Litter Quality of Populus Species as Affected by Free-Air Enrichment and N-Fertilization
Figure 2
Species effect: Litter factor scores in F1F2 space. Sample numbers consist of four figures indicating, respectively, ring number (1 to 4), species number (1 to 3), N fertilization (0 no, 1 yes) and litter or mineral soil sample (0, 1). Solid line: species 1; dashed line: species 2; dotted line: species 3.
