title: Drought predisposes piñon-juniper woodlands to insect attacks and mortality.
abstract: To test the hypothesis that drought predisposes trees to insect attacks, we quantified the effects of water availability on insect attacks, tree resistance mechanisms, and mortality of mature piñon pine (Pinus edulis) and one-seed juniper (Juniperus monosperma) using an experimental drought study in New Mexico, USA. The study had four replicated treatments (40 × 40 m plot/replicate): removal of 45% of ambient annual precipitation (H2 O-); irrigation to produce 125% of ambient annual precipitation (H2 O+); a drought control (C) to quantify the impact of the drought infrastructure; and ambient precipitation (A). Piñon began dying 1 yr after drought initiation, with higher mortality in the H2 O- treatment relative to other treatments. Beetles (bark/twig) were present in 92% of dead trees. Resin duct density and area were more strongly affected by treatments and more strongly associated with piñon mortality than direct measurements of resin flow. For juniper, treatments had no effect on insect resistance or attacks, but needle browning was highest in the H2 O- treatment. Our results provide strong evidence that ≥ 1 yr of severe drought predisposes piñon to insect attacks and increases mortality, whereas 3 yr of the same drought causes partial canopy loss in juniper.
authors: School of Forestry, Northern Arizona University, Flagstaff, AZ, 86011, USA.
authors: Monica L
authors: ML
authors: Gaylord
authors: School of Forestry, Northern Arizona University, Flagstaff, AZ, 86011, USA.
authors: Thomas E
authors: TE
authors: Kolb
authors: Department of Biology, MSC03 2020, 1 University of New Mexico, Albuquerque, NM, 87131-0001, USA.
authors: William T
authors: WT
authors: Pockman
authors: Department of Biology, MSC03 2020, 1 University of New Mexico, Albuquerque, NM, 87131-0001, USA.
authors: Jennifer A
authors: JA
authors: Plaut
authors: Department of Biology, MSC03 2020, 1 University of New Mexico, Albuquerque, NM, 87131-0001, USA.|Departamento de Ciencias del Agua y del Medio Ambiente, Instituto Tecnológico de Sonora, Ciudad Obregón México, 85000, México.
authors: Enrico A
authors: EA
authors: Yepez
authors: School of Geography and Development and Laboratory of Tree-Ring Research, University of Arizona, Tucson, AZ, 85721, USA.
authors: Alison K
authors: AK
authors: Macalady
authors: Department of Biology, MSC03 2020, 1 University of New Mexico, Albuquerque, NM, 87131-0001, USA.
authors: Robert E
authors: RE
authors: Pangle
authors: Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.
authors: Nate G
authors: NG
authors: McDowell
mesh_terms: D000818:Animals; D050260:Carbohydrate Metabolism; D002247:Carbon Isotopes; D001517:Coleoptera / Q000502:physiology*; D055864:Droughts; D018653:Juniperus / Q000254:growth & development* / Q000469:parasitology*; D009516:New Mexico; D028223:Pinus / Q000254:growth & development* / Q000469:parasitology*; D018515:Plant Leaves / Q000378:metabolism; D012116:Resins, Plant / Q000378:metabolism; D014197:Trees / Q000254:growth & development / Q000469:parasitology*
chemical_list: D002247:Carbon Isotopes; D012116:Resins, Plant