Environmental factors drive changes in plant functional traits, which in turn promote community recovery. The environmental conditions of the community are different at different recovery stages. Changing environmental factors may drive the changes in plant functional traits at the community level and affect species adaptation. We studied plant communities in five different recovery stages (herb, grass and shrub, shrub, tree and shrub, and tree) in the karst plateau of Zhenning, Guizhou (The vegetation in the study area has undergone a gradual natural recovery process after the forests were deforested in 1958–1960). We studied functional traits and their links to environmental factors. The main results include the following. (1) Over time, plant height, leaf dry matter content, leaf nitrogen content and leaf phosphorus content increased significantly in the tree stage, while leaf thickness and specific leaf area decreased significantly in the tree stage. (2) Soil organic carbon, soil N content, soil P content, soil C:P and soil C:K showed an increasing trend, and were significantly higher in tree stage than in other stages. Soil potassium content fluctuated and soil bulk density decreased gradually, reaching the lowest value in the tree stage, but the difference was not significant. (3) During the restoration process, the functional characteristics changed from a combination of plant communities with high specific leaf area and low dry matter content with a short plant height to plant communities with low specific leaf area and high dry matter content with a tall plant height. (4) As recovery proceeded, the study area gradually changed from a soil nutrient‐poor environment to a nutrient‐rich environment. Overall, the environmental factors vary greatly during the recovery of plant communities in karst areas. The plant community shifts from an aggressive (resource acquisition) to a conservative (environmental barrenness resistance) ecological strategy. The soil phosphorus content and soil C:K are the main environmental factors affecting the changes in functional traits during the restoration of karst plant communities in Zhenning.

Karst forests have complex and unique carbon cycle characteristics. Soil organic carbon saturation deficit (CSD) is an important indicator of soil organic carbon (SOC) sequestration potential; exploring its characteristics and driving factors is a priority theme in current research on the carbon cycles of terrestrial ecosystems. In this study, 171 topsoil samples from typical karst forests in southwest China were used as the study objects. A SOC maximum saturation capacity model was constructed using the boundary line method. The CSD is equal to the maximum saturated capacity of SOC minus the current SOC. We analyzed the CSD and its main driving factors in different regions and succession stages. The results showed that the fractions of carbon and SOC contents in the karst forests at different successional stages in descending order were as follows: climax stage > arbor stage > shrub stage > herb stage. The CSD was the highest at the herb stage in Maolan, Yuntai Mountain, and Dashahe at 83.04%, 89.99%, and 89.97%, respectively, followed by the shrub stage with 48.69%, 78.50%, and 84.95%, and the lowest at the arbor stage with 25.69%, 43.44%, and 60.49%. The main drivers of CSD in the karst forest of Maolan were litter carbon input, total nitrogen, total phosphorus, and total SOC, and were litter carbon input at Yuntai Mountain and litter carbon input and neutral phosphatase at Dashahe. The results indicate that the core driver of CSD in the karst forest is litter carbon input, and this can be adjusted in the future to regulate the carbon sequestration capacity of SOC.

The relationships among species diversity, functional diversity, functional redundancy, and community stability are central to community and ecosystem ecology. In this paper, a “space substitution for time” approach is used to study the plant communities at different stages of the natural recovery process of degraded karst vegetation on the karst plateau of Guizhou. These restoration stages include the herbaceous stage, herbaceous and shrub transition stage, shrub stage, tree and shrub transition stage, and tree stage. We calculated the functional diversity and functional redundancy of the community based on functional characteristics and mediated the relationship between functional diversity, functional redundancy, and stability of the plant community through changes in functional diversity and functional redundancy. This study aims to reveal the mechanisms of changes in species diversity and community stability and thus further reveals the intrinsic reasons for maintaining the stability of karst plant communities. The most important results include the following: (1) Species diversity, functional redundancy, and stability gradually increased with restoration, and there were significant differences among the different stages; functional diversity increased at first and then decreased, and reached the highest level at the tree and shrub transition stage; (2) Plant height and specific leaf area were functional traits that influenced the diversity and stability of the plant community, with plant height being positively correlated with plant community diversity and stability, and specific leaf area being negatively correlated with plant community diversity and stability; (3) During the community's recovery, functional diversity and functional redundancy interacted to maintain stability. In the early and late stages of recovery, the effect of functional redundancy on stability was greater than that of functional diversity, but it was the opposite in the middle stages; (4) The tree and shrub transition stage is the likely point at which the functional diversity of plant communities in karst areas reaches saturation, and the growth rate of functional redundancy after functional diversity saturation is greater than that before saturation. Overall, community stability increased with species diversity; habitat heterogeneity increased functional diversity in the early stages of recovery; and habitat homogeneity increased functional redundancy.

Soil organic carbon (SOC) forms the largest terrestrial organic carbon (C) pool, which is regulated by complex connections between exogenous C input, microbial activity, and SOC conversion. Few studies have examined the changes in natural abundance C due to microbial activity after exogenous C inputs in karst lime soils in China. In this research, the ¹³C isotope tracer technique was employed to investigate the priming effect of SOC on typical lime soil (0~20 cm) of ¹³C_litter and ¹³C_calcium carbonate (CaCO₃) through a mineralization incubation experiment. Samples were collected at 5, 10, 20, 40, 60, and 80 days of incubation and analyzed for SOC mineralization, SOC distribution across fractions (>250 μm, 53~250 μm, and 250 μm) and microaggregate (53~250 μm) C fractions by 2150.13, 2229.06, and 1575.06 mg C kg⁻¹ C_bulk on average and increased the mineral particulate C fraction (<53 μm) by 1653.98 mg C kg⁻¹ C_bulk. As the incubation time extended, a significantly positive correlation was apparent between SOC priming and soil fungal diversity, as well as between the mineral particulate C fraction and soil bacterial diversity. The effect of soil fungal diversity on SOC priming (R = 0.40, p = 0.003) significantly exceeded that of bacterial diversity on SOC sequestration (R = 0.27, p = 0.02). Our results reveal that after adding litter or CaCO₃, soil fungi stimulate SOC mineralization and decomposition and soil bacteria enhance SOC sequestration, with the effects of fungi being more pronounced. These findings can provide a theoretical basis for understanding C sequestration and emission reduction in karst lime soils.

Assessment of relationships between functional diversity and ecological stoichiometry in plant communities can aid in determining the relative variability and ecological complementarity of functional attributes among species, which is a better approach to understanding ecosystem processes and functions than studying species taxonomic diversity. Here, we analyzed the relationships among community weighted means of functional traits, functional diversity, and leaf and soil chemical properties of plant communities during various stages of vegetation restoration in Mao Lan National Karst Forest Nature Reserve, located in humid subtropical Guizhou of China. Our results showed significant changes in four weighted functional traits of plant communities at different restoration stages, namely, plant height, leaf width to leaf length ratio, and leaf area. Additionally, with the progression of the recovery of plant communities, functional richness, functional separation, and quadratic entropy, the coefficient tended to increase. Functional divergence tended to gradually decrease. The association of functional diversity with soil chemical properties was stronger than that with leaf ecological stoichiometry. Regarding leaf and soil chemical properties, soil phosphorus content and leaf C:P were particularly important in influencing functional diversity. Our overall findings indicate that functional traits shift from “acquisitive” to “conservative” as the community is restored. Karst plant communities reduce interspecific resource competition as restoration proceeds, thereby increasing functional overlap effects.

Assessing the functional traits and ecological stoichiometric characteristics of dominant species across different life forms within plant communities in karst environments and investigating the inherent connection between them can provide insights into how species adjust their functional attributes in response to habitat heterogeneity. This approach offers a more comprehensive understanding of ecosystem processes and functions in contrast to examination of the taxonomic diversity of species. This study examines the relationship between the functional characteristics of dominant species in plant communities of various life forms in karst environments, focusing on deciduous leaf–soil ecological stoichiometry. The investigation relies on community science surveys, as well as the determination and calculation of plant functional traits and ecological stoichiometries, in plant communities of various life forms in Guizhou (a province of China). The findings of our study revealed considerable variability in the functional trait characteristics of dominant species across different plant-community life forms. Specifically, strong positive correlations were observed among plant height (PLH), leaf area (LA), leaf dry matter content (LDMC), and specific leaf area (SLA) in the dominant species. Additionally, our results indicated no significant differences in leaf ecological stoichiometry among different life forms. However, we did observe significant differences and strong positive correlations between soil N:P, withered material C:N, and apomictic C:P. Furthermore, our study found that plant height (PLH), leaf area (LA), and specific leaf area (SLA) were particularly sensitive to the ecological stoichiometry of soil and apomixis. The results of our study suggest that the functional traits of diverse plant-community life forms in karst regions are capable of adapting to environmental changes through various expressions and survival strategies. The development of various plant-community life forms in karst areas is particularly vulnerable to phosphorus limitation, and the potential for litter decomposition and soil nutrient mineralization is comparatively weaker. The functional traits of various plant-community life forms in karst regions exhibit greater sensitivity to both the soil’s C:N ratio and the C:N ratio of apomictic material. Habitat variations may influence the ecological stoichiometric characteristics of the plant leaf–apomictic soil continuum.