Do plant species influence soil CO₂ and N₂O fluxes in a diverse tropical forest?

Abstract

[1] To test whether plant species influence greenhouse gas production in diverse ecosystems, we measured wet season soil CO 2 and N 2 O fluxes close to ∼300 large (>35 cm in diameter at breast height (DBH)) trees of 15 species at three clay-rich forest sites in central Amazonia. We found that soil CO 2 fluxes were 38% higher near large trees than at control sites >10 m away from any tree (P < 0.0001). After adjusting for large tree presence, a multiple linear regression of soil temperature, bulk density, and liana DBH explained 19% of remaining CO 2 flux variability. Soil N 2 O fluxes adjacent to Caryocar villosum, Lecythis lurida, Schefflera morototoni, and Manilkara huberi were 84%−196% greater than Erisma uncinatum and Vochysia maxima, both Vochysiaceae. Tree species identity was the most important explanatory factor for N 2 O fluxes, accounting for more than twice the N 2 O flux variability as all other factors combined. Two observations suggest a mechanism for this finding: (1) sugar addition increased N 2 O fluxes near C. villosum twice as much (P < 0.05) as near Vochysiaceae and (2) species mean N 2 O fluxes were strongly negatively correlated with tree growth rate (P = 0.002). These observations imply that through enhanced belowground carbon allocation liana and tree species can stimulate soil CO 2 and N 2 O fluxes (by enhancing denitrification when carbon limits microbial metabolism). Alternatively, low N 2 O fluxes potentially result from strong competition of tree species with microbes for nutrients. Species-specific patterns in CO 2 and N 2 O fluxes demonstrate that plant species can influence soil biogeochemical processes in a diverse tropical forest.

Effects of canopy tree species on belowground biogeochemistry in a lowland wet tropical forest

“…Some studies found significant species effects on belowground C and N cycling in southwestern Costa Rican and Brazilian rain forests (Reed et al, 2008;Wieder et al, 2008;Van Haren et al, 2010), while Powers et al (2004) found no significant species effects in an eastern Costa Rican rain forest. Beyond C and N, species effects on P cycling in lowland tropical forests may be especially important to consider for several reasons: P is relatively immobile; tropical soil P availability is typically low (e.g., Sanchez, 1976;Sanchez et al, 1982;Vitousek and Sanford, 1986); and P has been shown to limit ecosystem processes in tropical forests McGroddy et al, 2004;Wright et al, 2011;Santiago et al, 2012).…”

Remotely sensed canopy nitrogen correlates with nitrous oxide emissions in a lowland tropical rainforest

“…Despite increasing recognition that this diversity can drive spatial heterogeneity in local soil nutrient cycling (Binkley and Giardina , van Haren et al. , Keller et al. ), the magnitude and mechanisms by which plant traits influence important soil biogeochemical processes remain poorly defined at scales beyond individual trees (van Haren et al.…”

“…), the magnitude and mechanisms by which plant traits influence important soil biogeochemical processes remain poorly defined at scales beyond individual trees (van Haren et al. , Waring et al. ).…”

“…In Amazonia, species identity was by far the strongest predictor of N 2 O emissions beneath individual trees (van Haren et al. ). Emissions correlated negatively with tree growth rates and increased with C additions, leading the authors to conclude that denitrification may be reduced by strong plant competition for N or increased in species with greater belowground C inputs.…”

Spatial variations of nitrogen trace gas emissions from tropical mountain forests in Nyungwe, Rwanda

“…So far, only a few studies are available where variations in soil properties have been explicitly linked to spatial variation of N 2 O and NO emissions from tropical soils (e.g. Breuer et al, 2000;Ishizuka et al, 2005;Keller et al, 2005;van Haren, 2010).…”