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《Nature Climate Change》杂志发表生态与环境学院卢蒙博士及合作者的最新研�I�成�?/h1>
发布旉��Q?019-10-23 ��览�ơ数�Q?script>_showDynClicks("wbnews", 1367982545, 3514)

滨�v湿地为包括�h�c�d��内的众多生物提供了宝�늚�生态系�l�服务功能，然而这一重要的生态系�l�正日益受到��Zؓ�z�d��的威胁。自工业革命以来�Q�大气中的二氧化��I��CO₂�Q�浓度从280 ppm增加�?/span>410 ppm�Q�预计到2100�q�将��过900 ppm。在陆地生态系�l�中�Q?/span>CO₂��度的上升通常会促�q?/span>C3植物的光合作用和初��生��力，从而导致植物�Ş态的变化。但是，与木本植物或农作物相比，非木本克隆植物对CO₂升高的�Ş态响应模式却鲜有研究。考虑到绝大多数盐沼植被都是克隆植物，且其形态变化将直接军_��滨�v湿地生态系�l�的�l�构和功能，卢蒙博士及合作者在位于��国东�v�?/span>Chesapeake Bay的盐沼湿地开展了30余年�?/span>CO₂倍增实验�q�测量了��过20万株的植物�Ş态数据，以探讨全球变化背景下盐沼湿地植物形态变化对生态系�l�结构和功能的媄响�?/span>

��目�l�研�I�表明，30�q�的倍增CO₂控制实验提高了盐沼湿地生态系�l�初�U�生产力和植被的密度�Q�但降低了优势克隆物�U?/span>Schoenoplectus americanus的茎�U�直径和高度�Q?/span>Fig. 1�Q�。较��，较密的茎�U�与根和根状茎的扩张有关�Q�以减轻CO₂倍增条�g下导致的氮（N�Q�限�Ӟ��q�一点可��p��U�、细栏V��根状茎和凋落物中升高的N含量�Q�增加的植物�l�织��x��比（C�Q?/span>N ratio�Q�，和降低的土壤孔隙水无机��含量所证明�Q?/span>Fig. 2a�Q�。在另一�l�倍增CO₂和��d��Q?/span>CO₂ + N�Q�控制实验中�Q?/span>Schoenoplectus americanus的�Ş态变化得到反转，卌��U�直径和高度同时增加�Q?/span>Fig. 2b�Q�。因此我们得出，土壤有效氮是控制植物形态对CO₂��度变化响应的关键因子（Fig. 3�Q��?/span>

同时�Q�项目组�Ҏ��盐沼植被形态学和生物量的变化，模型模拟了未来气候变化和��^面上升情景下滨�v湿地生态系�l�土壤沉�U�物的积聚响应模式，�l�果表明CO₂�?/span>N的交互作用能促进盐沼湿地的抬升（Table 1�Q�，从而�ؓ滨�v湿地生态系�l�应�Ҏ�v�q�面上升提供有力的保障�?/span>

该研�I�成果发表在最��C��期的�?/span>Nature Climate Change》杂志�?/span>

全文链接�Q?/span>

https://www.nature.com/articles/s41558-019-0582-x

DOI�Q?/span>https://doi.org/10.1038/s41558-019-0582-x

Fig. 1 Elevated CO₂ responses of individual stem of S. americanus in the C₃ community of Experiment 1 from 1987 to 2016. The mean �u s.e.m. (n=5 replicate plots) of stem density (a), stem biomass (b), stem height (c), and stem diameter (d) are shown separately for ambient CO₂ (open circles) and elevated CO₂ chambers (filled circles).

Fig. 2 The response ratios of key parameters from the two experiments. Elevated CO₂ caused symptoms of N limitation such as increased root:shoot ratio and lower available soil N, effects that were mitigated by N addition. Each bar (elevated CO₂: open bars, elevated CO₂ plus N addition: filled bars) is the mean (�u s.e.m.) response ratio (Elevated/Ambient) in Experiment 1 (a) and Experiment 2 (b) across all years in the record.

Fig. 3 A conceptual framework for the responses of clonal plant aboveground growth pattern to CO₂ enrichment and nitrogen availability.

Table 1. Impacts of elevated CO₂ and N on plant growth and accretion. Mean values for frontal area per unit volume (m^-1), belowground organic accretion (mm yr^-1, from Pastore et al. 2017), total belowground productivity (g m^-2 yr^-1), stem density (shoot m^-2), aboveground biomass (g m^-2), and modeled aboveground mineral accretion (mm yr^-1) for Experiments 1 and 2. Means �u s.e.m. with the same letter in the same column and experiment are not significantly different from one another (A, B for Experiments 1 and a, b, c for Experiments 2).

　

Frontal Area

Measured Belowground Organic Accretion*

Belowground productivity

Stem density

Aboveground Biomass

Modeled Aboveground Mineral Accretion

Experiment 1

Ambient

2.2 (0.2)^A

N/A

269 (21)

538 (25)

497 (33)

4.5 (0.1)^A

CO₂

2.4 (0.2)^B

N/A

349 (28)

784 (30)

564 (33)

5.7 (0.1)^B

Experiment 2

Ambient

2.4 (0.2)^a

0.46 (0.3)

143 (23)

527 (23)

587 (52)

4.2 (0.1)^a

CO₂

2.6 (0.2)^a,b

1.84 (0.4)

228 (25)

598 (30)

645 (66)

4.9 (0.1)^b

CO₂+N

3.2 (0.3)^b

1.70 (0.6)

187 (35)

633 (31)

803 (83)

5.7 (0.1)^c

N

2.3 (0.2)^a

1.81 (0.5)

110 (15)

503 (28)

555 (60)

4.4 (0.1)^a

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