Effect of soil nutrient spatial heterogeneity by cutting disturbance on understory plant diversity in broadleaved-Korean pine forest in Changbai Mountain, China

The spatial variation of forest soil nutrients influences the species composition, distribution and diversity of forest plants, because soil nutrients are the most important environmental factors limiting the growth and survival of plants. We analyzed the effect of the spatial heterogeneity of soil nutrients on understory vegetation diversity in broadleaved-Korean pine forest, which had been undergone cutting disturbance. The results are of great significance in the sustainable management of the broadleaved-Korean pine forest and understanding the mechanism of correlation between heterogeneity and diversity. We sampled four plots of broadleaved-Korean pine forest in Jiaohe Forestry Bureau in Jilin province, China. Plot A, a control, was unlogged broadleaved-Korean pine forest. In plot B, C and D, forest was cut at 20%, 35% and 55% of the intensity in 2011. Cutting intensity influenced significantly on total nitrogen (TN), total phosphorous (TP), pH, soil organic matter (SOM), nitrate nitrogen (NN) and ammoniacal nitrogen except total potassium (p < 0.05). The values of TN, TP, pH and SOM showed that their quantities could decrease as cutting intensity increased. Species richness and diversity index of woody plants could increase in proportion to the cutting intensity, but species richness and diversity index of herbaceous plants might tend to decrease in early spring and summer. Coefficient of variation of TN, TP, SOM and NN could have either a positive or negative correlation with alpha-diversity indices of woody and herbaceous plants, while the other soil nutrient indices could have no correlation with diversity indices.