Linking Remotely Sensed Carbon and Water Use Efficiencies with In Situ Soil Properties

Bassil El Masri,Jingfeng Xiao,Sora L Kim,Benedict Ferguson,Joshua B Fisher,Haluk Cetin,Gary E Stinchcomb

doi:10.3390/rs13132593

Abstract

The capacity of terrestrial ecosystems to sequester carbon dioxide (CO2) from the atmosphere is expected to be altered by climate change and CO2 fertilization, but this projection is limited by our understanding of how the soil system interacts with plants. Understanding the soil–vegetation interactions is essential to assess the magnitude and response of terrestrial ecosystems to the changing climate. Here, we used soil profile and satellite data to explore the role that soil properties play in regulating water and carbon use by plants. Data obtained for 19 terrestrial ecosystem sites in a warm temperate and humid climate were used to investigate the relationship between remotely sensed data and soil physical and chemical properties. Classification and regression tree results showed that in situ soil carbon isotope (δ13C), and soil order were significant predictors (r2 = 0.39, mean absolute error (MAE) = 0 of 0.175 gC/KgH2O) of remotely sensed water use efficiency (WUE) based on the Moderate Resolution Imaging Spectroradiometer (MODIS). Soil extractable calcium (Ca), and land cover type were significant predictors of remotely sensed carbon use efficiency (CUE) based on MODIS and Landsat data-(r2 = 0.64–0.78, MAE = 0.04–0.06). We used gross primary productivity (GPP) derived from solar-induced fluorescence (SIF) data, based on the Orbiting Carbon Observatory-2 (OCO-2), to calculate WUE and CUE (referred to as WUESIF and CUESIF, respectively) for our study sites. The regression tree analysis revealed that soil organic matter and soil extractable magnesium (Mg), δ13C, and soil silt content were the important predictors of both WUESIF (r2 = 0.19, MAE = 0.64 gC/KgH2O) and CUESIF (r2 = 0.45, MAE = 0.1), respectively. Our results revealed the importance of soil extractable Ca, soil carbon (S13C is a facet of soil carbon content), and soil organic matter predicting CUE and WUE. Insights gained from this study highlighted the importance of biotic and abiotic factors regulating plant and soil interactions. These types of data are timely and critical for accurate predictions of how terrestrial ecosystems respond to climate change.

Highlights

We found that Moderate Resolution Imaging Spectroradiometer (MODIS) water use efficiency (WUE) outperformed WUESIF likely because gC/KgHhad
classification and regression trees (CART) CUESIF models did not show that soil depth was an important predictor of WUE and CUESIF, they did reveal an indirect indication of the soil depth-related properties in regulating WUE and carbon use efficiency (CUE) as evident in Figures 4, 5 and 8
Data from the 19 sites representative of the major land cover types occurring in a warm-temperate and humid climate were used to investigate the capability of satellite data to derive meaningful information about the soil–vegetation interactions

Summary

Introduction

Plant growth is tightly coupled with soil nutrients, nitrogen (N) and phosphorus (P) [1,2,3,4], and limitation of these nutrients is assumed to be one of the drivers of observed spatial variability in ecosystem carbon (C) fluxes [5,6,7], terrestrial. Soil P is a limiting factor of global terrestrial ecosystem productivity [12,13], and studies have shown that P limitation on plant growth occurs more frequently than previously thought [3]. Soil age is a key factor determining nutrient content and the type of nutrients that limit vegetation productivity [25,26]. The concentrations of soil nutrients vary with soil depth [28]. Root systems and plant uptake along with hydrology and microbial communities have strong effects on the vertical distribution of soil nutrients [28,31]

Methods

Results

Discussion

Conclusion