Growth dynamics of Shorea robusta Gaertn in relation to climate change: a case study from tropical region of Nepal

Key message: The growth of Shorea robusta is positively correlated with temperature, whereas the relation to moisture is weak. Abstract: Tree-ring analyses provide a rich archive of information on environmental attributes affecting tree growth. Tree-ring studies conducted so far have mostly focused on temperate species, and research on tropical trees is limited. This study aims to develop a tree-ring chronology of Shorea robusta and understand the climatic sensitivity of its growth in the tropical region of Nepal. Tree-ring samples of S. robusta were analysed following the standard dendrochronological sample analysis procedure. A 134-year-long ring-width chronology of S. robusta was developed, extending from 1851 to 2018, which is the longest chronology reported for this species. The chronology statistics revealed its high dendroclimatic potential with moderate R-bar, high expressed population signal, and low autocorrelation. The mean annual radial growth was 2.87 mm per year, while the mean basal area increment (BAI) was 9.245 cm2 per year. The ring width, BAI chronology and size-based growth analysis revealed an increasing growth trend of the species, which is likely favoured by the ongoing climate change. The tree growth of the species was positively correlated to temperature throughout the year; however, the relation to moisture parameters was weak. The temperature sensitivity of the species is stable over time, though a slight temporal difference exists in the strength of association