Table 1. Numbers of sites inventoried in each year by age since clearfelling (1 year old = 2nd season after harvesting). | ||||

Year | 1 year old | 2 year old | 3 year old | Total |

2006 | 2 | 21 | 3 | 26 |

2007 | 2 | 13 | 10 | 25 |

2008 | 7 | 18 | 8 | 33 |

2009 | 5 | 53 | 30 | 87 |

2010 | 22 | 48 | 23 | 93 |

2011 | 5 | 6 | 16 | 27 |

Total | 43 | 158 | 89 | 292 |

Table 2. Potential independent variables. | |

Variable | Range or categories |

Coordinate RT90* East/West | 1373546 to 1813800 |

Coordinate RT90 North/South | 6767903 to 7393400 |

Coast distance | 1 to 240 km |

Elevation | 7 to 660 m above mean sea level |

Temperature sum | 548.9 to 1267.7 degree days above 5 °C per year |

Clear-cut age | 1, 2 or 3 years |

Site index | T14 to T24 for pine and G14 to G28 for spruce (height in m after 100 years) |

Tree species | Norway spruce, Scots pine or lodgepole pine |

Stoniness | None, light, medium or heavy |

Site preparation | Disc trenching, patch scarification or mounding |

Mineral soil on site | 0% to 88% of planted seedlings surrounded by pure mineral soil |

* RT90 is a coordinate reference system with the following prog4string: +proj=tmerc +lat_0=0 +lon_0=15.80827777777778 +k=1 +x_0=1500000 +y_0=0 +ellps=bessel +units=m +no_defs |

Table 3. Simple correlations between variables. Numbers in bold are statistically significant. | |||||||||

Prob. attack | Clear-cut age | Mineral soil | Elevation | Coast distance | Temp. sum | Coordinate E/W | Coordinate N/S | Stoniness | |

Prob. attack | 1 | –0.14226 | –0.39653 | –0.40913 | –0.43813 | 0.418602 | 0.279088 | –0.08671 | 0.158614 |

Clear-cut age | –0.14226 | 1 | 0.098893 | 0.137607 | 0.218259 | –0.07446 | –0.22084 | –0.09351 | –0.01117 |

Mineral soil | –0.39653 | 0.098893 | 1 | 0.354485 | 0.395688 | –0.41492 | –0.18979 | 0.168581 | –0.15065 |

Elevation | –0.40913 | 0.137607 | 0.354485 | 1 | 0.800851 | –0.84688 | –0.70949 | –0.14989 | –0.00517 |

Coast dist. | –0.43813 | 0.218259 | 0.395688 | 0.800851 | 1 | –0.79097 | –0.66678 | 0.088094 | –0.01271 |

Temp. sum | 0.418602 | –0.07446 | –0.41492 | –0.84688 | –0.79097 | 1 | 0.305601 | –0.39451 | 0.042062 |

Coordinate E/W | 0.279088 | –0.22084 | –0.18979 | –0.70949 | –0.66678 | 0.305601 | 1 | 0.661445 | –0.05927 |

Coordinate N/S | –0.08671 | –0.09351 | 0.168581 | –0.14989 | 0.088094 | –0.39451 | 0.661445 | 1 | –0.07265 |

Stoniness | 0.158614 | –0.01117 | –0.15065 | –0.00517 | –0.01271 | 0.042062 | –0.05927 | –0.07265 | 1 |

Table 4. Regression model with proportion of seedlings attacked (λ = 0.39) as the dependent variable. If a λ-value is shown then this indicates the variable was subjected to a scaled power transformation. All interactions were made with transformed values. AIC = 349. Probabilities in bold are statistically significant. | ||||

Variable | λ-value | Coefficient | Standard error | P-value |

Intercept | 2.308e+04 | 1.477e+04 | 0.119299 | |

Clear-cut age | 0.30 | –3.583e–01 | 1.387e–01 | 0.010276 |

Proportion mineral soil | 0.70 | 3.740e–02 | 2.248e–02 | 0.097375 |

Temperature sum | 1.49 | –2.110e+00 | 7.051e–01 | 0.003013 |

Latitude | –2.00 | –4.618e+04 | 2.955e+04 | 0.119253 |

Clear-cut age × Mineral soil | 1.824e–02 | 8.515e–03 | 0.033027 | |

Mineral soil × Temp. sum | 6.809e–02 | 1.860e–02 | 0.000299 | |

Latitude × Temp. sum | 4.221e+00 | 1.411e+00 | 0.003011 | |

Mineral soil × Latitude × Temp. sum | –1.362e–01 | 3.720e–02 | 0.000299 |

Table 5. Regression model with proportion of attacked seedlings that died (λ = 1.275) as the dependent variable. If a λ-value is shown then this indicates the variable was subjected to a scaled power transformation. All interactions were made with transformed values. “% in mineral soil” is the percentage of seedlings at each site with a surround of mineral soil. | ||||

Variable | λ-value | Coefficient | Standard error | P-value |

Intercept | –0.189616 | 0.031980 | 1.61e–07 | |

% in mineral soil | 0.70 | –0.012979 | 0.003085 | 8.76e–05 |