Linking size-dependent growth and mortality with architectural traits across 145 co-occurring tropical tree species
Iida, Y. ; Poorter, L. ; Sterck, F.J. ; Kassim, A.R. ; Potts, M.D. ; Kubo, T. ; Kohyama, T.S. - \ 2014
Ecology 95 (2014)2. - ISSN 0012-9658 - p. 353 - 363.
rain-forest trees - mixed dipterocarp forest - functional traits - wood density - interspecific variation - demographic rates - severe drought - allometry - height - impact
Tree architecture, growth, and mortality change with increasing tree size and associated light conditions. To date, few studies have quantified how size-dependent changes in growth and mortality rates co-vary with architectural traits, and how such size-dependent changes differ across species and possible light capture strategies. We applied a hierarchical Bayesian model to quantify size-dependent changes in demographic rates and correlated demographic rates and architectural traits for 145 co-occurring Malaysian rain-forest tree species covering a wide range of tree sizes. Demographic rates were estimated using relative growth rate in stem diameter (RGR) and mortality rate as a function of stem diameter. Architectural traits examined were adult stature measured as the 95-percentile of the maximum stem diameter (upper diameter), wood density, and three tree architectural variables: tree height, foliage height, and crown width. Correlations between demographic rates and architectural traits were examined for stem diameters ranging from 1 to 47 cm. As a result, RGR and mortality varied significantly with increasing stem diameter across species. At smaller stem diameters, RGR was higher for tall trees with wide crowns, large upper diameter, and low wood density. Increased mortality was associated with low wood density at small diameters, and associated with small upper diameter and wide crowns over a wide range of stem diameters. Positive correlations between RGR and mortality were found over the whole range of stem diameters, but they were significant only at small stem diameters. Associations between architectural traits and demographic rates were strongest at small stem diameters. In the dark understory of tropical rain forests, the limiting amount of light is likely to make the interspecific difference in the effects of functional traits on demography more clear. Demographic performance is therefore tightly linked with architectural traits such as adult stature, wood density, and capacity for horizontal crown expansion. The enhancement of a demographic trade-off due to interspecific variation in functional traits in the understory helps to explain species coexistence in diverse rain forests
Wood density explains architectural differentiation across 145 co-occurring tropical tree species
Iida, Y. ; Poorter, L. ; Sterck, F.J. ; Kubo, T. ; Kassim, A.R. ; Potts, M.D. ; Kohyama, T.S. - \ 2012
Functional Ecology 26 (2012)1. - ISSN 0269-8463 - p. 274 - 282.
mixed dipterocarp forest - life-history strategies - rain-forest - functional traits - adult stature - demographic rates - allometry - height - growth - size
1. Because of its mechanical properties, wood density may affect the way that trees expand their stem and crown to exploit favourable light conditions in a mechanically stable way. From engineering theory and wood density properties, it is predicted that in terms of biomass investment, low-density wood is more efficient for vertical stem expansion, while high-density wood is more efficient for horizontal branch expansion. So far, these predictions have rarely been tested by empirical studies. 2. We tested these predictions for 145 co-occurring tree species in a Malaysian tropical rainforest. For each species, we selected trees across a broad size range and measured architectural dimensions (stem diameter, height of the lowest foliage and crown width). We used a hierarchical Bayesian model to estimate species-specific allometric relationships between architectural dimensions including estimated stem biomass. Then, we examined correlations between species wood density and estimated architectural variables at standardized heights. 3. When species were compared at standardized tree heights, wood density correlated negatively with stem diameter and positively with stem biomass at most reference heights. This indicates that species with low wood density produce thicker stems but at lower biomass costs. Wood density correlated positively with crown width and negatively with height of the lowest foliage, which indicates that high wood density species have wider and deeper crowns than low wood density species. These relationships were maintained at most reference heights. However, the relationship with crown width was nonsignificant above 18 m height. This may reflect large plastic response of lateral crown expansion to a local condition. 4. Wood density explains the trade-off between effective vertical stem expansion and horizontal crown expansion across co-occurring tropical tree species. Such mechanical constraints characterize the difference in tree architecture between low wood density species that show an efficient height expansion to attain better light conditions in the exposed canopy and high wood density species that show an efficient horizontal crown expansion to enhance current light interception and persistence in the shaded forest understorey. Our study thus suggests that the mechanical constraints set by wood density contribute to the co-existence of species differing in architecture and light capture strategy.
Height-diameter allometry of tropical forest trees
Feldpausch, T.R. ; Banin, L. ; Phillips, O.L. ; Baker, T.R. ; Lewis, S.L. ; Quesada, C.A. ; Affum-Baffoe, K. ; Arets, E.J.M.M. ; Berry, N.J. ; Bird, M. ; Brondizio, E.S. ; Camargo, P. de; Chave, J. ; Djagbletey, G. ; Domingues, T.F. ; Drescher, M. ; Fearnside, P.M. ; Franca, M.B. ; Fyllas, N.M. ; Lopez-Gonzalez, G. ; Hladik, A. ; Higuchi, N. ; Hunter, M.O. ; Iida, Y. ; Salim, K.A. ; Kassim, A.R. ; Keller, M. ; Kemp, J. ; King, D.A. ; Lovett, J.C. ; Marimon, B.S. ; Marimon-Junior, B.H. ; Lenza, E. ; Marshall, A.R. ; Metcalfe, D.J. ; Mitchard, E.T.A. ; Moran, E.F. ; Nelson, B.W. ; Nilus, R. ; Nogueira, E.M. ; Palace, M. ; Patino, S. ; Peh, K.S.H. ; Raventos, M.T. ; Reitsma, J.M. ; Saiz, G. ; Schrodt, F. ; Sonké, B. ; Taedoumg, H.E. ; Tan, S. ; White, L. ; Wöll, H. ; Lloyd, J. - \ 2011
Biogeosciences 8 (2011). - ISSN 1726-4170 - p. 1081 - 1106.
amazon rain-forest - elfin cloud forest - leaf gas-exchange - montane forest - aboveground biomass - spatial-patterns - hydraulic architecture - altitudinal transect - environmental-change - neotropical forest
Tropical tree height-diameter (H:D) relationships may vary by forest type and region making large-scale estimates of above-ground biomass subject to bias if they ignore these differences in stem allometry. We have therefore developed a new global tropical forest database consisting of 39 955 concurrent H and D measurements encompassing 283 sites in 22 tropical countries. Utilising this database, our objectives were: 1. to determine if H:D relationships differ by geographic region and forest type (wet to dry forests, including zones of tension where forest and savanna overlap). 2. to ascertain if the H:D relationship is modulated by climate and/or forest structural characteristics (e.g. stand-level basal area, A). 3. to develop H:D allometric equations and evaluate biases to reduce error in future local-to-global estimates of tropical forest biomass. Annual precipitation coefficient of variation (PV), dry season length (SD), and mean annual air temperature (TA) emerged as key drivers of variation in H:D relationships at the pantropical and region scales. Vegetation structure also played a role with trees in forests of a high A being, on average, taller at any given D. After the effects of environment and forest structure are taken into account, two main regional groups can be identified. Forests in Asia, Africa and the Guyana Shield all have, on average, similar H:D relationships, but with trees in the forests of much of the Amazon Basin and tropical Australia typically being shorter at any given D than their counterparts elsewhere. The region-environment-structure model with the lowest Akaike's information criterion and lowest deviation estimated stand-level H across all plots to within amedian -2.7 to 0.9% of the true value. Some of the plot-to-plot variability in H:D relationships not accounted for by this model could be attributed to variations in soil physical conditions. Other things being equal, trees tend to be more slender in the absence of soil physical constraints, especially at smaller D. Pantropical and continental-level models provided less robust estimates of H, especially when the roles of climate and stand structure in modulating H:D allometry were not simultaneously taken into account.
Tree architecture and life-history strategies across 200 co-occurring tropical tree species
Iida, Y. ; Kohyama, T.S. ; Kubo, T. ; Kassim, A.R. ; Poorter, L. ; Sterck, F.J. ; Potts, M.D. - \ 2011
Functional Ecology 25 (2011)6. - ISSN 0269-8463 - p. 1260 - 1268.
rain-forest trees - mixed dipterocarp forest - shade tolerance - allometry - growth - size - traits - height - heterogeneity - regeneration
1. Tree architecture is thought to allow species to partition horizontal and vertical light gradients in the forest canopy. Tree architecture is closely related to light capture, carbon gain and the efficiency with which trees reach the canopy. Previous studies that investigated how light gradients drive differentiation in tree architecture have produced inconsistent results, partially because of the differences in which tree species and ontogenetic stages were studied. 2. We examined the relationship between stem diameter, tree height, foliage height, crown width and life-history strategy over a broad size range of 200 randomly selected, co-occurring tree species in a lowland rainforest in Peninsular Malaysia. We developed a hierarchical Bayesian model to account for both intra- and interspecific variation and describe the relationships among tree architectural variables. We analysed interspecific variation in tree architectural variables in relation to adult stature and light requirement for species regeneration as a function of tree size. 3. There was little interspecific variation in architectural variables, this is partly because of large intraspecific variation in response to canopy heterogeneity, but it also suggests architectural convergence within this community. However, interspecific analyses showed that, for large-statured species, small size classes had thinner stems with narrow and shallow crowns, whereas large-size classes had wider crowns. Light-demanding species (as indicated by high sapling mortality in shaded conditions) showed weak trends in tree architecture and were only characterized by wide crowns at intermediate sizes. 4. In summary, tree architectural traits overlapped across the species community. This suggests that architectural convergence and equalizing effects occur in this diverse tropical forest and that community-wide allometric equations can be used to describe forest height and carbon storage. Light resource partitioning also occurs, indicating stabilizing effects. Interspecific architectural variation in relation to adult stature supports the theory of the trade-off between early reproduction and vegetative growth. In closed rainforests, adult stature imposes a stronger force on architectural differentiation of species than regeneration light requirements.
Strict mast fruiting for a tropical dipterocarp tree: a demographic cost–benefit analysis of delayed reproduction and seed predation
Visser, M.D. ; Jongejans, E. ; Breugel, M. van; Zuidema, P.A. ; Chen, Y.Y. ; Kassim, A.R. ; Kroon, H. de - \ 2011
Journal of Ecology 99 (2011)4. - ISSN 0022-0477 - p. 1033 - 1044.
rain-forest - evolutionary ecology - spatial-patterns - resource-allocation - woody-plants - el-nino - recruitment - dispersal - dynamics - impact
1. Masting, the production of large seed crops at intervals of several years, is a reproductive adaptation displayed by many tree species. The predator satiation hypothesis predicts that starvation of seed predators between mast years and satiation during mast years decreases seed predation and thus enhances tree regeneration. 2. Mast fruiting comes at demographic costs such as missed reproduction opportunities and increased density-dependence of recruits, but it remains unknown if predator satiation constitutes a sufficiently large benefit for masting to evolve as a viable life-history strategy. So far, no studies have quantified the net fitness consequences of masting. 3. Using a long-term demographic data set of the dipterocarp Shorea leprosula in a Malaysian forest, we constructed stochastic matrix population models and performed a demographic cost–benefit analysis. 4. For observed values of mast frequency and seed predation rates, we show that strict masting strongly increases fitness compared with fruiting annually. Model results also show that the demographic costs of mast fruiting are very low compared to the demographic losses due to seed predation in a scenario of annual fruiting. Finally, we find that mast fruiting would still be selected for even at low levels of seed predation and when including additional costs such as decreased adult growth rates, limiting crop size and density-dependent seedling survival. 5. Synthesis. Our results are consistent with the predictions of the predator satiation hypothesis: mast fruiting increases fitness for a range of seed predation levels. Under seed predation pressure annually fruiting species are at a strong disadvantage and as a result a mast fruiting strategy may swiftly confer a fitness advantage. Our study shows that demographic modelling allows the weighing of fitness benefits and costs of life-history phenomena such as strict masting.