碱化土壤的野外及实验室波谱响应特征及其转换

为了探讨不同测量环境下碱化土壤波谱相互转换的条件和规律,对新疆天山北坡奇台绿洲碱化土壤进行定点野外、实验室波谱测量及特征分析,并结合土壤理化性质,利用多元线性回归方法进行野外-实验室测量波谱之间的双向转换。结果表明:野外测量波谱与土壤pH值呈极显著的正相关关系,可有效监测土壤碱化程度。但实验室测量波谱与pH值之间不具有相关性。pH值对实验室测量波谱向野外测量波谱的转换影响最大,其次是实验室波谱的b3(630～690nm)和b2(521～600nm)波段反射率,而b1(450～520nm)、b4(760～900nm)波段反射率与野外测量波谱的各波段反射率之间均无明显对应关系。实验室测量波谱与有机质含量呈负相关关系,且对于土壤有机质具有良好的定量反演潜力。实验室波谱向野外波谱转换的模型涉及的因子较少,稳定性高且具有良好验证精度,转换效果较野外波谱向实验室波谱转换的模型理想。

Characteristics of laboratory-field measured spectra responding to alkalinized soil and conversion

To explore the conditions and rules of conversions between spectra of alkalinized soil under different measure environments, the paper investigated the laboratory-measured and field-measured spectra of alkalinized soil within the Qitai oasis at the northern slope area of Tianshan Mountain in Xinjiang. Based on the analysis of the characteristics of the laboratory-measured and field-measured spectra and physicochemical properties of alkalinized soil at the study spots, the spectral transformation between the laboratory-measured and field-measured spectra were built by multiple linear regression method. The results showed that there was a significant positive correlation between the field-measured spectra and the soil pH value, therefore soil alkalinization could be effectively monitored by using the field-measured spectra. Although the correlation between the laboratory-measured spectra and the soil pH value was insignificant, pH value has the greatest impact on the conversion from the laboratory-measured spectra to the field-measured spectra, followed by the band3 (630-690 nm) and the band2 (520-600 nm) of the laboratory-measured spectra. The laboratory-measured spectra of band1 (450-520 nm) and band4 (760-900 nm) had no significant correlations with the field-measured spectra of the band1 (450-520 nm), band2 (520-600 nm), band3 (630-690 nm) and band4 (760-900 nm). The laboratory-measured spectra were significantly negatively correlated to the soil OM(organic matter), therefore the laboratory-measured spectra had the potential for estimating the quantitative retrieval of the soil OM. The model for laboratory-to-field spectral measurement transformation was less complex with fewer variables, more stability and higher verified accuracy, so it was better than the model for filed-to-laboratory spectral transformation.