Light competition drives species replacement during secondary tropical forest succession

• Published in: Oecologia Vol. 205; no. 1; pp. 1 - 11
• Main Authors: Matsuo, Tomonari, Martínez-Ramos, Miguel, Onoda, Yusuke, Bongers, Frans, Lohbeck, Madelon, Poorter, Lourens
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.05.2024; Springer; Springer Nature B.V
• Subjects: Biomass; Biomedical and Life Sciences; Competition; Density; Dominance; Ecological succession; Ecology; Forests; Growth rate; Highlighted Student Research; Hydrology/Water Resources; Interception; Leaves; Life Sciences; Light; Light interception; Light levels; Old growth forests; Plant Sciences; Rain forests; Rainforest; Rainforests; Species; Trees; Tropical Climate; Tropical forests; Understory; Wood; Tropical forest succession; Light interception and use; Light competition; Functional traits; Species replacement
• DOI: 10.1007/s00442-024-05551-w
• ISSN: 0029-8549; 1432-1939

Light competition is thought to drive successional shifts in species dominance in closed vegetations, but few studies have assessed this for species-rich and vertically structured tropical forests. We analyzed how light competition drives species replacement during succession, and how cross-species variation in light competition strategies is determined by underlying species traits. To do so, we used chronosequence approach in which we compared 14 Mexican tropical secondary rainforest stands that differ in age (8–32 year-old). For each tree, height and stem diameter were monitored for 2 years to calculate relative biomass growth rate (RGR, the aboveground biomass gain per unit aboveground tree biomass per year). For each stand, 3D light profiles were measured to estimate individuals’ light interception to calculate light interception efficiency (LIE, intercepted light per unit biomass per year) and light use efficiency (LUE, biomass growth per intercepted light). Throughout succession, species with higher RGR attained higher changes in species dominance and thus increased their dominance over time. Both light competition strategies (LIE and LUE) increased RGR. In early succession, a high LIE and its associated traits (large crown leaf mass and low wood density) are more important for RGR. During succession, forest structure builds up, leading to lower understory light levels. In later succession, a high LUE and its associated traits (high wood density and leaf mass per area) become more important for RGR. Therefore, successional changes in relative importance of light competition strategies drive shifts in species dominance during tropical rainforest succession.