Table 1.
Temporal trends of plant phenology variables, mean calving date (calvdate) and population variables from the reindeer herd of the Kutuharju field reindeer research station in Kaamanen, northern Finland
| Variables | Estimate | SE | 95% CI | Total change over the study period |
|---|---|---|---|---|
| 1970–2015 | ||||
| Thermal growing season | ||||
| ThermalStartt | −0.24 | 0.08 | −0.41, −0.08 | –11 days |
| ThermalEndt | 0.09 | 0.13 | −0.17, 0.35 | +4.1 days |
| LTGSt | 0.34 | 0.14 | 0.04, 0.63 | +15 days |
| Calving season | ||||
| calvdatet | −0.14 | 0.04 | −0.23, −0.06 | –6.5 days |
| Population variables | ||||
| BCIAutumnt−1 | 0.29 | 0.04 | 0.21, 0.38 | From −8.4 to 4.8 |
| BCIWintert | 0.32 | 0.04 | 0.24, 0.39 | From −8.8 to 5.6 |
| BCISpringt | 0.31 | 0.07 | 0.16, 0.45 | From −9.1 to 4.8 |
| PMt−1 | 0.0002 | 0.001 | −0.001, 0.002 | From 16% to 17% |
| DENSt−1 | −0.04 | 0.19 | −0.42, 0.34 | –1.8 individuals |
| 1997–2015 | ||||
| Thermal growing season | ||||
| ThermalStartt | −0.84 | 0.28 | −1.44, −0.25 | –15 days |
| ThermalEndt | 0.04 | 0.43 | −0.86, 0.95 | +0.8 days |
| LTGSt | 0.89 | 0.47 | −0.10, 1.87 | +16 days |
| Vegetative growing season | ||||
| VegOnsett | −0.89 | 0.44 | −1.83, 0.06 | –16 days |
| VegEndt | −0.41 | 0.34 | −1.13, 0.30 | –7.5 days |
| LVGSt | 0.007 | 0.76 | −1.65, 1.66 | +0.12 days |
| Calving season | ||||
| calvdatet | −0.51 | 0.13 | −0.77, −0.25 | –9.2 days |
| Population variables | ||||
| BCIAutumnt−1 | 0.36 | 0.08 | 0.21, 0.52 | From −1.8 to 4.8 |
| BCIWintert | 0.38 | 0.06 | 0.26, 0.50 | From −1.3 to 5.5 |
| BCISpringt | 0.40 | 0.13 | 0.13, 0.66 | From −2.4 to 4.8 |
| PMt−1 | 0.006 | 0.003 | −0.0007, 0.01 | From 9.5% to 21% |
| DENSt−1 | −1.39 | 0.30 | −2.02, −0.76 | –25 individuals |
The parameter estimates (with SE) from LMs with year as a fixed covariate indicate the direction of the change over time of the variables over the whole study period (1970–2015) or just the last part of the study period (1997–2015). ThermalStart and ThermalEnd were the start and the end, respectively, of the thermal growing season. VegOnset and VegEnd represented, respectively, the onset and the end of the vegetative season, estimated by birch phenology. BCIAutumn was the females’ BCI averaged over the autumn (September–October–November), BCIWinter the females’ BCI averaged in winter (from December to March) and BCISpring stood for the females’ BCI in spring (April–May, see text for details). The estimates in bold type indicated a statistically significant temporal trend (whose 95% CI excluded 0). DENS, population density; LVGS, length of the vegetative season; PM, proportion of males in the herd; SE, standard error.