Relationship Between Soil Seed Bank and Canopy Coverage in a Mined Area

Abstract

The objective of this study was to evaluate and correlate information about soil seed bank and canopy (%Canopy Openness and Leaf area index-LAI) in a mined area in restoration process through natural regeneration. The study area is located in Zona da Mata of Minas Gerais, which presents predominance of Semideciduous Seasonal Forest, and has an area of 0.5 ha in process of natural regeneration after six years of bauxite exploitation (without any intervention). Along the area, ten plots of 45x29cm were allocated and distributed in the best way to represent the whole area in restoration process. Seed bank diversity and canopy characteristics were evaluated in these plots, the last one using a NIKON D40X photographic camera, with fisheye lens of 8mm. As results, 8280 individuals (tree, shrub, herbs, and vines) were found, totaling 51 species and 24 botanical families. The Shannon diversity index (H’) was 2.770, and the equability (J) was 0.705, which demonstrate an average diversity in this area, with a density of 2114.94 germinated seeds m-2. Through the evaluation of the seed bank, the presence of exotic species (23.5%), the dominance of the pioneer species (68.6%), as well as high dispersal by wind (52.9%) were verified in the area. According to canopy characteristics, a significant variation between different points/regions within the study area was found, while patterns of existence of certain herbs as a function of canopy openness (lower vegetal cover/clearings) were also identified, as well as in response to spatial proximity between the allocated plots, confirming the high correlation between these two variables and their importance in the process of forest restoration.

Soil Seed Banks in Two Environments of Forest Restoration Post Bauxite Mining: Native Tree Plantation and Natural Regeneration

“…These variations in the density of soil seeds in different areas can be related to several factors such as the type of disturbance, history of the area, the presence and quantity of dispersers and geographical barriers [34] . As observed, most of the species and individuals sampled in the seed bank are herbaceous (F1 and F2), which is common in this type of study, as noted by Balestrin et al [20] , Costalonga [35] , Martins [36] and Silva et al [37] as a characteristic of disturbed environments. In addition, the predominance of this life form can be explained by the life cycle of these species, high seed production and history of agricultural use in the area (pasture and coffee plantation), among other factors.…”

“…In this sense, the predominance of pioneer and native species on the soil seed bank strengthens the potential for vegetation recovery, in case of severe disturbances [44] . However, continuous monitoring of the area is necessary to prevent the high number of seeds of exotic species present in the soil from germinating and invading the area, which can hinder the establishment of native species and hinder the successional advance [7,20] .…”

“…topographic reconformation was performed in both areas, as well as the transposition of a 50 cm layer of topsoil that had been removed and stored before mining. Subsequently, the soil was prepared with subsoiling and the formation of level terraces [20] .…”

“…In this way, both areas have the same age of restoration and the evaluation of the seed bank occurred 7 years after mining and the application of reconformation and soil preparation techniques. At the time the seed bank was collected, F1 presented sparse tree individuals with an average of 3m in height, presence of patches of invasive grasses, low canopy coverage and presence of individuals naturally regenerated, in several stages of development [20] . On the other hand, in F2, arboreal individuals that were planted had an average height of 8m, greater canopy coverage and few regenerating individuals in the understory layer.…”

Floristics and Structure of Arboreal Components in a Restored Atlantic Forest Area

“…Phytosociological analyzes allows to assess environmental impact for the sustainable use, conservation and restoration of the ecosystems (Durigan, 2009). The successional stages and interventions to recover a forest closer to a stage of balance are evaluated by analyzes of the oristics and structure of the arboreal component and in this study a reference area for comparison is used a lot, and whether the area is really restored or close to a natural area (Souza et al, 2015;Balestrin et al, 2019;Gardon et al, 2020).…”