The Annexe and Glade margins of Manuka canopy

Grasses being mown in the large recreational area bordering the dense manuka canopy include Axonopus fissifolius, Paspalum dilatatum, Yorkshire fog, Agrostis capillaris, kikuyu (not dominant in the mown sward, but dominant on the margins among, and climbing, the native trees and shrubs) interspersed with seasonally-evident docks, Prunella, dandelions, Juncus articulatus, Lotus corniculata, Bellis perennis, White clover and others.

Among the manuka and scattered karamu of the margin beyond the edge of mowing, Vasey grass (Paspalum urvillei), Ox-eye daisy and Catsear (Hypochaeris radicata) are also common.

Our strategy to date has been to

  1. Remove or control aggressive exotic weeds threatening the trees, eg honeysuckle (done) and Watsonia and Aristea ecklonii, Blue corn-lily (done, with 2nd generation control ongoing), kikuyu, Vasey grass.
  2. Assist the development of increasingly dense shade and shelter of the manuka canopy edge, to help suppress current and future weeds and maintain moisture through dry periods, supporting ongoing multiplication and growth of the already-present kanuka, Coprosma robusta and lucida, ti kouka, totara, mingimingi, tanekaha, Pseudopanax arboreus and crassifolius, sedges and rushes, native lobelia, Shrubby toatoa, and other forest and scrubland species.

To assist the development of juvenile trees in this margin, we have replaced line-trimming with manual weeding.

Our next instinct to help increase the density and diversity of vegetation in this margin, has been to enrich the soil, which has highlighted the following issues:

Little leafy , or any, vegetation is being produced here. Even the exotic grasses are slow-growing and diminutive, providing insufficient plant material to effectively suppress the remaining Paspalum and other grasses, Creeping buttercup and Watsonia, whose control remains an ongoing though infrequent task.

(The scant kikuyu present here is actually helpful, as its long unrooted stolons and uncut stolons are easily pulled back from the shady forest edge, providing mulch, whether living or dead, to suppress the other species).

Rather than follow this instinct to enrich the soil, might it be better to maintain the present dry ridge character of this margin, controlling weeds only by uprooting when possible and cutting when required for fire prevention, using only the minimal mulch available?

With this minimal-intervention we would watch to see what Nature would establish here to achieve succession to densification of canopy by decreased light invasion and dessication from the large sunlit area of adjacent, of mown grass well-used by residents and dogs for recreation.

By controlling invasive, mainly mat-forming herbs and grasses, we are enabling the wild native regeneration of the margin.

By not mulching heavily to improve the nutrition and hydration of the soil, we presumably restrict the developing vegetation to dry ridge species, perhaps in due course even the natural replication of lichen and moss fields of which, we are told, this forest holds some of the best examples in Auckland.

In the meantime, should we see the emergence of fungi, mosses and lichens native to this dry kauri ridge and flourishing under podocarps eg tanekaha nearby, we would watch for and support the natural development in this margin of such precious and endangered habitat.

Any shared thoughts or experience would be welcome.

Publicado el viernes, 12 de julio de 2019 a las 09:38 PM por kaipatiki_naturewatch kaipatiki_naturewatch

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