Ecology of the Endangered Herb Scutellaria novaezelandiae
- Manaaki Whenua - Landcare Research New Zealand Ltd, Private Bag 6, Nelson, New Zealand
Scutellaria novaezelandiae is a small herb restricted to the Nelson/ Marlborough region. Aspects of its ecology were studied to assist in the management of wild populations. An absolute estimate of abundance is not possible as individual Scutellaria plants are indistinguishable and it grows in small patches up to 20 m². There are probably between 50 and 100 such patches in podocarp-beech forest below 200 m a.s.l. on freely drained alluvium and colluvium. The vigour of Scutellaria patches as estimated from changes in shoot frequency and seed production varies widely depending on site conditions. It cannot tolerate competition from ferns, herbs, weeds, and shrub growth which occurs once the ground surface stabilises. Patches of Scutellaria have a marked seasonal variation in mean height, reaching a Peak of approximately 12-15 cm during flowering (November-December), and then declining. Fresh Scutellaria seeds take several weeks to germinate and many enter the soil seed bank. Seedlings rarely appeared in bare ground plots at the field sites, but many emerged rapidly from topsoil samples placed in a glasshouse, along with abundant seedlings of vigorous adventive weeds. Scutellaria patches expand mainly by vegetative means. Scutellaria has been reduced in abundance by grazing at some sites, yet at others it has probably benefitted from grazing through the removal of competition from other plants, including adventive weeds. The implications of the results for the conservation of Scutellaria are mentioned.