Plant diversity characteristics and spatial distribution patterns in Kangnan forestry general farm, Gansu

By investigating the characteristics and spatial patterns of plant alpha diversity in the Kangnan forestry general farm, this study aims to provide a scientific basis for differentiated ecological conservation and forestry management in this forest area.

Using data from the second national census of forest and grassland genetic resources, the importance values of the tree layer, shrub layer and herb layer, as well as the plant α diversity index were calculated through statistical aggregation. The diversity characteristics were summarized, and combined with relevant analysis and spatial autocorrelation analysis, the spatial pattern of plant diversity in the forest area was revealed.

Key plot data indicate that the tree layer consists of a community dominated by species from the Fagaceae, Betulaceae, Cornaceae, and Pinaceae families. In the shrub layer, the Bambusoideae subfamily constitutes a single-dominant community accounting for 15.6% of the total, while in the herbaceous layer, communities dominated by the genus Carex accounted for 6.4%. Regarding the alpha diversity indices of forest vegetation, the Patrick richness index, Shannon-Wiener diversity index, Simpson diversity index, and Pielou evenness index generally showed a pattern of tree layer < herbaceous layer < shrub layer, indicating the presence of highly stable and less degraded plant communities. The alpha diversity indices of the tree layer in the forest area showed a strong and significant positive correlation with precipitation and a significant positive correlation with aspect; the alpha diversity indices of the shrub layer showed a significant negative correlation with elevation; the alpha diversity indices of the herb layer showed a strong and significant negative correlation with slope and a significant negative correlation with elevation. The spatial autocorrelation of the plant α-diversity indices in the sample plots showed a confidence level of over 99% and exhibited significant positive spatial correlation, with the strength of spatial autocorrelation being highest in the tree layer, followed by the herb layer and then the shrub layer. Except for the evenness index of the shrub layer, which showed no high/low clustering, the plant α-diversity indices of the other layers all exhibited varying degrees of high-high and low-low clustering, as well as low-high and high-low clustering anomalies.

Overall, plant diversity in the forest area remains stable, but some communities are at risk of degradation; tree layer diversity is significantly influenced by precipitation and aspect, shrub layer diversity is markedly influenced by elevation, and herb layer diversity is influenced by both slope and elevation; spatial autocorrelation of plant diversity in the forest area is pronounced, with both highly stable high-high clusters and degraded low-low clusters, as well as anomalous low-high and high-low clusters. These characteristics provide important theoretical foundations and technical references for forest management across the entire region.