Objective On the basis of pipe model and the theory of water transportation pattern through tree rings, we investigated the canopy productivity structure of Larix olgensis and leaf biomass models for four larch subspecies to provide a theoretical and technological background for evaluating canopy productivity and studying the pattern of water transportation through tree rings.
Method We analyzed the canopy productivity structure and fitted leaf biomass models with the data collected from canopy analysis, biomass sampling and dye tracer experiment in tree trunks, as well as comparing the selected predictors and the estimation accuracy of the models for varied larch subspecies at different ages.
Result (1) The sectional area of current-year ring of 11-year-old Larix olgensis at breast height accounted for 19.64% of the total sectional area capable of conducting water but provided the water transportation for 29.8% of the total canopy leaf area, indicating that the water transportation rate of current-year ring was faster than others. (2) Based on pipe model and the theory of water transportation pattern through tree rings, both leaf area and leaf biomass were affected to a certain degree by the water transportation capacity and branch mechanical support capacity, which were represented by two types of predictor variables relating to branch mass and water transportation capacity, respectively. (3) The biomass models with two types of predictor variabels for the four Larix subspecies had high estimation accuracy. (4) In order to facilitate the application, models with two predictors were fitted, and predicted values given by these reduced models were highly correlated to leaf biomass observations for the four Larix subspeices. (5) We fitted an ANCOVA model of leaf biomass on sectional area of branch at base, with the four Larix subspeices incorporated. Statistical tests for testing homogeneous intercept and slope showed that the slope and intercept for Larix gmelinii were significantly different from those for other three subspecies, and so was Larix principis from Larix leptolepis. In comparison, the difference between Larix principis and Larix olgensis was not significant. The results reflectd the differences in the canopy shape of the four larch subspecies.
Conclusion The pipe model and theory of water trasportation pattern have a wide application prospect in studying tree productivity structure and productivity evaluation. According to this, explanatory variables for leaf biomass can be divided into two categories, related to branch mass and water trasportation capability, respectively. The fitted standard model and reduced models of leaf biomass could produce accurate estimates for the four Larix subspecies.
DownLoad: