In this study, we explored the characteristics of the carbon (C), nitrogen (N), phosphorus (P), and potassium (K) content, as well as the ecological stoichiometry characteristics of economically important tree species from frigid karst and arid areas. Our goal was to elucidate the growth rates, stochiometric homeostasis, and nutrient limitations of these species, which would provide theoretical guidance to improve the ecological environment of the karst area. The study area was in the Salaxi region in Bijie, Guizhou Province, China, which is home to two economically important tree species, Rosa roxburghii and Juglans regia. We compared the nutrient contents and ecological stoichiometry characteristics of these species, as well as the relationships among the C, N, and P contents and the stoichiometric ratio of leaf-litter-soil. The results showed that among the different components of these species, the soil organic C content was the highest in J. regia leaves, whereas total N and total P contents were the highest in R. roxburghii leaves, and total K content was the highest in the root zone soil of J. regia. The available K in the root zone soil was higher for J. regia than for R. roxburghii, indicating that J. regia has superior drought tolerance. The N resorption rate of R. roxburghii was higher than that of J. regia, indicating that the root zone soil of R. roxburghii lacked N elements compared with J. regia. The ecological stoichiometry characteristics exhibited the trend of litter > leaves > root zone soil. The leaf N:P ratio of R. roxburghii was <14, indicating that the growth of R. roxburghii was mainly affected by N. The C:P and N:P ratios of leaves were lower in R. roxburghii than in J. regia given the same planting period; the growth rate of R. roxburghii was higher than that of J. regia. The N:P ratio of litter was higher in J. regia than in R. roxburghii, indicating that the litter of J. regia retained more nutrients. The C:N ratio of the root zone soil was higher in J. regia than in R. roxburghii, indicating that J. regia had a greater ability to retain fertilizer. There was a significantly positive relationship between the total P content of root zone soil and the total P content of leaves, which revealed that the P content in plant leaves was derived mainly from the P content in the soil. There was also a significantly positive relationship between total N content of the root zone soil and the litter C:N ratio, which indicated that the N content of the root zone soil was closely related to litter decomposition.