Uncoupled surface and below-ground soil respiration in mangroves: implications for estimates of dissolved inorganic carbon export
Uncoupled surface and below-ground soil respiration in mangroves: implications for estimates of dissolved inorganic carbon export
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DOI：
10.1007/s10533-011-9616-9
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发表时间：
2012-07-01
期刊：
影响因子：
4
通讯作者：
Tirendi, Frank
中科院分区：
文献类型：
--
作者：
Alongi, Daniel M.;de Carvalho, Narciso A.;Tirendi, Frank
在东帝汶七片不同地形高度的红树林中检查了地表和地下呼吸速率之间的潜在差异。暴露在空气中的土壤和被淹没的土壤之间的表面呼吸差异不一致，但表面呼吸速率随着潮汐升高而增加。随着森林覆盖率的增加，暴露在空气中的土壤的净初级生产力（NPP）下降，这表明树冠下的光照受到限制。在空气暴露和淹没条件下，NPP 和呼吸均呈线性相关。不同森林的土壤表面 DIC 释放速率各不相同，仅与土壤碳 (TOC) 和氮 (TN) 及其化学计量比相关。在松散土壤的最大深度检测到硫酸盐减少，仅与离散深度间隔的 TOC 和 TN 含量相关。排水沟中的 DIC 浓度相当于孔隙水浓度。硫酸盐还原剂 (SRC) 的碳矿化率相当于在潮汐高度高于平均海平面 (MSL) 0.5 米的森林土壤表面测量的总碳氧化率 (TCO)。然而，在高于 MSL 1.0 至 2.5 m 的森林中，SRC 逐渐大于 TCO。大多数地下沉积物中矿化的碳似乎通过地下水渗出森林。因此，表面呼吸速率低估了地形高度高于 MSL 0.5 m 的森林中总底栖碳矿化速率，这表明许多红树林输出的呼吸碳量也被低估了。
Potential disparities between rates of surface and below-ground respiration were examined in seven mangrove forests of different topographic height in Timor Leste. Differences in surface respiration between air-exposed and inundated soils were inconsistent, but surface respiration rates increased, with tidal elevation. Net primary production (NPP) on air-exposed soils declined with increasing forest cover indicating light limitation beneath the canopy. NPP and respiration were linearly related under both air-exposed and inundated conditions. Rates of DIC release from the soil surface varied among forests, correlating only with soil carbon (TOC) and nitrogen (TN) and their stoichiometric ratios. Sulfate reduction was detected to maximum depth of unconsolidated soil, correlating only with TOC and TN content at discrete depth intervals. DIC concentrations in drainage channels were equivalent to porewater concentrations. The rate of carbon mineralized by sulfate reducers (SRC) was equivalent to rates of total carbon oxidation (TCO) measured at the soil surface in forests at tidal heights a parts per thousand currency sign0.5 m above mean sea-level (MSL). However, SRC was increasingly greater than TCO in forests residing from 1.0 up to 2.5 m above MSL. Most carbon mineralized in subsurface deposits appears to seep out of the forest via groundwater. Rates of surface respiration therefore underestimate rates of total benthic carbon mineralization in forests at topographic heights a parts per thousand yen0.5 m above MSL, suggesting that the amount of respiratory carbon exported from many mangrove forests has also been underestimated.