Contrasted allometries between stem diameter, crown area, and tree height in five tropical biogeographic areas

2016

Article référencé dans le Web of Science WOS:000387723300005

Blanchard Elodie, Birnbaum P., Ibanez T., Boutreux T., Antin Cécile, Ploton Pierre, Vincent Grégoire, Pouteau Robin, Vandrot H., Hequet Vanessa, Barbier Nicolas, Droissart Vincent, Sonke B., Texier Nicolas, Kamdem N. G., Zebaze D., Libalah M., Couteron Pierre

Trees : Structure and Function, 2016, 30 (6), 1953-1968 ISSN 0931-1890

Across five biogeographic areas, DBH-CA allometry was characterized by inter-site homogeneity and intra-site heterogeneity, whereas the reverse was observed for DBH-H allometry. Tree crowns play a central role in stand dynamics. Remotely sensed canopy images have been shown to allow inferring stand structure and biomass which suggests that allometric scaling between stems and crowns may be tight, although insufficiently investigated to date. Here, we report the first broad-scale assessment of stem vs. crown scaling exponents using measurements of bole diameter (DBH), total height (H), and crown area (CA) made on 4148 trees belonging to 538 species in five biogeographic areas across the wet tropics. Allometries were fitted with power functions using ordinary least-squares regressions on log-transformed data. The inter-site variability and intra-site (sub-canopy vs. canopy trees) variability of the allometries were evaluated by comparing the scaling exponents. Our results indicated that, in contrast to both DBH-H and H-CA allometries, DBH-CA allometry shows no significant inter-site variation. This fairly invariant scaling calls for increased effort in documenting crown sizes as part of tree morphology. Stability in DBH-CA allometry, indeed, suggests that some universal constraints are sufficiently pervasive to restrict the exponent variation to a narrow range. In addition, our results point to inverse changes in the scaling exponent of the DBH-CA vs. DBH-H allometries when shifting from sub-canopy to canopy trees, suggesting a change in carbon allocation when a tree reaches direct light. These results pave the way for further advances in our understanding of niche partitioning in tree species, tropical forest dynamics, and to estimate AGB in tropical forests from remotely sensed images.

Sciences du monde végétal [076] ; Etudes, transformation, conservation du milieu naturel [082]

NOUVELLE CALEDONIE ; INDONESIE ; INDE ; GUYANE FRANCAISE ; CAMEROUN ; GABON ; ZONE TROPICALE

Fonds IRD [F B010068675]

fdi:010068675