Two-compartment models for describing temporal variation in the effective leaf area index of Robinia pseudoacacia stands on the Loess Plateau

Abstract

Leaf area index (LAI) is a key parameter in many ecological models and its phenology significantly affects on net ecosystem production in deciduous forests. We examined trends in LAIe (effective leaf area index) using two-compartment models to test effects of stand age and slope aspect on seasonal rates of LAIe increase (k₁) and decrease (k₂). LAIe measurements were acquired from 24 sample plots over five months and used to develop robust predictive models for modeling LAIe dynamics. Generally, the stands’ k₁ values were substantially greater than their k₂ values. The LAIe increased rapidly between leaf emergence and saturation, and then lower slowly from leaf saturation to senescence. The strongest increase in LAIe was observed in 11- to 15-year-old stands on shady slopes (k₁ = 4.76) and in young stands (<10 years) on sunny slopes (k₁ = 3.94), but k₂ values were largest in mature stands. The trees on shady slopes generally had higher k₁ and lower k₂ values than those on sunny slopes, except in the youngest stand. The results showed that two-compartment models can robustly describe leaf growth and loss rates in black locust stands, and that both stand age and aspect both strongly affect the rate and magnitude of changes in LAIe during the growing season. Hence, the two-compartment model is recommended as an effective method when monitoring the LAIe quantitative dynamics of broad-leaved forest.

Keywords:

• LAIe
• two-compartment models
• dynamic variability
• stand age
• slope aspect
• black locust plantation

Acknowledgments

We thank the anonymous reviewers for their constructive and valuable comments and the editors for their assistance in refining this paper.

Disclosure statement

No potential conflict of interest was reported by the authors.

Funding

This research was financed as part of a Research Special Topic under the auspices of the Forestry Science and Technology Support Plan, Researches and Demonstration of the Key Technology for Plantation Sustainable Management in the Loess Plateau, headed by Professor Zhao Zhong [grant number 2012BAD22B0302]. Additional funding was provided by the Programs of National Silviculture Teaching Team, Ministry of Education [grant number Z105021003] and Project “2662015QC048” supported by the Fundamental Research Funds for the Central Universities.