Land use and land cover changes in coastal and inland wetlands cause soil carbon and nitrogen loss

Abstract

Aim Natural wetlands are widely considered important for mitigation of climate change, but they have been impacted by land use and land cover change (LULCC), often resulting in ecosystem degradation and significant changes in soil carbon (C) and nitrogen (N) dynamics. However, the impact of various LULCC types on wetland soil C and N dynamics remains unclear. Location Global. Time period 1982–2021. Major taxa studied Wetland. Methods We present a global meta‐analysis using a database of 487 sites compiled from the literature, demonstrating the response of soil C and N concentrations and stocks in coastal wetlands, riparian wetlands and peatlands to various types of LULCCs, including agricultural lands, drained wetlands, aquaculture ponds, pastures and constructed wetlands. Results The conversion of coastal wetlands, riparian wetlands and peatlands to most LULCC types decreased the mean soil C and N concentrations and stocks by 17.8 ± 10.3, 25.3 ± 13.4 and 23.2 ± 6.3%, respectively. The loss of wetland soil C owing to LULCC is estimated to cause a potential CO2 emission of 1.8–22.8 Mg CO2 equivalent emission/ha/year, except for conversion to constructed wetlands. The soil C and N contents were more sensitive to LULCCs, relative to the stocks. We also found that the patterns of soil C and N variations were closely related to the conversion time since completion of LULCC. After LULCC, the response of soil C and N variables was sensitive to changes in plant biomass, soil water conditions, bulk density, pH and NH4+‐N concentration, with the major controlling factors varying with the conversion age. Main conclusions Our results highlight the important role of LULCC in triggering soil C and N loss in natural wetlands, which enhances the greenhouse effect. As such, our study calls for sustainable land management strategies aiming at wetland conservation as a powerful tool to mitigate climate warming.

Effects of spatial variability in vegetation phenology, climate, landcover, biodiversity, topography, and soil property on soil respiration across a coastal ecosystem

“…Chen et al [ 143 ] reported that seawater intrusion due to sea level rise reduced soil carbon emissions from freshwater wetlands in the Yellow River estuarine delta of China. The transformation of land use may significantly impact the ecological, topographic, and biochemical features within TAIs, warranting further investigation into its effects on soil respiration [ 144 ]. Nevertheless, the developed framework presented in this study offers the opportunity to bring together different data streams and characterize the spatial heterogeneity driving the ecosystem processes and therefore can be used to perform more in-depth investigation for specific case studies.…”

China's wetland soil organic carbon pool: New estimation on pool size, change, and trajectory

“…The main texts and the supplementary files, if available, of these 241 papers were checked to identify databases with SOC density measurements. Raw data were obtained from tables or when not available in tables, extracted by digitizing graphs using GetData Graph Digitizer (version 2.24; http://www.getdata-graph-digitizer.com/) and Origin (version 2021b; OriginLab Corporation), which have provided highly accurate extracted data (>99%) for various meta‐analyses and synthesis (He et al, 2021; Tan et al, 2022). The final dataset comprised 181 studies published during 2000–2020.…”

“…com/) and Origin (version 2021b; OriginLab Corporation), which have provided highly accurate extracted data (>99%) for various meta-analyses and synthesis (He et al, 2021;Tan et al, 2022). The final dataset comprised 181 studies published during 2000-2020.…”

“…Wetlands are an important part of terrestrial carbon pool in the global carbon cycle (DeLaune et al, 2018;Jackson et al, 2017;Mitsch et al, 2013). Wetland soil organic carbon (SOC) shows high spatial heterogeneity because of its vulnerability to climate change and human influence (Jobbágy & Jackson, 2000;Tan et al, 2022).…”

“…Wetlands are an important part of terrestrial carbon pool in the global carbon cycle (DeLaune et al, 2018; Jackson et al, 2017; Mitsch et al, 2013). Wetland soil organic carbon (SOC) shows high spatial heterogeneity because of its vulnerability to climate change and human influence (Jobbágy & Jackson, 2000; Tan et al, 2022). Changes in wetland SOC storage have effects on climate through greenhouse gas emissions, even with a slight magnitude, which may lead to critical disturbance to the global carbon cycle and climate (Bloom et al, 2017; Mitsch et al, 2013; Tan et al, 2020).…”