Importance of resin ducts in reducing ponderosa pine mortality from bark beetle attack

• Published in: Oecologia Vol. 164; no. 3; pp. 601 - 609
• Main Authors: Kane, Jeffrey M, Kolb, Thomas E
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Berlin/Heidelberg : Springer-Verlag 01-11-2010; Springer; Springer-Verlag; Springer Nature B.V
• Subjects: Agricultural pests; Analysis; Animal and plant ecology; Animal, plant and microbial ecology; Animals; Annual variations; Arizona; Bark; Bark beetles; Biological and medical sciences; Biomedical and Life Sciences; Carbon; Coleoptera - physiology; Dead wood; Drought; Droughts; Ecology; Evergreen trees; Forests; Fundamental and applied biological sciences. Psychology; General aspects; Growth rings; Health aspects; Hydrology/Water Resources; Ips spp; Life Sciences; Mortality; Northern Arizona, USA; PHYSIOLOGICAL ECOLOGY - ORIGINAL PAPER; Pine trees; Pinus - anatomy & histology; Pinus - growth & development; Pinus - physiology; Pinus ponderosa; Plant defense; Plant Sciences; Resin canals; Resins; Resins, Plant; Scolytidae; Tree growth; tree mortality; Tree ring; Trees; Xylem; United States; North America; Arizona; America; Tree mortality; Northern Arizona, USA; spp; Tree ring; Plant defense; Ips spy; Coleoptera; Insecta; Mortality; Ips; Pinus ponderosa; Arthropoda; Gymnospermae; Tree; Coniferales; Spermatophyta; Curculionidae; Invertebrata; Resins
• ISSN: 0029-8549; 1432-1939
• DOI: 10.1007/s00442-010-1683-4

The relative importance of growth and defense to tree mortality during drought and bark beetle attacks is poorly understood. We addressed this issue by comparing growth and defense characteristics between 25 pairs of ponderosa pine (Pinus ponderosa) trees that survived and trees that died from drought-associated bark beetle attacks in forests of northern Arizona, USA. The three major findings of our research were: (1) xylem resin ducts in live trees were >10% larger (diameter), >25% denser (no. of resin ducts mm⁻²), and composed >50% more area per unit ring growth than dead trees; (2) measures of defense, such as resin duct production (no. of resin ducts year⁻¹) and the proportion of xylem ring area to resin ducts, not growth, were the best model parameters of ponderosa pine mortality; and (3) most correlations between annual variation in growth and resin duct characteristics were positive suggesting that conditions conducive to growth also increase resin duct production. Our results suggest that trees that survive drought and subsequent bark beetle attacks invest more carbon in resin defense than trees that die, and that carbon allocation to resin ducts is a more important determinant of tree mortality than allocation to radial growth.