Interspecific association and environmental interpretation of dominant species in shrub layer of Pinus massoniana community on Chinese islands

Understanding the factors driving species coexistence and competition in the shrub layer of semi-natural forests is crucial for effective forest management and conservation. However, there is limited knowledge about the interspecific associations of the main species in the shrub layer of Pinus massoniana communities in the semi-natural forest of Sandu Gulf, Ningde, Fujian Province, China. Therefore, this study aimed to investigate the influence of the abiotic environment on plant communities within the semi-natural forest of P. massoniana on the islands of Sandu Gulf. By exploring these interspecific associations, we sought to provide a more accurate understanding of the causes and processes of species coexistence and competition. The ultimate goal of this project was to offer a reference basis for optimizing the shrub layer structure in P. massoniana (plantation) forests. We found that (1) Heptapleurum heptaphyllum was the most dominant species in the shrub layer, while Smilax china de..., Primarily, we wanted to determine the dominant position of each species in the shrub layer. For this, the average importance value (IV%) of all species in each of the 40 sample plots was used to screen the dominant species in the shrub layer. The calculation formula used is as follows (Chen et al., 2021):
IV% = (relative abundance + relative frequency + relative coverage) / 3.
Relative abundance = (the abundance of a certain species in the quadrat / the sum of the abundance of all species) × 100%
Relative frequency = (frequency of a certain species in the sample / total frequency of all species) × 100%
Relative coverage = (the coverage of a certain species in the sample/the total coverage of all species) × 100%
Niche and interspecific association analyses were conducted for dominant species with IV% >1 in the shrub layer, using each site (or each environmental gradient) and each species importance value as different resource levels and species resource utilization states, respectivel..., SPSS，R，Canoco，Origin，Excel were used for analysis., # Data from: Interspecific association and environmental interpretation of dominant species in shrub layer of Pinus massoniana community on Chinese islands

[https://doi.org/10.5061/dryad.w3r2280wv](https://doi.org/10.5061/dryad.w3r2280wv)

## Description of the data and file structure

The dataset contains multiple CSV files. There are a total of seven files, which are:

* Degree_Table.csv,

- 24.11.26_Importance_values_for_all_shrub_species.csv,

* Soil_Info.csv,

- Species_importance_values_at_available_potassium_gradients.csv,

* Importance_values_of_dominant_species.csv,

- Species_importance_values_at_pH_gradients.csv, and

* Species_importance_values_at_total_potassium_gradients.csv.

Among them, Degree_Table.csv is primarily used for phylogenetic analysis. The files 24.11.26_Importance_values_for_all_shrub_species.csv and Importance_values_of_dominant_species.csv are the most critical data, especially the latter, which is used for analyzing niche width, redundancy analysis (RDA)...