ELSEVIER Ecological Modelling 94 (1997) 287-297 E(OmGl(gl. nlODLqLl.lnG Modelling micro-habitat temperature for Dendroctonus ponderosae (coleoptera: scolytidae) Paul V. Bolstad a,*, Barbara J. Bentz b, Jesse A. Logan b a Department of Forest Resources, University of Minnesota, 1530 N. Cleveland Ave, St. Paul, &IN 55108, USA Forest Sciences Lab-USFS, lntermountain Research Station, Logan, UT 84321, USA Received 23 August 1995; accepted 27 February 1996 Abstract We evaluate two landscape-scale microhabitat temperature prediction models suitable for the mountain pine beetle, Dendroctonus ponderosae Hopkins (coleoptera: scolytidae). Both models are based on maximum and minimum air temperatures measured at meteorological stations. The first, 'lapse' model employs temperature observations for a single nearby weather station, adjusting maximum and minimum temperatures based on elevation differences and appropriate historical vertical lapse rates. The second, 'geographic trend surface' model is based on the locations, elevations, and daily temperature measurements of surrounding weather stations. Predicted air temperatures are adjusted with a radiance-based exposure index to estimate sub-cortical phloem temperatures. Model parameters were estimated using original field measurements at three sites, and using 25 years of regional temperature measurements for sites in the western United States. Stand air temperature and phloem predictions were validated in comparisons with four withheld weather stations, and against one year of independently measured temperatures from four forest stands. Mean errors (observed minus predicted) of daily maximum stand air temperature ranged from -3.9 to 1.5°C, while mean prediction errors for daily minimum air temperatures ranged from -6.3 to 1.7°C. The geographic trend surface model performed slightly better across a range of sites, both for maximum and minimum air temperatures. Phloem temperature predictions were generally more variable, particularly for maximum temperatures on south sides of trees. Standard deviations in prediction errors were generally lower for minimum temperatures and did not differ by model form or tree exposures. © 1997 Elsevier Science B.V. All rights reserved Keywords: Model; Temperature; Insect; Phenology; Landscape 1. Introduction The mountain pine beetle (Dendroctonus pon- derosae Hopk.) is a predominantly univoltine phloem feeder common in lodgepole (Pinus contorta Doug. ex Loud.) and ponderosa pine (P. ponderosae Doug. * Corresponding author. Tel.: + 1-612-6251703; fax: + 1-612- 625-5212; e-mail: pbolstad@forestry.umn.edu. ex Laws.) forests of westem North America. Due to periodic outbreaks the mountain pine beetle is an agent of large economic and ecological importance. Because the mountain pine beetle characteristically spends the majority of its life stages in the inner bark and phloem, knowledge of subcortical environmental conditions is key to understanding mountain pine beetle biology. Temperature is among the most important factors governing mountain pine beetle population dynamics 0304-3800/97/$17.00 © 1997 Elsevier Science B.V. All rights reserved. PI1 S0304-3800(96)00021 -X