Foliar herbivory and leaf traits of five native tree species in a young plantation of Central Panama

This study examined foliar herbivory on 1 year-old tree saplings planted in previously abandoned fields in central Panama. Plots (15 x 15 trees) of Anacardium excelsum (Anacardiaceae), Dalbergia retusa (Fabaceae), Pachira quinata (Malvaceae), Tabebuia rosea (Bignoniaceae), and Terminalia amazonia (Combretaceae) were tested for herbivory using leaf counts and digital image analysis. Values of foliar carbon, foliar nitrogen, specific leaf area (SLA), and leaf toughness were analyzed to describe mechanical defenses and leaf nutrients on young and mature leaves of each of these species. For all five species, less than 10% of total leaf area was found to be damaged by arthropods. Significant (P-value < 0.001) differences in herbivory were found among both the tree species and the insect feeding guilds considered: chewing, skeletonizing, mining, and leaf-rolling. On mature leaves, Anacardium excelsum had the highest amount of leaf damage (3.53%) while Dalbergia retusa exhibited the lowest herbivore damage (1.72%). Tabebuia rosea had statistically significantly higher damage than other species for young leaves caused by leaf-rolling insects (4.21% rolling of 5.55% total damage). Leaf toughness was negatively correlated with SLA and foliar N. Linear regressions showed that herbivory was positively correlated with foliar N for young leaves and negatively correlated with foliar N for mature leaves. No statistically significant relationships were found between herbivory and the mechanical properties of toughness and SLA. Overall, results from this study indicate that, as young saplings, the species evaluated did not suffer high amounts of foliar herbivory in the plantation environment.