hydraulics in regulating the height of trees at a given trunk diameter (see also Kempes et al. 2011). Recently, Feldpausch (2011) conducted a pantropical analysis of diameter-height et al. tree allometries and concluded that regional variation in this allometry was an important source of variation in tree AGB. They then developed a set of region-specific diameter-height allometries to minimize bias due to the variation in canopy height across tropical forest regions (see also Banin 2012). They investigated whether some of the climatic variables et al., in the WorldClim database may predict a significant fraction of the variation in the relationship. For a given trunk diameter, they found a positive correlation between tree height and precipitation seasonality only. Their finding is counter-intuitive because height should peak at intermediate precipitation seasonality values, and be lower in both dry and ever-wet forests (see e.g. Hall & Swaine, 1981, Fig. 5.1; Wang 2006). This is probably et al., because the Feldpausch (2011) database did not include many dry-vegetation sites. et al. Here, we readdressed the question of the bioclimatic dependency of the relationship in tropical trees. Our dataset had only a limited overlap with that used in Feldpausch (2011) and Banin (2012), and we found different results. Our major et al. et al. finding is that the diameter-height relationship depends linearly on a compound bioclimatic variable which itself is a linear function of climatic water deficit, temperature seasonality, E, and precipitation seasonality. Indeed, we found that a large fraction of the residual variation in the diameter-height relationship is attributable to the variable and that a single model (Eq. E, 6) may be used to predict total tree height from trunk diameter and across the tropics. E
hydraulics in regulating the height of trees at a given trunk diameter (see also Kempes et al. 2011). Recently, Feldpausch et al. (2011) conducted a pantropical analysis of diameter-height tree allometries and concluded that regional variation in this allometry was an important source of variation in tree AGB. They then developed a set of region-specific diameter-height allometries to minimize bias due to the variation in canopy height across tropical forest regions (see also Banin et al., 2012). They investigated whether some of the climatic variables in the WorldClim database may predict a significant fraction of the variation in the relationship. For a given trunk diameter, they found a positive correlation between tree height and precipitation seasonality only. Their finding is counter-intuitive because height should peak at intermediate precipitation seasonality values, and be lower in both dry and ever-wet forests (see e.g. Hall & Swaine, 1981, Fig. 5.1; Wang et al., 2006). This is probably because the Feldpausch et al. (2011) database did not include many dry-vegetation sites. Here, we readdressed the question of the bioclimatic dependency of the relationship in tropical trees. Our dataset had only a limited overlap with that used in Feldpausch et al. (2011) and Banin et al. (2012), and we found different results. Our major finding is that the diameter-height relationship depends linearly on a compound bioclimatic variable E, which itself is a linear function of climatic water deficit, temperature seasonality, and precipitation seasonality. Indeed, we found that a large fraction of the residual variation in the diameter-height relationship is attributable to the variable E, and that a single model (Eq. 6) may be used to predict total tree height from trunk diameter and E across the tropics.
Chave_GCB13_final_main_1.docx