Litter Traits of Native and Non-Native Tropical Trees Influence Soil Carbon Dynamics in Timber Plantations in Panama.
Kerdraon, D., Drewer, J., Castro, B., Wallwork, A., Hall, J. S., & Sayer, E. J. . 2019.
Abstract
Tropical reforestation initiatives are widely recognized as a key strategy for mitigating
rising atmospheric CO2 concentrations. Although rapid tree growth in young secondary forests
and plantations sequesters large amounts of carbon (C) in biomass, the choice of tree species for
reforestation projects is crucial, as species identity and diversity affect microbial activity and soil C
cycling via plant litter inputs. The decay rate of litter is largely determined by its chemical and physical
properties, and trait complementarity of diverse litter mixtures can produce non-additive effects,
which facilitate or delay decomposition. Furthermore, microbial communities may preferentially
decompose litter from native tree species (homefield advantage). Hence, information on how
different tree species influence soil carbon dynamics could inform reforestation efforts to maximize
soil C storage. We established a decomposition experiment in Panama, Central America, using
mesocosms and litterbags in monoculture plantations of native species (Dalbergia retusa Hemsl. and
Terminalia amazonia J.F.Gmel., Exell) or teak (Tectona grandis L.f.) to assess the influence of different
litter types and litter mixtures on soil C dynamics. We used reciprocal litter transplant experiments to
assess the homefield advantage and litter mixtures to determine facilitative or antagonistic effects on
decomposition rates and soil respiration in all plantation types. Although litter properties explained
some of the variation in decomposition, the microclimate and soil properties in the plantations
also played an important role. Microbial biomass C and litter decomposition were lower in Tectona
than in the native plantations. We observed non-additive effects of mixtures with Tectona and
Dalbergia litter on both decomposition and soil respiration, but the effect depended on plantation type.
Further, there was a homefield disadvantage for soil respiration in Tectona and Terminalia plantations.
Our results suggest that tree species diversity plays an important role in the resilience of tropical
soils and that plantations with native tree species could help maintain key processes involved in soil
carbon sequestration.
Key Words
tropical forest; soil carbon; homefield advantage; litter decomposition; litter traits; non-additive effects; plantations; soil respiration
