Canopy modification of base cations deposition in a subtropical broadleaved forest: Spatial characteristics, canopy budgets and acid neutralizing capacity
Canopy modification of base cations deposition in a subtropical broadleaved forest: Spatial characteristics, canopy budgets and acid neutralizing capacity
复制标题
DOI：
10.1016/j.foreco.2020.118863
复制
发表时间：
2021-02
影响因子：
3.7
通讯作者：
Xinchao Sun;Zhao Zhang;Yanhong Cao;Li Liu;F. Hu;Xiaoqiang Lu
中科院分区：
文献类型：
--
作者：
Xinchao Sun;Zhao Zhang;Yanhong Cao;Li Liu;F. Hu;Xiaoqiang Lu
大气沉积的盐基阳离子与冠层接触，改变了它们的化学特性，并通过补充森林生态系统中的盐基阳离子库，在抵消土壤酸化和养分失衡方面发挥着至关重要的作用。然而，站点特性对流域内不同地形梯度上的盐基阳离子通量（TF）和树干茎流（SF）的影响还不太清楚。本文研究了中国东南部亚热带山地阔叶林上、下坡样地降水中钾、钙、镁、钠盐离子浓度和通量、酸中和能力和碱度。此外，冠层收支模型被用来区分干沉降（DD）和冠层交换（CE）净TF +SF（NTF）通量的相对贡献。结果表明，无论是UP还是LP，TF和SF的盐基阳离子年体积加权平均浓度均显著高于BPin。UP和LP之间TForSF基阳离子的年通量没有显着差异，导致NTF通量相当。然而，DD和CE对NTF的相对贡献在两个斜坡上是不同的。NTF K+通量以CE为主，与坡位无关。与K+不同，NTF中Ca ~（2+）和Mg ~（2+）通量在UP中以DD为主，而在LP中以CE为主。此外，TF和SF的ANC和ALK显著高于BP，表明冠层下的雨水变得不那么酸性，可能部分减轻土壤酸化的风险，特别是在休眠季节。本研究可以提供洞察的空间变异性的化学特征的盐基阳离子，并提高我们的理解，发生在林冠层内的外部和内部的养分输入的数量和控制。
Atmospheric deposition of base cations in contact with the canopy alters their chemical characteristics and plays a vital role in offsetting soil acidification and nutrient imbalance by replenishing the base cationic pool in forest ecosystems. However, the effects of site characteristics on deliveries of base cations fluxesviathroughfall (TF) and stemflow (SF) across topographic gradients within a watershed remain less understood. Here, we examined the concentrations and fluxes of base cations (potassium (K+), calcium (Ca2+), magnesium (Mg2+) and sodium (Na+)), acid neutralizing capacities (ANC) and alkalinity (ALK) in bulk precipitation (BP),TFandSFin an upper slope plot (UP) and a lower slope plot (LP) in a subtropical broadleaved montane forest, Southeast China. In addition, a canopy budget model was applied to distinguish the relative contributions of dry deposition (DD) and canopy exchange (CE) to netTF+SF(NTF) flux. Results showed that annual volume weighted mean concentrations of base cations inTFandSFwere significantly higher than those inBPin both UP and LP. Annual fluxes ofTForSFbase cations had no significant differences between UP and LP, resulting in a comparable of the NTF fluxes. However, the relative contributions of DD and CE to NTF were different at the two slope plots. NTF K+flux was dominated by CE regardless of slope position. Unlike K+, NTF Ca2+and Mg2+fluxes were dominated by DD in UP, while CE in LP. In addition, ANC and ALK ofTFandSFwere significantly higher compared toBP, suggesting rainwater beneath the canopy became less acidic and may mitigate in part the risk of soil acidification, especially in the dormant season. This study can provide insights into the spatial variability of chemical characteristics of base cations, and improve our understanding of the quantities and controls of external and internal nutrient inputs occurring within the canopy in forest watershed.