Fig 1.
Map of the sampling points across the Fénay landscape, Burgundy, France.
Green, forest plots; yellow, farmed plots. Black circles, sampling points; blue triangle, Bretenière climate station. Blue lines are waterways.
Fig 2.
Two main analyses were led: 1) a mapping step identified the variations of the spatial patterns of our variables and potential variations of the levels; 2) a second step based on a PLS PM method identified the main drivers of soil microbial communities and their evolution over time based on the different variables. This part was led with an iterative method where measurable variables, architecture and the significance of interactions were evaluated.
Fig 3.
Interpolated mapping of the soil variables organic carbon (A, B), C:N ratio (C, D) and cumulative days of water stress (E, F) for the 2011 sampling campaign (A, C, E) and the 2016 campaign (B, D, F). The Matérn model was used to fit the experimental variogram. The ranges of the models were A: 144.33 m; B: 126.70 m; C: 126.24 m; D: 114.63 m. The estimated water stress in the topsoil is represented at the plot scale. Scatter plots on the right of the figure correspond to the variation of the parameter in 2016 depending on the same parameter in 2011. Green dots, forest plots; orange dots, farmed plots. Plot lines, equation y = x.
Table 1.
Summary of the statistics of microbial variables, soil parameters and farming practices.
Fig 4.
Mapping of the farming practices according to crop categories (A, B), soil preparation categories (C, D), phosphate amounts (E, F) and total TFI (G, H) for the 2011 sampling campaign (A, C, E, G) and the 2016 campaign (B, D, F, H). The legend is the same for both sampling campaigns and is indicated under each pair of maps. Hashed black, plots with missing data (NA); hashed green, forest plots. A comparison between the 2011 and 2016 campaigns is given on the right of the figure, 1) by barplots for crop categories and soil preparation categories, with the proportion of each category in 2016 depending of the category in 2011, and 2) by scatter plots for phosphate amounts and total TFI with the 2016 values as a function of the 2011 values. Only farmed plots (orange dots) are represented. Plot lines, equation y = x.
Fig 5.
Interpolated mapping of the soil microbial biomass in 2011 (A) and 2016 (B), and complete path model (C). In the interpolated maps, the color scale is the same for the two sampling campaigns and indicates the extrapolated values. The ranges of the models were 199.98 m (A) and 81.69 m (B). The scatter plot on the right of the maps corresponds to the variation of each parameter in 2016 depending on the same parameter in 2011. Green dots, forest plots; orange dots, farmed plots. Line, equation y = x. In the complete path model for biomass analysis (C), circles represent the latent variables (LVs), with anthropogenic LVs in black and ecological LVs in gray. Path coefficients were computed from regressions and allowed us to estimate the strength and direction of relations between LVs. Black arrow, positive impact; gray arrow, negative impact; double arrow, temporal impact. Significant impacts were evaluated based on a t-test: P < 0.1; *: P < 0.05; **: P < 0.01; ***: P < 0.001). Crosses indicate inaccurate path coefficients according to a bootstrap validation.
Fig 6.
Interpolated mapping of soil bacterial richness in 2011 (A) and 2016 (B), and complete path model (C). In the interpolated maps, the color scale is the same for the two sampling campaigns and indicates the extrapolated values. The ranges of the models were 349.00 m (A) and 101.35 m (B). The scatter plot on the right of the maps corresponds to the variation of the parameter in 2016 depending on the same parameter in 2011. Green dots, forest plots; orange dots, farmed plots. Line, equation y = x. Concerning the complete path model for biomass analysis (C), circles correspond to the latent variables (LVs), with anthropogenic LVs in black and ecological LVs in gray. Path coefficients were computed from regressions and allowed us to estimate the strength and direction of relations between LVs. Black arrow, positive impact; gray arrow, negative impact; double arrow, temporal impact. Significant impacts were evaluated based on a t-test: P < 0.1; *: P < 0.05; **: P < 0.01; ***: P < 0.001). Crosses indicate inaccurate path coefficients according to a bootstrap validation.