| Characteristic | Overall N = 1081 |
Ground cover
|
||
|---|---|---|---|---|
| bare N = 391 |
grassland N = 341 |
gravel N = 351 |
||
| day | ||||
| 1 | 66 (61%) | 24 (62%) | 19 (56%) | 23 (66%) |
| 2 | 42 (39%) | 15 (38%) | 15 (44%) | 12 (34%) |
| replicate | ||||
| 2 | 37 (34%) | 13 (33%) | 12 (35%) | 12 (34%) |
| 3 | 36 (33%) | 13 (33%) | 11 (32%) | 12 (34%) |
| 4 | 35 (32%) | 13 (33%) | 11 (32%) | 11 (31%) |
| time | ||||
| 1 | 17 (16%) | 6 (15%) | 5 (15%) | 6 (17%) |
| 2 | 18 (17%) | 6 (15%) | 6 (18%) | 6 (17%) |
| 3 | 18 (17%) | 6 (15%) | 6 (18%) | 6 (17%) |
| 4 | 18 (17%) | 6 (15%) | 6 (18%) | 6 (17%) |
| 5 | 15 (14%) | 6 (15%) | 6 (18%) | 3 (8.6%) |
| 6 | 6 (5.6%) | 3 (7.7%) | 1 (2.9%) | 2 (5.7%) |
| 7 | 8 (7.4%) | 3 (7.7%) | 2 (5.9%) | 3 (8.6%) |
| 8 | 8 (7.4%) | 3 (7.7%) | 2 (5.9%) | 3 (8.6%) |
| filterpaper_petridsh | 83.8 (81.0, 86.1) | 83.1 (79.3, 86.2) | 83.6 (81.0, 85.3) | 83.8 (81.6, 86.4) |
| total weight | 84.5 (81.7, 87.1) | 85.2 (80.0, 88.6) | 83.9 (81.5, 85.6) | 84.5 (82.4, 87.2) |
| (Missing) | 2 | 0 | 2 | 0 |
| wt_sediments_30min | 0.29 (0.04, 1.16) | 1.15 (0.61, 2.39) | 0.04 (0.01, 0.12) | 0.21 (0.02, 0.61) |
| wt_sediments_min | 0.01 (0.00, 0.04) | 0.04 (0.02, 0.08) | 0.00 (0.00, 0.00) | 0.01 (0.00, 0.02) |
| 1 n (%); Median (Q1, Q3) | ||||
Testing for difference in Sediment detachment by ground cover
Data
Linear mixed effects models tessting difference in sediment detachmenyt by ground cover
| Fixed Effects Summary with p-values | ||||||||
|---|---|---|---|---|---|---|---|---|
| effect | Term | Estimate | Std. Error | t-value | df | p value | CI Lower | CI Upper |
| fixed | (Intercept) | 0.035 | 0.431 | 0.082 | 62.173 | 0.935 | −0.827 | 0.898 |
| fixed | day2 | 0.139 | 0.276 | 0.504 | 5.370 | 0.634 | −0.556 | 0.835 |
| fixed | grassland | −0.510 | 0.593 | −0.860 | 78.490 | 0.392 | −1.691 | 0.671 |
| fixed | gravel | −0.171 | 0.565 | −0.302 | 78.030 | 0.763 | −1.295 | 0.954 |
| fixed | time2 | 0.966 | 0.565 | 1.710 | 78.030 | 0.091 | −0.159 | 2.091 |
| fixed | time3 | 0.195 | 0.565 | 0.345 | 78.030 | 0.731 | −0.930 | 1.320 |
| fixed | time4 | −0.185 | 0.565 | −0.327 | 78.030 | 0.744 | −1.309 | 0.940 |
| fixed | time5 | −0.104 | 0.565 | −0.184 | 78.030 | 0.854 | −1.229 | 1.021 |
| fixed | time6 | 0.199 | 0.700 | 0.284 | 78.032 | 0.777 | −1.195 | 1.592 |
| fixed | time7 | 0.409 | 0.700 | 0.585 | 78.032 | 0.560 | −0.984 | 1.803 |
| fixed | time8 | −0.066 | 0.700 | −0.094 | 78.032 | 0.925 | −1.460 | 1.328 |
| fixed | grassland:time2 | −0.976 | 0.819 | −1.191 | 78.274 | 0.237 | −2.606 | 0.655 |
| fixed | gravel:time2 | −1.104 | 0.799 | −1.382 | 78.030 | 0.171 | −2.695 | 0.486 |
| fixed | grassland:time3 | −0.185 | 0.819 | −0.226 | 78.274 | 0.822 | −1.816 | 1.446 |
| fixed | gravel:time3 | 1.183 | 0.799 | 1.481 | 78.030 | 0.143 | −0.408 | 2.773 |
| fixed | grassland:time4 | 0.189 | 0.819 | 0.231 | 78.274 | 0.818 | −1.441 | 1.820 |
| fixed | gravel:time4 | 0.006 | 0.799 | 0.008 | 78.030 | 0.994 | −1.584 | 1.597 |
| fixed | grassland:time5 | 0.135 | 0.819 | 0.165 | 78.274 | 0.869 | −1.496 | 1.766 |
| fixed | gravel:time5 | 0.047 | 0.900 | 0.052 | 78.032 | 0.959 | −1.744 | 1.838 |
| fixed | grassland:time6 | −0.153 | 1.283 | −0.119 | 80.997 | 0.905 | −2.706 | 2.400 |
| fixed | gravel:time6 | −0.345 | 1.058 | −0.326 | 78.892 | 0.746 | −2.451 | 1.762 |
| fixed | grassland:time7 | −0.267 | 1.073 | −0.249 | 78.334 | 0.804 | −2.402 | 1.869 |
| fixed | gravel:time7 | −0.651 | 0.978 | −0.666 | 78.030 | 0.508 | −2.599 | 1.297 |
| fixed | grassland:time8 | 0.414 | 1.074 | 0.385 | 79.284 | 0.701 | −1.725 | 2.552 |
| fixed | gravel:time8 | 0.217 | 0.978 | 0.222 | 78.030 | 0.825 | −1.731 | 2.165 |
✅ Main effect of ground cover
| Comparison | Estimate | p-value | Interpretation |
|---|---|---|---|
grassland vs. bare |
-0.51 | 0.393 | ❌ Not significant |
gravel vs. bare |
-0.171 | 0.763 | ❌ Not significant |
Interpretation: There is no statistically significant main effect of ground cover on sediment detachment across all time points. Sediment levels under grassland and gravel are not significantly different from bare soil when averaged over time.
Overall effect estimate
| Type III ANOVA Results from LMER Model | ||||
|---|---|---|---|---|
| Effect | Chisq | Df | Pr(>Chisq) | Signif. |
| (Intercept) | 0.007 | 1.000 | 0.935 | |
| day | 0.254 | 1.000 | 0.614 | |
| gcover | 0.754 | 2.000 | 0.686 | |
| time | 5.771 | 7.000 | 0.567 | |
| gcover:time | 12.260 | 14.000 | 0.585 | |
🔍 Main Interpretation There is no statistically significant main effect of ground cover (bare, grassland, gravel) on sediment detachment across all times and days. The mixed-effects model revealed that ground cover type, time of sampling, day of experiment, and their interactions did not have statistically significant effects on sediment detachment (all p-values > 0.05). This suggests that under the experimental conditions, sediment detachment was relatively stable across different ground cover types and sampling times.