The above‐ground coarse wood productivity of 104 Neotropical forest plots

Abstract

The net primary production of tropical forests and its partitioning between long-lived carbon pools (wood) and shorter-lived pools (leaves, fine roots) are of considerable importance in the global carbon cycle. However, these terms have only been studied at a handful of field sites, and with no consistent calculation methodology. Here we calculate above-ground coarse wood carbon productivity for 104 forest plots in lowland New World humid tropical forests, using a consistent calculation methodology that incorporates corrections for spatial variations in tree-size distributions and wood density, and for census interval length. Mean wood density is found to be lower in more productive forests. We estimate that above-ground coarse wood productivity varies by more than a factor of three (between 1.5 and 5.5MgCha^a^) across the Neotropical plots, with a mean value of 3.1MgCha^a^. There appear to be no obvious relationships between wood productivity and rainfall, dry season length or sunshine, but there is some hint of increased productivity at lower temperatures. There is, however, also strong evidence for a positive relationship between wood productivity and soil fertility. Fertile soils tend to become more common towards the Andes and at slightly higher than average elevations, so the apparent temperature/productivity relationship is probably not a direct one. Coarse wood productivity accounts for only a fraction of overall tropical forest net primary productivity, but the available data indicate that it is approximately proportional to total above-ground productivity. We speculate that the large variation in wood productivity is unlikely to directly imply an equivalent variation in gross primary production. Instead a shifting balance in carbon allocation between respiration, wood carbon and fine root production seems the more likely explanation.Correspondence: Y. Malhi, fax + 44 (0)131 662 0478,

Tropical forests and the global carbon cycle: impacts of atmospheric carbon dioxide, climate change and rate of deforestation

“…Malhi et al (2004) report from several sites, based on stem increment measurements an average NPP of 663 g C m Ϫ2 yr Ϫ1 , but they also list more productive sites in the western basin with more than 1000 g C m Ϫ2 yr Ϫ1 . The corresponding LPJ result is 981 g C m Ϫ2 yr Ϫ1 , an overestimation for the conditions at Manaus, but possibly nearer the average for the basin.…”

“…The corresponding LPJ result is 981 g C m Ϫ2 yr Ϫ1 , an overestimation for the conditions at Manaus, but possibly nearer the average for the basin. Malhi et al (2004) attribute within-basin productivity differences to soil fertility, which is not currently simulated in the LPJ. Direct measurements of heterotrophic respiration in similar stands and with comparable protocols are very difficult to find, and we were therefore unable to check the LPJ estimate of R h of 931 g C m Ϫ2 yr Ϫ1 .…”

Mortality as a key driver of the spatial distribution of aboveground biomass in Amazonian forest: results from a dynamic vegetation model

“…Net primary production allocated to aboveground wood (NPP AGW ) was estimated for 104 Amazonian forest sites by Malhi et al (2004), based on dendrometric measurements conducted at the same site during two or more censuses. Only trees that reached the minimal census size of 10 cm dbh were considered.…”

Contribución de los bosques tropicales de montaña en el almacenamiento de carbono en Colombia

“…A partir de la biomasa aérea, se realizó la estimación del carbono promedio almacenado, siguiendo las recomendaciones del IPCC (2006) y otros estudios (Malhi et al, 2004, Chave et al, 2006, Aragão et al, 2009, que sugieren calcular el carbono almacenado como 50% de la biomasa. El dióxido de carbono equivalente (CO 2 e) corresponde a la medida métrica utilizada para comparar las emisiones de varios gases de efecto invernadero (GEI), basada en el potencial de calentamiento global de cada uno.…”