## 4 Discussion
### Structure of Soil \(CO_{2}\) Efflux  
One of the main reasons for the lack of HR and RR data from regular long-term observations is the difficulty and complexity of separating the components of soil respiration in the field [(19; 20)]. Most of the approaches are not suitable for long-term, full-year, frequent (not less than 1 per month, but, actually, 1/Mo is not frequent) observations. This is probably why the few regular observations of HR in the field are based on simple methods for separating HR from SR, such as girdling, trenching, root exclusion, and component integrations [(39; 40)]. However, these methods vary in the degree to which they isolate HR. \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline  & \multicolumn{3}{c}{**SR**} & \multicolumn{3}{c}{**HR**} & \multicolumn{3}{c}{**RR**} \\ \cline{2-13}
**Period 1** & \multicolumn{3}{c}{**2022–2023**} & \multicolumn{3}{c}{**2023–2024**} & \multicolumn{3}{c}{**2022–2023**} & \multicolumn{3}{c}{**2023–2024**} & \multicolumn{3}{c}{**2022–2023**} & \multicolumn{3}{c}{**2023–2024**} \\ \cline{2-13}  & **F** & **G** & **F** & **G** & **F** & **G** & **F** & **G** & **F** & **G** \\ \hline Summer (January–August) & 214 & 333 & 194 & 262 & 163 & 112 & 120 & 83 (9) & 51 & 222 & 179 (14) & 74 (9) & 179 (11) \\ Autumn (September–November) & 141 & 127 & 118 & 122 & 83 (3) & 33 (2) & 64 (2) & 33 (3) & 59 (7) & 94 (6) & 54 (7) & 90 (6) \\ Winter (December–February) & 55 (5) & 37 (4) & 72 (5) & 63 (3) & 32 (3) & 10 (2) & 43 (3) & 23 (4) & 23 (6) & 27 (4) & 28 (6) & 40 (5) \\ Spring (March–May) & 91 (5) & 170 & 106 & 174 & 174 & 12 & 56 (3) & 29 (2) & 55 (3) & 33 (3) & 35 (6) & 142 (8) & 51 (6) & 141 (12) \\ \hline Cold season (November–April) & 101 & 78 (5) & 123 & 101 & 59 (4) & 21 (2) & 74 (3) & 40 (5) & 43 (7) & 58 (5) & 49 (7) & 61 (6) \\ Warm season (May–October) & 402 & 587 & 370 & 525 & 277 & 164 & 210 & 134 & 125 & 424 & 160 (391) \\  & (16) & (16) & (11) & (15) & (8) & (6) & (4) & (9) & (15) & (17) & (12) & (17) \\ \hline Year & 504 & 667 & 495 & 626 & 336 & 185 & 284 & 174 & 168 & 483 & 210 & 453 (15) \\  & (15) & (16) & (13) & (15) & (9) & (6) & (5) & (11) & (16) & (18) & (14) & (18) \\ \hline \hline \end{tabular}  
* 1 June was taken at the beginning of the year. Confidence intervals (95%) are shown in brackets.  
\end{table} 
Table 3: Mean values of the seasonal total soil (SR), SOM-derived heterotrophs (HR) and root-derived (RR) respiration (CO\({}_{2}\)) in the forest (F) and the grassland (G) ecosystems for two years observation. For instance, the HR contribution estimates we obtained here were lower than the previously conducted SR component determined in these areas using the component integration method: 45-80% vs. 80-99% in the forest and 15-40% vs. 40-90% in the grassland [22; 41]. These differences were expected due to the methodological underestimation of HR from the rhizosphere and root decomposition [42; 43]. If the RR contribution obtained using the component integration method is subtracted from our RR estimates, the contribution of the rhizosphere and detritus to SR will be 1/2 in the grassland and 1/3 in the forest. On the other hand, these will contribute to a total HR of 2/3 in the grassland and 2/5 in the forest. This is a very rough estimate, but it provides an overview of the sources of CO\({}_{2}\) emissions in the two contrasting ecosystems. The absence of clear seasonal patterns in HR share was unexpected. This means that CO\({}_{2}\) fluxes from roots, rhizodeposits, and detritus vs. from SOM and forest floor litter are generally in balance throughout the year. However, the mean share of HR in total seasonal SR during the offseason was a little, but significantly, lower than during summer or winter. These mean differences (in absolute share HR in SR) were 7% in the forest and 10% in the grassland (two-way ANOVA, \(p<0.05\)). The composition of soil microbial communities changes with the seasons [44].