Temporal dynamics in soil organic carbon(SOC)play a crucial role in the global carbon cycle.How warming affects SOC change has been widely studied at the site scale,mainly through short-term manipulative experiments.D...Temporal dynamics in soil organic carbon(SOC)play a crucial role in the global carbon cycle.How warming affects SOC change has been widely studied at the site scale,mainly through short-term manipulative experiments.Decades-long SOC dynamics in ecosystems can be complicated,particularly as real-world warming rates varied on decade-scale.However,the lack of long-term repeated observations on whole-profile SOC limits our understanding of SOC dynamics across large regions.Herein,we reconstructed 45 years of SOC dynamics(1970–2014)in topsoil(0–30 cm)and subsoil(30–100 cm)using 10,639 soil profiles from forest and cropland across the contiguous United States,and investigated their relations with key dynamic environments(e.g.,climate,vegetation and nitrogen).We further examined the spatial pattern of SOC stock changes at a finer scale(∼2 km)using machine learning techniques.Our results revealed ecosystem-dependent,two-stage changes of SOC stock,characterized by continental-scale halts in SOC loss following warming deceleration since the late 1990s.This shift led to an overall increase in SOC stock of 1.41%in forest and 1.14%in cropland within the top 1-meter over 45 years.Temperature was the primary factor related to topsoil SOC losses,whereas soil water content may primarily control subsoil SOC change.Notably,a threshold effect of warming rates on SOC loss was identified in both topsoil and subsoil.These findings provide new insights into long-term whole-profile SOC dynamics at a large scale,offering valuable implications for carbon sequestration to support sustainable development in different ecosystems.展开更多
Coastal wetlands are important blue carbon ecosystems that play a significant role in the global carbon cycle.However,there is insufficient understanding of the variations in soil organic carbon(SOC)stocks and the mec...Coastal wetlands are important blue carbon ecosystems that play a significant role in the global carbon cycle.However,there is insufficient understanding of the variations in soil organic carbon(SOC)stocks and the mechanisms driving these ecosystems.Here we analyze a comprehensive multi-source dataset of SOC in topsoil(0e20 cm)and subsoil(20e100 cm)across 31 coastal wetlands in China to identify the factors influencing their distribution.Structural equation models(SEMs)reveal that hydrology has the greatest overall effect on SOC in both soil layers,followed by vegetation,soil properties,and climate.Notably,the mechanisms driving SOC density differ between the two layers.In topsoil,vegetation type and productivity directly impact carbon density as primary sources of carbon input,while hydrology,primarily through seawater salinity,exerts the largest indirect influence.Conversely,in subsoil,hydrology has the strongest direct effect on SOC,with seawater salinity also influencing SOC indirectly through soil and vegetation mediation.Soil properties,particularly pH,negatively affect carbon accumulation,while climate influences SOC indirectly via its effects on vegetation and soil,with a diminishing impact at greater depths.Using Random Forest,we generate high-resolution maps(90 m90 m)of topsoil and subsoil carbon density(R2 of 0.53 and 0.62,respectively),providing the most detailed spatial distribution of SOC in Chinese coastal wetlands to date.Based on these maps,we estimate that SOC storage to a depth of 1 m in Chinese coastal wetlands totals 74.58±3.85 Tg C,with subsoil carbon storage being 2.5 times greater than that in topsoil.These findings provide important insights into mechanism on driving spatial pattern of blue carbon and effective ways to assess carbon status on a national scale,thus contributing to the advancement of global blue carbon monitoring and management.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.42471468)the Leading Funds for the First Class Universities(Grants No.020914912203 and 020914902302)。
文摘Temporal dynamics in soil organic carbon(SOC)play a crucial role in the global carbon cycle.How warming affects SOC change has been widely studied at the site scale,mainly through short-term manipulative experiments.Decades-long SOC dynamics in ecosystems can be complicated,particularly as real-world warming rates varied on decade-scale.However,the lack of long-term repeated observations on whole-profile SOC limits our understanding of SOC dynamics across large regions.Herein,we reconstructed 45 years of SOC dynamics(1970–2014)in topsoil(0–30 cm)and subsoil(30–100 cm)using 10,639 soil profiles from forest and cropland across the contiguous United States,and investigated their relations with key dynamic environments(e.g.,climate,vegetation and nitrogen).We further examined the spatial pattern of SOC stock changes at a finer scale(∼2 km)using machine learning techniques.Our results revealed ecosystem-dependent,two-stage changes of SOC stock,characterized by continental-scale halts in SOC loss following warming deceleration since the late 1990s.This shift led to an overall increase in SOC stock of 1.41%in forest and 1.14%in cropland within the top 1-meter over 45 years.Temperature was the primary factor related to topsoil SOC losses,whereas soil water content may primarily control subsoil SOC change.Notably,a threshold effect of warming rates on SOC loss was identified in both topsoil and subsoil.These findings provide new insights into long-term whole-profile SOC dynamics at a large scale,offering valuable implications for carbon sequestration to support sustainable development in different ecosystems.
基金supported by the National Key Research and Development Program Plan(Grant No.2022YFC3800802)the Special Fund of Jiangsu Province Carbon Peak and Carbon Neutral Technology Innovation(Grant No.BK20220037)+1 种基金Fundamental Research Funds for the Central Universities(Grant No.0209-14380115)grant from State Key Laboratory of Resources and Environmental Information System.
文摘Coastal wetlands are important blue carbon ecosystems that play a significant role in the global carbon cycle.However,there is insufficient understanding of the variations in soil organic carbon(SOC)stocks and the mechanisms driving these ecosystems.Here we analyze a comprehensive multi-source dataset of SOC in topsoil(0e20 cm)and subsoil(20e100 cm)across 31 coastal wetlands in China to identify the factors influencing their distribution.Structural equation models(SEMs)reveal that hydrology has the greatest overall effect on SOC in both soil layers,followed by vegetation,soil properties,and climate.Notably,the mechanisms driving SOC density differ between the two layers.In topsoil,vegetation type and productivity directly impact carbon density as primary sources of carbon input,while hydrology,primarily through seawater salinity,exerts the largest indirect influence.Conversely,in subsoil,hydrology has the strongest direct effect on SOC,with seawater salinity also influencing SOC indirectly through soil and vegetation mediation.Soil properties,particularly pH,negatively affect carbon accumulation,while climate influences SOC indirectly via its effects on vegetation and soil,with a diminishing impact at greater depths.Using Random Forest,we generate high-resolution maps(90 m90 m)of topsoil and subsoil carbon density(R2 of 0.53 and 0.62,respectively),providing the most detailed spatial distribution of SOC in Chinese coastal wetlands to date.Based on these maps,we estimate that SOC storage to a depth of 1 m in Chinese coastal wetlands totals 74.58±3.85 Tg C,with subsoil carbon storage being 2.5 times greater than that in topsoil.These findings provide important insights into mechanism on driving spatial pattern of blue carbon and effective ways to assess carbon status on a national scale,thus contributing to the advancement of global blue carbon monitoring and management.
