Towards a standardized protocol for measuring leaf area index in deciduous forests with litterfall collection
2019
Wang, Xingchang | Liu, Fan | Wang, Chuankuan
The leaf litter collection method is often used as a baseline for assessing leaf area index (LAI) measurements in forests by optical methods, but different protocols for measuring specific leaf area (SLA) may introduce biases in stand-level LAI estimates, which have not been quantified yet. To develop a standardized protocol for measuring SLA of leaf litter for estimating LAI via litterfall collection, we quantified the relative errors (RE) in the SLA measurements introduced by six protocols commonly-used in the literature with 46 deciduous woody species in a temperate forest, and assessed the stand-level LAI estimates derived from the SLA with eight permanent plots in the forest. The mean leaf area shrinkage from the litter collection across the species varied from 7.31 – 25.41% among the protocols, while the mean leaf mass loss varied from 2.07 – 24.68%. Compared with the reference, the mean RE of SLA introduced by the rest five protocols varied from −25.59 – 7.18%, and the subsequent RE of the stand-level LAI varied from −32.43 – 8.97%. We recommended a practical and reliable protocol for measuring SLA from leaf litter, i.e., weighing the dry mass first, then measuring the leaf area after rehydration with wet-filter-papers, and finally correcting for the leaf area shrinkage relative to the green leaf. We also provided general models for correcting for the SLA biases due to area shrinkage and mass loss of senesced leaves in temperate forests. Our findings will extend the direct measurements of LAI and improve the estimation of carbon and nutrient budgets in forest ecosystems.
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