Acknowledgements
We are grateful to the National Parks of the United States including Yosemite, Sequoia, and King Canyon National Parks for providing permission to conduct research in the parks. Thanks also to Ministry of Education Republic of China (Taiwan) for offering a scholarship to YMW. This research is also supported by the Valentine Eastern Sierra Reserve (UC Santa Barbara Natural Reserve System) through VESR Graduate Student Funding to YMW, and a UW Research Competition Award to SDS. We thank Benton Veire and Matthew Medeiros for helping us to conduct the field work, and Ph.D. committees of YMW for providing suggestions to this study. The authors have no conflicts of interests to declare.