Relationships between tree biomass productivity and local species diversity

Abstract

This study evaluated the relationship between the productivity of aboveground coarse woody biomass and species richness at individual species and community levels in two large and fully stem-mapped temperate forest plots in northeastern China. Although productivity-diversity relationships (PDRs) have been investigated for different forest ecosystems, specific patterns have rarely been documented for individual species. In our study, the PDR patterns were found to be scale dependent at the community level in both research forests. Productivity is positively linked with species richness at the 20 x 20 m sampling scale. At the 40 x 40 m scale, however, significantly positive PDRs were only observed in the mature forest. A summary statistic combining both productivity and richness characteristics was used to investigate whether and at which spatial scale individual species show positive, negative, or neutral PDRs. The results show that 66.7% of all focal species exhibited positive or negative PDRs in the near-mature forest, while 64.3% exhibited positive or negative PDRs in the mature forest. Contrary to expectations, there were few species showing positive PDRs in either forest. PDR patterns were found to be scale dependent in both forest types: Negative PDRs dominate at close neighborhoods in the near-mature forest, while both positive and negative PDRs were found in the mature forest. To our knowledge, this is the first analysis that evaluates the PDRs of individual species based on facilitative and competitive effects in their neighborhoods.