Local distribution pattern of Brachypodium pinnatum (Poaceae) - Field experiments in xeric loess grassland in N. Hungary

Gábor Endresz, Ágnes Zöld-Balogh, Tibor Kalapos

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

In surviving fragments of the natural forest-steppe vegetation on the Hungarian Great Plain the perennial rhizomatous grass Brachypodium pinnatum (L.) BEAUV. (Poaceae) succesfully occupies full sun to shade microhibitats on slopes facing N or E, but remarkably avoids adjacent grasslands on hillsides exposed to S or W. To test whether the hot and dry microclimate of the latter exceeds the tolerance limits for this broadleaved species originally typical in the understorey of xerothermic oak forests, a field experiment was conducted when B. pinnatum plants were transplanted in soil monoliths from a xero-mesic grassland on the NE slope to an adjacent xeric grassland on the SW side (treatment) or within the same sward (control). The response of shoot phenology, leaf photochemistry and VA mycorrhizal colonization of the roots were examined. In spring shoot development was faster on the SW slope, but final shoot height and foliage area remained below that on the NE slope. During the summer drought 80% of the shoots on the SW slope died back, while senescence was only 20% on the NE side. Leaf photochemistry suffered photodamage in summer on the SW slope, but not on the NE one. Autum rains triggered a vigorous development of new shoots on the SW slope, while not on the NE side. The frequency of VAM-infected roots and of vesicles remained invariant during the vegetation period, while the proportion of arbuscules showed a consistent seasonal trend paralelling host plant physiological activity being high during the spring and autumn, while greatly depressed during the hot and dry summer. The decline in summer was more marked on the SW slope witnessing a mass shoot dieback, and the production of new shoots here were associated with a threefold enhancement of arbuscule frequency compared to that on the NE side. These results show that the growth of developed B. pinnatum plants suffer substantial reduction and even damage on the SW slope confirming the original hypothesis that the physical environment there is not conducive for this grass and thus may explain its local distribution pattern.

Original languageEnglish
Pages (from-to)249-265
Number of pages17
JournalPhyton - Annales Rei Botanicae
Volume45
Issue number2
Publication statusPublished - Dec 30 2005

Keywords

  • Brachypodium pinnatum
  • Drought response
  • Gramineae
  • Phenology
  • Photoinhibition
  • Poaceae. - Ecology
  • VA mycorrhiza
  • Xeric grassland. - Vegetation of Hungary

ASJC Scopus subject areas

  • Global and Planetary Change
  • Physiology
  • Ecology, Evolution, Behavior and Systematics
  • Plant Science

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