*Soil Degradation Processes Linked to Long-Term Forest-Type Damage DOI: http://dx.doi.org/10.5772/intechopen.106390*

The risk of heavy metal accumulation with toxic manifestations threatens not only tree species, but also predators. Numerous ground beetles (Carabidae) and ants (Formicidae) are mainly food-bound to phytophagous insects, earthworms, countless larvae and springtails [61]. On the other hand, the immobilization of heavy metals takes place in cells of specialized metallogeneic microorganisms by binding to metallothionein-based amino acids. Immobilization of heavy metals in amino acids changes course of humus formation. The rate of biosorption on the soil microbial active surfaces typically decreases in order Zn > Cd > Pb > Cu > Cr [62]. Alterations in the forest ecosystems as a result of heavy metal pollution include (**Figure 7**):


Petroleum products belong to secondary persistent organic compounds, similar to benzo(a)pyrene, polychlorinated dibenzo-p-dioxins or dibenzofurans, which are removed from the soil for more than 2 years [65]. Like benzo(a)pyrene, they consist of polycyclic aromatic hydrocarbons that directly harm the health of organisms. Oil pollution is significantly more caused by human activity than by natural (geogenic) sources. It begins with mining, combustion of petroleum products (fossil fuels), accidental or operational spills and corrosion of industrial materials. Oil products in the forest ecosystem load surface humus the most, which at the same time prevents their

#### **Figure 7.**

*Forests dying at regions loaded by acid deposition were transformed to substitute stands of resistant introduced tree species which have provided cover for regeneration of indigenous forest communities after pollution decrease.*

penetration into deeper occurring soil. The load of surface humus decreases activity of soil microorganisms. The decrease of soil biological activity is mostly caused by aromatic nuclei imitating lignin, which either block formation of amino acids or replace carbon compounds in fungi [66]. Subsequently, the humus decomposition is disrupted, foreshadowing disruption of processes to get available nutrients from the soil. Nevertheless, the load of petroleum substances is irregularly concentrated in surroundings of industrial areas and vertically along different intensities of wood logging in floodplains, hillycountries, highlands and high-mountain forests [67].
