New indices to balance α-diversity against tree size inequality

• Published in: Journal of forestry research 2024-12, Vol.35 (1), p.229-237, Article 31
• Main Authors: Zhang, Li, Quinn, Brady K., Hui, Cang, Lian, Meng, Gielis, Johan, Gao, Jie, Shi, Peijian
• Format: Article
• Language: English
• Subjects: Biodiversity; Biomedical and Life Sciences; Climate change; Correlation; Diameters; Diversity indices; Ecological effects; Ecological function; Forest communities; Forestry; Global climate; Inequality; Life Sciences; Original Paper; Size distribution; Species diversity; Species richness; Trees; Variation
• ISSN: 1007-662X; 1993-0607
• DOI: 10.1007/s11676-023-01686-3

The number and composition of species in a community can be quantified with α-diversity indices, including species richness ( R ), Simpson’s index ( D ), and the Shannon–Wiener index ( H ′ ). In forest communities, there are large variations in tree size among species and individuals of the same species, which result in differences in ecological processes and ecosystem functions. However, tree size inequality (TSI) has been largely neglected in studies using the available diversity indices. The TSI in the diameter at breast height (DBH) data for each of 999 20 m × 20 m forest census quadrats was quantified using the Gini index (GI), a measure of the inequality of size distribution. The generalized performance equation was used to describe the rotated and right-shifted Lorenz curve of the cumulative proportion of DBH and the cumulative proportion of number of trees per quadrat. We also examined the relationships of α-diversity indices with the GI using correlation tests. The generalized performance equation effectively described the rotated and right-shifted Lorenz curve of DBH distributions, with most root-mean-square errors (990 out of 999 quadrats) being