木荷防火林土壤分形维数与土壤养分的关系

Relationship between Soil Fractal Dimension and Soil Nutrients in Schima superba Firebreak Forests

摘要: 为探究不同林龄木荷防火林带土壤颗粒组成、分形维数及养分含量的变化特征。以8a、18a和32a木荷防火林带为研究对象，测定土壤不同粒级含量及全氮、全磷、全钾、碱解氮、有效磷、速效钾等指标，采用单因素方差分析和回归分析方法，分析分形维数与各养分指标的相关性。结果表明，土壤颗粒组成以砂粒和粉粒为主，黏粒含量较低。随林龄增加，砂粒含量呈先降后升的变化趋势，粉粒含量呈先升后降的变化趋势，黏粒含量持续升高；而分形维数逐次降低，8a、18a和32a分别为2.72、2.64和2.58。土壤全氮、全磷、全钾、碱解氮和速效钾含量随林龄增加总体呈升高趋势，有效磷在各林龄间无显著差异。分形维数与全磷、全钾和碱解氮呈显著负相关；与全氮、有效磷和速效钾的相关性未达显著水平。木荷防火林带建设促进了土壤养分积累，但土壤质地总体偏砂。研究结果可为南方木荷防火林带土壤质量评估与可持续经营提供科学依据。

Abstract: This study examined the variations in soil particle size composition, fractal dimension, and nutrient content within Schima superba firebreak forests of varying stand ages. Soil samples from 8-year-old, 18-year-old, and 32-year-old Schima superba firebreak forests were analyzed for particle size fractions and concentrations of total nitrogen (TN), total phosphorus (TP), total potassium (TK), alkali-hydrolyzable nitrogen (AN), available phosphorus (AP), and available potassium (AK). One-way analysis of variance (ANOVA) and regression analyses were used to investigate the relationships between fractal dimension and the measured nutrient indices. The results indicated that the soil was predominantly composed of sand and silt, with a low clay content. As stand age increased, the sand content first decreased and then increased, the silt content initially increased before decreasing, and the clay content progressively increased. Conversely, the fractal dimension successively decreased, with values of 2.72, 2.64, and 2.58 recorded for the 8a, 18a, and 32a stands, respectively. The concentrations of TN, TP, TK, AN, and AK generally rose with increasing stand age, whereas AP did not differ significantly among the stand ages. A significant negative correlation was observed between the fractal dimension and TP, TK, and AN; however, its correlations with TN, AP, and AK were not statistically significant. The establishment of Schima superba firebreak forests enhanced soil nutrient accumulation, although the soil texture remained predominantly sandy. These findings offer a scientific basis for assessing soil quality and guiding the sustainable management of Schima superba firebreak forests in southern China.