Physiological Response and Multi-Elemental Content in Lichens Growing on Agricultural Fences: A Pilot Study Comparing No-Tillage and Organic Cropping.

The objective of this study is to compare the physiological response (content and degradation of photosynthetic pigments, membrane oxidation products and soluble proteins) and multi-element content of Ramalina celastri (lichenized fungi) growing on agricultural fences with no-tillage (associated with transgenic crops and agrochemical application), organic cropping and a non-cultivated area. We found that R. celastri did not differ in its physiological response to agricultural practices, except for the contents of chlorophyll b and phaeophytin a which were high in both cultivated areas. Lichens growing in organic cropping fields have higher arsenic, chromium, uranium and internal transition elements common in the earth's crust, possibly due to the greater resuspension of the material during soil tillage. Lichens that grow on posts close to no-tillage field had higher bromine contents (present in numerous pesticides). We found evidence that R. celastri behaves as a tolerant species to air pollution in agricultural environments.

Air quality monitoring system using lichens as bioindicators in Central Argentina.

Air quality studies with bioindicators have not been well developed in South America. In the city of Córdoba, there are not permanent air pollutant measurements by equipment. In order to develop an air quality biomonitoring system using lichens, we applied a systematic sampling in the city of Córdoba, Argentina. A total of 341 plots were sampled in the area of the city which is a square of 24 × 24 km. In each sample plot we selected three phorophytes and estimated the frequency and cover of lichen species growing at 1.5 m on trunks. We also calculated the Index of Atmospheric Purity (IAP) using lichen frequencies. Maps with number of lichen species, cover values, and IAP were performed. The lichen community was described with nine species where Physcia undulata and Physcia endochryscea were the most frequent. Moreover, these two species were dominant in the community with the highest cover index. The central area of the city is considered a lichen desert with poor air quality. The southeast and northwest areas of the city showed the highest IAP values and number of species. In general, the city shows fair air quality and few areas with good and very good air quality.