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| Titel |
Edaphic, structural and physiological contrasts across Amazon Basin forest–savanna ecotones suggest a role for potassium as a key modulator of tropical woody vegetation structure and function |
| VerfasserIn |
J. Lloyd, T. F. Domingues, F. Schrodt, F. Y. Ishida, T. R. Feldpausch, G. Saiz, C. A. Quesada, M. Schwarz, M. Torello-Raventos, M. Gilpin, B. S. Marimon, B. H. Marimon-Junior, J. A. Ratter, J. Grace, G. B. Nardoto, E. Veenendaal, L. Arroyo, D. Villarroel, T. J. Killeen, M. Steininger, O. L. Phillips |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 22 ; Nr. 12, no. 22 (2015-11-18), S.6529-6571 |
| Datensatznummer |
250118167
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| Publikation (Nr.) |
 copernicus.org/bg-12-6529-2015.pdf |
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| Zusammenfassung |
| Sampling along a precipitation gradient in tropical South
America extending from ca. 0.8 to 2.0 m a−1, savanna soils had
consistently lower exchangeable cation concentrations and higher
C / N ratios than nearby forest plots. These soil
differences were also reflected in canopy averaged leaf traits with
savanna trees typically having higher leaf mass per unit area but
lower mass-based nitrogen (Nm) and potassium
(Km). Both Nm and
Km also increased with declining mean annual
precipitation (PA), but most area-based leaf traits
such as leaf photosynthetic capacity showed no systematic variation
with PA or vegetation type. Despite this invariance,
when taken in conjunction with other measures such as mean canopy
height, area-based soil exchangeable potassium content, [K]sa ,
proved to be an excellent predictor of several photosynthetic
properties (including 13C isotope
discrimination). Moreover, when considered in a multivariate context
with PA and soil plant available water storage
capacity (θP) as covariates, [K]sa
also proved to be an excellent predictor of stand-level canopy area,
providing drastically improved fits as compared to models
considering just PA and/or θP. Neither calcium, nor magnesium, nor soil pH could substitute for
potassium when tested as alternative model predictors
(ΔAIC > 10). Nor for any model could simple soil
texture metrics such as sand or clay content substitute for either
[K]sa or θP. Taken in conjunction
with recent work in Africa and the forests of the Amazon Basin, this
suggests – in combination with some newly conceptualised
interacting effects of PA and θP
also presented here – a critical role for potassium as a modulator
of tropical vegetation structure and function. |
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