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The regeneration dynamics of sugar maple-dominated stands in northeastern North America are intricately influenced by global changes such as soil acidification, invasive species, forest management, and climate shifts. A notable challenge is the expansion of American beech and its bark disease, threatening mature trees and ecosystem services. Although sylvicultural practices aim to control beech regeneration and enhance high-value species, their impact on understory plant communities remains poorly documented. In Valcartier, eastern Canada, we conducted a field experiment to assess the short-term effects of soil scarification and diverse soil amendments (nitrogen fertilization, liming, wood ash) on understory plant communities in a beech-invaded sugar maple stand. Over four years, we inventoried vegetation and measured various biotic and abiotic variables. Results showed that soil scarification significantly reduced diversity metrics like Simpson dominance, functional diversity, and redundancy (a metric correlated to community stability and resilience to disturbance). Negative effects of scarification were exacerbated by nitrogen, lime, or wood ash additions. Lime amendment without scarification enhanced diversity, suggesting its potential to support understory community stability. While scarification and amendments can promote sugar maple, yellow birch, and pin cherry seedling establishment, they have collateral effects on the understory, impacting productivity, diversity, and resilience in the short term. Land managers should exercise caution when combining these treatments, as they may transiently alter the stability and resilience of the understory and other forest functions. A more sustainable approach involves applying scarification and amendments on small, well-distributed patches within the targeted stands for treatment, avoiding extensive application over large areas. • Scarification reduced the stability and resilience of the plant community. • Negative effects of scarification are amplified by fertilizer, lime, or ash. • Lime has the potential to support plant community stability and resilience. • Seasonality and current site conditions shape plant diversity structure. • Scarification would be advisable to use only on well-dispersed patches. [ABSTRACT FROM AUTHOR]

Land degradation exacerbates poverty and food shortages in Sub-Saharan Africa. Tree planting is traditionally used to restore degraded lands, but the tree species used are often poorly adapted to the local climate conditions. We evaluated the suitability and efficiency of three planting techniques (half-moon, standard plantation and zaï) in a semi-arid climate using seedlings from two native Senegalia species: Senegalia gourmaensis and Senegalia dudgeonii. A total of 116 nursery-grown seedlings were planted on degraded lands using these three planting techniques. Data on soil water content, seedling survival and growth rates were measured over 1.5 years. The effects of the planting techniques on these variables were significantly different (p < 0.001). The lowest water content was measured in the topsoil horizon (0–10 cm) and the highest in the deeper horizons (∼50 cm). At the end of the experiment, the survival rate of S. gourmaensis was 72.2% - 62.5% and 57.5% in half-moon, standard plantation and zaï, respectively. For S. dudgeonii, it was 50%, 62.5% and 47.5% in half-moon, standard plantation and zaï, respectively. There was a significant difference in height and collar diameter between S. gourmaensis and S. dudgeonii using the three planting techniques (p < 0.001). Based on our results, we recommend using the half-moon or standard plantation for Senegalia species. Senegalia species are suitable for planting in degraded land in semi-arid areas when using the appropriate planting technique. [ABSTRACT FROM AUTHOR]

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