Litter and soil play an important role in influencing hydrological processes and the global water cycle. Artificial afforestation, as a part of vegetation restoration, was constructed in the gully erosion areas of latosol with the objective to prevent erosion. Variations in the hydrological properties in soils that have undergone vegetation restoration from gully erosion are not well understood. In this study, we examine the variations in the litter thickness and mass, soil structure and porosity, and hydrological properties of four forest types (eucalyptus–grass forest, bamboo–grass forest, acacia–grass forest, and shrub–grass forest). The results show that the total litter thickness varied from 1.71 to 3.74 cm and was highest in the acacia–grass forest. The total litter mass for the acacia–grass forest, 3.49 ± 0.06 t·ha⁻¹, was significantly higher than that for the other forest types. The mass of the undecomposed litter (UL) layer was significantly lower than that of the semi-decomposed litter (SL). (2) The maximum water-retention capacity (W_max) and effective water-retention capacity (W_eff) of the SL layer were greater than those of the UL layer. The W_max and W_eff for the acacia–grass forest were markedly larger than those of the eucalyptus–grass, bamboo–grass, and shrub–grass forests. The water absorption rates of the SL and UL layers were highest during the onset of the immersion experiment, declined exponentially with time, and declined rapidly in the first 2 h. (4) The soil bulk density ranged from 1.46 g·cm⁻³ to 1.54 g·cm⁻³, and the total porosity ranged from 32.06% to 37.13%. The soil bulk density increased with the increasing soil depth, while the total porosity decreased gradually. The soil water-holding capacity of the soil layer of 0–60 cm in the acacia–grass forest (301.76 t·ha⁻¹) was greater than that of the other forest types. A comprehensive evaluation of the water conservation capacity by the entropy weight method showed that the water conservation capacity was greatest in the acacia–grass forest. The higher water-holding capacity of the acacia–grass forest may be more effective in enhancing rainfall interception, minimizing splash erosion, and decreasing surface runoff. Here, the results indicate that acacia–grass forest restoration can mitigate soil erosion by favoring soil and water conservation, improving the environment in the gully erosion area of latosol.

Litter is one of the key components of the forest ecosystem and plays a role as the second active layer influencing hydrological processes, which has affected the global water cycle. Soil- and water-conservation forests were constructed by artificial afforestation as a part of vegetation restoration in the eroded area of Latosol, and little is known about the differences in the hydrological properties of vegetation restoration in the eroded area of Latosol in the tropical region. We investigated the litter thickness, mass, and hydrological properties in three soil- and water-conservation forests (Eucalyptus robusta, Hevea brasiliensis, and Acacia mangium) through in situ surveys and laboratory experiments. The results showed that (1) the total litter thickness varied from 2.16 to 5.53 cm and was highest in the A. mangium forest. The total litter mass for A. mangium, 14.66 ± 1.09 t·ha⁻¹, was significantly higher than that for E. robusta (5.45 ± 0.59 t·ha⁻¹) and H. brasiliensis (3.01 ± 0.14 t·ha⁻¹). The mass of the semi-decomposed litter (SDL) layer was markedly higher than that of the un-decomposed litter (UDL) layer. (2) The maximum water-retention capacity (W_max) and effective water-retention capacity (W_eff) of the SDL layer were larger than the UDL layer for three forest plantations. The W_max and W_eff for the A. mangium stand were significantly higher than those for the E. robusta and H. brasiliensis stand. (3) The water-absorption rate of the SDL and UDL layer were highest at the onset of the immersion experiment, declined exponentially with time, and especially declined rapidly in the first 2 h. A higher water-holding capacity of A. mangium may be more effective in enhancing rainfall interception, minimizing splash erosion, and decreasing surface runoff. These results indicate that planting A. mangium in E. robusta and H. brasiliensis forests and then turning them into mixed forests should improve soil and water conservation and maximize their ecological benefits.

The water conservation capacity of the litter and soil layers of forest ecosystems improves the function of forest ecosystems in conserving soil and water. Plantation restoration plays a key role in preventing soil erosion. In order to evaluate the water conservation capacity of plantation restoration in Latosol soil-eroded region, we analyzed the litter thickness and mass, water absorption process, water holding recovery process, and soil water holding capacity of five restoration types (Hevea brasiliensis, Acacia mangium, Eucalyptus robusta, Acacia–Eucalyptus, and Acacia–Hevea) in the Mahuangling Watershed, Hainan province. The results showed that the thickness of the litter ranged from approximately 3.42 ± 0.24 to 4.73 ± 0.81 cm, and the litter mass ranged from 5.04 ± 1.52 t·ha⁻¹ to 13.16 ± 1.76 t·ha⁻¹, with higher litter mass in the SL layer than in the UL layer. The litter mass of A. mangium was higher than that of H. brasiliensis, E. robusta, Acacia–Eucalyptus, and Acacia–Hevea, which was 3.16 ± 1.76 t·ha⁻¹. A. mangium forest was significantly higher than other plantation restoration types in terms of the maximum water retention capacity (Q_max) and the effective water retention capacity (Q_eff). The soil bulk weight ranged from approximately 1.52 ± 0.09 to 1.59 ± 0.08 g·cm⁻³, and porosity ranged from 31.77 ± 4.72 to 35.62 ± 3.02%, both of which increased with the depth of the soil layer. The water holding capacity of 0–60 cm soil varied from approximately 12.94 ± 7.91 to 45.02 ± 31.79 t·ha⁻¹, with A. mangium having the best soil permeability and the strongest soil water holding capacity. The entropy weight method was used to conduct a comprehensive evaluation, and the results showed that the water conservation capacity of the soil layer was 1.26 times higher than that of the litter layer, in which the water conservation capacity of A. mangium was the strongest, with a comprehensive evaluation value of 0.2854, which effectively intercepted rainfall and reduced surface runoff. Hence, we suggest that the planting of A. mangium should be considered in future ecological restoration projects of the erosion area of Mahuangling in order to improve the function of conserving soil and water in a restoration forest ecosystem.

Magnoliaceae plants have high ornamental value, resulting in their widespread use in landscaping construction, and play a major role in the ecological functions of soil and water conservation. However, the landscape value of magnolias from the perspective of the water conservation capacity of the litter and soil layers is not yet fully understood; this restricts the popularization and application of Magnoliaceae plants in landscaping. In this study, we determined the characteristics of the litter thickness and mass, water absorption process, and soil water-holding capacity associated with five Magnoliaceae plants (Michelia shiluensis, M. crassipes, M. foveolata, M. maudiae, and M. odora). (1) The total litter thickness ranged from 2.29 to 5.58 cm, with M. crassipes achieving the highest value. The total litter mass for M. shiluensis (25.11 ± 2.58 t·ha⁻¹) was largely greater than that for the other magnolias. The mass of the un-decomposed litter (UL) layer was 1.31- to 3.82-fold larger than that of the semi-decomposed litter (SL). (2) The maximum water retention capacity (H_max) and effective water retention capacity (H_eff) of M. shiluensis were markedly larger than those of the other magnolias. (3) The W_max and W_eff of the UL layer were greater than those of the SL layer. (4) The soil bulk density varied from approximately 1.22 ± 0.08 g·cm⁻³ to 1.55 ± 0.08 g·cm⁻³, and the total soil porosity varied from 40.03 ± 3.44% to 46.42 ± 1.02%. The soil bulk density rose with an increasing soil depth, yet the total porosity was reduced. The soil water-holding capacity of the 0–30 cm soil layer varied from approximately 26.23 to 70.33 t·ha⁻¹, with soil near M. crassipes having the greatest water-holding capacity. The soil water infiltration recorded for M. crassipes was significantly higher than that of the other magnolias. The water conservation capacities associated with M. crassipes and M. shiluensis were the largest, which may suggest that these species are better at increasing rainfall interception, lightening splash erosion, and reducing surface runoff. Hence, we suggest that M. crassipes and M. shiluensis should be prioritized in landscaping applications.