Mulching in lowland hay meadows drives an adaptive convergence of above- and below-ground traits reducing plasticity and improving biomass: A possible tool for enhancing phytoremediation

Abstract

We aimed to understand the effect of mulching (i.e., cutting and leaving the crushed biomass to decompose in situ) on above- and below-ground plant functional traits and whether this practice may be a potential tool for enhancing the phytoremediation of lowland hay meadows. To this aim, we evaluated at the community level seven years of mulching application in a PCBs and HMs soil-polluted Site of National Interest (SIN Brescia-Caffaro) through the analysis of the floristic composition and the above- and below-ground plant traits. We found that the abandonment of agricultural activities led to a marked increase in the soil organic carbon and pH, and the over-imposed mulching additionally induced a slight increase in soil nutrients. Mulching favored the establishment of a productive plant community characterized by a more conservative-resource strategy, a higher biomass development, and lower plasticity through an adaptative convergence between above- and below-ground organs. In particular, the analysis of the root depth distribution highlighted the key role of roots living in the upper soil layer (10 cm). Mulching did not show a significant effect on plant species known to be effective in terms of PCB phytoremediation. However, the mulching application appears to be a promising tool for enhancing the root web that functions as the backbone for the proliferation of microbes devoted to organic contaminants’ degradation and selects a two-fold number of plant species known to be metal-tolerant. However, besides these potential positive effects of the mulching application, favoring species with a higher biomass development, in the long term, may lead to a biodiversity reduction and thus to potential consequences also on the diversity of native species important for the phytoremediation.

Woody and herbaceous invasive alien plant species‐derived biochars are potentially optimal for soil amendment, soil remediation, and carbon storage

“…Also, biochar can create ecological niches for soil microorganisms, stimulating their growth, pollutant degradation (Brewer et al., 2014), and mineralization (Ni et al., 2020). Therefore, biochar could be used in polluted soils in combination with other practices, such as mulching, that promote the growth of the microbial community (Dalle Fratte et al., 2022). However, it is important to note that soil metal pollution is often in the polymetallic form; therefore, biochar addition may have different effects according to the pollutant's combination.…”

Mixed-Species Stands Improve the Coordination between Leaf and Fine Root Traits in a Common Garden Experiment

“…The coordination between leaves and fine roots means that the aboveground and under-ground parts must be coordinated in terms of access to a distribution of limited resources and adaptation to environmental factors [29]. However, there are also "management constraints" that may lead to functional convergence between aboveground and belowground traits, i.e., leaf and fine root traits exhibit coordinated changes at the community level [69]. Different plants may exhibit a convergence of functional traits under the same habitat conditions, as plants with similar functional traits may be more likely to gain an advantage in competition and thus achieve population continuity [70,71].…”

Comparison of Different Mechanical Pretreatment Methods for the Anaerobic Digestion of Landscape Management Grass

“…A cost-effective alternative would be to simply mulch the areas and leave the substrate in the meadow, which is also possible with the AG mounted mower. This method is very likely to have a negative effect on the diversity of native species, as it has a greater impact on the fine-root features in the upper soil layer and also slightly increases the nutrient content in the soil, establishing a more productive plant community [89].…”