Using Direct and Indirect Methods to Assess Changes in Riparian Habitats

Abstract

Hydrological regime disturbances in riparian ecosystems affect the interactions between soil properties and vegetation. The proper assessment of changes occurring in river valley forests is a basis for planning in sustainable forest management. The existing habitat conditions in plant communities can be assessed by both direct and indirect measurements. The aim of the study was to compare the results obtained with direct and indirect methods of data collection. We also evaluated the validity of the studied variables. Our study was based on data from plots established in 90-year-old forests in the Odra river valley (SW Poland). Habitat features, such as soil moisture (F), nitrogen (N), and soil reaction (R), were expressed directly using field measurements and indirectly using Ellenberg’s indicator values, calculated based on the presence/absence of species in a plot (aEIVs) as well as on species cover (wEIVs). Only in the case of nitrogen did the use of both methods of estimating habitat features give the same results for selected riverside forests. In ordination and regressive analyses, use of direct or indirect methods strongly influences the results of calculations. Analyses conducted on the basis of selected parameters indicate a significant decrease in soil moisture and a change in soil reaction in the riparian forest located on the edge of the floodplain, which indicates that the habitat transformation has already begun. We concluded that the use of Ellenberg’s indicator values (EIVs) for monitoring riparian habitats has numerous disadvantages, and therefore data based on direct measurement should be preferred.

The asymmetry of the aquatic macrophyte response to temperature increases with global warming and has to be accounted for in phytoindication

“…The accuracy of the phytoindication method depends on the number of sources of information (species in the description) and the consistency of the sources of this information (the real correlation of indicator values with environmental properties). Phytoindication assessments of environmental factors for habitats are integrated signals of the relationship between species and the environment at the community level and provide reliable information on long-term environmental conditions characterizing the habitat (Halarewicz et al 2021). An increase in the number of species on which the assessment is based increases the accuracy of the assessment, but this is associated with an increase in spatial coverage due to the dependence of the number of species and area.…”

Changes in Habitat Conditions of Invaded Forest Communities in Podunajská Nížina and the Impact of Non-Native Species on Biodiversity (SW Slovakia)

“…We assume that in addition to the factors listed in points (i)-(iii) (see above), there are others. Some were reported by Halarewicz et al (2021); for example, plants react to habitat changes with a delay and the mean indicator values may not reflect the current state of habitat. Moreover, it needs to be taken into account that there is a strong linear dependency between data pertaining to vegetation and the ecological factors.…”

The role of soil and plant cover as drivers of soil macrofauna of the Dnipro River floodplain ecosystems

“…In floodplain ecosystems the intensity of dynamic phenomena in vegetation cover is very significant (Benjankar et al, 2011;Richards et al, 2002). Nevertheless, the nature of interrelation of plants and ecological processes allows using plants for indication of ecological regimes (Halarewicz et al, 2021;Yakovenko et al, 2019). Obviously, such an approach is sensitive to the ecological factors, the rhythm of which is consistent with the dynamics of the plant community.…”

“…For other ecological properties, direct and phytoindication estimates differed greatly. Therefore, the authors recommend researchers to prefer the direct measurements of environmental properties (Halarewicz et al, 2021). Obviously, direct and phytoindication estimates characterize different aspects of the dynamics of environmental properties.…”