@Article{BrumVIASAPDABBPO:2019:HyNiSe,
author = "Brum, Mauro and Valdeboncoeur, Matthew A. and Ivanov, Valeriy and
Asbjornsen, Heidi and Saleska, Scott and Alves, Luciana F. and
Penha, Deliane and Dias, Jadson D. and Arag{\~a}o, Luiz Eduardo
Oliveira e Cruz de and Barros, Fernanda and Bittencourt, Paulo and
Pereira, Luciano and Oliveira, Rafael S.",
affiliation = "{Universidade Estadual de Campinas (UNICAMP)} and {University of
New Hampshire} and {University of Michigan} and {University of New
Hampshire} and {University of Arizona} and {University of
California} and {Universidade Federal do Oeste do Par{\'a}
(UFOPA)} and {Universidade de S{\~a}o Paulo (USP)} and {Instituto
Nacional de Pesquisas Espaciais (INPE)} and {Universidade Estadual
de Campinas (UNICAMP)} and {Universidade Estadual de Campinas
(UNICAMP)} and {Universidade Estadual de Campinas (UNICAMP)} and
{Universidade Estadual de Campinas (UNICAMP)}",
title = "Hydrological niche segregation defines forest structure and
drought tolerance strategies in a seasonal Amazon forest",
journal = "Journal of Ecology",
year = "2019",
volume = "107",
pages = "318--333",
keywords = "2015 ENSO, Amazon functional diversity, cavitation, embolism
resistance, hydraulic traits, root depth, stable isotopes, water
potential.",
abstract = "1. The relationship between rooting depth and above-ground
hydraulic traits can potentially define drought resistance
strategies that are important in determining species distribution
and coexistence in seasonal tropical forests, and understanding
this is important for predicting the effects of future climate
change in these ecosystems. 2. We assessed the rooting depth of 12
dominant tree species (representing c. 42% of the forest basal
area) in a seasonal Amazon forest using the stable isotope ratios
(\δ18O and \δ2 H) of water collected from tree xylem
and soils from a range of depths. We took advantage of a major
ENSO-related drought in 2015/2016 that caused substantial
evaporative isotope enrichment in the soil and revealed water use
strategies of each species under extreme conditions. We measured
the minimum dry season leaf water potential both in a normal year
(2014; \Ψnon-ENSO) and in an extreme drought year (2015;
\ΨENSO). Furthermore, we measured xylem hydraulic traits
that indicate water potential thresholds trees tolerate without
risking hydraulic failure (P50 and P88). 3. We demonstrate that
coexisting trees are largely segregated along a single
hydrological niche axis defined by root depth differences, access
to light and tolerance of low water potential. These differences
in rooting depth were strongly related to tree size; diameter at
breast height (DBH) explained 72% of the variation in the
\δ18Oxylem. Additionally, \δ18Oxylem explained 49% of
the variation in P50 and 70% of P88, with shallow-rooted species
more tolerant of low water potentials, while \δ18O of xylem
water explained 47% and 77% of the variation of minimum
\Ψnon-ENSO and \ΨENSO. 4. We propose a new formulation
to estimate an effective functional rooting depth, i.e. the likely
soil depth from which roots can sustain water uptake for
physiological functions, using DBH as predictor of root depth at
this site. Based on these estimates, we conclude that rooting
depth varies systematically across the most abundant families,
genera and species at the Tapaj{\'o}s forest, and that
understorey species in particular are limited to shallow rooting
depths. 5. Our results support the theory of hydrological niche
segregation and its underlying trade-off related to drought
resistance, which also affect the dominance structure of trees in
this seasonal eastern Amazon forest. 6. Synthesis. Our results
support the theory of hydrological niche segregation and
demonstrate its underlying trade-off related to drought resistance
(access to deep water vs. tolerance of very low water potentials).
We found that the single hydrological axis defining water use
traits was strongly related to tree size, and infer that periodic
extreme droughts influence community composition and the dominance
structure of trees in this seasonal eastern Amazon forest.",
doi = "10.1111/1365-2745.13022",
url = "http://dx.doi.org/10.1111/1365-2745.13022",
issn = "0022-0477",
language = "en",
targetfile = "brum_hydrological.pdf",
urlaccessdate = "27 abr. 2024"
}