Temporal variation and climate dependence of soil respiration and its components along a 3000 m altitudinal tropical forest gradient

Abstract

[1] To simulate the effect of temperature on soil respiration rates, we translocated soil cores among four sites (3030, 1500, 1000, and 200 m asl) along an altitudinal tropical forest gradient in the Peruvian Andes, traversing a difference in mean annual temperature of 13.9°C. Rates of total (R s ) and heterotrophic (R sh ) respiration were measured twice a month from April 2007 to March 2009 and additionally for full 24 h periods. The diurnal range in R s increased with altitude; this variation was mainly root and litter derived, whereas R sh varied only slightly over full 24 h periods. Although mean annual daytime R s rates were not significantly different among the four sites (4.45-4.05 mmol CO 2 m −2 s −1 ), the annual amount of respired C decreased with increasing altitude from 1639 g C m −2 yr −1 at 200 m asl to 1064 g C m −2 yr −1 at 3030 m asl. The contribution of R sh to R s was not correlated with elevation and ranged from 25% to 60%. The temperature dependence of R s was lower at the midelevation sites (Q 10 of 2.07 and 2.94 at 1500 and 1000 m asl, respectively) than at the highest and lowest sites of the gradient (Q 10 of 4.33 and 6.92 at 3030 and 200 m asl, respectively). The temperature sensitivity of R sh was higher for the sites at 3030 and 200 m asl and increased with time, i.e., with the loss of the most labile C pools.

Different effects of warming and cooling on the decomposition of soil organic matter in warm–temperate oak forests: a reciprocal translocation experiment

“…In addition, if we do not consider the direction of soil monolith transfer, both high and lowelevation soils had 44 % greater CO 2 flux when they were incubated in the low-elevation site than those incubated in the high-elevation site, indicating that the temperature difference between the two sites determined the different CO 2 flux rates. In combination with higher soil C stock at the higher-elevation site (Table 1), similar CO 2 flux rate between both soils incubated in situ implies that more C would be stored in the soil at the high-elevation site (Zimmermann et al 2009(Zimmermann et al , 2010.…”

Fluvial dynamics of dissolved and particulate organic carbon during periodic discharge events in a steep tropical rainforest catchment

“…The d 13 C of DOC and POC typically become progressively enriched deeper in the soil profile (Wynn et al 2004), a result of kinetic fractionation during the decomposition of soil organic matter, which leads to the accumulation of 13 C in the remaining organic material. Accompanying the enrichment of d 13 C, the molar C : N decreases with increasing soil depth (Rasse et al 2006;Zimmermann et al 2010) as microbial processing respires the carbon, which is then lost as CO 2 , but continues to cycle the nitrogen through the microbial community.…”

Temporal Variability of Soil Respiration in Experimental Tree Plantations in Lowland Costa Rica

“…Despite an increasing body of empirical data from tropical forests, there is a lack of agreement on several issues. For instance, diel variations in Rsoil have been observed in some evergreen tropical forests, but not in others [33][34][35][36][37][38]. That issue underlies an important concern: most measurements of tropical forest Rsoil are made only in the daytime, especially in remote locations.…”

“…That issue underlies an important concern: most measurements of tropical forest Rsoil are made only in the daytime, especially in remote locations. If fluxes are significantly different at night than during daylight hours, then we have a poor grasp of what average tropical forest Rsoil truly is [35]. Additionally, daytime photosynthesis by a productive tree canopy may drive diel variations in Rsoil, via temporally variable canopy-to-root carbon translocation [39][40][41].…”