Available Data

The environmental data available for the experimental plots are:

(1) maximum soil water content (vwcmax)

(2) minimum soil water content (vwcmin)

(3) maximum air temperature at 30cm above ground (air30max)

(4) minimum air temperature at 30cm above ground (air30min)

(5) maximum air temperature at 150cm above ground (air150max)

(6) minimum air temperature at 150cm above ground(air150min)

(7) maximum soil temperature at 20cm below ground (soilTmax)

(8) minimum soil temperature at 20cm below ground (soilTmin)

All these data are at daily basis. The biological data available are the height and diameter at 5cm of the planted spruces which were measured once from 2004 to 2006 and measured every two weeks in 2006 from May to September.

Data preparation

The environmental data used for this project are from April to September (growing season) since the data in the other months might not related to the spruce growth. April to June was defined as spring and July to September was defined as summer. The weekly average of the environmental data of the target plots was calculated. Finally, the environmental data was organized in matrix 1 and biological data was organized in matrix 2 to run the Principle Component Analysis (PCA).

Method

Pcord program was used to run the PCA which was used to analyze the linkage between tree growth and the changes of the resources availability intrannually and interannually. The seasonal changes (spring and summer) were analyzed each year separately from 2004 to 2006. The yearly changes by season were analyzed as well from 2004 to 2006.