Tropical forest wood production: a cross‐continental comparison

Summary Tropical forest above‐ground wood production ( AGWP ) varies substantially along environmental gradients. Some evidence suggests that AGWP may vary between regions and specifically that A sian forests have particularly high AGWP . However, comparisons across biogeographic regions using standardized methods are lacking, limiting our assessment of pan‐tropical variation in AGWP and potential causes. We sampled AGWP in NW A mazon (17 long‐term forest plots) and N B orneo (11 plots), both with abundant year‐round precipitation. Within each region, forests growing on a broad range of edaphic conditions were sampled using standardized soil and forest measurement techniques. Plot‐level AGWP was 49% greater in B orneo than in A mazonia (9.73 ± 0.56 vs. 6.53 ± 0.34 Mg dry mass ha −1 a −1 , respectively; regional mean ± 1 SE ). AGWP was positively associated with soil fertility ( PCA axes, sum of bases and total P). After controlling for the edaphic environment, AGWP remained significantly higher in B ornean plots. Differences in AGWP were largely attributable to differing height–diameter allometry in the two regions and the abundance of large trees in B orneo. This may be explained, in part, by the greater solar radiation in B orneo compared with NW A mazonia. Trees belonging to the dominant SE Asian family, D ipterocarpaceae, gained woody biomass faster than otherwise equivalent, neighbouring non‐dipterocarps, implying that the exceptional production of B ornean forests may be driven by floristic elements. This dominant SE Asian family may partition biomass differently or be more efficient at harvesting resources and in converting them to woody biomass. Synthesis . N B ornean forests have much greater AGWP rates than those in NW A mazon when soil conditions and rainfall are controlled for. Greater resource availability and the highly productive dipterocarps may, in combination, explain why A sian forests produce wood half as fast again as comparable forests in the A mazon. Our results also suggest that taxonomic groups differ in their fundamental ability to capture carbon and that different tropical regions may therefore have different carbon uptake capacities due to biogeographic history.