Can Naturalness Indicator Values Reveal Habitat Degradation? A Test of Four Methodological Approaches

Assessment of Naturalness: The Response of Social Behavior Types of Plants to Anthropogenic Impact

The aims of this research are to assess the relationship between the concepts of hemeroby and naturalness of plant communities and to test the hypothesis about the ordinal nature of the response of social behavior types of plants under anthropogenic influence. Study area is the recreational zone of the Botanical Garden of Dnipro National University, named after Oles Gonchar, Dnipro City, Ukraine (48.43°N 35.05°E). Four polygons (105 relevés in each) were examined. Two polygons were in the zone after park reconstruction, and two were in the zone without reconstruction. The vegetation community ordination was performed using RLQ analysis. The Q-table was represented by eight dummy variables, which indicated social behavior types. The most important predictors of naturalness were aggressive alien species and invaders and weeds (positive dependence) and disturbance tolerants (negative dependence). The most important predictors of hemeroby were aggressive alien species (negative dependence) and ruderal competitors, invaders, and disturbance tolerants (positive dependence). Naturalness and hemeroby reflect different strategies for transforming a plant community and are not completely symmetrically opposed concepts. The response of a plant community is multivariate, so the naturalness metric based on the social behavior types is only able to distinguish well between the extreme states of a plant community, but is a poor measure for a more detailed assessment of naturalness.

An Approach to Thresholds for Evaluating Post-Mining Site Reclamation

Here, a time-scale conceptual threshold model for assessing, evaluating, documenting, and monitoring post-mining sites reclamation progress was developed. It begins from initial state I0 down to degraded state D0 (which depends on the mining). Reclamation starts with soil reconstruction R−2 up to revegetation R−1 (red zones) to reach minimum threshold R0 (amber zone). Beyond R0 are green zones R1, R2, and R3 representing soil/abiotic conditions, biological, and improved threshold, respectively. The model also identifies potential drivers, land-use options, targets, and endpoints along the threshold reclamation ladder. It is applicable to all degraded ecosystems and adoptable in national and international laws. In this approach study, we identified threshold biotic/abiotic indicators for ascertaining success from R0, future work focuses on measurement and ascribing of threshold values to each of the threshold stage.

Karst environments and disturbance: evaluation of the effects of human activity on grassland and forest naturalness in dolines

Karst depressions (dolines) have the potential to act as safe havens for a high diversity of valuable species. We showed that local anthropogenic disturbances play a significant role in determining the naturalness of dolines. We compared the number of specialist species, competitor species, generalist species and species of disturbed habitats between natural and disturbed dolines in two Hungarian karst areas, where different types of anthropogenic disturbances have been shaping the vegetation for centuries. We found that these disturbances have the potential to negatively influence the naturalness of dolines, reducing the number of valuable species, thus affecting the conservation value of dolines. To maintain the naturalness of vegetation in these doline habitats, the populations of ruderal competitors should be eliminated, and sustainable forest management should be adapted. However, there are still open questions about the effects of different disturbances on the naturalness in dolines that need to be answered to determine which conservation strategies will be particularly suitable for valuable species in a warming climate.

Bioindication of human-induced soil degradation in enclosed karst depressions (dolines) using Ellenberg indicator values (Classical Karst, Slovenia)

One of the frequently used bioindication methods is Ellenberg indicator values (EIVs), which are commonly applied in Central Europe as bioindicators of ecological characteristics. However, very few studies have tested EIVs as a bioindication of human-induced soil degradation. We tested the ability of EIVs to distinguish between localities of degraded karst depressions (dolines) and localities of semi-natural (agricultural) soils in preserved dolines on the Kras Plateau (Classical Karst, SW Slovenia). We compared the results of bioindications of soil nutrient content (N), soil reaction (R) and soil moisture (M) with measured soil parameters. Low values of organic carbon, a slightly alkaline soil reaction and low organic sulphur content are chemical indicators of soil degradation in dolines, in comparison with preserved reference dolines (high organic carbon, slightly acid reaction, higher S). EIV reaction is the most reliable plant indicator value that can distinguish between degraded and non-degraded soil plots. According to a regression tree, sulphur (S) and C/N are the most important factors for division on the basis of EIV reaction. By applying the EIV reaction of diagnostic plant species, we significantly improved bioindication of soil degradation, although in the case of EIV nutrients, bioindication was not improved.