Author?& Address

題目：

Responses of soil C pools to combined warming and altered precipitation regimes: A meta-analysis

通訊作者：

Fuzhong Wu

地址：

Key Laboratory for Humid Subtropical Eco-Geographical Processes of the Ministry of Education, School of Geographical Sciences, Fujian Normal University, Fuzhou, China

Abstract

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Aim

全球變暖和降水變化極大地影響土壤碳庫，并反過來反饋到氣候變化中。然而，土壤碳庫如何對(duì)變暖和降水改變的綜合影響作出反應(yīng)仍不清楚。

Location

Global.

Time period

1996–2021.

Major taxa studied

Soil organic C pools.

Method

本研究利用34篇文獻(xiàn)中的657個(gè)觀測數(shù)據(jù)，定量分析了氣候變暖和降水變化對(duì)土壤有機(jī)碳(SOC)、可溶性有機(jī)碳(DOC)和微生物生物量碳(MBC)的單獨(dú)和聯(lián)合影響。

Results

在所有增溫增雨試驗(yàn)中，SOC和MBC分別平均增加了4.0%和15.4%。相反，增溫和降水減少導(dǎo)致SOC和MBC的平均降幅分別為8.2%和12.3%。DOC對(duì)復(fù)合增溫和降水變化的響應(yīng)較為邊緣。對(duì)聯(lián)合處理的響應(yīng)方向和幅度更接近于單獨(dú)增溫處理。此外，這些綜合效應(yīng)在很大程度上受到改變的降水幅度的影響。增溫和降水變化聯(lián)合處理對(duì)土壤碳庫的影響大于單獨(dú)處理，但與單獨(dú)處理的影響之和無顯著差異，總體表現(xiàn)為相加效應(yīng)。土壤碳庫對(duì)氣候變暖和降水變化的響應(yīng)在草地上比在森林中更明顯。

Main conclusion

研究結(jié)果表明，在增溫和降水變化的聯(lián)合作用下，降水變化對(duì)土壤碳庫的調(diào)節(jié)作用往往優(yōu)于氣候變暖，從而提高了我們對(duì)氣候變化情景下土壤碳循環(huán)的理解。

Result

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FIGURE 1

Schematic of dissolved organic carbon (DOC) inputs and microbial biomass carbon (MBC) in the soil system. The blue arrows and text represent the sources of DOC, and the microbes in red represent MBC. The brown blob of matter is soil organic matter (SOM), and the green matter is dissolved organic matter (DOM).

FIGURE 2

Characteristics of the study sites selected for the meta-analysis. (a) Distribution of study sites at the global scale, (b) mean annual temperature and precipitation of study sites, and (c) density observed by soil depth.

FIGURE 3

Conceptual diagram of interaction types. Treatments are hypothetical control, individual warming (W) and individual increased precipitation (IP). The effect of treatment W is the change in response due to W above the baseline effect of the control (W???control), shown in blue. Similarly, the effect of treatment IP is the change in response due to IP above the baseline effect of the control (IP???control), shown in purple. An interaction of combined treatment (W?+?IP) is additive if the response to the application of both W and IP is the sum of the effects of both treatments above baseline (response?=?(W?+?IP)???control). The dashed black line shows this additive prediction. The interaction is synergistic if the response is greater than the sum of the effects of both treatments (response > (W?+?IP)???control), which is depicted in green. The interaction is antagonistic if the response is less than the sum of the effects of both treatments (response < (W?+?IP)???control), depicted in yellow.

FIGURE 4

Individual and combined effects of warming and altered precipitation regimes on soil C pools. Effects of warming (W), increased precipitation (IP), combined warming and increased precipitation (W?+?IP) (top), decreased precipitation (DP), and combined warming and decreased precipitation (W?+?DP) (bottom) on (a, d) soil organic carbon (SOC), (b, e) dissolved organic carbon (DOC), and (c, f) microbial biomass carbon (MBC) are shown. Results are expressed as the percentage change relative to the control (%). Solid yellow dots indicate the significant positive effects, solid green dots indicate the significant negative effects and solid purple dots indicate the non-significant effects. Values indicate the means with 95% confidence intervals (CIs), and n indicates the number of observations. The vertical dashed lines are zero lines.

FIGURE 5

Interactive effects of warming and altered precipitation regimes on soil C pools. Effects of combined warming and increased precipitation (W?+?IP) and combined warming and decreased precipitation (W?+?DP) on (a) soil organic carbon (SOC), (b) dissolved organic carbon (DOC) and (c) microbial biomass carbon (MBC) are revealed using the weighted mean Hedges'?d?and the corresponding frequency distribution of interaction types among individual observations. Values represent means with 95% confidence intervals (CIs), and the number of observations is given along the?y-axis.

FIGURE 6

Individual and interactive effects of warming and altered precipitation among different ecosystem types. Effects of warming (W), increased precipitation (IP), decreased precipitation (DP), combined warming and increased precipitation (W?+?IP), and combined warming and decreased precipitation (W?+?DP) on (a, d) soil organic carbon (SOC), (b, e) dissolved organic carbon (DOC) and (c, f) microbial biomass carbon (MBC) are shown. Interactive effects of warming and altered precipitation on (g) soil organic carbon (SOC), (h) dissolved organic carbon (DOC) and (i) microbial biomass carbon (MBC) have been revealed using the weighted mean Hedges'?d?in different ecosystems. Significant (α?<?0.05)?Qb?(between-group heterogeneity) indicates that the response ratios differ among ecosystems. Values represent means with 95% confidence intervals (CIs), and the number of observations is given along the?y-axis. The vertical dashed lines are zero lines.

Conclusion

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本研究對(duì)了解自然生態(tài)系統(tǒng)土壤碳庫對(duì)氣候變化的響應(yīng)具有重要意義。土壤SOC、DOC和MBC在增溫和降水增加的聯(lián)合作用下呈增加趨勢，在增溫和降水減少的聯(lián)合作用下呈降低趨勢。結(jié)果中觀察到的變化可以歸因于降水變化，這表明與變暖相比，土壤C庫對(duì)降水變化的敏感性更大。增溫和降水改變對(duì)土壤碳庫的相加效應(yīng)以協(xié)同或拮抗作用為主，而復(fù)合效應(yīng)可能受氣候、土壤因子和試驗(yàn)設(shè)置的影響。此外，相對(duì)于增溫幅度，降水變化幅度對(duì)土壤碳庫的響應(yīng)影響較大。在生態(tài)系統(tǒng)類型上，草地土壤C庫對(duì)復(fù)合增溫和降水變化的敏感性高于森林。本研究揭示了全球氣候變化下降水變化對(duì)土壤碳循環(huán)的重要調(diào)控作用。

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