Mountain ecosystems are at risk from climate change and may be experiencing accelerated warming relative to lower environments. Understanding climatic and ecosystem processes at meso-, topo-, and micro-scales is limited, and constrains our ability to accurately evaluate vulnerability, and assess responses under future climates. Of special interest for climate studies are upper subalpine forests, the alpine treeline ecotone, and the alpine zones. We will use case-study ecosystems to address climatic processes and ecological responses at topo- and micro-scales, including: 1) treeline ecotone and role of phenotypic plasticity in Pinus albicaulis, 2) rocky ecosystems and Ochotona princeps, 3) demography of subalpine Pinus flexilis throughout the late Holocene, 4) response of alpine plant species to 10 years climate (GLORIA analyses). Methods and locations will vary with the sub-studies, but will involve tree-ring techniques, forest ecological plot methods, thermal monitoring with thermochrons, mammal behavioral studies, and GLORIA vegetation monitoring protocols. Locations include the eastern Sierra Nevada, CA, and mountains of the western and central Great Basin, NV and CA.