Environment|
DNA testing has shown that New Zealand's own pohutukawa is the oldest in Oceania and its parent is the original ancestor for the whole species throughout Oceania and Asia, according to Shane Wright of Auckland University. Dr Wright gave a presentation at the recent AGM of the Waitakere Ranges Protection Society, showing the wide dispersal of this genus throughout the Pacific and beyond. Metrosideros is part of the myrtle family and contains metrosideros excelsa &endash; the pohutukawa - and the rata. It has the advantage of seeds that need only slight winds to move them and it is a superlative pioneer. It is 'ecologically very plastic,' said Dr Wright. 'It will colonise any niche it can find very quickly'. This was vividly shown by pohutukawa growing on lava fields, such as in the Kermadecs and Rangitoto Island. Dr Wright's team at Auckland University set out to collect all species and sub-species of the genus, a task completed in January 2002 when the final form was found in the highlands of New Guinea. Only wild species were collected and they were then tested using DNA characters to distinguish then from each other. Metrosideros perforata &endash; a white rata found in the Waitakere Ranges &endash; was found to be the oldest genus in the species, the ancestor for all other groups. Curiously the species then spread outwards through Oceania and Asia, the opposite direction to the usual pattern which is for Asia to be the homeland for plants in Oceania. This dispersal occurred about 7-10 million years ago. New Zealand is also the ancestral home of the subgenous metrosideros &endash; our Christmas tree. Trees descending from this parent are found throughout Oceania, as much as 7000 km away. This dispersal occurred a half million to one million years ago. Dr Wright advanced the following theory to explain the species curious dispersal. This is that before the Ice Age 2 million years ago, New Zealand was warmer than it is now. The warm SE trade wind carried the seed of metrosideros into the centre of Oceania. During the Ice Age, cold SW winds took the species into eastern Oceania, with Tahiti the springboard to take it into Hawaii. As well as being easily lofted by wind, seeds of metrosideros can survive at very high altitudes. Take a look at a fabulous
web site on weeds at http://www.envbop.govt.nz/green/weeds.htm Weeds to watch out for in Spring Laingholm Weedfree has sent out the alert for a number of weeds which flower at this season of the year. Of particular interest to Piha is Climbing Asparagus which the newsletter describes as 'the single worst weed we have in Laingholm'. It has made inroads into Piha too, and is hard to get rid of, though not impossible if you keep on it. Climbing Asparagus has small delicate fern like leaves and slim but wiry stems. It scrambles over everything, smothering seedlings and plants, and will grow in shade or sun. Its small white flowers come out round about now, then develop into orange-red berries (September to December). They drop everywhere and birds spread the seeds as well. There are a number of methods for dealing with Climbing Asparagus. You can carefully pull up small plants or carefully spray with herbicide. Large plants can be cut at 30 to 60 cm high, then sprayed. Or plants can be cut at the base then regrowth resprayed or continually cut till it gives up. Best chemical is glyphosate. Read the directions first. For more information call ARC Enviroline 370 4420 for pest fact sheet #41. Summer is agapanthus time around Piha and the ubiquitous blue and white flower heads demonstrate dramatically the hold this pest has taken on the Piha landscape. The earliest bach owners began the plague and natural spread and more plantings have increased the plant population. Our property provides an example. Dr Colin Finlay planted agapanthus on his section at the extreme southern end of Marine Parade, Piha. These have climbed up the cliff face by the start of the Tasman Lookout Track and appear far into the bush, spread by seeds transported by birds or wind. The plants are so tenacious that when we pulled some out and hung them in trees, they are now growing there, airborne, two years later! There are defenders of agapanthus who think they are pretty, but do we want our coastal cliffs smothered in blue, as they surely will be in time? To remove them will be a difficult task - abseilers would have to be used. There are special rare plants on our Piha cliffs, such the beautiful West Coast hebe, that could be overcome by the voracious agapanthus. Agapanthus is a South African import that thrives in sun or shade, so they can colonise the bush, creating a dense carpet. Already some of roadsides look more like Whangaparoa or a city motorway than West Coast. Clumps of agapanthus can be seen in the sandhills at North Piha. Agapanthus are very hard to get rid of. Grazon spray with an added penetrant works on it, but this can only be purchased in large quantities. Waitakere City is trialling Yates Hydrocotyl weedkiller and this could be tried by local people. The other alternative is to dig them out. It's hard work as the plants form dense mats, so the sooner you get into it the easier it will be. You can't just leave rhizomes and tops sitting about as they continue their evil work. You can dry them and then burn them (but not in the high risk fire season) or bury them in landfill. As a stop-gap measure, you can cut off flower heads to stop the seeds spreading. Seed heads need to be buried, burned or removed. Two varieties of these highly invasive plants are found at Piha. Climbing asparagus -asparagus scadens. This has delicate, feathery leaves and slender stems. Long tendrils snake their way up shrubs and trees to a height of 2.5 - 5 metres. The plant forms a canopy that can smother trees. It also ringbarks host trees, killing them, and can spread along the ground in a mat preventing the regeneration of native bush. The roots are tuberous. Bushy asparagus - asparagus densiflorus. This is similar to a. scadens but has slightly larger, firmer leaves, and spiny erect or spreading stems. It forms a thick blanket on the ground,choking out native seedling growth. It has fleshy underground bulbous tubours. Both these plants like shade and grow best in the forest. South African in origin, they were both originally grown as garden plants and a. densiflorus was frequently used in hanging baskets. It is no longer permitted to be sold or propagated. Although asparagus plants were only first found in the Waitakeres in the 1970s, they are now found throughout bush in the West Coast region, even in areas far from tracks. The seeds are spread by birds and the plants can also spread through their tubours. There is the possibility that these plants will spread to fragile sand dune areas. Small, single plants can be removed by digging them up. They are usually easy to dislodge but you must take care to remove all the roots and tubours and dispose of them carefully. Larger plants can be sprayed with Roundup till wet but not dripping. The addition of Pulse will aid penetration. Plants high in trees can be cut first and the lower growth sprayed. Take great care as Roundup can damage native bush and follow up later to ensure that the spraying has been effective. Always read the spraying instructions on herbicides. Cape Ivy (senecio angulatus) is a particularly nasty weed species found all over Piha on the edges of roads and on properties. The leaves of this plant are uniformly mid-green, fleshy and, as the name suggests, shaped like ivy. The stems are fleshy and there are trusses of bright yellow flowers in the winter. The dense, heavy plant smothers everything at ground level and on banks and can grow up to two metres over shrubs and trees. Although removing a clump of cape ivy can look daunting, it's a better prospect that some of Piha's other weed species. Best approach is to cut or slash the growth down to ground level and spray any regrowth. The mounds of plant removed can be spread out on open ground to dry so that it can be broken down. The spray to use is Tordon Brushkiller during the plants period of active growth. The strength is 60 ml Brushkiller plus 10 mls Pulse penetrant to 10 litres of water. Read the spray instructions carefully and keep away from native plants. One way to help prevent spray drift is to attach a hood-shaped device to the spray nozel. This can be improvised from a large, light plastic flower pot or plastic kitchen storage container. You poke or drill a hole in the bottom of the container if it does not have one, insert the spray wand through the hole and screw the nozzle back on. You may have to experiment to get this right. This way you can pass the spray over unwanted plants with the plastic shield almost touching the plants and you can spot spray areas of regrowth. Speculation has surrounded the appearance of a large hole in the bush on the long straight stretch of road at the start of the Piha Road. The answer is an effort to get rid of a particularly nasty climber called elaeagnus. Originally used as a hedging plant this vigorous climber has colonised the area around Waiatarua (there is a big growth opposite the start of the Piha Road) and main inroads into the watershed area of the Waitakere Ranges. Elaeagnus can climb up the tallest kanuka, ponga or cabbage tree and kills its hosts by smothering them or toppling them with its weight. The removal effort was a joint one between Waitakere City, Auckland Regional Council and Watercare Services. A tractor with flail-mowing arm cut down the elaeagnus then minced it up. Then the area is to be replanted and any regrowth will be removed. Elaeagnus is difficult to remove. The plants need to be felled by slashing or chainsawing then the stumps painted liberally with herbiside before covering with plastic orsacking to shut out the light. Escort is used to deal with any regrowth. Also notice on the Piha Road the wonderful display of large brown heads of gahnia or sedge. Maybe the mild winter explains the abundance of heads as well as those on the local flax. This is also the time of year to spot the bright yellow heads of ginger plants around Piha and there are a surprising number of these visible on hillsides and roadsides. You can spray ginger with Round-up or dig them out. In fact there's an enterprising local man offering to do this for a modest rate so why not add to the local economy and do your bit to the environment at the same time? Dispose of roots carefully as they do not rot down and can resprout. The heads of pampas, cortaderia selloana and C. jubata, are visible all over Piha in the late summer and autumn, with particularly thick infestations in some areas. A single head of pampas can produce as many as 100,000 seeds, so these South American imports (introduced in the 19th century as stock food) are particularly efficient colonisers. They like open areas, such as road sides, tracks, coastal hills, sand dunes and wetlands. Pampas plants quickly grow into dense clumps, a tangle of dried leaves at the base, topped by razor-edged green leaves. The thick clumps prevent natives coming away and the tinder dry leaves are a fire risk. During the fire up the above Piha Road in February 1999, you could see the role the pampas played in fuelling the fire, as the dry bushes burst into flames, scattering sparks. Pampas also provide havens for pests like possums, rats and rabbits. It is important when eradicating pampas to distinguish it from the native toetoe. The Auckland Regional Council has eliminated pampas from the Camel Rock so you can be sure that what you are looking at there is the native toetoe.The main way of spotting the difference is the flowering period.Toetoe flowers earlier than pampas, from October to January. Pampas flowers late January to May. Pampas is either purple-pink or white, while toetoe is cream-yellow. Pampas tends to stand erect while toetoe generally droops. The leaves are different too. Toetoe have distinctive secondary veins between the mid-rib and the margins of the leaves and when toetoe leaves die, they hang straight down, whereas pampas tend to spiral. Native toetoe is waxy at the base of the stem so you can do a touch check on plants. There are a number of methods of getting rid of pampas. Very small plants can usually be pulled out by hand. Larger plants can be sprayed when they are not in flower, particularly after flowering. Roundup is effective but can kill natives such as manuka. One way to avoid this is to give a 5 second burst with the spray nozzle right in the middle of the plant. Gallant is a more expensive spray, but it is selective to monocotyledons (grasses) so does not harm broadleaf natives. It is best to do a trial run before spraying a big area, and always read the label on sprays before proceeding. You can attack pampas with a slasher, but this is hard work as it you will get ripped by leaves as you reach into the base of the plant. Be sure to wear protective clothing and gloves. Any regrowth can be sprayed. To help stop spread, you can cut the flower heads off low down. Always dispose of the heads with care as you could spread millions of pampas babies. Where pampas is serving a useful purpose, like holding a bank together, you could replant with flax, native toetoe, coprosmas or rengarenga lillies. All of these plants are easily grown from locally collected seed, gathered in mid to late summer. Other weed species are also visible around Piha. As a matter of fact, it's downright depressing to walk round Piha and see more weeds that natives on road verges and in some properties. Other weed species making inroads are bamboo, climbing dock, Cape ivy (fleshy leaved climber with yellow flowers), Japanese honeysuckle (a climber with white and pale yellow flowers), jasmine vines (white and pink flowers), and blue morning glory climber. You can spray all these climbers with Round-up in summer (add Pulse for Cape ivy). Read the instructions and keep away from native plants. |
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In July 2000 the Parliamentary Commissioner for the Environment responded to West Coast groups and individuals concerned about subdivision in the Waitakere Ranges foothills with the following letter. The letter makes a strong statement in favour of protecting the Ranges from subdivision. It is titled: 'Letter from the Commissioner to groups and individuals regarding land subdivision in the Waitakere Ranges, July 2000.' |
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Waitakere Ranges Protection Society - http://www.waitakereranges.org.nz The fabulous weed site - http://www.envbop.govt.nz/green/weeds.htm |