Karst region is widely distributed in the world, characterized by high soil resource heterogeneity with low resource availability due to the high bare rock ratio, serious soil erosion, and high habitat fragmentation. In recent years, due to the combination of soil erosion and the rapid expansion of rural and urban areas, cultivated land has reduced sharply within the karst region, with abandoned land areas increasing annually. In the process of natural restoration of karst abandoned farmland, plant colonization and community composition in the early stage of succession have a profound influence on the prediction of the direction of succession in the later stage. Plant functional traits refer to all the attributes that have potentially important effects on plant settlement, survival, and adaptation. They can reflect the adaptation of plants to different environments and the physiological or evolutionary trade-offs between different functions within the plant. As a new research method, plant functional traits are widely used to explain the ecological processes and species strategies, and the responses of functional traits to environmental resources at different spatial scales. The response of functional traits to environmental resources shows different patterns at different spatial scales. However, the influence of soil resource heterogeneity on plant functional traits patterns and its scaling effects remains unclear, which is crucial for effective vegetation restoration in karst abandoned land. In this study, we took the herbaceous community at the early successional stage of karst abandoned farmland as the research object. Based on four spatial scales (1 m × 1 m, 5 m × 5 m, 10 m × 10 m, 15 m × 15 m), we investigated the patterns of functional traits structure of the species, the weighted mean value of the community, and the soil integrated resource heterogeneity, in order to elucidate the different ecological mechanisms affecting the functional traits structure and the adaptation strategies of the co-existing species in the community to the soil resource heterogeneity. We hope the results can provide a theoretical basis for the functional restoration of karst ecosystems. The results showed that: (1) In highly heterogeneous habitats, at larger scales (10 m × 10 m or 15 m × 15 m), plant height, leaf area, leaf dry matter content, and leaf nitrogen content showed trait aggregation, while leaf thickness showed trait dispersion. At smaller scales (1 m × 1 m), leaf dry matter content showed trait aggregation, while specific leaf area and plant height showed trait dispersion. At the medium scale, there was no significant change in the community-weighted mean and integrated resource heterogeneity. (2) Gramineae increased and Sedum and Leguminosae decreased in large-scale (15 m × 15 m) highly heterogeneous habitats. Sedum and Leguminosae increased, while Gramineae and Apiaceae decreased in small-scale (1 m × 1 m) highly heterogeneous habitats. The study showed that species functional traits structure, community weighted means, and patterns of the integrated resource heterogeneity all had spatial scale effects in a highly resource heterogeneous environment in karst. Habitat filtering had a dominant effect at large scales, while limiting similarity and habitat filtering acted together in small-scale communities. Resource acquisition strategies of plants adapted to heterogeneous environments were more oriented towards acquisitive strategies at large scales, and more conservative strategies at small scales.