**4. Interpreting active hillslope processes using polypore species**

The indication and dating of hillslope processes connected with biotic communities is limited by the suitability of species (see in the previous sections) and by the time scale pursued by the research. Whereas the former applications of dendrochronologic dating focused on the identification of processes that occurred on a scale of years to hundreds of years (Stoffel et al., 2005; for overview see Fig. 3), and effort has been made to extend the time-span of reference datasets, the dating of current dynamics encounters several problems. Aside from minimal time, which is necessary for tree-ring growth, there are further constraints regarding the differences in the wood anatomy of different species and the limits of dating decomposed trunks. Dating at a time scale of months to a few years, therefore, calls for other proxy data.

An opportunity is given by a study of the succession of organisms at newly established habitats that have been formed as a result of Earth surface dynamics (e.g., Beschel, 1961; Pérez, 2010). Considering hillslope processes, these habitats may include log jams and trunk dams, which are colonised by various species (Masser et al., 1984). In this section, we focus on polypores (*Polyporales*).

size of distributed model was set to 400 m2, which reflects the precision of the input digital data (cf. Hengl, 2006). As the accumulation width is calculated from slope inclination and the "x" value, it can reach high values in locations with flat terrain; but, in fact, the accumulation width is always limited by the neighbouring trunk dams. The maximum accumulation width can be derived from a simple equation assuming the regular

where PS is pixel size (i.e., 20 m for a pixel area of 400 m2), and tL is the total length of trunks per pixel (i.e., 100 m). The result is a maximum accumulation width of 4 m, which was the value put as an upper limit into the model before acquiring the results of VAM.

The results of the modelling are shown in Fig. 7C, indicating that VAM varies between 1 - 70 m3 per 400 m2, i.e., 25 – 1750 m3.ha-1, but these values seem to be far from the real situation. The reason is that the "x" value was set constant, and therefore, the model assumes that the lower the slope inclination, the higher the accumulation width (see above) and VAM (see also Fig. 6C). In fact, the real processes operating on low gradient slopes will hardly enable accumulation of the material in the trunk dam with a similar efficiency as on highly inclined slopes. Evidently, there are other factors that influence the potential of trunk dams to be filled with accumulated material, such as the length of slope above the trunk dam, the surface material on the slope, and the disturbance regimes affecting the movement of material (e.g., overland flow, zoodisturbances, forest management measures). However, the slope inclination tends to be the most important of these factors according to our observations. The model (Fig. 7C) was therefore weighted again by the slope inclination to give higher importance to slopes with a high gradient and vice versa. The results of VAM in Fig. 7D vary between 2.2 - 4.0 m3 per 400 m2, which corresponds quite well to the empirical values gained during the field survey. Nevertheless, the development of the model is still in

progress, and the results may differ when computed for more variable input values.

The indication and dating of hillslope processes connected with biotic communities is limited by the suitability of species (see in the previous sections) and by the time scale pursued by the research. Whereas the former applications of dendrochronologic dating focused on the identification of processes that occurred on a scale of years to hundreds of years (Stoffel et al., 2005; for overview see Fig. 3), and effort has been made to extend the time-span of reference datasets, the dating of current dynamics encounters several problems. Aside from minimal time, which is necessary for tree-ring growth, there are further constraints regarding the differences in the wood anatomy of different species and the limits of dating decomposed trunks. Dating at a time scale of months to a few years,

An opportunity is given by a study of the succession of organisms at newly established habitats that have been formed as a result of Earth surface dynamics (e.g., Beschel, 1961; Pérez, 2010). Considering hillslope processes, these habitats may include log jams and trunk dams, which are colonised by various species (Masser et al., 1984). In this section, we focus

**4. Interpreting active hillslope processes using polypore species** 

max a = PS2/tL (2)

distribution of trunk dams:

therefore, calls for other proxy data.

on polypores (*Polyporales*).

Polyporous fungi belong to dead-wood-dependent organisms, and they contribute to the continuity of forest renewal by accelerating wood decay processes. The fungi-accelerated wood decay, in turn, improves the integrity of forest ecology and, therefore, the ecology of polypores must be reflected in forest management approaches (Lindblad, 1998). The diversity and abundance of polyporous fungi depends on the species diversity of trees, forest connectivity and the number of downed logs (Edman & Jonsson, 2001; Hottola, et al. 2009). Species richness also plays a role in the decay stage of wood and tree diameter, although the latter relation is a current topic of discussion (Junninen & Komonen, 2011). Although some polypores are able to establish ectomycorrhizal relationships, most polypore species are wood-dependent parasites, saprotrophs and necrotrophs. The reproduction principles and their relation to life histories and the diversity of polypore species are well discussed by Kauserud et al. (2008).


Table 3. Selected Central European polypore species suitable for the indication of log jam dynamics and their usual habitats.

The fundamental importance for biogeomorphologic studies is represented by the basic ecological and morphological characteristics of polypores, especially the following:


Biogeomorphologic Approaches to

in the dynamics of the log jam.


a Study of Hillslope Processes Using Non-Destructive Methods 37

woody debris. To understand the evolutionary history of the log jam, we analysed the distribution of polypore individuals on the major trunks located in the channel. The results indicate that different polypore species are located in variable positions within the trunk both in terms of the cross-section position through the trunk (Fig. 9) and of the position along the trunk. The typical morphology of the present species is depicted in Fig. 10. The deformations of individuals and the relation of different types of species and of living and decomposed polypores to positions within the trunk allowed us to specify the major events

Fig. 10. Front and side views of the polypores on trunk number 1 and 1c. A - *Fomitopsis sp.*, B

Fig. 11. Interpretation of the evolutionary history of two log jams based on polypore anatomy. The actual position after disturbance is shown by the white line and the hypothetic horizontal position by white dashed line. The black and white schemes in the

While the minimal height of living individuals above the water surface was approximately 0.5 m, the dead individuals were frequently located in the contact zone with the water surface. The presence of old decomposed polypores in an unsuitable position in contact with the water surface indicates the occurrence of an event that moved the trunk downward. The tilting and rotation of individuals caused by the movement of the host trunk is shown in Fig.

right bottom depict evolutionary histories of the two log jams.

Fig. 8. Geomorphologic sketch of the study site showing the positions of trunks in the channel of a small water stream.

Polypores, which are suitable for the interpretation of the evolutionary history of log jams and fallen trees, predominantly grow horizontally with detectable increment rates. The indication of hillslope processes (erosion, shallow landslides) that affected the log jams and fallen trees is then allowed by the identification of the deformations of individuals. The most common deformations are tilting from the horizontal position and abnormal increments caused by the rotation of the host wood.

Fig. 9. Position of polypores on trunk number 1 and 1c (Fig. 8). Sp. 1 - *Fomitopsis sp.*, sp. 2 - *Daedalea sp.*, necr. - decomposed individuals.

We have carried out a detailed case study of the dynamics of a log jam in a small water stream and compared it with other examples from Central European forests. Fig. 8 presents a geomorphologic sketch of the study site with a log jam in the channel. The log jam was formed as a result of tree downing induced by lateral erosion in a deeply incised channel. After the major trunk was embedded in the channel, it stopped other allochthonous coarse

Fig. 8. Geomorphologic sketch of the study site showing the positions of trunks in the

Polypores, which are suitable for the interpretation of the evolutionary history of log jams and fallen trees, predominantly grow horizontally with detectable increment rates. The indication of hillslope processes (erosion, shallow landslides) that affected the log jams and fallen trees is then allowed by the identification of the deformations of individuals. The most common deformations are tilting from the horizontal position and abnormal increments

Fig. 9. Position of polypores on trunk number 1 and 1c (Fig. 8). Sp. 1 - *Fomitopsis sp.*, sp. 2 -

We have carried out a detailed case study of the dynamics of a log jam in a small water stream and compared it with other examples from Central European forests. Fig. 8 presents a geomorphologic sketch of the study site with a log jam in the channel. The log jam was formed as a result of tree downing induced by lateral erosion in a deeply incised channel. After the major trunk was embedded in the channel, it stopped other allochthonous coarse

channel of a small water stream.

caused by the rotation of the host wood.

*Daedalea sp.*, necr. - decomposed individuals.

woody debris. To understand the evolutionary history of the log jam, we analysed the distribution of polypore individuals on the major trunks located in the channel. The results indicate that different polypore species are located in variable positions within the trunk both in terms of the cross-section position through the trunk (Fig. 9) and of the position along the trunk. The typical morphology of the present species is depicted in Fig. 10. The deformations of individuals and the relation of different types of species and of living and decomposed polypores to positions within the trunk allowed us to specify the major events in the dynamics of the log jam.

Fig. 10. Front and side views of the polypores on trunk number 1 and 1c. A - *Fomitopsis sp.*, B - *Daedalea sp.*

Fig. 11. Interpretation of the evolutionary history of two log jams based on polypore anatomy. The actual position after disturbance is shown by the white line and the hypothetic horizontal position by white dashed line. The black and white schemes in the right bottom depict evolutionary histories of the two log jams.

While the minimal height of living individuals above the water surface was approximately 0.5 m, the dead individuals were frequently located in the contact zone with the water surface. The presence of old decomposed polypores in an unsuitable position in contact with the water surface indicates the occurrence of an event that moved the trunk downward. The tilting and rotation of individuals caused by the movement of the host trunk is shown in Fig.

Biogeomorphologic Approaches to

a Study of Hillslope Processes Using Non-Destructive Methods 39

grazed land (Cluzeau et al., 1992; Trimble & Mendel, 1995). Despite producing important information about the rates of animal induced surface dynamics, these studies are scale dependent because their methodical background is time-exhaustive (detailed mapping and experiments). The opportunity to generalise the results of these studies lies in drawing from

The example for consideration will be given from the study area, which was presented in the case studies in this chapter. The forest ecosystems of the studied catchment are diversified by patches of rock-mantled slopes and talus scree deposits, which have formed by the disintegration of rock-cliffs built by basaltic rocks since the Late Glacial Period. There are more than 100 such talus slope deposits exceeding an individual area of 400 m2. During the study of these deposits, we focused on different types of processes, among which zoodisturbances tend to play an important role. Nevertheless, the monitoring of animal trampling on talus slope deposits exceeded the possibility of the research, so the other approach had to be adopted. The major trampling specie in the area is mouflon (*Ovis musimon*), which is an introduced specie in the Czech Republic (Heroldova & Homolka, 2001). As shown by Cransac & Hewison (1997), the seasonal activity and selection of habitats of mouflon hordes in their original environment is dependent on several variables, such as feeding activity and climate. During the year, the hordes are partly bound to rocky habitats. In our study area, it was confirmed by observation that talus slope deposits indeed represent an alternative habitat for mouflon hordes. The information about mouflon ethology together with the observation at talus slope deposits, where the presence of mouflon hordes was confirmed, enabled the specification of results from the field mapping of microtopographic features (especially clast flows) present on talus slope deposits (Raska, 2010). A similar approach could be applied to reveal the spatial behaviour and specific

To summarise, we are aware that there are many biogeomorphologic studies that are relatively close to non-destructive approaches, but were not mentioned in this chapter due to its limited extent. We refer readers to more complete reviews of biogeomorphology, dendrogeomorphology, and zoogeomorphology as well as the problem of soil erosion, which is too broad to be discussed in detail herein. The main aim of the chapter was to emphasise the importance of non-destructive biogeomorphologic approaches for a better understanding of the interwoven relationships between the Earth surface and organisms and to document this with two methods, which are currently being developed and applied

Certain parts of the research were performed thanks to financial support from the research project IGA UJEP Disturbance regimes in the Quaternary morphogenesis of the Elbe river valley in the central part of the Ceske stredohori Mts. The author would like to thank

Abe, K. & Ziemer, R.R. (1991). Effect of Tree Roots on Shallow-Seated Landslides. *USDA* 

*Forest Service Gen. Technical Report PSW-GTR*, Vol.130, pp. 11-20

ethological information about the ecological behaviour of the studied species.

effects of other trampling species or burrowing animals.

at the catchment scale within the presented case studies.

Language Editing Services for the English style revision.

**6. Acknowledgements** 

**7. References** 

11, which depicts sample trunk number 1 (Fig. 11 left; see position in Fig. 8) and a comparative case of log jam from Western Carpathians (Fig. 11 right). The reconstruction of evolutionary history based on the identification of tilting and rotation determined the main processes that play a role in consecutive stages of log jam evolution and the interrelation with the surface morphology and dynamics of the locality. These processes include the initial fall of the tree, sliding, rotation and trunk breach.
