Application of Forest Integrity Assessment to Determine Community Diversity in Plantation Forests Managed Under Carbon Sequestration Projects in the Western Qinba Mountains, China

The development of carbon sequestration projects in plantation forests has the potential to offer win-win outcomes for the environment and economy. The Climate, Community, and Biodiversity (CCB) Standards ensure that a particular forest project will deliver tangible climate, community, and biodiversity benefits. According to the CCB Standards, it is necessary to assess community diversity in plantation forests. Our study provides indicators of community diversity based on Forest Integrity Assessment (FIA) according to the CCB Standards for carbon sequestration projects in Tianshui City, Gansu Province, China, which is located in the western Qinba Mountains. Herein, we estimated plantation forest conditions based on a forest condition assessment. Linear regression models were used to explore the relationships between FIA scores and community diversity (such as species richness, Shannon-Wiener index, inverse Simpson's index, and Pielou's evenness index quantified by species abundance) in plantation forests managed under carbon sequestration projects. The high community diversity reaches the CCB Standards. FIA scores were closely associated with Pielou's evenness index of plant communities in plantation forests managed under carbon sequestration projects (R2 = 0.104; mean square error = 0.014; standard error = 0.104; p = 0.012). A complex topography had positive effects on species richness, while a rich standing condition had negative effects on the Shannon-Wiener index. Forest conditions have been used as indicators of community diversity in plantation forests managed under carbon sequestration projects. The occurrence of climber and animal species should be used as indicators for enhancing community diversity to meet the CCB Standards. Furthermore, plant species richness benefits from a complex topography. However, our study had the limitation that the FIA could not cover the full range of environmental conditions. Our study provides a practical reference for applying the CCB Standards to plantation forests managed under carbon sequestration projects.