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| Titel |
Coordination of physiological and structural traits in Amazon forest trees |
| VerfasserIn |
Jon Lloyd, Sandra Patino, Nikolaos Fyllas, Tim Baker, Carlos Alberto Quesada, Romilda Paiva, Michael Schwarz, Hans ter Steege, Oliver Phillips |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250050235
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| Zusammenfassung |
| Our aim was to examine interactions between structural and physiological trait characteristics
for Amazon forest trees and to determine if integrated trait dimensions can be identified. Data
on leaf and leaflet size, the ratio of leaf area to sapwood area (ΦLS) were obtained for 1040
trees species located in 53 tropical forest plots across across the Amazon Basin and
incorporated into an analysis using an index of diffusional limitations to photosynthetic CO2
assimilation based on carbon isotope ratios and previously acquired data on species
maximum height (Hmax), seed size, leaf mass per unit area (MA), foliar nutrients and branch
xylem density (Ïx).
Where appropriate, responses were first partitioned into genetic and environmental
effects. Strong bivariate relationships were observed for a many of the genetic and
environmentally dependent trait components. For example, for the derived genetic
components, leaf size is significantly correlated with foliar nitrogen and phosphorus
concentrations, with ΦLS also correlating with foliar [N] and [P] as well as negatively with
MA. Negative associations were also found between Ïx and foliar [P] and [K] and with a
positive relationship between Ïx and MA. Both MA and seed size increase with
Hmax.
As there was evidence of different bivariate relationships between the measured traits for
species associated with low versus high fertility soils, we utilised a common principal
components (CPC) method to reveal associations embedded in the trait variance-covariance
matrix, this analysis effectively allowing the PCA eigenvalues to vary between the two soil
fertility dependent groups. This analysis identified five significant integrated trait dimensions
for Amazon forest trees. The first involves primarily cations, foliar carbon and MA and
seems to be associated with differences in foliar construction costs. The second relates to the
classic ”leaf economic spectrum” of plant resource utilisation. but with increased
individual leaf areas and a higher ΦLS newly identified components. The third
dimension relates primarily to increasing Hmax and involves greater MA (primarily
attributed to increased leaf thicknesses) with reductions in ΦLS and with carbon
isotopes suggesting a general decline in the ratio of leaf internal to ambient carbon
dioxide concentrations with increasing Hmax. Although species from high fertility
sites had higher eigenvector values for these first three dimensions, the final two
dimensions were found to be more important for low fertility soil associated species. The
fourth dimension showed seed size and ΦLS to be negatively correlated ( with the
fifth dimension linking together a range of shade tolerance characteristics such as
low Hmax, greater seed size and high wood densities. Also associated with this
dimension (which was virtually insignificant for high fertility soil associated species)
were increased MA, higher foliar [C] and greater diffusional limitations for CO2
diffusion.
Environmental conditions were also found to influence the structural traits examined with
Ïx decreasing with increased soil fertility but decreasing with increased temperatures. This
soil fertility response appears to be synchronised with increases in foliar nutrient
concentrations and reductions in foliar [C]. Leaf and leaflet area and ΦLS are less responsive
to the environment than Ïx, although there was some evidence of both ΦLS and Ïx
decreasing as precipitation increases.
We conclude that physiological and structural traits coordinate in distinct ways for
tropical tree species, but that the nature of this association may differ according to a species
preferred soil fertility ”niche” and with the nature of these associations somewhat modified
by a species’ actual growth environment. |
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