## 2 Materials and Methods  
### Eddy Covariance and Net Ecosystem Exchange  
Subsequent to calculating NEE with the EC technique, it is usually partitioned into the components of \(R_{eco}\) and GPP, according to Equation (1). The partitioning is done using models that predict the rates of \(R_{eco}\) during daylight hours from nighttime observations (when GPP is zero) [19; 20]:  
\[\text{NEE}\ =\ R_{eco}\ +\ \text{GPP} \tag{1}\]  
In Equation (1), \(R_{eco}\) includes the contribution of CO\({}_{2}\) from heterotrophic respiration (R\({}_{h}\)) emitted by soil microbes and fauna, and autotrophic respiration (R\({}_{a}\)) emitted by vegetation; these components are not partitioned by typical NEE methods [16; 17]. NEE is based on established science and provides the commercial integrated carbon quantity of interest, net sequestered carbon or NEE employing widely used algorithms [19] in 600+ publications [21]. It can also be expressed as net ecosystem production (NEP): NEP = \(-\)NEE = \((-\)GPP) \(-\)\(R_{eco}\)[22]. While NEE does not directly probe soil carbon pools, \(R_{eco}\) provides a universal method to assess and quantify dynamic soil carbon sequestration, an approach that characterizes flux rather than bulk carbon pools that are regarded as static over time [23; 24]. The use of \({}^{13}\)CO\({}_{2}\) isotopic flux partitioning (IFP) [25], particularly attractive for forests (e.g., C3 woody species [26]), further differentiates and quantifies daytime and nighttime respiration providing the basis for new NEE derivative commercial high precision derivative products (e.g., Day \(R_{eco}\), Night \(R_{eco}\)) in contrast to non-isotopicNEE measurements and model based methods [27]. The need for improved quantification of soil carbon has been identified [28; 29; 30; 31; 32]. Fluxes derived from the EC methodology are commonly measured at micrometeorological towers with high-frequency instruments (10 Hz) and averaged over 15, 30, or 60 min periods to isolate turbulence effects from other scalar influences [33]. The towers commonly include other instruments to measure meteorological variables such as air and soil temperatures at different heights and depths (\(T_{air}\); T\({}_{soil}\)), incoming global radiation (Rg) or photosynthetically active radiation (PAR), vapor pressure deficit (VPD) or relative humidity (rH). As the measurement sites might be located in remote places in the ambient environment 24 h a day, 365 days a year, it is common to have \(\sim\)35% of missing data [34] due to system malfunctioning that cannot be repaired in real-time. For instance, storms, snows, high winds, and the insects or animals that live in the forest can damage the instruments, causing a break in data until repairs can be made, often resulting in gaps of days to weeks. Moreover, EC methodology can underestimate NEE over low turbulence conditions [35], thus these points have to be removed. This process may increase the number of missing data points to over 50% [36], but it is necessary to avoid biased data. The friction velocity (\(u_{*}\); Equation (2)) is a measure of turbulence, thus a \(u_{*}\) threshold can be used to classify the data into low and high turbulence periods. Some methodologies to estimate the \(u_{*}\) threshold are described in [35; 37]. \[u_{*}=\ \left(-\overline{u^{\prime}w^{\prime}}\right)\ ^{1/2} \tag{2}\]  
To calculate a CO\({}_{2}\) budget over a year or any time frame, it is necessary to integrate the flux value over the period, that is, to sum NEE measured at each interval over the whole period. We argue here that the universally accepted relationship (1), established by over 600 publications, is a requirement for the commercialization of forest carbon sequestration, and, further, we argue that the soil carbon component designated as a commercial entity cannot be separated from its above ground counterpart (e.g., forest, agriculture, grazing). The EC methodology integrates soil CO\({}_{2}\) efflux (\(R_{exo}\)) and photosynthesis (GPP) (e.g., (1)).