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Variation in vegetative water use in the savannas of the North Australian Tropical Transect
Author(s) -
Cook Garry D.,
Williams Richard J.,
Hutley Lindsay B.,
O'Grady Anthony, P.,
Liedloff Adam C.
Publication year - 2002
Publication title -
journal of vegetation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 115
eISSN - 1654-1103
pISSN - 1100-9233
DOI - 10.1111/j.1654-1103.2002.tb02065.x
Subject(s) - transect , arid , tropics , environmental science , monsoon , storm , physical geography , soil water , tropical savanna climate , hydrology (agriculture) , geography , ecology , climatology , geology , ecosystem , soil science , biology , geotechnical engineering , meteorology
. The decline in tree density on sandy soils in savannas is highly correlated with declining mean annual rainfall along the North Australian Tropical Transect (NATT). We reanalyse various data on water use by individual trees and argue that a common relationship can be used to estimate annual water use by tree stands along the NATT from ca. 600 mm mean annual rainfall to at least 1600 mm. Where rainfall is less than 600 mm, trees of a given size use less water than at sites where rainfall is higher. We use these relationships to relate water use at the stand scale with mean annual rainfall along the NATT. From this we show that the empirical data imply that the minimum depth of sandy soil that needs to be exploited by trees declines with increasing aridity along the NATT from more than 5 m to less than 1 m. This finding is consistent with other observations and the pattern that with increasing aridity, an increasing proportion of rainfall coming from isolated storms rather than from periods of extended monsoon activity.