Photosynthesis Traits of Pioneer Broadleaves Species from Tailing Dumps in Călimani Mountains (Eastern Carpathians)

Abstract

The reforestation and stable ecological restoration of tailings dumps resulting from surface mining activities in the Călimani Mountains represent an ongoing environmental challenge. To assess the suitability of different tree species for restoration efforts, photosynthetic traits were monitored in four broadleaf pioneer species—green alder (Alnus alnobetula (Ehrh.) K. Koch), aspen (Populus tremula L.), silver birch (Betula pendula Roth.), and goat willow (Salix caprea L.)—that naturally colonized the tailings dumps. Green alder and birch had the highest photosynthetic rate, followed by aspen and goat willow. Water use efficiency parameters (WUE and iWUE) were the highest for green alder and the lowest for birch, with intermediary values for aspen and goat willow. Green alder also exhibited the highest carboxylation efficiency, followed by birch. During the growing season, net assimilation and carboxylation efficiency exhibited a maximum in late July and a minimum in late June. The key limitation parameters of the photosynthetic process derived from the FvCB model (Vcmax and Jmax) were the highest for green alder and exhibited a maximum in late July, regardless of the species. Based on photosynthetic traits, the green alder—a woody N2-fixing shrub—is the most well-adapted and photosynthetically efficient species that naturally colonized the tailings dumps in the Călimani Mountains.

Valsalnicola oxystoma (Rehm) D.M. Walker & Rossman - primary biotic agent responsible for the dieback and high mortality of green alder in Călimani and Rodnei Mountains (North-Eastern Romania)

“…In the Călimani Mountains, the green alder scrub covers 63.48 ha (Anonymous 2022). Important disturbances affected the scrub in the past: fires, deforestation, and sheep grazing but the most important historical disturbance consisted of abandoned open sulfur exploitation quarries slowly recovering where scrubs with A. alnobetula scrubs vegetated (Popa & Popa 2021). The exploitation leading to vegetation destruction beginning in 1969, and the date of abandonment being 1997, the presence of P. mugo scrub with A. alnobetula corresponds to relatively early secondary succession in this area.…”

Climate Change and Air Pollution Effect on Forest Ecosystems

“…In many cases, human activities change the condition of natural vegetation, leading to disturbances such as the degradation of vegetation, the erosion of soil, a decline in land productivity and even a reduction in ecosystem services. Gaining a better understanding of natural colonization with a pioneer woody species, for example by studying primary natural succession, can offer valuable knowledge about the species that are most adapted to these particular environmental conditions [3]. For the sustainable management of forests, knowledge on the increments of the main dendrometric characteristics of trees (diameter, height and volume) and the relationships among them, can contribute to adaptations in silvicultural work, with the purpose of reducing the risks generated by environmental factors at the stand level.…”