Land surface temperature (LST), an increasingly used metric to describe climate variation, interacts with vegetation as cooling driven by evapotranspiration is linked to reductions in LST and air temperature (Ta) at a microclimate scale, with large variation among vegetation type. Relationships between LST and Ta are commonly used to ask about landscape-level variation. By scaling up from vegetation to landscape, we asked: how does vegetated cover influence local distributions and interactions of LST and Ta across an elevation gradient? In the winter of 2016 to summer of 2017, we observed LST- relationships in four representative communities at three elevations along a 1600 m elevation transect in Southern California: Creosote Bush Scrub, recently burned Pinyon-Juniper, unburned Pinyon-Juniper, and Yellow Pine forest. To measure horizontal variation in LST, we captured thermal imagery at 10 minute intervals for 24 hours at each site. To measure the vertical profile of plant influence on microclimate, calculated as lapse rate (∆Temperature/∆Height, °C m-1), we used coupled air temperature sensors at 0.1 m and 1.5 m above ground, under plant canopy and in interspaces.
At all sites, canopy cover effectively reduces LST during the day, with little difference between canopy and interspace at night. This pattern is reflected in averaged LST, as well as the clustering of LST as quantified through spatial autocorrelation. The daytime differences as well as structure and clustering of LST increase as canopy size increases.The effect of canopy cover on lapse rate reflects the pattern of LST at sites with large patch size, but not at sites with small patch size. The variation in vertical profile of Ta increases with elevation and canopy patch size, with little difference between canopy and interspace throughout the day in Creosote Bush Scrub and burned Pinyon-Juniper, and great difference during the day in unburned Pinyon-Juniper and Yellow Pine forest.