Oral Submission Presentation by Blake Foster - New Zealand ...

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History of wilding spread Pre 1970s. Very few trees were present on Pukaki Downs station before the 1970s. From photos taken prior to that time and talks with local people, it appears that small areas of trees (nearly all introduced conifers) were present around the early lake-side station homesteads at Dusky, Mackenzie Peaks, and Pukaki Downs. Most of these trees were submerged when L. Pukaki was raised in the early 1970s. On the area presently occupied by Pukaki Downs station, Lodgepole or contorta pine (Pinus contorta) and Corsican pine (P. nigra) must have been growing somewhere at or between Mackenzie Peaks and Pukaki Downs stations, as both species were present as wildings alongside the shores of the lake after it was raised. A plot established by NL in the contorta pine in 1983 contained trees aged 22. Five kilometres to the west on the Twizel River flats, the only current evidence of ‘early’ introduced trees are three felled contorta pine by the musterer’s hut at the junction of Gladstone Stream and the Twizel river. One tree was aged at 50 years old when felled in the early 2000s. To the north, on the present Ferintosh station, there were radiata pine (P. radiata), European larch (Larix decidua) and Douglas fir (Pseudotsuga menziesii) present when the lake was raised. All three species were probably planted, but larch was moving down the lake shore (G. Seymour, pers comm.), most likely establishing from seed from trees planted possibly over 100 years ago, just north of the Ferintosh homestead by the mouth of Whale Stream. To the south on Rhoborough Downs, a plantation of Douglas-fir was present alongside the lake just north of the current dam site. The upper-most parts of this remained above the lake (aged at 27 years in 1983 – NL plots), from which spread has occurred since. Also on Rhoborough Downs and close to the Pukaki Downs boundary was a stand of Corsican and ponderosa pine and European larch planted by a water reservoir around the 1960s. These have also spread to the south since (but not nearly as vigorously as the contorta pine), and no evidence was seen that they have spread north onto Pukaki Downs (lack of Corsican pine wildings near boundary). 1970s. With the raising of the lake, began a period of lakeshore tree establishment by the Ministry of Works and Development (MOWD). The trees were planted to slow erosion of the newly formed lakeshore banks and also for ‘amenity’ purposes. The first recording of ‘Pukaki’ planting was in 1970, with the first mention of Pukaki Downs in 1972. The 1985 Dept of Lands and Survey report on the MOWD plantings records that 10,500 ‘Pinus species (mixed)’ were planted on Pukaki Downs in 1977. This planting went on into the early 1980s (completed in 1983). Virtually all these trees were established between the highway (SH80) and the lakeshore, from Jack Steel Stream to just north of Boundary Stream, on land which is now administered by Land Information New Zealand (LINZ). One exception was some shelterbelt trees planted further south on the western side of the road, close to the current Pukaki Downs yards. The main species present there are Corsican, ponderosa, Scots (Pinus sylvestris) and Big Cone pine (P. coulteri), but mixed in with these is a small component of contorta pine. The MOWD plantings on LINZ land involved a wide range of species, often planted as individuals or small groups, but also including larger plantations (a few hectares) of larch, Douglas-fir and Big Cone pine, established in the early 1980s. About this time, there were additional amenity tree plantings of widely spaced deciduous trees, such as oak (Quercus spp), ash (Fraxinus spp) and rowan Sorbus spp). In the MOWD report, the last mention of contorta pine was in 1965. This was at the time when there was some publicity about the spreading tendency of this species, especially in the Central Plateau area of the North Island. Consequently, it was resolved that there should be no more planting of this species in the upper Waitaki catchment. However, there is strong circumstantial evidence that there was a ‘contaminant’ of contorta pine in the mixed conifer species which were supplied for planting in the 1970s. These probably explain the 35-year-old contorta trees which are still growing between the highway and the lake - seen by NL between Big Rock Stream and the old Dusky 3
homestead trees (but they were also present further north on the lake shore – removed some years ago – G. Seymour, pers comm). It is very likely that most of the contorta wildings currently on Ferintosh and the northern half of Pukaki Downs originated from the ‘mistake’ plantings established on ‘LINZ’ land by the lake shore in the mid 1970s . The contorta wildings on the southern half of Pukaki Downs most probably established from seed blown from the older and much denser lake-side stands of contorta pine growing closer to the homestead – along the eastern lakeshore margins of block 32. 1980s. Apart from fringe spread alongside the wilding forests by the eastern lakeshore margins of block 32 (in the south-eastern part of Pukaki Downs), wilding trees in the 1980s would not have been very apparent to those not deliberately looking for them. One has to look fairly hard at 1986 aerial photographs to see evidence of wildings. Although the older lake-side forests close to the homestead are obvious, 10-year old plantations on LINZ land north of the northern boundary can only just be seen. Just a kilometre or so further north again, a closer inspection of the photo reveals scattered trees (most likely contorta pine) along the lakeshore south of Big Rock Stream, plus a few outlier trees with small downwind (S side) areas of fringe spread at the top of blocks 16 and 24. Even closer inspection can just detect the odd lone tree in the northern parts of the middle terrace flats, the most obvious of the larger ones looking like larch – both on the flats and the steep scarp slope running up onto the Little Rhoboro Hills. 1990s. During this decade, the major battles with wilding spread were waged in the south eastern part of the property (block 32) along the western margins of the lakeshore wilding forests – although higher sheep numbers meant that there was not much new recruitment of wildings at that time. Plantings of less spread-prone ponderosa and Douglas-fir were carried out along these forest margins, probably in order to restrict this fringe spread. It appears that during the 1980s and 90s some seed from these contorta stands blew over SH80 in a south-westerly direction to give rise to the denser wilding stands in blocks 9 and 10, west of the airstrip, not far above the Rhoboro Downs boundary. Elsewhere on the station, wilding trees were still not obvious - an NL slide (from the air) of the Big Rock Creek stream area (top of blocks 16 and 24) taken in 1990, shows very few conifers – although two have discernable fringe spread. However, it was in this decade that the foundations were laid for the later major advance of wildings elsewhere on the property. Many of the older scattered trees which were seen (and found felled) all over Pukaki Downs, particularly in the north and western parts (and out onto neighbouring DOC land) can be aged back to an arrival date around 15-20 years ago – indicating that they arrived in the early 1990s. Even though they would have been present as small seedlings, there is no sign of these trees in an NL slide taken in the Twizel catchment in 1993, when the present owner was showing the area to forest company representatives looking for afforestation opportunities. As stated above, all the evidence points to these outlier wildings having established from seed disseminated from the MOWD lakeside contorta ‘mistake’ plantings established in the early/mid 1970s. The fact that they are widely scattered out to a distance of 10kms indicates that the seed was lifted high before dropping in a widely scattered ‘salt and pepper-like’ distribution. The wind carrying the seed must have had more of a north-easterly flow than usual, as some were carried right ‘around the corner’ of the Rhoboro Hills (over the Little Rhoboro Hills ridge) and up into the junction area of the Duncan and Mackenzie Streams (the topmost tributaries of the Twizel River). Such a wind-flow pattern is different from the normal prevailing nor-west winds (see ‘2000s on’ below). It is these trees which have given arise to the very obvious ‘islands’ of fringe spread (often between 500 – 1000 m 2 in size), currently aged around 5-6 years old (and just starting to cone). The majority of the scattered outlier parent wilding trees were removed between 2004-2008, but not before they had produced viable seed and initiated the present islands of 5-6 year olds. In the upper Twizel river area there is one major exception to the wilding origin being the Lake Pukaki shoreline plantings. This 4
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Oral Submission Presentation by Blake Foster - New Zealand ...

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