Carbon dynamics of mature and regrowth tropical forests derived from a pantropical database (TropForC‐db)

Abstract

Tropical forests play a critical role in the global carbon (C) cycle, storing ~45% of terrestrial C and constituting the largest component of the terrestrial C sink. Despite their central importance to the global C cycle, their ecosystem-level C cycles are not as well-characterized as those of extra-tropical forests, and knowledge gaps hamper efforts to quantify C budgets across the tropics and to model tropical forest-climate interactions. To advance understanding of C dynamics of pantropical forests, we compiled a new database, the Tropical Forest C database (TropForC-db), which contains data on ground-based measurements of ecosystem-level C stocks and annual fluxes along with disturbance history. This database currently contains 3568 records from 845 plots in 178 geographically distinct areas, making it the largest and most comprehensive database of its type. Using TropForC-db, we characterized C stocks and fluxes for young, intermediate-aged, and mature forests. Relative to existing C budgets of extra-tropical forests, mature tropical broadleaf evergreen forests had substantially higher gross primary productivity (GPP) and ecosystem respiration (Reco), their autotropic respiration (Ra) consumed a larger proportion (~67%) of GPP, and their woody stem growth (ANPPstem) represented a smaller proportion of net primary productivity (NPP, ~32%) or GPP (~9%). In regrowth stands, aboveground biomass increased rapidly during the first 20 years following stand-clearing disturbance, with slower accumulation following agriculture and in deciduous forests, and continued to accumulate at a slower pace in forests aged 20-100 years. Most other C stocks likewise increased with stand age, while potential to describe age trends in C fluxes was generally data-limited. We expect that TropForC-db will prove useful for model evaluation and for quantifying the contribution of forests to the global C cycle. The database version associated with this publication is archived in Dryad (DOI: 10.5061/dryad.t516f) and a dynamic version is maintained at https://github.com/forc-db.

Patterns of tree mortality in a temperate deciduous forest derived from a large forest dynamics plot

“…ANPP stem was calculated using allometric relationships (Appendix : Table S2) based on the change in D for stems that were alive in both census periods (following variable definition in Anderson‐Teixeira et al. ). Recruitment was calculated by summing the annual biomass change for stems added to the census in 2013 (i.e., stems that grew into the size class since the 2008 census).…”

Global change effects on humid tropical forests: Evidence for biogeochemical and biodiversity shifts at an ecosystem scale

“…A recent data synthesis of 845 plots across the tropics showed that aboveground biomass in regenerating forests accumulated most rapidly during the first 20 years following clearing, with slower but positive biomass accumulation occurring up to 100 years, at which point regenerating forest biomass was similar to that in mature forests. In this study there was faster biomass accumulation in rainforests and montane forests versus tropical deciduous forests [ Anderson‐Teixeira et al ., ]. Similarly, a review of 44 tropical studies showed that regrowth of native forests after land abandonment was faster in wet versus seasonal tropical forests during the first 20 years, with C accumulation on average 2–3.5 Mg C ha −1 per year during the initial stages of regrowth [ Silver et al ., ].…”

“…However, secondary forests generally do not acquire aboveground biomass levels comparable to mature tropical forests during the first decades of growth. In a data synthesis of 845 plots across the tropics, both aboveground and root biomass were greater for mature forests (>100 years old) versus young (<20 years old) and intermediate‐aged (20–100 years old) forests [ Anderson‐Teixeira et al ., ]. For example, study in the eastern Amazon compared mature forests with secondary forest stands at 10, 20, and 40 years after agricultural abandonment and showed that mature forests had greater aboveground biomass and C storage than secondary forests because of more woody tissue, even though secondary forests had greater foliar biomass [ Johnson et al ., ].…”

The carbon fluxes in different successional stages: modelling the dynamics of tropical montane forests in South Ecuador

“…In the global carbon cycle, tropical forests are considered to act as a carbon sink (Houghton et al 2009;Beer et al 2010;IPCC 2013). However, at the local scale, forests act as either sources or sinks, depending upon their successional stage and disturbance state (Luyssaert et al 2008;Morton et al 2014;Anderson-Teixeira et al 2016;Gatti et al 2014).…”