## 3 Results and Discussion
### Morphological Decay Pattern  
The identification of degradation patterns in most archaeological wood is based on their distinct decay patterns left behind like fingerprints due to the absence of the active degrading agents. Therefore, the characteristic troughs that are seen in the degraded cell walls are a particular distinguishing feature [1]. The microstructure of the archaeological elm and poplar samples was evaluated by means of light and scanning electron micro  
Figure 2: Fourier-transform infrared spectroscopy (FTIR) spectra of recently cut and archaeological elm (**a**,**b**) and poplar (**c**,**d**) in the region of 4000–2000 cm\({}^{-1}\) and 2000–400 cm\({}^{-1}\). Red lines are for recently cut samples and black lines are for archaeological samples. scopies. The light microscopy analyses of the recently cut and archaeological elm and poplar samples are presented in Figures 3 and 4. Figure 3: Light microscopy of cross-sections of recently cut (**a**) and archaeological elm (**b–d**) and from tangential section of archaeological elm using polarized light (**e.f**). Arrows indicate the damaged parts of archaeological wood samples. As compared with the recently cut sample (Figure 3a), extensive degradations were observed in the cross-section of the archaeological elm (Figure 3b-d). Only a few cells, i.e., particularly those cells at the annual ring boundary area, look intact (black arrows in Figure 3b,d). The degradation occurred from the lumen towards the ML (yellow arrow in Figure 3d), and the residual materials were left in the lumen (white arrows in Figure 3d). The middle lamellas remained intact in terms of degradation, but in some cases began to collapse (blue arrows in Figure 3c) due to stress, e.g., cutting process for sample degradation, and the final degradation pattern was not observed in the lumen. Figure 4: Light microscopy of cross-sections of recently cut (**a**) and archaeological poplar (**b**) and from tangential section of archaeological elm using polarized light (**c–e**). Arrows indicate the fungal hyphae (**c,d**) and bacterial degradation patterns (**e**) of archaeological wood samples. preparation. This degradation pattern is typically associated with erosion bacteria degradation [21; 37; 40; 46; 52]. The fine degradation pattern of bacteria was also found as grainy structures in the tangential section (white arrows in Figure 3e,f). No fungal hyphae were detected in the cross and tangential sections, and thus it is assumed that the archaeological elm was mainly degraded by erosion bacteria. Evidence of degradation by erosion bacteria means that the wood must have been stored for a long time under water-saturated, low-oxygen, or even oxygen-free conditions [1; 53; 54]. The fact that no fungal hyphae were found does not mean that fungi did not also decompose the wood, but probably in a relatively short time window before the conditions shifted in favor of the bacteria. Otherwise, fungal degradation patterns or hyphae would still be detectable. The buried storage conditions of this archaeological elm wood seem to have changed very quickly to dry conditions. The gravelly, sandy soil suggests the possibility that the water was able to drain away quickly. It can also be assumed that the wood dried very quickly afterwards, as otherwise traces and hyphae of fungus would have been found. The cross-section investigation of recently cut and archaeological poplar showed that the wood cells were highly degraded (Figure 4a,b), while the MLs stayed intact in the archaeological sample (Figure 4b). The collapse of the residual cell wall, mainly just the ML, (Figure 4b circle) is based on the reaction of stress by reduced strength. This could be pictured evidence of a brown-rot attack in the cross-sections. Fungal hyphae were not detected in the cross-section of archaeological poplar, but they were obviously shown in the tangential sections (Figure 4c-e). The direction of the fungal hyphae does not follow any particular orientation, as they are extended through the cells tangentially.