Forests dominated by different tree species have diverse effects on soil fertility and understory vegetation. We evaluated four mixed forests dominated separately by Koelreuteria bipinnata (KB), Taxodium distichum (TD), Populus nigra (PN), and Ligustrum compactum (LC), and a non-forest land in a coastal reclaimed area of Eastern China in this study, in terms of soil physical and chemical property modifications and understory vegetation recruitment after a 12-year natural growth period.
Results/Conclusions
Among the estimated forest types, four mixed forests were statistically higher than non-forest land in all the determined soil parameters except for bulk density and pH. TD-dominated forest showed statistically greater soil water content than LC-, KB-, and PN-dominated forests. PN-dominated forest showed higher soil capillary porosity and maximum moisture capacity when compared with the other forests. Meanwhile, the soil permeability coefficient of KB was significantly higher than that of TD, PN, or LC. Concerning soil chemical properties, TD presented greater values than KB, PN, and LC in organic matter content, total nitrogen, hydrolysable nitrogen, total potassium, and cation exchange capacity in both 0~20 cm and 20~40 cm soil layers. As regarding to canopy tree growth and understory vegetation recruitment, LC mixture best advanced individual growth and facilitated understory species, showing stronger superiority in recovering plant biodiversity from reclaimed land compared with the other forests. Our results indicate that TD dominated forest has stronger capacity to enhance soil water availability and improve soil nutrition while LC best facilitated understory recruitment in reclaimed area. Besides, thinning the original planting intensity might be greatly effective in improving stem growth in coastal forests. These results are expected to benefit the sustainable management of mixed plantations in the subtropical area of Eastern China to a certain extent.