This study was aimed to explore the impact mechanism of long-term different land use patterns on the physical and chemical properties and aggregate stability of tropical soils, thereby providing a scientific foundation for enhancing soil fertility and improving soil structure in tropical regions. For this purpose, three land use types with a history of nearly 30 years were selected as the research objects, namely artificially managed rubber plantation (MR), naturally managed rubber plantations (NR), and low human-disturbed longan orchards (NL). The basic physical and chemical properties of soil, the distribution of water-stable aggregates, and the characteristics of aggregate stability in the 0-20 cm, 20-40 cm, and 40-60 cm soil layers were specifically analyzed. With the increase of soil depth, the soil pH in both MR and NL patterns showed a decreasing trend. In different profile layers, the pH of MR was lower than that of NL and NR. Under each soil layer, the contents of large soil aggregates (>2 mm, 1-2 mm) in the NR pattern were significantly higher than those in MR and NL. Conversely, the contents of small soil aggregates (<0.25 mm, 0.25-0.5 mm) were significantly lower than those in MR and NL patterns. Both the Mean Weight Diameter (MWD) and Geometric Mean Diameter (GMD) of soil water-stable aggregates in the NR pattern were significantly higher than those in MR and NL, and the fractal dimension (D) value was significantly lower than that in MR and NL. This indicates that the soil aggregates under the natural management pattern are more stable. Analysis of variance showed that land use patterns had an extremely significant impact on soil particle size distribution and aggregate stability. Soil depth significantly influenced the distribution of aggregates in the <0.25 mm, 0.25-0.5 mm, 0.5-1 mm, and 1-2 mm particle size fractions, with the intensity of the impact increasing as aggregate size decreased. The interaction effect between land use pattern and soil depth significantly affected soil aggregates (>2 mm, 1-2 mm) and the fractal dimension (D) value. Correlation analysis revealed that the soil aggregate stability indices (content of aggregates >2 mm, MWD, GMD) were negatively correlated with soil available phosphorus and positively correlated with soil organic matter (SOM); the fractal dimension (D) was negatively correlated with the content of soil aggregates (>2 mm) and significantly positively correlated with the content of soil aggregates (<0.25 mm). In conclusion, land use pattern is the most critical factor affecting soil aggregate stability. The naturally managed rubber plantation pattern can significantly increase the content of soil aggregates, enhance soil aggregate stability, and thereby improve soil structure.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |