neill;A. Krusche;H. Elsenbeer
中科院分区：
文献类型：
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作者：
S. Germer;A. Zimmermann;C. Neill;A. Krusche;H. Elsenbeer
降雨量，穿透雨和茎流的监测事件的基础上，在一个不受干扰的开放的热带雨林与大量的棕榈树位于巴西亚马逊盆地西南部。从24株胸径>5cm的树木以及8株幼龄和4株成年巴巴苏棕榈（Attalea speciosa Mart.）在雨季的高峰期，计算了3种阔叶树和3种棕榈树的降雨、穿透雨和茎流中Na+、K+、Ca 2+、Mg 2+、NH 4+、Cl-、SO 42-、NO3-和H+的浓度和通量以及茎流体积加权平均浓度和通量。大多数溶质的浓度较高，在茎流比在降雨量和增加树木和棕榈树的大小。NO3-从降雨到树干茎流和穿透雨的浓度富集特别高（81倍）。NO3-和H+的茎流通量超过穿透雨通量，但其他溶质的茎流通量小于穿透雨通量。树干液流溶质通量的森林土壤中占主导地位的通量巴巴苏棕榈，这只占4%的总茎数和10%的总断面积。对于NO3-，茎流贡献了51%的总质量的氮输送到森林地面（茎流+穿透雨），并代表了超过2000倍的增加NO3-通量相比，将已交付的降雨单独在同等面积。由于这些高度局部化的水和NO3-通量在时间和空间上持续存在，它们有可能影响土壤水分，微生物种群和其他土壤生态地球化学特征的模式，这些特征有助于创造氮淋溶和反硝化的热点，这可能是总生态系统通量的重要组成部分。由于这些热点发生在非常小的区域，它们可能在以前的研究中没有被发现，需要被认为是棕榈丰富的热带森林的地球化学的一个重要特征。
Rainfall, throughfall and stemflow were monitored on an event basis in an undisturbed open tropical rainforest with a large number of palm trees located in the southwestern Amazon basin of Brazil. Stemflow samples were collected from 24 trees with a diameter at breast height (DBH)>5cm, as well as eight young and four full-grown babassu palms (Attalea speciosa Mart.) for 5weeks during the peak of the wet season. We calculated rainfall, throughfall and stemflow concentrations and fluxes of Na+, K+, Ca2+, Mg2+, NH4+, Cl-, SO42-, NO3-and H+and stemflow volume-weighted mean concentrations and fluxes for three size classes of broadleaf trees and three size classes of palms. The concentrations of most solutes were higher in stemflow than in rainfall and increased with increasing tree and palm size. Concentration enrichments from rainfall to stemflow and throughfall were particularly high (81-fold) for NO3-. Stemflow fluxes of NO3-and H+exceeded throughfall fluxes but stemflow fluxes of other solutes were less than throughfall fluxes. Stemflow solute fluxes to the forest soil were dominated by fluxes on babassu palms, which represented only 4% of total stem number and 10% of total basal area. For NO3-, stemflow contributed 51% of the total mass of nitrogen delivered to the forest floor (stemflow+throughfall) and represented more than a 2000-fold increase in NO3-flux compared what would have been delivered by rainfall alone on the equivalent area. Because these highly localized fluxes of both water and NO3-persist in time and space, they have the potential to affect patterns of soil moisture, microbial populations and other features of soil biogeochemistry conducive to the creation of hotspots for nitrogen leaching and denitrification, which could amount to an important fraction of total ecosystem fluxes. Because these hotspots occur over very small areas, they have likely gone undetected in previous studies and need to be considered as an important feature of the biogeochemistry of palm-rich tropical forest.