Competitive abilities of three indigenous New Zealand plant species in relation to the introduced plant Hieracium pilosella

• Published in: Basic and applied ecology 2001, Vol.2 (3), p.243-250
• Main Authors: Moen, Jon, Meurk, Colin D.
• Format: Article
• Language: English
• Subjects: competition; competitive effect and response; competitive hierarchies; Hieracium pilosella; light; management; New Zealand montane plants; soil fertility
• ISSN: 1439-1791
• DOI: 10.1078/1439-1791-00052

The competitive abilities of three montane indigenous New Zealand plant species ( Acaena buchananii, Festuca novae-zelandiae, and Raoulia australis) when growing with the locally invasive, introduced Hieracium pilosella were compared in an outdoor pot experiment. Competitive ability was divided into the competitive effect, or the ability to deplete resources, and the competitive response, or the ability to tolerate low resource levels. The plants were grown in pots with or without Hieracium, in shade or full sunlight, and with high or low soil fertility. The competitive response rankings showed consistent hierarchies in the different treatments with Festuca being less suppressed than Acaena and Raoulia. Festuca performed especially well in low soil fertility and in shaded treatments, while the other two species were strongly suppressed by Hieracium even in those conditions. However, all three species did relatively better (less badly) in the low fertility and shaded treatments than in the more resource-rich treatments when interacting with Hieracium. The effect on Hieracium biomass of the indigenous species was generally small and the rankings of competitive effect showed no agreement between the species in the different environmental treatments. We suggest that competitive rankings based on the competitive response component is likely to be a more sensitive measure of competitive ability for these indigenous, slow-growing plants. The results also indicates that these two components of a plant's competitive ability were negatively correlated and thus reflect trade-offs in dealing with competitive situations. Finally, in competition with Hieracium, low-growing indigenous species are likely to perform best when nutrients and light are maintained at low levels. Die Konkurrenzfähigkeit dreier auf Neuseeland heimischer Pflanzenarten ( Acaena buchananii, Festuca novae-zelandiae und Raoulia australis) gegenüber der invasiven und eingeführten Art Hieracium pilosella wurde in einem Freilandtopfexperiment verglichen. Konkurrenzfähigkeit wurde dabei unterteilt in Konkurrenzwirkung, d. h. die Fähigkeit, Ressourcen zu verringern, und Konkurrenzantwort, d. h. die Fähigkeit, niedrige Ressourcenniveaus zu ertragen. Die Pflanzen wurden in Töpfen mit bzw. ohne Hieracium, im Schatten bzw. in vollem Sonnenlicht, und mit hoher bzw. geringer Bodenfertilität gehalten. Die Konkurrenzantworten in allen Behandlungen folgten durchweg den gleichen Rangstufen, wobei Festuca weniger ei