Early growth and sensitivity to climate and shade intensity of <i>Cariniana pyriformis</i> in northern South America

Abstract Climate change and forest degradation are expected to alter tropical forests and the services they provide. Understanding how tropical forests and their constituent species respond to these pressures is important to ensure forest resilience and maintain their services. One such species is abarco (Cariniana pyriformis), a highly valuable timber species, which is typically harvested from natural forests with limited silvicultural knowledge about the species. To support evidence-informed decisions on the use of abarco for reforestation and quantify its early growth, we (i) compared growth, survival, forking, and phytosanitary status between two contrasting shade conditions (full sun exposure and natural partial shade) and (ii) analysed how climate variables correlate with growth, mortality, and phytosanitary status within each shade condition. Growth was measured in terms of diameter at breast height (dbh), total height (h), and crown diameter (cd). We used data from permanent plots with inter- and intra-annual measurements over the first six years of tree growth. Dbh, h, and cd exhibited a roughly linear pattern under both shade conditions, with an increasing trend towards the end of the study. Only dbh differed significantly between shade conditions at six years, being higher under full sun. The periodic annual increment for dbh and h showed increasing trends, suggesting that growth may continue to increase after the study period. Abarco’s growth variables correlated with at least 5 of the 10 climate variables examined, with relative humidity showing the strongest correlation. The species is likely to perform well in areas with high precipitation, temperature, and radiation. Survival was high and correlated with radiation and precipitation but not with shade conditions. The proportion of forked individuals was high, especially in full sun, and insect attacks and disease symptoms were more frequent in partial shade but only during the early years. We provide guidelines for reforesting abarco under changing climatic conditions.