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Tree Growth
 
Developing sustainable mine rehabilitation is achieved not only through short term environmental management strategies, but also continuous monitoring to ensure the long term health and succession of the rehabilitated forest. Jarrah is the dominant tree species in most of our rehabilitated areas so measuring growth and mortality rates of this species provides us with a good indicator of how they are growing compared with trees in the native forest.
 
While most of the rehabilitated areas being monitored are still relatively young, preliminary results have been surprising. In the unmined forest, jarrah is relatively slow-growing, although it does respond well to thinning and high fertiliser application. Jarrah has not been successfully grown in plantations overseas due to it displaying poor form (multiple stems), or just slow growth rates. By contrast, the overall survival of jarrah trees in the rehabilitated forest has been very high, despite their susceptibility to Phytophthora dieback. The form of the trees is also encouraging, with single-stemmed trees predominating. Growth rates have been two or three times that of the comparable native forest.
 
Is this high growth rate of jarrah sustainable in the long term? We expect the jarrah tree growth rates to slow down and plateau eventually, due to lack of water if nothing else.  Research projects continue to monitor the growth rates of the trees and their water usage.
 


looking at tall trees from ground level

Click image to enlarge.


The trees in rehabilitated mined areas grow about one metre per year.