Mercury (Hg) poses significant risks to human health, the environment, and plant physiology, with its effects influenced by chemical form, concentration, exposure route, and organism vulnerability. This study evaluates the physiological impacts of Hg on Handroanthus impetiginosus (Ip & ecirc; Roxo) seedlings through SPAD index measurements, chlorophyll fluorescence analysis, and Hg quantification in plant tissues. Four-month-old seedlings were exposed for eight days to distilled water containing Hg at 0, 1, 3, 5, and 7 mg L-1. The SPAD index decreased by 28.17% at 3, 5, and 7 mg L-1, indicating reduced photosynthetic capacity. Chlorophyll a fluorescence analysis revealed a 50.58% decline in maximum efficiency (Fv/Fm) and a 58.33% reduction in quantum yield (Phi PSII) at 7 mg L-1, along with an 83.04% increase in non-photochemical quenching (qn), suggesting oxidative stress and PSII damage. Transpiration decreased by 26.7% at 1 mg L-1 and by 55% at 3, 5, and 7 mg L-1, correlating with Hg levels and leaf senescence. Absorption, translocation, bioconcentration, and bioaccumulation factors varied among treatments. Hg accumulated mainly in stems (40.23 mu g g-1), followed by roots (0.77 mu g g-1) and leaves (2.69 mu g g-1), with limited translocation to leaves. These findings highlight Hg's harmful effects on H. impetiginosus, an ecologically and commercially valuable species, addressing a gap in research on its Hg tolerance and phytoremediation potential.

We tested the hypothesis that the number of seedlings from the soil seed bank (SSB) in forests polluted by heavy metals and disturbed by recent fires decreases. It was also assumed that the consequences of pollution and fires for the soil seed bank are additive. We estimated the number of seedlings from the SSB of pine forests located near the Karabash copper smelter (KCS) (contaminated by Cu, Zn, Pb, and Cd) and from uncontaminated forests of the Ilmen State Reserve (ISR). In both areas, samples of the forest litter and humus horizon were taken from forests recently exposed to ground fires and long-term unburned forests. Samples were exhibited from June to September, conducting seven rounds of counting seedlings. Small peculiarities of the emergence of seedlings on the samples of the forest litter and the humus horizon were established. However, the regularities of the reaction of SSB to pollution and fire disturbances did not depend on the soil horizon. The number of seedlings on substrates from contaminated forests was 5-8 times lower than the number of seedlings on substrates from background forests. A decrease in the number of seedlings on polluted substrates was accompanied by an increase in the share of dicots in the total number of seedlings. The relationship between the number of seedlings and the age of fires was not found. The additivity of the consequences of pollution and fires has also not been established. Of the two types of damage, pollution and fires, the pollution factor is of leading importance for SSBs. The results indicate a low recovery capacity of the herb-shrub layer of polluted forests.

In the summer of 2021, Greece experienced significant forest fires and mega-fires across multiple regions, leading to human casualties and damage to the natural environment, infrastructure, livestock, and agriculture. The current study aims to assess the ecosystem condition in terms of the natural regeneration and soil conditions of an area burnt by a forest fire (2021), specifically in the Ancient Olympia region situated in West Peloponnese (Ilia Prefecture), Greece. A standardized field sampling methodology was applied to record natural regeneration at chosen sites where a forest fire had also previously occurred (in 2007), resulting in the natural re-growth of the Pinus halepensis forest. Furthermore, an analysis was conducted on the geochemical, mineralogical, and sedimentological properties of soils obtained from this location. The findings of the research demonstrate the decline in the established natural regeneration of the Pinus halepensis forest and the overall tree layer. Species characteristic of post-fire ecological succession were observed in the shrub and herb layers, displaying varying coverage. The examination of soil mineralogy, sedimentology, and geochemistry indicated that the soil characteristics in the area are conducive to either natural or artificial regeneration. Ultimately, recommendations for landscape rehabilitation strategies are provided to inform decision-making processes, considering future climate conditions.

This study assessed whether a natural regeneration or active tree-planting reforestation strategy better restored the C and N-cycle processes and associated microbiota within soils after 18 years in a Premontane Wet Life zone site in Monteverde, Costa Rica, compared to adjacent old secondary forest and pasture soils (both >60 years). Our findings apply to small-scale restoration sites (<0.5 ha plots) commonly used in Monteverde. Both restoration strategies showed recovering soil C and N-cycle processes with similar levels of TN, NH4+, NO3-, Biomass-C, and efficiency of organic C use. Both strategies appeared to positively influence the recovery of the levels and community compositional stability of the Actinobacterial, Acidobacterial, N-fixing (N-Fixer) bacterial, ammonium-oxidizing bacterial, and complex organic C-degrading fungal communities. The main differences between the two strategies were that the tree-planted and pasture soils had similar compositions of the Actinobacterial, N-Fixer, and Fungal complex organic C degrader, while the natural regeneration and pasture soils had similar compositions of these groups and the Acidobacteria. However, the community compositions of all five microbial groups were different between restored forest and the old secondary forest soils. These results suggest that while the soil ecosystems from both reforestation strategies are recovering, after 18 years, there is still more recovery to occur. Lastly, possible indicators of post-restoration soil ecosystem enhancement included increasing constancy of critical microbial group composition, efficiency of organic C conversion to biomass, Biomass-C,NH4+, NO3-, and levels of Acidothermus, Acidobacteria subgroups 2, 3, and 5, Archaeorhizomyces, Anaeromyxobacter, Bradyrhizobium, Nitrosomonas, Flavobacterium, and Nitrospira.

Since the mid-2000s, drilling and production of oil and gas activities have grown exponentially in the southwestern United States. The clearing of pre-existing vegetation and topsoil to build well pads is known to have a broad range of ecological, biological, hydrological, and health impacts, therefore ecosystem restoration of the well pads is generally required. This process, however, is often complicated by limited funding, various governing bodies and ownership, and frequent extreme weather events. To ensure that well pad construction does not result in damaging, irreversible environmental change in the region, a prioritization strategy is needed to maximize the effectiveness of restoration efforts. The objective of this study is to develop a methodology to prioritize well pads where ecosystem restoration is urgently needed. In this methodology, a set of locational soil (e.g., soil fragility, wind and water erodibility) and land cover (e.g., land cover, proximity to streams) attributes were derived from publicly available datasets and a restoration priority score system along with a weighting factor were assigned to individual attributes. Accordingly, a total restoration priority score (TRPS) was calculated for individual well pads. This methodology was applied to a dataset of >10,000 well pads located in the Permian Basin and the surrounding area. This method effectively filtered out a large number of sites with low TRPS, and identified a small portion of high-score, clustered well pads. The identification of such well pads makes the logistical challenge of targeted restoration much easier for stakeholders tasked with maximizing the effectiveness of restoration efforts with limited funding. Despite some known limitations and inaccuracies, this method is low-cost and can be easily adaptable to humid and sub-humid systems, and even to restoration relevant to non-oil and gas exploration activities, such as solar and wind development, in the southwestern United States and many other areas worldwide.