Waihi North Project: Assessment of Terrestrial Ecological Values & Effects 62138 WNP AEE 42 5.3.1.1.2 Pine forest (with rewarewa) Mature radiata pine (Pinus radiata) are scattered throughout the southern fragment of SNA 166 but comprise more dominant stands (and canopy cover) in the north of this fragment. This vegetation type accounts for 25 ha of the southern fragment (e.g. Figure 21, Figure 23). In these areas, pine is emergent over a canopy that comprises a mixture of pine (up to 25%), spindly (<10 cm DBH) rewarewa (up to 25%) and tōwai (up to 25%), with some mamaku (up to 10 %). Understorey species include hangehange, silver fern, mamaku and rewarewa, and indigenous vegetation accounts for approximately 90% cover, with exotic species such as barberry and Japanese honeysuckle having a lesser presence. Other native species present in the understorey include mingimingi (Leucopogon fasciculatus), prickly mingimingi (Leptecophylla juniperina subsp. juniperina), karamu (Coprosma lucida), pigeonwood (Hedycarya arborea), kānuka, and māpou. The ground cover here has a greater species diversity than the rewarewa scrub, probably as a result of higher light levels through the more open canopy created by the emergent pines. Seedling regeneration from the species present in the other tiers was visible, however, the native grass (Oplismeus hirtellus subsp. hirtellus) was most prolific. 5.3.1.1.3 Rewarewa forest (with pine) Rewarewa forest (as defined by the Atkinson 1985 method) makes up around 18 ha of the SNA 166 southern fragment and is comprised primarily of rewarewa , towai and mamaku. From two plots, the average Diameter Breast Height (DBH) measurements for rewarewa was 7.14 and 8.5 cm, indicating most of these trees are relatively young, roughly 10 years old (Bergin et al. 2012) although environmental factors (e.g soil fertility, exposure) may have slowed growth. Excepting the pine, only the outermost edges of this area are infested with weedy species and the interior is nativedominated. Weeds include pampas (Cortaderia selloana), gorse blackberry, woolly nightshade (Solanum mauritianum), barberry and Japanese honeysuckle (Lonicera japonica). In addition to the rewarewa, towai and mamaku, silver fern, basket grass (Oplismenus hirtellus subsp. imbecillis), hound’s tongue fern, hangehange , drooping spleenwort (Asplenium flaccidum), karamu (Coprosma robusta), and māhoe are present. None of these species are threatened or rare and they are indicative of a naturally regenerating ecological system. The canopy and sub-canopy are generally represented by dense, regenerating rewarewa and towai of similar age and size (Figure 24), the understorey is generally sparse to open, particularly where pine needles are abundant. However, some seedling establishment around the outer edges of the SNA 166 southern fragment and within rewarewa-dominant vegetation indicates that some natural regeneration is occurring, though rewarewa and towai are dominant at this level as well. In some previously disturbed areas, the ground fern Deparia petersenii subsp. congrua has formed a low but dense ground cover. This fern has a creeping rhizome habit, which can increase soil stability. A single kauri (Figure 21, Figure 25) was recorded toward the south eastern edge of the SNA 166 southern fragment and a single pōhutukawa in the centre of the rewarewa dominant scrub vegetation. Kānuka also occurs at the southern edges near the watercourse, although is not in great abundance. Kauri, pōhutukawa and kānuka are now threatened species (‘Nationally Vulnerable’, de Lange et al. 2018). However, while kauri and pōhutukawa were recorded in other parts of the SNA 166 northern and southern fragments (Bioresearches 2012) and surrounding areas, the two individuals recorded toward the south eastern edge of the SNA were substantially older than surrounding vegetation.
RkJQdWJsaXNoZXIy MjE2NDg3