Assessing forest health via linking the geochemical properties of a soil profile with the biochemical parameters of vegetation

The transfer of chemical elements/compounds within the soil–plant chain is a part of the biochemical cycling, and this system is controlled by biotic and abiotic factors which determine the final mobility and availability of chemical variables. Heavy metal contamination and low pH are stress factors that lead to changes in the contents of important foliage compounds, which can be used as nonspecific indicators of plant stress. In this study, Norway spruce forests in the Sokolov region, being a part of the “Black Triangle,” were selected to assess geochemical and biochemical interactions in the natural soil/plant system. The authors studied the relationship between soil and spruce needle contents of macronutrients and potentially toxic elements and tested whether the soil parameters and their vertical distribution within a soil profile (two organic and two mineral horizons) affect foliage biochemical parameters (contents of photosynthetic pigments, phenolic compounds and lignin). Factor analysis was used to identify underlying variables that explained the pattern of correlations within and between the biochemical and geochemical datasets. Aluminum (Al) and arsenic (As) were identified as toxic elements with high bio-availability for spruce trees, and both were taken up by trees and translocated to the foliage. The correlations between two toxic element contents in needles (Al and As) and the contents of soluble phenolic compounds and total carotenoid to chlorophyll ratio suggest that these latter two biochemical parameters, which both proved to be sensitive to the soil geochemical conditions, can serve as suitable non-specific stress markers.

Keywords
Norway spruce (Picea abies L. Karst) health; Non-specific stress markers; Heavy metal stress; Factor analysis; Phenolic compounds; Photosynthetic pigments