2

Appendix I

Table A1. Proportional loadings of the accumulation of eleven different nutrients onto the first four principal components, and the total and cumulative variance explained by these four principal components.

PC1 / PC2 / PC3 / PC4
Aluminum / 0.0786 / -0.0879 / 0.1170 / -0.2275
Boron / 0.0206 / -0.0280 / 0.1659 / -0.2284
Calcium / 0.2946 / -0.4894 / -0.5155 / -0.1542
Iron / 0.0965 / -0.1251 / 0.3017 / -0.1589
Magnesium / 0.2697 / -0.4004 / -0.3006 / -0.0137
Manganese / 0.1819 / -0.3004 / 0.3764 / 0.7530
Nitrogen (total) / 0.1437 / -0.1713 / 0.4001 / -0.1710
Phosphorus / 0.8222 / 0.5621 / -0.0502 / 0.0295
Potassium / 0.1905 / -0.1532 / 0.2158 / 0.0431
Sulfur / 0.1406 / -0.1570 / 0.3982 / -0.4944
Zinc / 0.1971 / -0.3039 / 0.0480 / 0.0592
Proportion of variance / 0.47 / 0.30 / 0.07 / 0.04
Cumulative variance / 0.47 / 0.77 / 0.84 / 0.88

Figure A1. Method of selecting focal patches for the study. On each of three different mountains, an elevational transect was set up with roughly ten points. At each of these points, two focal patches were selected at the same elevation: one in an early-melting “ridge” habitat and one in a late-melting “snowbed” habitat. The patches were evaluated as all of the Salix herbacea stems growing in a 10-cm diameter ring centered on a permanently-placed nail.

Figure A2. Accumulation of nutrients on across the three mountain transects, in g/10cm2/ burial period, characterized in ridge and snowbed microhabitats. Accumulation is measured using four pairs of anion- and cation-exchange surfaces (Plant Root Simulators, Western Ag Innovations, Saskatoon, Saskatchewan, Canada) per patch; probes were initially deployed to 58 patches across an elevation and snowmelt gradient. Because accumulation is in the units of burial time and because probes take up most easily available ions first before later accumulating more latent forms of the nutrients, it is not possible to compare nutrient supply rates to other studies in similar ecosystems. Nutrient accumulations were log-transformed before being used for analysis in models.