Scaling Approach for Estimating Stand Sapwood Area from Leaf Area Index in Five Boreal species

Abstract

This paper presents a scaling approach for estimating sapwood area at the stand level using knowledge obtained for individual trees of five boreal species: Populus tremuloides (Michx.), Pinus contorta (Doug. ex Loud. var. latifolia Engelm.), Pinus banksiana (Lamb.), Picea mariana (Mill.) BSP, and Picea glauca (Moench) Voss. Previously developed allometric models for sapwood depth and diameter at breast height for individual tree species were used to build stand level sapwood area estimates as well as stand level leaf area estimates, in pure and mixed vascular vegetation stands. A stand’s vegetation heterogeneity is considered in the scaling approach by proposing regression models for each species. The new combined scaling approach drew strong linear correlations at the stand scale between sapwood area and leaf area using observations taken in mixed stands of Southern Alberta, Canada. This last outcome suggests a good linear relationship between stand sapwood area and stand leaf area. The accuracy of the results was tested by observing each regression model’s adequacy and by estimating the error propagated through the whole scaling process.

Allometric relationships between sapwood area and shrub dimensions for six common Southern African savanna bush encroacher species: Universal or species‐specific?

“…This result is meaningful because it supplies further support for the potential of estimating sapwood area based on aerial imagery (Mitra et al, 2020). Whereas previous studies found a linear relationship between crown size and properties of water conductance (Ahongshangbam et al, 2020; Quiñonez‐Piñón & Valeo, 2019; Tziaferidis et al, 2021), the relationships detected in our study were slightly exponential, presumably due to the inclusion of smaller samples. Another reason for a divergent allometric relationship might be the time of sampling.…”

Allometric Relationships Between Sapwood Area and Shrub Dimensions for 6 Common Southern African Savanna Bush Encroacher Species: Universal or Species-Specific?

“…This result is meaningful because it supplies further support for the potential of estimating sapwood area based on aerial imagery (Mitra et al, 2020). Whereas previous studies found a linear relationship between crown size and properties of water conductance (Ahongshangbam et al, 2020;Quinonez-Pinon & Valeo, 2019;Tziaferidis, 2021), the relationships detected in our study were slightly exponential, presumably due to the inclusion of smaller samples. Another reason for a divergent allometric relationship might be the time of sampling.…”

Modelling Canopy Actual Transpiration in the Boreal Forest with Reduced Error Propagation

“…Based on our previous work [25,26], the importance of accurate estimates of sapwood area and sapwood depth to model robust allometric correlations [28] cannot be underestimated. Allometric correlations to scale up sap flow to sap flux and to canopy transpiration normally require estimates or measurements of the structural characteristics of trees, such as diameter at the breast height, leaf area, and leaf area index.…”

“…Our previous work demonstrates that accurate estimates of canopy sapwood area [25,26,28] are predicated on obtaining sapwood depth values with a negligible error. Hence, sapwood areas of single trees can produce accurate regression models for estimating canopy sapwood area while considering the canopy's heterogeneity.…”

“…This paper presents the computation of sap flow radial variations for each tree species included into the scaling approach. We use the allometric models-sapwood area and leaf area-reported in [28] to scale tree sap flow to canopy actual transpiration in a five-day Atmosphere 2020, 11, 1158 3 of 30 period. These canopy actual transpiration estimates are compared to actual evapotranspiration (E a ) and actual transpiration values calculated with the Penman-Monteith equation, and the modified Penman-Monteith equation, respectively.…”