Janzen-Connell patterns are not the result of Janzen-Connell process: Oak recruitment in temperate forests

A - Papers appearing in refereed journals

Deniau, M., Jung, V., Le Lann, C., Morra, T., Murray, P. J. and Prinzing, A. 2017. Janzen-Connell patterns are not the result of Janzen-Connell process: Oak recruitment in temperate forests. Perspectives In Plant Ecology Evolution And Systematics. 24 (February), pp. 72-79. https://doi.org/10.1016/j.ppees.2016.12.001

AuthorsDeniau, M., Jung, V., Le Lann, C., Morra, T., Murray, P. J. and Prinzing, A.
Abstract

According to the Janzen-Connell hypothesis, seedling mortality is greater close to conspecific (or closely related) adult trees because of higher enemy pressure, ultimately increasing local tree-species diversity. However, this pattern (i.e. a decline of seedling performance close to conspecific or closely related adults) could also result from other processes: (1) heterospecific adults might positively affect seedlings; (2) conspecific (or closely related) adults might negatively affect seedlings by causing a deterioration of the microenvironment. We tested these hypotheses, accounting also for sizes of adults. We planted oak-seedlings in a temperate forest, characterized their adult neighbourhoods, measured 26 microenvironmental conditions, seedling mortality during one year, budburst and leaf herbivory. We detected Janzen-Connell-like patterns (frequent lack of budburst close to conspecific adults; high seedling mortality close to closely related adults) that were consistent with the Janzen-Connell process. However, these patterns were either counteracted by non-Janzen-Connell processes such as a favourable microenvironment or were weak with little explained variance. We detected Janzen-Connell-like patterns that were not consistent with the Janzen-Connell process: proximity to heterospecific adults per se decreased leaf herbivory partly due to microenvironmental effects, such that a lower leaf herbivory decreased seedling mortality. Overall, the spatial pattern of tree recruitment may resemble that predicted by Janzen-Connell but result from different processes: notably heterospecific adults creating refuges from enemies, facilitating the establishment of oaks below non-oaks without hindering their establishment below oaks.

KeywordsBudburst; Community dynamics; Intraspecific and interspecific facilitation; Leaf herbivory; Plant Population; Quercus sp.
Year of Publication2017
JournalPerspectives In Plant Ecology Evolution And Systematics
Journal citation24 (February), pp. 72-79
Digital Object Identifier (DOI)https://doi.org/10.1016/j.ppees.2016.12.001
Open accessPublished as non-open access
Output statusPublished
Publication dates
Online02 Dec 2016
Publication process dates
Accepted01 Dec 2016
PublisherElsevier
Elsevier Gmbh, Urban & Fischer Verlag
Copyright licensePublisher copyright
ISSN1433-8319

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