Tree‐to‐tree interactions slow down Himalayan treeline shifts as inferred from tree spatial patterns
Aim The spatial patterns of tree populations reflect multiple ecological processes. However, little is known on whether these patterns mediate responses to climate in marginal tree populations such as those forming alpine tree lines. We examined the influence of tree‐to‐tree interactions on the resp...
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Published in | Journal of biogeography Vol. 47; no. 8; pp. 1816 - 1826 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Oxford
Wiley Subscription Services, Inc
01.08.2020
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Subjects | |
Online Access | Get full text |
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Summary: | Aim
The spatial patterns of tree populations reflect multiple ecological processes. However, little is known on whether these patterns mediate responses to climate in marginal tree populations such as those forming alpine tree lines. We examined the influence of tree‐to‐tree interactions on the responsiveness of tree lines to climate warming.
Location
Central Himalayas.
Taxon
Betula utilis; Abies spectabilis.
Methods
We analysed a network of 17 tree line sites located across the central Himalayas, encompassing a wide longitudinal gradient characterized by increasing precipitation eastwards. We quantified the changes in density and the spatial patterns of three 50‐year age classes of the two main tree species found at the tree line (Betula utilis and Abies spectabilis), and related them to reconstructed shifts in tree line elevation.
Results
Younger trees showed clustering near the tree line, while older trees tended to show random spatial distribution. Clustering decreased as climate conditions ameliorated, that is, in the wetter eastern sites. Lower rate of tree line elevation change was observed at the sites with higher clustering intensity.
Main Conclusions
Our study indicates that tree aggregation weakens tree line responsiveness to climate warming, and thus warming‐induced drought stress tends to lower tree line shift rates by enhancing clustering. It also highlights the complexity and contingency of site‐dependent tree line responses to climate. Hence, to advance our understanding of tree line processes, we should consider both direct and indirect influences of relevant biotic (tree‐to‐tree interactions) and abiotic (climate) drivers of tree line dynamics. |
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ISSN: | 0305-0270 1365-2699 |
DOI: | 10.1111/jbi.13840 |