Abstract:

Objective: This study aims to clarify the altitudinal distribution patterns of species diversity of different plant life forms in broadleaved species–Pinus koraiensis forests in Mt. Changbai, and to reveal their environmental implications, thereby providing a scientific basis for the conservation of biodiversity in temperate montane forests. Method: Based on data from 45 established forest community plots (with 50 m elevation intervals), this study explored the variation in plant diversity along the altitudinal gradient in broadleaved species–P. koraiensis forests. Nonlinear regression, correlation analysis, and variance partitioning methods were used to elucidate the differential effects of topographic factors (elevation, slope, aspect), soil properties (pH value, carbon, nitrogen, and phosphorus content), climatic parameters (mean annual temperature), and biotic factors (canopy density, tree height, diameter at breast height, and crown width) on the diversity of trees, shrubs, and herbaceous plants. Result: 1) A total of 40 tree species (12 families, 23 genera), 58 shrub species (17 families, 28 genera), and 105 herb species (41 families, 87 genera) were recorded. The small-diameter trees (DBH ≤ 5 cm) had high proportion, indicating favorable forest regeneration. 2) Within the elevation range of 700–1050 m, shade-tolerant species dominated in terms of individual number and importance value, while the basal area was primarily dominated by the constructive species P. koraiensis and the dominant species Tilia amurensis. The proportion of coniferous tree species increased with elevation. 3) Arbor species richness exhibited a unimodal pattern along the altitudinal gradient, shrub species richness decreased consistently, and herb species richness showed an initial decline followed by an increase. 4) Topographic, soil, and climatic factors jointly influenced the diversity of the arbor layer, with temperature variation driven by elevation explaining 27.0% of the variance. Shrub layer diversity was mainly controlled by topographic factors (30.7%), while herb layer diversity was significantly affected by topography, soil, mean annual temperature, as well as forest canopy density and arbor layer DBH (P<0.05). Conclusion: The altitudinal differentiation of plant diversity in the Changbai Mountain broadleaved species–P. koraiensis forests is jointly driven by multiple factors including topography, climate, soil, and canopy structure. Trees, shrubs, and herbs exhibit distinct response patterns to elevation and environmental factors.

Key words: broadleaved species–Pinus koraiensis forest, community composition, terrain, soil, climate, species diversity