Pikao new zealnad11/10/2023 ![]() ![]() Marram as a Conservation Problemīoth marram and tree lupin are regarded as important threats to pingao 11. It has been suggested that this desiccation slows pingao’s growth, resulting in burial and death 6,7. Secondly, because marram grows quickly, developing extensive root and rhizome systems it is able to outcompete pingao for moisture, resulting in desiccation on pikao 6,7. First, due to marram's superior sand trapping abilities, it is able to deprive pingao of sand causing it to go moribund. These fragmented rhizomes can remain viable after extended immersion in seawater 1, enhancing their colonising abilities. The rhizomes are extremely vigorous and can colonise new areas by breaking off (e.g. Marram’s primary method of reproduction is vegetative rhizomes 6 although it also produces seeds 1. Marram, although hardy 1,8, may have a lower tolerance to salinity than pingao 9,10 which may be a factor that explains differences in pingao and marram-dominated dune systems. It typically forms taller steeper dunes that are more densely vegetated, frequently exclude any other vegetation to form pure marram dunes 3. ![]() Marram's leaf structure and arrangement allows it to trap sand more efficiently than pingao 7. The exact location of marram or pingao dominated dunes will depend on the sand source, shape of the beach or embayment, and the direction of the prevailing wind 7. Pingao may be found in areas that feature more coarse sand and gravel, such as Kaitorete Spit (south of Christchurch 7 ). Slower burial typically occurs with coarser particles as they are more difficult for the wind to transport 7. Those areas where pingao remains may be because they are areas receiving slower burial, which do not favour marram growth 7. Consequently, marram tends to dominate areas that accumulate sand rapidly at the expense of pingao 7. Unlike pingao however, marrram thrives under rapid burial 1, surviving burial rates that would bury pingao, making marram a highly competitive plant. Marram requires active sand burial to stimulate growth (like pingao), and both species go moribund when sand movement is limited 6. Marram suffers from a lack of vigour in warmer climates 4 and this has been suggested as a reason why marram is more of a conservation management problem in the cooler southern areas of New Zealand 5. New Zealand lies within marram's native latitudes of 30 to 63 degrees 2 providing a temperate climate that it favours 3. ![]() It is a silvery green coloured perennial grass, native to Europe and has been widely introduced around the world as a dune stabiliser 1. Marram grass ( Ammophila arenaria) is an exotic sand-binder and dune builder and can be found on virtually every beach in New Zealand. Threats and damage as a result of human recreation and coastal development tends not to be such a problem as many of the areas where these activities occur have already been largely denuded of pingao. In ecosystems where pingao still inhabits large areas the greatest threats are competition from the introduced plants marram grass and tree lupin, and browsing by stock, deer, rabbits and hares. The threats to the continued existence of pingao are many and varied. ![]()
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