Tropical forest carbon balance in a warmer world: a critical review spanning microbial‐ to ecosystem‐scale processes

Abstract

Tropical forests play a major role in regulating global carbon (C) fluxes and stocks, and even small changes to C cycling in this productive biome could dramatically affect atmospheric carbon dioxide (CO(2) ) concentrations. Temperature is expected to increase over all land surfaces in the future, yet we have a surprisingly poor understanding of how tropical forests will respond to this significant climatic change. Here we present a contemporary synthesis of the existing data and what they suggest about how tropical forests will respond to increasing temperatures. Our goals were to: (i) determine whether there is enough evidence to support the conclusion that increased temperature will affect tropical forest C balance; (ii) if there is sufficient evidence, determine what direction this effect will take; and, (iii) establish what steps should to be taken to resolve the uncertainties surrounding tropical forest responses to increasing temperatures. We approach these questions from a mass-balance perspective and therefore focus primarily on the effects of temperature on inputs and outputs of C, spanning microbial- to ecosystem-scale responses. We found that, while there is the strong potential for temperature to affect processes related to C cycling and storage in tropical forests, a notable lack of data combined with the physical, biological and chemical diversity of the forests themselves make it difficult to resolve this issue with certainty. We suggest a variety of experimental approaches that could help elucidate how tropical forests will respond to warming, including large-scale in situ manipulation experiments, longer term field experiments, the incorporation of a range of scales in the investigation of warming effects (both spatial and temporal), as well as the inclusion of a diversity of tropical forest sites. Finally, we highlight areas of tropical forest research where notably few data are available, including temperature effects on: nutrient cycling, heterotrophic versus autotrophic respiration, thermal acclimation versus substrate limitation of plant and microbial communities, below-ground C allocation, species composition (plant and microbial), and the hydraulic architecture of roots. Whether or not tropical forests will become a source or a sink of C in a warmer world remains highly uncertain. Given the importance of these ecosystems to the global C budget, resolving this uncertainty is a primary research priority.

Soil Carbon Dioxide Fluxes from Three Forest Types of the Tropical Montane Rainforest on Hainan Island, China

“…Besides, atmospheric carbon dioxide (CO 2 ) concentration and nitrogen (N) deposition may interactively impact soil respiration in terrestrial ecosystems . Soil CO 2 fluxes were also found to vary with vegetation species (Adachi et al 2006;Akburak and Makineci 2013;Huang et al 2014;Katayama et al 2009;Nottingham et al 2012;Soe and Buchmann 2005) and the degree of mineralization (Cardoso et al 2013;Silvola et al 1996;Wood et al 2012).…”

Molecular identification of endophytic fungi isolated from the tuber of Dahlia variabilis and exploration of their ability in producing ß-galactosidase

“…The condition could lead to reduce their productivities (Lambin 1999;Astiani 2016;Astiani et al 2016). Since tropical forests play a major role in regulating global carbon, fluxes and stocks-especially in peatland (Anderson 1983;Maltby and Immirzi 1993;Brown 2002;Hooijer et al 2010), even a very small alteration to carbon balance in a biome, could have a significant effect on atmospheric greenhouse gasses especially carbon dioxide (Rieley and Page 2005;Hooijer et al 2006;Uryu et al 2008;Wood et al 2012). Globally, however, deforestation and forest degradation is threatening forest CO2 sequestering function of forest Saatchi et al 2011), and deforestation and degradation account for approximately 12% of global GHG emission (Van der Werf et al 2009).…”

Can Soil Organic Carbon Pools Indicate the Degradation Levels of Pastures in the Atlantic Forest Biome?

“…The largest reduction of C in the tropics has been related to the oxidation of organic matter caused by increased microbial activity in the soil of this region due to weather conditions such as high temperatures and soil moisture (Davidson et al, 2000;Scala-Jr et al, 2000;Wood et al, 2012).…”