Department of Fish and Wildlife Sciences, 875 Perimeter Drive, University of Idaho, Moscow, ID 83844, United States.
J Therm Biol. 2019 Apr;81:41-48. doi: 10.1016/j.jtherbio.2019.02.011. Epub 2019 Feb 12.
Summer temperature patterns within tree cavities might influence occupancy of cavities by different animals such as birds and bats, and furthermore, cavity temperatures can influence processes such as embryonic development or the development of young. Our study aimed to identify the environmental variables influencing cavity temperatures during summer (June-July) in quaking aspen (Populus tremuloides) in southeastern Idaho. We collected temperature data between June 22 and July 27, 2015 using iButtons distributed across 30 tree cavities in 30 aspen stands in the Craters of the Moon National Monument, Idaho. We used every third day of data to ensure temporal independence amongst readings from the same cavity. We used a multi-model selection framework to examine how environmental characteristics might influence cavity thermal environments, and we modeled how environmental variables, tree, and cavity characteristics might influence daily maximum cavity temperatures. Cavity temperatures ranged as low as 1 °C to as high as 46 °C. Approximately 13% of the cavities experienced temperatures above 40 °C for at least an hour, and these temperatures are noted to be lethal to developing avian embryos. The two top competing models explaining the daily maximum cavity temperatures included tree diameter at cavity height, canopy cover, cavity orientation, and daily maximum ambient temperature. Daily maximum cavity temperatures were significantly associated with daily maximum ambient temperatures and canopy cover; warmer cavities were positively associated with warmer ambient temperatures and negatively associated with canopy cover. Because cavities in aspen are an important resource for multiple species, understanding the factors that influence the microclimate of tree cavities can have broad implications for cavity using species in the context of changing climates.
夏季树洞内部的温度模式可能会影响不同动物（如鸟类和蝙蝠）对树洞的占有情况，此外，树洞温度还会影响胚胎发育或幼体发育等过程。我们的研究旨在确定影响爱达荷州东南部颤杨（Populus tremuloides）夏季（6 月至 7 月）树洞温度的环境变量。我们于 2015 年 6 月 22 日至 7 月 27 日期间使用 iButton 收集了温度数据，这些 iButton 分布在爱达荷州月球陨石坑国家纪念碑的 30 个颤杨林中的 30 个树洞中。我们每三天使用一次数据，以确保同一树洞中读取的数据具有时间独立性。我们使用多模型选择框架来研究环境特征如何影响树洞的热环境，并建立模型来研究环境变量、树木和树洞特征如何影响每日最大树洞温度。树洞温度低至 1°C，高至 46°C。约有 13%的树洞经历了至少一小时的温度超过 40°C，这些温度被认为对发育中的鸟类胚胎是致命的。解释每日最大树洞温度的两个最具竞争力的模型包括树洞高度处的树干直径、树冠覆盖率、树洞朝向和每日最大环境温度。每日最大树洞温度与每日最大环境温度和树冠覆盖率显著相关；较温暖的树洞与较温暖的环境温度呈正相关，与树冠覆盖率呈负相关。由于白杨树上的树洞是多种物种的重要资源，因此了解影响树洞小气候的因素对于气候变化背景下树洞利用物种具有广泛的意义。
