Functional identity explains carbon sequestration in a 77‐year‐old experimental tropical plantation

Abstract

Planting forests is an important practice for climate change mitigation, especially in the tropics where the carbon (C) sequestration potential is high. Successful implementation of this mitigation practice requires knowledge of the role of species identity and diversity on carbon accrual of plantations. Despite this need, solid data on the long-term development of forest plantations are still very scarce. Monospecific and two species mixture plots of a 77-year-old tree diversity experiment in Yangambi in the Congo basin were fully inventoried. We calculated above-ground C stocks using allometric equations, and soil C stocks by analyzing soil samples at multiple depths. Linear mixed effects models were used to analyze the effect of taxonomic and functional identity and diversity on the aboveground and soil carbon stocks. A high variability in aboveground C stocks across tree species combinations was observed. Apart from a species identity effect, the proportion of planted species in the total stand basal area (BA(pl)) and effective species richness were identified as compositional parameters with a significant effect on the aboveground carbon (AGC), with BApl being more important. Both AGC and BA(pl) were coupled to the functional identity of the planted species; the planting of short-lived pioneers led to low AGC. We found no clear benefits, but also no drawbacks, for AGC of two species mixture plots over monospecific plots or including nitrogen fixing species in the plantation scheme. However, the latter was the only compositional parameter with a significant positive effect on the soil carbon stock up to 1 m depth. We conclude that the different plantation configurations gave rise to a wide range in carbon stocks. This was predominantly caused by large differences in AGC sequestration over the past 77 years. Altogether, short-lived pioneer species had a low BApl resulting in low carbon sequestration, while partial shade tolerant species achieved the highest AGC stocks. Tolerating spontaneous ingrowth during the plantation development can further increase the AGC stock, given that the appropriate functional type is planted

An individual‐based forest model to jointly simulate carbon and tree diversity in Amazonia: description and applications

“…This demonstrates that tropical tree species, when grown alone, do display the large range of variation in the ecosystem properties we evidenced in our simulations (see also Bauters et al. ).…”

“…In our simulations, the major impact of species diversity on GPP was the selection effect, the influence of a selective group of efficient species on the ecosystem, rather than a complementarity effect in resource acquisition across species niches. This finding contrasts with some empirical studies where a stronger complementarity than selection effect was evidenced (Loreau and Hector 2001), but is in agreement with empirical results in tropical forests (Bauters et al 2015, Finegan et al 2015, Chiang et al 2016, Prado-Junior et al 2016. However, our model does not include any other resource limitation than light, especially nutrient and water limitations.…”

“…Litterfall is a reasonably good proxy for NPP in tropical forests (Malhi et al 2011), and basal area is a good proxy for AGB. This demonstrates that tropical tree species, when grown alone, do display the large range of variation in the ecosystem properties we evidenced in our simulations (see also Bauters et al 2015).…”

“…This finding contrasts with some empirical studies where a stronger complementarity than selection effect was evidenced (Loreau and Hector ), but is in agreement with empirical results in tropical forests (Bauters et al. , Finegan et al. , Chiang et al.…”

Functional diversity improves tropical forest resilience: Insights from a long‐term virtual experiment

“…Previous biodiversity–ecosystem functioning studies yielded contrasting results on the relative importance of the different biodiversity effects in tropical forests. While the complementarity effect was identified as the dominant effect in some studies (Huang et al, ; Niklaus et al, ), the selection effect was identified in others (Bauters et al, ; de Avila et al, ; Finegan et al, ; Lohbeck, Bongers, Martinez‐Ramos, & Poorter, ; Maréchaux & Chave, ; Tobner et al, ). Our results suggest that the mechanisms through which biodiversity influences forest functioning depend to a great extent on the state of the ecosystem and its history of disturbances, with a complementarity effect dominating in recently (i.e.…”