Modelling the growth response to climate change and management of Tectona grandis L. f. using the 3-PGmix model

Abstract

Key message: Teak (Tectona grandis L. f.) is a native tree species of India. It is one of the most desirable timber species because of its strength, fine texture, and durability. Its growth is strongly dependent on the climatic conditions, but empirical data are often unavailable to support management decisions. The physiological principles for predicting growth incorporated in the 3-PGmix model make it a useful tool in modelling the growth responses and management in the changing climate. We assessed that under elevated atmospheric carbon dioxide (CO2) concentration and no thinning, teak would store more carbon than currently. Context: Uncertainty and lack of scientific understanding about the growth response to climate change and thinning regimes have created challenges in teak sustainability, both regionally and globally. Aims: This research examines climate change and management implications on teak growth in India using the 3-PGmix model. Methods: The 3-PGmix model was coupled with climate scenarios (Representative Concentration Pathway (RCP) 4.5 and 8.5) to forecast growth response up to the year 2100 with 1981–2010 as the baseline under thinning (G-quality, P-quality) regimes. Thinning under G-quality is performed at earlier stand age than P-quality, and then simulations under ‘no thinning’ based on stocking/ha at different thinning intensity. Results: Under ‘no thinning’, predicted net primary productivity (NPP) for RCP4.5 and RCP8.5 became 5.77 t/ha/year and 5.28 t/ha/year in 2100. However, under increasing CO2, it became 7.39 t/ha/year and 8.22 t/ha/year respectively in 2100. In the future, increasing CO2 would be the dominating factor for an increase in teak growth; however, abnormal precipitation and warmer temperature could produce an unforeseen growth condition. The carbon stock and CO2 sequestration are predicted to be higher under no thinning, which signifies the CO2 fertilisation effect in teak. Conclusion: The set of parameters used in 3-PGmix offers an opportunity to predict teak responses to future climatic conditions and management treatments.