An ecological paradox: high species diversity and low position of the upper forest line in the A ndean D epression
Abstract Systematic investigations of the upper forest line ( UFL ) primarily concentrate on mid and high latitudes of the Northern Hemisphere, whereas studies of Neotropical UFL s are still fragmentary. This article outlines the extraordinary high tree diversity at the UFL within the Andean Depress...
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Published in | Ecology and evolution Vol. 4; no. 11; pp. 2134 - 2145 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
01.06.2014
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Online Access | Get full text |
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Summary: | Abstract
Systematic investigations of the upper forest line (
UFL
) primarily concentrate on mid and high latitudes of the Northern Hemisphere, whereas studies of Neotropical
UFL
s are still fragmentary. This article outlines the extraordinary high tree diversity at the
UFL
within the Andean Depression and unravels the links between the comparatively low position of the local
UFL
, high tree‐species diversity, and climate. On the basis of Gentry′s rapid inventory methodology for the tropics, vegetation sampling was conducted at 12
UFL
sites, and local climate (temperature, wind, precipitation, and soil moisture) was investigated at six sites. Monotypic forests dominated by
Polylepis
were only found at the higher located margins of the Andean Depression while the lower situated core areas were characterized by a species‐rich forest, which lacked the elsewhere dominant tree‐species
Polylepis
. In total, a remarkably high tree‐species number of 255 tree species of 40 different plant families was found. Beta‐diversity was also high with more than two complete species turnovers. A non‐linear relationship between the floristic similarity of the investigated study sites and elevation was detected. Temperatures at the investigated study sites clearly exceeded 5.5°C, the postulated threshold value for the upper tree growth limit in the tropics. Instead, quasi‐permanent trade winds, high precipitation amounts, and high soil water contents affect the local position of the
UFL
in a negative way. Interestingly, most of the above‐mentioned factors are also contributing to the high species richness. The result is a combination of a clearly marked upper forest line depression combined with an extraordinary forest line complexity, which was an almost unknown paradox. |
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ISSN: | 2045-7758 2045-7758 |
DOI: | 10.1002/ece3.1078 |