## 1 Introduction  
Forests play a critical role in the global carbon cycle. In the northern hemisphere alone, forests sequester about \(7\times 10^{8}\) metric tons of carbon annually [1]. Forested ecosystems capture carbon dioxide (CO\({}_{2}\)) through photosynthesis and lose CO\({}_{2}\) through respiration which includes soil respiration (R\({}_{\rm s}\)). R\({}_{\rm s}\) is a significant carbon flux back to the atmosphere and even small changes can have significant impacts on CO\({}_{2}\) concentrations in the atmosphere. Therefore, forests are being investigated extensively as they likely will play a large role in the management of global CO\({}_{2}\) emissions [2]. In fact, U.S. forested land offsets about 12% of the annual greenhouse gas emissions [3]. Recent research has suggested that if the globe were forested to its potential, forests could reduce the atmospheric carbon pool by 25% [4]. R\({}_{\rm s}\) makes up 30%-80% of total ecosystem respiration. Variations in R\({}_{\rm s}\) have been identified both spatially and temporally by researchers, and these variations are affected by both biotic and abiotic factors [5]. The biotic factors can include canopy cover, leaf area, and litter deposits. Biotic and abiotic factors can directly influence each other and often interact. Soil moisture and soil temperature are considered the two most influential abiotic factors influencing soil respiration [6]. Soil moisture and soil temperatures' effect on R\({}_{\rm s}\) varies depending on climate and soil conditions. Among different ecosystems, a study found the soil temperature sensitivity of R\({}_{\rm s}\) per 10 \({}^{\circ}\)C temperature change at a global scale to be between 1.43 and 2.03 [7]. In most studies investigating both soil temperature and moisture, soil temperature has the most influence on R\({}_{\rm s}\) when soil moisture is not limiting or in excess [8]. As of now, we have a relatively good understanding of R\({}_{\rm s}\) under managed forest ecosystems such as pine plantations. In the present study, R\({}_{\rm s}\) was examined under different overstories and understories in a high-elevation Southern Appalachian forest in order to get a better understanding of R\({}_{\rm s}\) under a natural hardwood system. Vegetation has been found to affect the soil microclimate, the quantity and quality of litter deposited, as well as the rate of root respiration [9]. Studies have not examined in-depth the comparison of R\({}_{\rm s}\) across the overstories and understories in Appalachian forests. In particular, the high-elevation Appalachian forests are biologically very complex, and thus understanding how they cycle carbon under the smaller spatial scales could help us scale up to the landscape. In 1974, the National Academy of Sciences challenged the forestry and remote-sensing sectors to come together, observe, and overcome any obstacles in their way of integrating [10]. In these areas of study, it is neither practical nor economically feasible to gather all the data needed using field measurements. Remotely sensed data can build upon existing data sets to fill in gaps in the landscape. Currently, remote sensing's applications in forestry cover a wide range of subjects, including terrain analyses, forest management, updating forest inventories, forest cover type delineation, and mapping burned areas [10]. This study will also investigate its application in estimating R\({}_{\rm s}\). Relating R\({}_{\rm s}\) to easily obtained remotely sensed variables has several advantages. It is cheaper, allows estimations of R\({}_{\rm s}\) at regional, continental, and global scales, and can be used to view remote locations [11]. Several studies have found relationships between R\({}_{\rm s}\) and remotely sensed temperature or plant cover [12; 13]. Vegetation reflectance can give us further insight into plant phenology by examining the variation in near-infrared and visible bands.