Humusové formy dle humusového indexu a poměr C/N v lesních porostech různé skladby a struktury napříč klimatickými podmínkami ČR

Forest floor properties strongly reflect nutrient cycling, yet widely used rapid classifications may overlook important soil properties‘ variability. We described humus forms and quantified C/N ratios (0–5 cm) in four forest stand types – deciduous and coniferous monocultures, even‑aged mixed, and uneven‑aged mixed stands – distributed across lowland, mid‑altitude and high‑altitude conditions in the Czech Republic. A total of 122 soil pits across 5 localities were described. Field sampling followed a star‑shaped design with soil pits at fixed intervals; humus forms were assigned using the French classification (Brethes et al. 1995) as a basis for Humus Index (Ponge et al. 2002). Despite large contrasts in climate, bedrock and stand composition, three humus forms were described (dysmoder, eumoder, dysmull), indicating possible limited sensitivity of the classification. C/N ratios varied widely and were consistently lowest under broadleaved monocultures and highest under conifer‑dominated stands. Mixed stands often showed intermediate C/N values. Several differences were statistically significant within lowlands and mid‑altitudes. Our results suggest that stand composition can outweigh climatic setting in shaping topsoil organic matter quality. Moreover, the Humus Index may be a suitable tool for quick topsoil conditions assessment although, it is important to select and verify the correct classification of humus forms.