郭岩山不同海拔天然栲树林土壤硅形态特征

目的 探究郭岩山不同海拔天然栲树林土壤硅形态的变化特征及其与土壤理化性质的相关关系,进一步揭示亚热带地区土壤硅形态含量对环境变化的响应机制。 方法 本研究以郭岩山自然保护区不同海拔天然栲树林土壤为研究对象,在郭岩山自然保护区海拔600、700、800、900 m分别设置标准地,采集不同海拔各土层（0～20、20～40、40～60 cm）的土样,测定土壤不同硅形态含量,分析环境变化对土壤中硅形态的影响。 结果 （1）高海拔土壤有效硅（258.26 mg·kg−1）、水溶性硅（155.69 mg·kg−1）、活性硅（388.97 mg·kg−1）及无定形硅（1 561.97 mg·kg−1）含量均显著高于低海拔土壤有效硅（93.16 mg·kg−1）、水溶性硅（78.38 mg·kg−1）、活性硅（231.84 mg·kg−1）及无定形硅（832.24 mg·kg−1）。深土层（40～60 cm）的土壤有效硅含量（227.53 mg·kg−1）显著高于0～20 cm（120.79 mg·kg−1）及20～40 cm（171.37 mg·kg−1）土层;（2）土壤有效硅含量与活性硅及水溶性硅含量呈极显著正相关,其中,活性硅是有效硅增加最重要的直接贡献形态,而水溶性硅是土壤硅转化过程中重要的过渡性形态;（3）土壤有机质和土壤pH值对各土壤硅形态含量的影响最显著,解释率分别达14.1%和9.2%,其中,土壤有机质与无定形硅及水溶性硅呈正相关,与土壤活性硅及有效硅呈负相关,而土壤pH值与有效硅、活性硅呈正相关,与无定形硅呈负相关。 结论 海拔引起的环境及土壤理化性质变化可改变土壤硅形态含量。研究结果为天然栲树林有效利用土壤硅及调控土壤硅形态提供了参考依据,对天然栲树林的保护具有重要的科学指导意义。

Soil Silicon Form Characteristics of Natural Castanopsis fargesii Forest at Different Altitudes in Guoyan Mountain

Objective To better understand the characteristics of soil silicon morphology variation and its correlation with soil physi-chemical properties in Castanopsis fargesii stands at differentaltitudes in Guoyan Mountain for further illuminatingthe response mechanism of soil silicon morphology content to environmental changes in subtropical areas. Methods In order to gather soil samples from various soil layers (0−20, 20−40, and 40−60 cm) at differentaltitudes in Guoyanshan Nature Reserve, standard plots were set up at 600, 700, 800, and 900 m, respectively. Different soil silicon forms were extracted and measured to examine the effects of environmental changes on soil silicon forms. Results (1) Available silicon(258.26 mg·kg−1), water-soluble silicon (155.69 mg·kg−1), active silicon (388.97 mg·kg−1) and amorphous silicon (1561.97 mg·kg−1) in the high-altitidesoil weresignificantly higher than those in thelow altitudesoils with the data of 93.16, 78.38, 231.84, and 832.24 mg·kg−1, respectively. The availablesilicon (227.53 mg·kg−1) in deep soil layer (40−60 cm) was significantly higher than that in 0−20 cm (120.79 mg·kg−1) and 20-40 cm (171.37 mg·kg−1) soil layers. (2) The content of available silicon in soil was significantly positively correlated with the content of active silicon and water-soluble silicon. Active silicon was the most important direct contributing form to the increase of availablesilicon, andwater-soluble silicon was an important transitional form in the soil silicon transformation process.(3) Soil organic matter and soil pH had the most significant effects on the content of each soil silicon form, which explained the variations of14.1% and 9.2%, respectively. Soil organic matter was positively correlated with amorphous silicon and water-soluble silicon, and negatively correlated with soil active silicon and effective silicon, while soil pH was positively correlated with availablesilicon and active silicon, and negatively correlated with amorphous silicon. Conclusion Variations on environment and soil physical and chemical properties caused by altitude can change the content of silicon in soil.This study offers a foundation for successful soil silicon use and soil silicon morphology control in natural Castanopsis fargesii forest, which is crucial scientific advice for the preservation of natural Castanopsis fargesii forest.