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EcologyThe Wollemi Pine grows in a sandstone canyon in a ferny warm temperate rainforest. It grows on the steep lower slopes and ledges of the canyon on an acidic, sandy loam soil with pH of about 4.5. The main vascular associate plant species are Coachwood (Ceratopetalum apetalum), Sassafras (Doryphora sassafras), Lilly Pilly (Acmena smithii), Soft Treefern (Dicksonia antarctica), shield ferns (Lastriopsis spp.) and Umbrella Fern (Sticherus flabellatus). Population parameters
GrowthA remarkable aspect of the Wollemi Pine's ecology is that it is able to produce viable seed with no detectable genetic variation in its population. Over 200 seedlings have been counted. Some of these are tagged and are being monitored for survival and growth rates. The seedlings grow on average only 1 cm per year and most are less than 30 cm high. Many of these seedlings will die unless there is a canopy opening that allows light in penetrate to the ground - thus providing energy for the seedlings to grow. Given the right conditions the trees grow quickly for the first 15-20 metres until they reach the canopy then they put more of their energy into the bulk of their trunks and root systems. Their stem to diameter growth rate is a binomial rather than a linear relationship. CoppicingThrough the millions of years of population decline, the Wollemi Pine has maintained its fitness for sexual reproduction but has adopted a secondary reproductive strategy - that of self-coppicing (see Characteristics). Coppicing also helps the tree to survive disturbance. While tree ring analysis has revealed that trees with a diameter of 0.8 m may be 350+ years old, the coppice roots may be thousands of years old. The extensive root system of the Wollemi Pine may also explain how it has survived droughts - the roots penetrate into creekbeds and into cracks in the sandstone cliffs. DisturbanceAll populations have been burnt or subjected to rock fall or windstorm damage. It is postulated that if these disturbance events happen too often they may reduce or eliminate the Wollemi Pine's population. On the other hand, if there is no disturbance the other rainforest plants may dominate the glades and prevent the Wollemi Pine's seedlings from growing into adult trees. The main threat to the survival of the Wollemi Pine is visitation by humans - see protecting it. They may trample the seedlings, compact the soil and risk introducing the deadly root pathogen Phytophthora cinnamomii - see fungal associations & pathogens - which could wipe out the wild population of the Wollemi Pine. Some big ecological questionsThe long-term aim of the ecological research into the Wollemi Pine is to track the survivorship of the trees and the seedlings. This may reveal some insight into how to manage disturbance such as wildfire at the sites.
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