Fig. 6From: Evaluating the productivity of ancient Pu’er tea trees (Camellia sinensis var. assamica): a multivariate modeling approachEquations for quantifying productivity (y). Submodel (y1, y2, and y3) weights were determined by coefficients (Fig. 5). The environmental suitability model (y1) was formed by quadratic functions based on Fig. 2, and linear models were used for the productivity (y), tree growth (y2), and management (y3) modelsBack to article page