Comparison of Belowground Biomass in C3- and C4-Dominated Mixed Communities in a Chesapeake Bay Brackish Marsh
Comparison of Belowground Biomass in C3- and C4-Dominated Mixed Communities in a Chesapeake Bay Brackish Marsh
复制标题
切萨皮克湾咸湿沼泽中以 C3 和 C4 为主的混合群落地下生物量的比较
DOI：
10.1007/s11104-005-3275-3
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发表时间：
2006
期刊：
影响因子：
4.9
通讯作者：
J. Reynolds
中科院分区：
文献类型：
--
作者：
C. Saunders;J. Megonigal;J. Reynolds
地下生物量是调节沿海沼泽生态系统功能的关键因素，包括土壤有机质（SOM）的积累和这些系统跟上海平面上升的能力。然而，地下生物量对环境和植被变化的响应很少受到重视沼泽研究。本文提出了一种利用稳定碳同位素和颜色鉴别美洲香木（Schoenoplectus americanus（E.A.）沃克ex Schinz和R. Keller（C3）和Spartina patens（Ait.）穆尔(C4)出现在切萨皮克湾半咸水沼泽中C3−和C4占主导地位的群落中。我们确定的生物量类的功能意义是强调其化学，深度剖面，生物量和剖面相对于非生物和生物因素的变化的差异。C3根茎的纤维素和木质素含量最低，分别为29.19%和14.43%，C：N和木质素：N的比值最低，分别为46.97和0.16。我们区分了两种类型的C3根，其中，暗红色的C3根有非常高的C：N（195.35）和木质素：N（1.14）的比例，与其他根和根茎类在这里检查，并与以前公布的值相比。C4占主导地位的群落的地下生物量（4119.1 g m-2）显着高于C3占主导地位的群落（3256.9 g m-2），这是由于更大的总根生物量和3.6倍的C3根：根茎比在C4占主导地位的社区。C3根茎在C4优势群落中的分布较浅，而C3根系则较深。C3根茎深度分布的变异主要由C4生物量解释，C3根系主要由地下水位高度解释。我们的研究结果表明，地下生物量在这个系统中是敏感的地下水位高度（在8厘米的范围内）的轻微变化，并减少重叠C3和C4根剖面在C4占主导地位的社会可能占较大的总根生物量在该社区观察。考虑到未来大气CO2浓度升高和海平面加速上升可能会增加大西洋和墨西哥湾沿岸沼泽的C3丰度，量化C3和C4地下生物量模式对环境和生物因素的响应的调查有助于提高我们对全球变化对沿海湿地生态系统影响的理解。
Belowground biomass is a critical factor regulating ecosystem functions of coastal marshes, including soil organic matter (SOM) accumulation and the ability of these systems to keep pace with sea-level rise. Nevertheless, belowground biomass responses to environmental and vegetation changes have been given little emphasis marsh studies. Here we present a method using stable carbon isotopes and color to identify root and rhizomes of Schoenoplectus americanus (Pers.) Volk. ex Schinz and R. Keller (C3) and Spartina patens (Ait.) Muhl. (C4) occurring in C3− and C4-dominated communities in a Chesapeake Bay brackish marsh. The functional significance of the biomass classes we identified is underscored by differences in their chemistry, depth profiles, and variation in biomass and profiles relative to abiotic and biotic factors. C3 rhizomes had the lowest concentrations of cellulose (29.19%) and lignin (14.43%) and the lowest C:N (46.97) and lignin:N (0.16) ratios. We distinguished two types of C3 roots, and of these, the dark red C3 roots had anomalously high C:N (195.35) and lignin:N (1.14) ratios, compared with other root and rhizome classes examined here and with previously published values. The C4-dominated community had significantly greater belowground biomass (4119.1 g m−2) than the C3-dominated community (3256.9 g m−2), due to greater total root biomass and a 3.6-fold higher C3-root:rhizome ratio in the C4-dominated community. C3 rhizomes were distributed significantly shallower in the C4-dominated community, while C3 roots were significantly deeper. Variability in C3 rhizome depth distributions was explained primarily by C4 biomass, and C3 roots were explained primarily by water table height. Our results suggest that belowground biomass in this system is sensitive to slight variations in water table height (across an 8 cm range), and that the reduced overlap between C3 and C4 root profiles in the C4-dominated community may account for the greater total root biomass observed in that community. Given that future elevated atmospheric CO2 and accelerated sea-level rise are likely to increase C3 abundance in Atlantic and Gulf coast marshes, investigations that quantify how patterns of C3 and C4 belowground biomass respond to environmental and biological factors stand to improve our understanding of ecosystem-wide impacts of global changes on coastal wetlands.