Improving the design of long-term monitoring experiments in forests: a new method for the assessment of local soil variability by combining infrared spectroscopy and dendrometric data

Abstract

Abstract& Key message Near-and mid-infrared spectroscopy

Tree genotype and seasonal effects on soil properties and biogeochemical functioning in Mediterranean pine forests

“…confirmed by NIR-MIR spectroscopy without preliminary calibration, which provided an overall view of the soils. Because NIR and MIR spectra reflect a set of soil constituents that can be determined simultaneously, the use of raw spectra alone has been proposed previously to monitor soil properties in an integrative way to discriminate between different levels of an ecological factor (Cécillon et al, 2009;Akroume et al, 2016). However, this issue remains controversial (Terhoeven-Urselmans et al, 2006;Viscarra Rossel et al, 2006;Ludwig et al, 2008Ludwig et al, , 2015, and these techniques should be used in combination with calibration and multivariate regression methods to obtain a precise characterization of the soil properties of experimental sites.…”

“…The MIR method is assumed to be a suitable predictor for organic matter composition, whereas the NIR one is commonly used to predict soil C and N stocks (Ludwig et al, 2008;Soriano-Disla et al, 2014). However, these assumptions are still under debate and the combined use of NIR and MIR is recommended for more efficient characterization of soil (Viscarra Rossel et al, 2006;Akroume et al, 2016). Compared with MIR, the total NIR spectrum showed the effect of tree genotype better on our soils.…”

“…Because infrared spectroscopic techniques are sensitive to specific molecular vibrations of both organic and mineral soil components and can also measure accurately several physical, chemical and biological properties at the same time, they are widely recognized as suitable tools for assessing and monitoring soil (Viscarra Rossel et al, 2006;Knox et al, 2015;Ludwig et al, 2015). Although inherent differences in the near-infrared (NIR) and mid-infrared (MIR) spectral regions occur (for example in the NIR region overlapping combinations and overtone peaks may appear, and in the MIR region many bands correspond to simple compounds) (Bellon-Maurel & McBratney, 2011), both approaches have been used widely for qualitative and quantitative analysis of soil (Reeves, 2010;Akroume et al, 2016). Therefore, infrared approaches may be appropriate where precise identification of components is not required (Reeves et al, 2000).…”

“…Therefore, infrared approaches may be appropriate where precise identification of components is not required (Reeves et al, 2000). Indeed, Akroume et al (2016) suggested the application of principal component analysis to raw spectral data as a fitted representative of the global status of soils. By doing this, they demonstrated that the use of NIR and MIR spectroscopy without calibration was a useful tool for characterizing the overall heterogeneity of soil chemical properties.…”

Soil microbial functions are affected by organic matter removal in temperate deciduous forest

“…Moreover, Achat et al (2015b) indicated that long term impact of intensive forestry remains poorly examined and notably on soil microbial compartment. In the present study, we measured soil parameters and associated microbial functions in six temperate beech forest sites of a new long-term observational French network, comparing OM removal treatment and conventional forest management (Akroume et al, 2016). This large-scale investigation aims to mimic the effect of middle / long-term OM removal thanks artificial and annual exportation of woody debris and litter layer (Stone, 2001).…”