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Field maple (Acer campestre L.) is naturally distributed in most of Europe, with the exception of its northern parts. Field maple can serve as a valuable model for researching the sensitivity of its populations to habitat fragmentation, considering the lack of silvicultural treatments in its stands. The research aims to determine the interpopulation and intrapopulation variability of field maple populations from Bosnia and Herzegovina in the nursery test.The authors researched measured root collar diameter, height, observed forkness and calculated slenderness coefficient of the one-year-old generative material from 18 Bosnian-Herzegovinian populations of field maple, produced in the nursery of Žepče. The descriptive statistics and variance analysis was performed.All analyzed traits showed a high degree of intrapopulation as well as interpopulation variability, as confirmed by the analysis of variance. The highest average height was found in the provenance Bosanski Brod (46.08 cm) and the smallest in Bosanska Dubica (19.11 cm). Kreševo provenance had the highest average root neck dia-meter (8.27 mm) and Bosanska Dubica (5.24 mm) the lowest. A very low percentage of forkness (6.86%) was determined, and the values of the slenderness coefficient were acceptable for all provenances.The results indicate the need for further systematic research on this ecologically valuable species.

A hypergraph is Sperner if no hyperedge contains another one. A Sperner hypergraph is equilizable (resp., threshold) if the characteristic vectors of its hyperedges are the (minimal) binary solutions to a linear equation (resp., inequality) with positive coefficients. These combinatorial notions have many applications and are motivated by the theory of Boolean functions and integer programming. We introduce in this paper the class of $1$-Sperner hypergraphs, defined by the property that for every two hyperedges the smallest of their two set differences is of size one. We characterize this class of Sperner hypergraphs by a decomposition theorem and derive several consequences from it. In particular, we obtain bounds on the size of $1$-Sperner hypergraphs and their transversal hypergraphs, show that the characteristic vectors of the hyperedges are linearly independent over the reals, and prove that $1$-Sperner hypergraphs are both threshold and equilizable. The study of $1$-Sperner hypergraphs is motivated also by their applications in graph theory, which we present in a companion paper.