Spatial analysis of root hemiparasitic shrubs and their hosts: a search for spatial signatures of above- and below-ground interactions

Bjørn Dueholm, David Bruce, Philip Weinstein, Susan Semple, Birger Møller , Jacob Weiner

Research output: Contribution to journalArticlepeer-review

Abstract

Root hemiparasitic plants take up resources from the roots of neighbouring plants, which they use for fuelling their own growth. While taking up resources from the hosts below-ground, they may simultaneously compete with the hosts for sunlight. Suppression caused by the parasitism could result in openings in the vegetation structure and increased mortality levels. On the other hand, the root hemiparasites may also be constrained by the hosts, restricting the parasites to a limited number of locations within a community. These vegetation alterations and location restrictions can be referred to as spatial signatures of the root hemiparasites. In order to search for such spatial signatures, we investigated a population of a predominant Acacia species in Australia co-occurring with established root hemiparasitic shrubs, using intensity estimates of the Acacia and dead shrubs to be indicators of parasite populations. We find evidence that the root hemiparasitic shrubs, like herbaceous root hemiparasites, prefer growing at distances from neighbouring plants that fulfil resource requirements both below-ground and above-ground. Assuming that root hemiparasites are limited by their hosts, we present an optimal host density and distance to host hypothesis (‘Goldilocks hypothesis’) to account for such a vegetation pattern. Although mortality appeared to primarily result from intraspecific competition and shoot parasitism, the root parasitism could explain some of the mortality in open areas. It is likely that both processes occur simultaneously. In spite of differing annual and perennial life strategies among root hemiparasites, root parasitism across systems may follow these two general processes in the formation of vegetation patterns.
Original languageEnglish
Pages (from-to)185-196
Number of pages12
JournalPlant Ecology
Volume218
Issue number2
DOIs
Publication statusPublished - Feb 2017
Externally publishedYes

Keywords

  • Spatial analysis
  • root hemiparasitic shrubs
  • spatial signatures
  • vegetation structure

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