DIGITALNA ARHIVA ŠUMARSKOG LISTA
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| ŠUMARSKI LIST 9-10/2018 str. 83 <-- 83 --> PDF |
In the three sample plots of the plant community, the heavily disturbed soil had significantly lower sucrase, catalase, urease, and chitinase activities than the lightly disturbed soil (Figure 3, Table 2). Sucrase enzyme activity showed significant differences between lightly and moderately disturbed soils between treatments in both Ligustrum lucidum and Ficus virens communities (Figure 3). No significant changes were observed in catalase activity between lightly and moderately disturbed soils in the three plant communities, and significant differences were noted in urease and chitinase activities between mildly and moderately disturbed soils in both L. lucidum and F. virens communities (Figure 3). These results indicate that the sucrase enzyme is most sensitive to tourism disturbance and the catalase enzyme is the least. Each of the enzymes examined in this study can act as important indicators of certain soil characteristics. For example, the sucrase enzyme is highly significant because it can be used to characterize the carbon cycle and microbial metabolic activity of soil (Li et al., 2015; Tomkiel et al., 2015). It is able to reflect the transformation rules concerning accumulation and decomposition of SOC (Sumathi and Thaddeus, 2013; Li, 2015). Tourism disturbance decreases the soil sucrase activity, indicating that the transformation of organic matter in soil decreases with increasing disturbance intensity. The decreased mineralization of plant litter, root exudates, and roots in turn reduce the soil organic matter and the soil sucrase transformational substrate. As for catalase, it is an indicator of the microbial oxidation reduction system and thus can characterize the microbial oxidizing ability of microorganisms in the soil (Tomkiel et al., 2015). Compared with lightly disturbed soils, catalase was usually lower in the moderately and heavily disturbed soils in this study, which might be because tourism disturbance suppresses the growth and reproduction of microorganisms and reduces the catalase source to a certain extent. Finally, urease and chitinase enzymatic activities can contribute to the soil nitrogen cycle and related soil activities, which are affected by soil nitrogen availability (Dindar et al., 2015). Tourism disturbance destroys the litter layer and the humus layer, decreases the soil organic matter, and reduces the soil nitrogen content, urease activity, and chitinase activity. Furthermore, severe tourism disturbance results in compacted and exposed soil and changes the hydrothermal conditions of the soil, which is not beneficial for soil microbial abilities, and thus, urease activity and other enzyme activities decrease (Li 2015; Tomkiel et al., 2015). The correlational analyses between the soil carbon and nitrogen forms and soil enzyme activities show that all, except NH4+–N, exhibit significant positive correlations with sucrase, catalase, urease, and chitinase activity (Table 2). The close relationship between soil carbon and nitrogen |