DATA
Data Tables
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The following data table illustrates the variables measured under different biochar application rates (Table 2,3,4). The response variables are: methane flux (μmol·m⁻²·s⁻¹), carbon dioxide flux (μmol·m⁻²·s⁻¹), diameter at breast height (DBH) (cm), height (cm), crown diameter (cm), base to crown height (cm), internode elongation (cm), pH, electrical conductivity (μS·cm⁻¹), available nitrogen (mg·kg⁻¹), available ammonium (mg·kg⁻¹), total organic carbon (TOC) (%), total carbon (%), total nitrogen (%), microbial biomass carbon (mg·kg⁻¹), and microbial biomass nitrogen (mg·kg⁻1).
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In the tree performances, the data for internode elongation is highly inconsistent and lacks practical significance. Therefore, we have decided to exclude this metric from further analysis.
Table 2. Data table of GHG emissions ( fluxes of methane and carbon dioxide)
Table 3. Data table of tree performances (Diameter at breast height, Height, Crown diameter, Base to crown, Internode elongation)
Table 4. Data table of soil properties (pH, Electrical Conductivity, Available Nitrogen, Available Ammonium, Total Organic Carbon, Total Carbon, Total Nitrogen, Microbial Biomass Carbon, and Microbial Biomass Nitrogen)
Exploratory Graphics
Figure 5. Quantile-quantile plots of tree performances
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To test the normality of the data, we conducted a Shapiro-Wilk normality test and created a Quantile-quantile plot. Using tree performances as an example, it can be seen that the data points generally align well with the 45-degree line, indicating that these Quantile-quantile plots suggest most of the data is close to a normal distribution (Figure 5).
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Figure 6 presents violin and box plots illustrating the distribution of four tree characteristics—Diameter at Breast Height (DBH), Height, Crown Diameter, and Base-to-Crown Distance—across three treatment levels (0 t/ha, 20 t/ha, 40 t/ha). The plots indicate a general trend of increasing median values and variability with higher treatment levels, suggesting a positive response in tree growth characteristics to the treatments.
Figure 6. Violin and box plots of tree performances
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We also use box plots to provide a preliminary overview of the distribution and variability of several soil properties across different biochar application levels. The Figure 7 indicates varied responses in soil chemistry and microbiology to treatment intensity, with notable trends such as increased organic carbon and nitrogen availability in higher treatment levels, suggesting potential alterations in soil nutrient dynamics and microbial activity.
Figure 7. Box plots of soil properties
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Given these observations, our next steps in data processing should include handling outliers and ensuring normality where necessary to meet the assumptions of subsequent statistical tests. It may also be beneficial for us to investigate the relationships between treatments and specific soil parameters using regression or ANOVA to understand the impact of treatment levels more comprehensively.
