Pathogen Damage in a Tropical Rain Forest: The Effects of Biological and Physical Factors on Pathogen Damage to Virola koschnyi .

Abstract

Devastating to native flora and fauna, the continual deforestation of Costa Rica has created an urgent need for reforestation. This deforestation occurs due to human need for pastures to graze livestock and a high demand for hardwood building materials, leaving the land barren and completely degraded of natural resources. Traditionally, when confronted with this challenge, plantation forestry utilizes exotic species. In efforts to reduce deforestation pressure on remnant natural forests, farmers are now encouraged to replant using native tree species. Using native species for reforestation efforts creates an environment that may develop into a habitat much like the ecosystem that was destroyed, housing the same endemic plant and animal species. An investigation of the performance of such native species in plantations is underway. My research this summer focused on pathogen damage to new leaves of the tropical tree Virola koschnyi . In tropical forests, approximately 11% of the annual leaf area produced is consumed by herbivores and pathogens, a significant enough resource loss that it negates investments made in reproduction efforts. I investigated how biological and physical factors affected the occurrence of damage to leaves by pathogens. Specifically, I looked for correlations between pathogen damage and differing light levels, position in the canopy, and tree location within the plantation/forest settings. I also examined at what age V. Koschnyi leaves are attacked by principal pathogens and whether pathogen damage is correlated with herbivore damage.