Nutrient fluxes in rainfall, throughfall and stemflow in Eucalyptus stands on the Zululand coastal plain, South Africa
Nutrient fluxes in rainfall, throughfall and stemflow in Eucalyptus stands on the Zululand coastal plain, South Africa
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DOI：
10.2989/20702620.2011.639506
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发表时间：
2011-01-01
影响因子：
0.8
通讯作者：
de Clercq, W.
中科院分区：
文献类型：
--
作者：
Dovey, S. B.;du Toit, B.;de Clercq, W.
对南非祖鲁兰北部杜库杜库和南部夸姆博纳比商业种植林区树冠关闭后（成熟）桉树林的两个地点进行了四年的大气沉降评估。本研究的目的是确定养分添加与降雨、径流和茎流对该地区商业林业的影响程度和相关性。冠层阳离子交换与降雨和冠层排水一起使用，以获得湿、干和总大气沉降。在整个研究期间，在降雨、径流和茎流中测量的养分浓度在不同来源和地点之间变化很大。降雨两侧呈弱酸性，但在穿过树冠后酸性减弱。树冠交换和干燥沉积物的收集导致树冠下的阳离子浓度增加，而树冠通常从降雨中吸收氮（N），从而降低了树冠下方的浓度。研究表明，大气沉降是每个地点的桉树林中大量养分增加的原因。每个地点所有年份的年平均沉积量达库杜库的氮、钙、镁和钾 (K) 通量分别为 11.0、6.0、2.7 和 10.2 kg ha(-1) y(-1)，夸姆博纳比 (KwaMbonambi) 分别为 10、10.6、7.5 和 18.8 kg ha(-1) y(-1)。有机氮通量在杜库杜库 (Dukuduku) 和夸姆博纳比 (KwaMbonambi) 分别贡献了 8.1 kg ha(-1) y(-1) 和 7.1 kg ha(-1) y(-1) 总氮沉降量。尽管钾沉降值很高，但所有其他营养素的添加量虽然也很高，但仍在当地和国际研究报告的范围内。在完整的旋转过程中，这些地点记录的大气沉降水平可能有可能提供干木采伐过程中损失的大部分养分。这项研究增加了对快速生长的人工林营养可持续性的理解，证明了大气沉降作为祖鲁兰沿海平原人工种植桉树营养添加源的重要性。
Atmospheric deposition was assessed at two sites over a four-year period in post-canopy-closure (mature) Eucalyptus stands in the northern Dukuduku and southern KwaMbonambi commercial plantation forestry areas of Zululand, South Africa. The aim of this study was to determine the magnitude and relevance of nutrient addition with rainfall, throughfall and stemflow to commercial forestry in this region. Canopy cation exchange was used with rainfall and canopy drainage to derive wet, dry and total atmospheric deposition. Nutrient concentrations measured in the rainfall, throughfall and stemflow varied widely throughout the study period, and between sources and sites. Rainfall was slightly acidic at both sides, but became less acidic upon passing through the tree canopies. Canopy exchange and collection of dry deposition resulted in increased cation concentrations under the tree canopy, while the canopy generally absorbed nitrogen (N), from the rainfall, reducing the below canopy concentrations. Atmospheric deposition was shown to be responsible for large quantities of nutrients added to the eucalypt stands at each site. Annualised deposition averaged across all years at each site amounted to N, calcium, magnesium, and potassium (K) fluxes of 11.0, 6.0, 2.7 and 10.2 kg ha(-1) y(-1) at Dukuduku and 10, 10.6, 7.5 and 18.8 kg ha(-1) y(-1) at KwaMbonambi, respectively. Organic N fluxes contributed a further 8.1 kg ha(-1) y(-1) at Dukuduku and 7.1 kg ha(-1) y(-1) at KwaMbonambi to the total N deposition. Although K deposition values were high, additions of all other nutrients, although also high, were within the ranges reported in local and international research. Over the course of a full rotation, the atmospheric deposition levels recorded at these sites may have potential to supply a large proportion of the nutrients that are lost during stem-wood harvesting. This study adds value to understanding of nutritional sustainability of fast-growing plantation forests, demonstrating the importance of atmospheric deposition as a nutrient addition source to plantation-grown eucalypts along the Zululand coastal plain.