Biogeographic variation in temperature sensitivity of decomposition in forest soils

Abstract

Determining soil carbon (C) responses to rising temperature is critical for projections of the feedbacks between terrestrial ecosystems, C cycle, and climate change. However, the direction and magnitude of this feedback remain highly uncertain due largely to our limited understanding of the spatial heterogeneity of soil C decomposition and its temperature sensitivity. Here we quantified C decomposition and its response to temperature change with an incubation study of soils from 203 sites across tropical to boreal forests in China spanning a wide range of latitudes (18°16′ to 51°37′N) and longitudes (81°01′ to 129°28′E). Mean annual temperature (MAT) and mean annual precipitation primarily explained the biogeographic variation in the decomposition rate and temperature sensitivity of soils: soil C decomposition rate decreased from warm and wet forests to cold and dry forests, while Q10‐MAT (standardized to the MAT of each site) values displayed the opposite pattern. In contrast, biological factors (i.e. plant productivity and soil bacterial diversity) and soil factors (e.g. clay, pH, and C availability of microbial biomass C and dissolved organic C) played relatively small roles in the biogeographic patterns. Moreover, no significant relationship was found between Q10‐MAT and soil C quality, challenging the current C quality–temperature hypothesis. Using a single, fixed Q10‐MAT value (the mean across all forests), as is usually done in model predictions, would bias the estimated soil CO2 emissions at a temperature increase of 3.0°C. This would lead to overestimation of emissions in warm biomes, underestimation in cold biomes, and likely significant overestimation of overall C release from soil to the atmosphere. Our results highlight that climate‐related biogeographic variation in soil C responses to temperature needs to be included in next‐generation C cycle models to improve predictions of C‐climate feedbacks.

Rising Temperature May Trigger Deep Soil Carbon Loss Across Forest Ecosystems

“…The rate of SOC decomposition at each temperature was calculated on the basis of soil weight, net CO 2 accumulation in the headspace, sealing time (respiration time), and the headspace volume. [ 38,67 ]…”

The continent-scale variations in soil microbial respiration in forest ecosystems: diverged pattern and mechanism

“…We found that climate affected indirectly Rm's variation by changing different soil physicochemical and microbial properties at different scales (Fig. 5), although some previous studies demonstrated Rm was related to MAT and MAP at different scales (e.g., Li et al, 2020). At the continental scale, climate affected indirectly Rm by altering mainly LOC, fungal and gram-positive bacterial biomass (Fig.…”

How will a drier climate change carbon sequestration in soils of the deciduous forests of Central Europe?

“…The effects of temperature and precipitation on the C dynamics of forest and forest soils have been reported in numerous studies (e.g. Wei et al 2010;Balasmeh and Karmaker 2020;Li et al 2020), but results have been mixed, in part because climate has both direct effects on soil C balance through effects on biological processes, as well as indirect effects through changes to vegetation, root activity, and litter inputs. Thus, despite its important role in the biosphere and the global environmental system, interactions among physical, chemical and biological processes regulating SOM stabilization, accumulation, and turnover are poorly understood.…”